tag:blogger.com,1999:blog-56247178644558294842024-03-10T22:10:00.212+01:00Learning Instrumentation And Control EngineeringWe Provide Tools and Basic Information for Learning Process Instrumentation and Control Engineering.Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comBlogger222125tag:blogger.com,1999:blog-5624717864455829484.post-47767498757846242032022-04-01T20:06:00.001+01:002022-04-01T21:28:24.881+01:00Instrument Air System Design, Sizing and Distribution<p><b> Design of Instrument Air System</b></p><p style="text-align: justify;">Every plant requires instrument air system for some form of pneumatic control. The design of the design, sizing and distribution of instrument air is different from plant to plant depending on the location, the environment, and the number of instruments to be supplied instrument gas.</p><p style="text-align: justify;">Below is illustrated a typical instrument air system design that you will find in a typical plant. Note that the blocks 1 to 5 illustrated in the schematic below are typically part of a vendor package. The vendor supplies these units as a package:</p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUMoICWQ8pCZvNB4z4r6CGvdfSIqATqAJOuQxa2Ph80dJDBa85zM74RPq2-6PDaPVj21CWwuhdZaa2UlOmdI7auw_yzD7cDGw6W3WARlt9BbM6Uap0fCsg47sKFsZdH2VAXor1srX5fbvDcNH71w54ObGW-1SFil6B7YUPkBKftEX82vj1yUrcOW9URw/s1730/Instrument%20Air%20Design%20System%204.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1730" data-original-width="1592" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUMoICWQ8pCZvNB4z4r6CGvdfSIqATqAJOuQxa2Ph80dJDBa85zM74RPq2-6PDaPVj21CWwuhdZaa2UlOmdI7auw_yzD7cDGw6W3WARlt9BbM6Uap0fCsg47sKFsZdH2VAXor1srX5fbvDcNH71w54ObGW-1SFil6B7YUPkBKftEX82vj1yUrcOW9URw/w588-h640/Instrument%20Air%20Design%20System%204.png" width="588" /></a></div><p><b>Sizing and Distribution</b></p><p>Normally, instruments in the unit requiring an air supply will be fed from carbon steel air headers or sub-headers. Take-off valves in all Unit areas will be provided by piping on the instrument air main header. </p><p>These take-off valves will be installed at each rack column. Connections to instrument air main headers will always be at the upper section of the pipe. Branch-off points for future extensions in an instrument main header will be provided with an isolating valve and plug. </p><p>The sub-headers will be provided with drain valves at low point and at dead ends and are to be sized in accordance with the following table:</p><div><table border="1" cellpadding="0" cellspacing="0" class="MsoTable15Grid4Accent5" style="border-collapse: collapse; border: none; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184;">
<tbody><tr>
<td style="background: #5B9BD5; border-right: none; border: solid #5B9BD5 1.0pt; mso-background-themecolor: accent5; mso-border-bottom-alt: solid #5B9BD5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-left-alt: solid #5B9BD5 .5pt; mso-border-left-themecolor: accent5; mso-border-themecolor: accent5; mso-border-top-alt: solid #5B9BD5 .5pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 5; text-align: center;"><b><span lang="EN-US" style="color: white; font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin; mso-themecolor: background1;">No. of Instrument Air
Users<o:p></o:p></span></b></p>
</td>
<td style="background: #5B9BD5; border-left: none; border: solid #5B9BD5 1.0pt; mso-background-themecolor: accent5; mso-border-bottom-alt: solid #5B9BD5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-right-alt: solid #5B9BD5 .5pt; mso-border-right-themecolor: accent5; mso-border-themecolor: accent5; mso-border-top-alt: solid #5B9BD5 .5pt; mso-border-top-themecolor: accent5; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 1; text-align: center;"><b><span lang="EN-US" style="color: white; font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin; mso-themecolor: background1;">Nominal Diameter<o:p></o:p></span></b></p>
</td>
</tr>
<tr>
<td style="background: #DEEAF6; border-top: none; border: solid #9CC2E5 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68; text-align: center;"><b><span style="font-family: Cambria, serif; font-size: 12pt;">1-6</span></b><b><span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid #9CC2E5 1.0pt; border-left: none; border-right: solid #9CC2E5 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #9CC2E5 .5pt; mso-border-left-themecolor: accent5; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: center;">1/2"<span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #9CC2E5 1.0pt; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4; text-align: center;"><b><span style="font-family: Cambria, serif; font-size: 12pt;">7-12</span></b><b><span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #9CC2E5 1.0pt; border-left: none; border-right: solid #9CC2E5 1.0pt; border-top: none; mso-border-alt: solid #9CC2E5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #9CC2E5 .5pt; mso-border-left-themecolor: accent5; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: center;">3/4"<span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #DEEAF6; border-top: none; border: solid #9CC2E5 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68; text-align: center;"><b><span style="font-family: Cambria, serif; font-size: 12pt;">13-25</span></b><b><span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid #9CC2E5 1.0pt; border-left: none; border-right: solid #9CC2E5 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #9CC2E5 .5pt; mso-border-left-themecolor: accent5; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: center;">1"<span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="border-top: none; border: solid #9CC2E5 1.0pt; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4; text-align: center;"><b><span style="font-family: Cambria, serif; font-size: 12pt;">26-50</span></b><b><span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #9CC2E5 1.0pt; border-left: none; border-right: solid #9CC2E5 1.0pt; border-top: none; mso-border-alt: solid #9CC2E5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #9CC2E5 .5pt; mso-border-left-themecolor: accent5; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: center;">1 1/2"<span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #DEEAF6; border-top: none; border: solid #9CC2E5 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-themecolor: accent5; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 176.95pt;" valign="top" width="236">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68; text-align: center;"><b><span style="font-family: Cambria, serif; font-size: 12pt;">51-100</span></b><b><span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid #9CC2E5 1.0pt; border-left: none; border-right: solid #9CC2E5 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid #9CC2E5 .5pt; mso-border-bottom-themecolor: accent5; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #9CC2E5 .5pt; mso-border-left-themecolor: accent5; mso-border-left-themetint: 153; mso-border-right-themecolor: accent5; mso-border-right-themetint: 153; mso-border-themecolor: accent5; mso-border-themetint: 153; mso-border-top-alt: solid #9CC2E5 .5pt; mso-border-top-themecolor: accent5; mso-border-top-themetint: 153; padding: 0cm 5.4pt 0cm 5.4pt; width: 233.9pt;" valign="top" width="312">
<p align="center" class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: center;">2"<span lang="EN-US" style="font-family: "Calibri Light",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-ascii-theme-font: major-latin; mso-bidi-theme-font: major-latin; mso-hansi-theme-font: major-latin;"><o:p></o:p></span></p>
</td>
</tr>
</tbody></table></div><div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-41052572567943921992022-03-27T20:32:00.000+01:002022-03-27T20:32:22.762+01:00Recommended Practice in the Use of Orifice Plates<p><span style="font-family: Cambria, serif; font-size: 12pt; text-align: justify;">Orifice plates are the most common flow device you
will find in any process plant. Although not very high in accuracy but they are
rugged, have low maintenance cost and have been applied successfully in process
instrumentation to measure flow. </span></p><p><span style="font-family: Cambria, serif; font-size: 12pt; text-align: justify;">Listed in the table below are recommended
practices when it comes to industrial application of Orifice plates:</span></p><table border="1" cellpadding="0" cellspacing="0" class="MsoTable15Grid5DarkAccent5" style="border-collapse: collapse; border: none; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184; width: 671px;">
<tbody><tr>
<td style="background: #5B9BD5; border-right: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-bottom-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 5;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;"> </span></b></p>
</td>
<td style="background: #5B9BD5; border-left: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-bottom-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-right-alt: solid white .5pt; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 1;"><b><span lang="EN-US" style="color: white; font-family: "Cambria",serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">Recommended Practice
in the Use of Orifice Plates<o:p></o:p></span></b></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">1<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Orifice plates,
with flange taps, square edge and concentric orifice </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are </span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">normally used on pipe sizes from 2”</span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;"> and above.<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">2<o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Eccentric or Segmental orifice plates
</span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are typically</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> specified on fluids with suspended solids, sediments
and on biphasic streams.<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">3<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Quarter Circle
orifice plates </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are typically</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">
specified for high viscosity fluids with a Reynolds number between 2500 and
10000.<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">4<o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">The full-scale value </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">for measurements is
normally</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> selected equal to the maximum flow
rounded off at 1-5 % above or adjusted to 1.2 times the normal operating flow
if the maximum flow is unknown.<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">5<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Standard calibrated
ranges of differential pressure </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are typically</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> used for the calculation with a preference for
250 mbar.</span><span lang="en-NG" style="font-family: "Cambria",serif; font-size: 12.0pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: #0C00;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">6<o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">The recommended values of Beta ratio
will be selected within 0.2 - 0.75, preferably between 0.4 – 0.75. <o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">7<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Orifice bore will
be rounded off to the nearest 0.1 mm.<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">8<o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Bleed and vent holes </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are usually</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> specified for orifice plates in horizontal pipe
and with a bore diameter of at least 20 mm. </span><span lang="en-NG" style="font-family: "Cambria",serif; font-size: 12.0pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: #0C00;"><o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 68;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">9<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 64; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Orifice plates for
pipe sizes of ½”, ¾”, 1” and 1”1/2 </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are usually</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> installed between flanges in meter runs
prefabricated. <o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style="background: #5B9BD5; border-top: none; border: solid white 1.0pt; mso-background-themecolor: accent5; mso-border-alt: solid white .5pt; mso-border-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 28.1pt;" width="37">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; mso-yfti-cnfc: 4;"><b><span lang="EN-US" style="color: white; font-family: "Trebuchet MS",sans-serif; font-size: 12.0pt; mso-ansi-language: EN-US; mso-themecolor: background1;">10<o:p></o:p></span></b></p>
</td>
<td style="background: #DEEAF6; border-bottom: solid white 1.0pt; border-left: none; border-right: solid white 1.0pt; border-top: none; mso-background-themecolor: accent5; mso-background-themetint: 51; mso-border-alt: solid white .5pt; mso-border-bottom-themecolor: background1; mso-border-left-alt: solid white .5pt; mso-border-left-themecolor: background1; mso-border-right-themecolor: background1; mso-border-themecolor: background1; mso-border-top-alt: solid white .5pt; mso-border-top-themecolor: background1; padding: 0cm 5.4pt 0cm 5.4pt; width: 474.9pt;" width="633">
<p class="MsoNormal" style="line-height: normal; margin-bottom: 0cm; text-align: justify;"><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;">Meter sections will be preferably
flanged. Meter runs and relevant orifice bores </span><span lang="EN-GB" style="font-family: Cambria, serif; font-size: 12pt;">are usually</span><span lang="en-NG" style="font-family: Cambria, serif; font-size: 12pt;"> sized using the Manufacturer proprietary
algorithms.</span><span lang="en-NG" style="font-family: "Cambria",serif; font-size: 12.0pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: #0C00;"><o:p></o:p></span></p>
</td>
</tr>
</tbody></table><br /><div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-4345655359594434232022-03-26T19:29:00.001+01:002022-03-26T19:29:48.162+01:00Instrument Ranges Used in Process Control System Design<p style="text-align: justify;">In process control design process variables such as temperature, pressure, flow, level, valve signals, analyzers etc are ranged in such a manner to be proportional to the primary signal as much as possible for control purposes. The table below shows the typical instrument scales employed in process control system design:</p><p style="text-align: justify;"><table border="1" cellpadding="0" cellspacing="0" class="MsoTable15Grid1Light" style="border-collapse: collapse; border: none; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themetint: 102; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184;">
<tbody><tr style="mso-yfti-firstrow: yes; mso-yfti-irow: -1; mso-yfti-lastfirstrow: yes;">
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 5; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Instrument Variable<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border-left: none; border-right: solid #999999 1.0pt; border-top: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; mso-yfti-cnfc: 1; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Scale<o:p></o:p></span></b></p>
</td>
</tr>
<tr style="mso-yfti-irow: 0;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Temperature<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Direct Reading<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 1;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Pressure<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Direct Reading<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 2;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Flow (differential)<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">0 – 100 linear<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 3;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Flow (Linearized)<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">0 – 100 linear<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 4;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Level<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">0 – 100 linear<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 5;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Analyzer<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Direct Reading<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 6; mso-yfti-lastrow: yes;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Signal to Valves<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 191.35pt;" valign="top" width="255">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">0 – 100%<o:p></o:p></span></p>
</td>
</tr>
</tbody></table></p><p style="text-align: justify;">As far as possible, the instrument ranges will be selected such that the normal value will be between 50 and 75% of the adjusted range taking into account the specified minimum and maximum values and trip settings will lie between 10% and 90% of the adjusted range.</p><p style="text-align: justify;">Typical accuracy of the pressure and differential pressure Smart transmitters will be +/- 0.25% of the calibrated span.</p><p style="text-align: justify;">Typical accuracy of temperature Smart transmitters will be +/- 0.3% of the calibrated span.</p><p style="text-align: justify;">Typical accuracy of the other transmitters will be as far as possible better than +/- 0.5%.</p><div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-44838113707020887512022-03-26T16:57:00.003+01:002022-03-26T16:57:48.527+01:00Best Practice for the Selection of Types of Protection in Hazardous Areas For Process Instruments<p> <span style="font-family: "Trebuchet MS", sans-serif; text-align: justify;">All installed
process instruments in hazardous areas are required to have a type of protection
that ensures safety of personnel as well as that of the instruments.</span></p>
<p style="margin: 0cm; text-align: justify;"><span lang="en-NG" style="color: black; font-family: "Trebuchet MS",sans-serif;">The following table provides the
guidelines to select the type of protection according to the zone of risk:</span></p><p style="margin: 0cm; text-align: justify;"><span lang="en-NG" style="color: black; font-family: "Trebuchet MS",sans-serif;"><table border="1" cellpadding="0" cellspacing="0" class="MsoTable15Grid1Light" style="border-collapse: collapse; border: none; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themetint: 102; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184;">
<tbody><tr style="mso-yfti-firstrow: yes; mso-yfti-irow: -1; mso-yfti-lastfirstrow: yes;">
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 5; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Type of Protection<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border-left: none; border-right: solid #999999 1.0pt; border-top: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; mso-yfti-cnfc: 1; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Meaning<o:p></o:p></span></b></p>
</td>
</tr>
<tr style="mso-yfti-irow: 0;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Intrinsic
Safety<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 1;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Flameproof Enclosure<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 2;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex e<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Increased
Safety<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 3;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex m<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Encapsulation<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 4; mso-yfti-lastrow: yes;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 148.6pt;" valign="top" width="198">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex p<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 290.6pt;" valign="top" width="387">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Pressurized
Apparatus<o:p></o:p></span></p>
</td>
</tr>
</tbody></table><br /></span></p><p style="margin: 0cm; text-align: justify;"><span lang="en-NG" style="color: black; font-family: "Trebuchet MS",sans-serif;"><table border="1" cellpadding="0" cellspacing="0" class="MsoTable15Grid1Light" style="border-collapse: collapse; border: none; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themetint: 102; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-yfti-tbllook: 1184; width: 642px;">
<tbody><tr style="mso-yfti-firstrow: yes; mso-yfti-irow: -1; mso-yfti-lastfirstrow: yes;">
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 5; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Device<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border-left: none; border-right: solid #999999 1.0pt; border-top: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p align="center" style="margin: 0cm; mso-yfti-cnfc: 1; text-align: center;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Zone 0<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border-left: none; border-right: solid #999999 1.0pt; border-top: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p align="center" style="margin: 0cm; mso-yfti-cnfc: 1; text-align: center;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Zone 1<o:p></o:p></span></b></p>
</td>
<td style="background: #BDD6EE; border-bottom: solid #666666 1.5pt; border-left: none; border-right: solid #999999 1.0pt; border-top: solid #999999 1.0pt; mso-background-themecolor: accent5; mso-background-themetint: 102; mso-border-alt: solid #999999 .5pt; mso-border-bottom-alt: solid #666666 1.5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 153; mso-border-bottom-themetint: 153; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p align="center" style="margin: 0cm; mso-yfti-cnfc: 1; text-align: center;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Zone 2<o:p></o:p></span></b></p>
</td>
</tr>
<tr style="mso-yfti-irow: 0;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Transmitter/Positioner<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i (preferred)<o:p></o:p></span></p>
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d
(alternative)<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i (preferred)<o:p></o:p></span></p>
<p style="margin: 0cm;"><span lang="FR" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: FR;">Ex d, Ex e, Ex m (alternatives)<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 1;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Switch/Push-Button<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex de<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i (preferred)<o:p></o:p></span></p>
<p style="margin: 0cm; text-align: justify;"><span lang="FR" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: FR;">Ex e, Ex m (alternatives)<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 2;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Temperature Sensor<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex e<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex e<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 3;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Solenoid Valve<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 4;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Junction Box<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex e<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex e<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 5;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Fire & Gas Detector<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 6;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b>Analyzer</b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex I, Ex d<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex i, Ex d<o:p></o:p></span></p>
</td>
</tr>
<tr style="mso-yfti-irow: 7; mso-yfti-lastrow: yes;">
<td style="border-top: none; border: solid #999999 1.0pt; mso-border-alt: solid #999999 .5pt; mso-border-themecolor: text1; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 138.85pt;" valign="top" width="185">
<p style="margin: 0cm; mso-yfti-cnfc: 4; text-align: justify;"><b><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Local Panel<o:p></o:p></span></b></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 59.35pt;" valign="top" width="79">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">-<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 106.35pt;" valign="top" width="142">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d or Ex p<o:p></o:p></span></p>
</td>
<td style="border-bottom: solid #999999 1.0pt; border-left: none; border-right: solid #999999 1.0pt; border-top: none; mso-border-alt: solid #999999 .5pt; mso-border-bottom-themecolor: text1; mso-border-bottom-themetint: 102; mso-border-left-alt: solid #999999 .5pt; mso-border-left-themecolor: text1; mso-border-left-themetint: 102; mso-border-right-themecolor: text1; mso-border-right-themetint: 102; mso-border-themecolor: text1; mso-border-themetint: 102; mso-border-top-alt: solid #999999 .5pt; mso-border-top-themecolor: text1; mso-border-top-themetint: 102; padding: 0cm 5.4pt 0cm 5.4pt; width: 177.15pt;" valign="top" width="236">
<p style="margin: 0cm; text-align: justify;"><span lang="EN-GB" style="color: black; font-family: "Trebuchet MS",sans-serif; mso-ansi-language: EN-GB;">Ex d or Ex p<o:p></o:p></span></p>
</td>
</tr>
</tbody></table><br /></span></p><p style="margin: 0cm; text-align: justify;"><span style="font-family: Trebuchet MS, sans-serif;">Note: As the Directive ATEX 94/9/EC is mandatory, only “Ex” equipment CE marked compliant with this ATEX Directive may be installed within the European Union.</span></p><p style="margin: 0cm; text-align: justify;"><span style="font-family: Trebuchet MS, sans-serif;"><span lang="en-NG"></span></span></p><p style="margin: 0cm; text-align: justify;"><span style="font-family: Trebuchet MS, sans-serif;">Instruments will typically be designed to have immunity for radio frequency and electromagnetic interferences.</span></p><div style="text-align: justify;"><br /></div><div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-3802551636216616822017-04-30T19:25:00.000+01:002018-03-13T08:11:08.437+01:00Control Valve Actuators Failure Modes<div dir="ltr" style="text-align: left;" trbidi="on">
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Control valves can be built from various combinations of valve actuator and valve body. The combination of actuator and valve body is usually chosen to provide a particular failure mode should the instrument air supply fail for any reason.</div>
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The most common control valve actuator used in the industry is the diaphragm actuator. Diaphragm actuators, as in the case of valve bodies, can be classified as either direct or reverse acting. </div>
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<b>Read Also</b> : <a href="http://www.instrumentationtoolbox.com/2014/03/control-valve-actuators-basic-types-and.html" target="_blank">Control Valve Actuators: Basic Types and Designs</a></div>
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Any failure mode can be obtained with a combination of direct or reverse acting</div>
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actuator and direct or reverse acting valve body. The two most common failure mode of control valves are :</div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Fail Open</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Fail Close</div>
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These two failure modes can be achieved by an Air to Close Valve (ATC) and an Air to Open valve (ATO).</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVqET3GMB6w38PY7P7dawWqj6-YbByK_krmUW8bHdagVzhSed5RP1S24N5NXjupada-0YPy9tOSb8ih-JjAxMdCUwiX8cRbtgyGrrrC4MNmGkrxE2meAfNoYU9aMK1RD2NvTlOJAEGc8Os/s1600/Diaphragm+Actuators+-+Reverse+acting+and+Direct+acting.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVqET3GMB6w38PY7P7dawWqj6-YbByK_krmUW8bHdagVzhSed5RP1S24N5NXjupada-0YPy9tOSb8ih-JjAxMdCUwiX8cRbtgyGrrrC4MNmGkrxE2meAfNoYU9aMK1RD2NvTlOJAEGc8Os/s640/Diaphragm+Actuators+-+Reverse+acting+and+Direct+acting.png" width="640" /></a></div>
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<b>Air to Close Control Valve (ATC)</b></div>
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An air to close (ATC) valve and therefore fail open valve, can be obtained with the combination of a reverse acting actuator and a reverse acting valve body or a direct acting actuator and a direct acting valve body.</div>
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<b>Air to Open Control Valve (ATO)</b></div>
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An air to open (ATO) valve and therefore fail close valve, can be obtained with a combination of direct actuator and reverse body or reverse actuator and direct Body.</div>
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<b>Valve Body and Actuator Combination and Their Failure Modes</b></div>
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The action of an actuator can easily be determined (usually by whether the air is supplied to the upper or lower half of the housing). Direct or reverse acting valve bodies are not always readily identifiable. Most often, reference to the nameplate or flow sheet is usually necessary to correctly identify the action of a valve body – reverse acting or direct acting.</div>
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Listed in the table below are all possible combinations of valve body and actuator and their failure modes:</div>
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<table border="1" cellpadding="3" cellspacing="3" style="background-color: white; border-collapse: collapse; border: 1px solid black; color: #222222; width: 90%;">
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Valve Actuator </b></div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Valve Body</b></div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Valve Action</b></div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Failure Mode</b></div>
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<td><div style="text-align: center;">
Direct </div>
</td>
<td><div style="text-align: center;">
Direct</div>
</td>
<td><div style="text-align: center;">
Air to Close</div>
</td>
<td><div style="text-align: center;">
Fail Open</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
Reverse</div>
</td>
<td><div style="text-align: center;">
Reverse</div>
</td>
<td><div style="text-align: center;">
Air to Close</div>
</td>
<td><div style="text-align: center;">
Fail Open</div>
</td>
</tr>
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<td><div style="text-align: center;">
Direct</div>
</td>
<td><div style="text-align: center;">
Reverse</div>
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<td><div style="text-align: center;">
Air to Open</div>
</td>
<td><div style="text-align: center;">
Fail Closed</div>
</td>
</tr>
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<td><div style="text-align: center;">
Reverse</div>
</td>
<td><div style="text-align: center;">
Direct</div>
</td>
<td><div style="text-align: center;">
Air to Open</div>
</td>
<td><div style="text-align: center;">
Fail Closed</div>
</td>
</tr>
</tbody></table>
</center>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-13026376145928760522017-04-30T15:23:00.001+01:002017-04-30T19:25:49.004+01:00Basics of Split-Range Control in Control Valve Applications<div dir="ltr" style="text-align: left;" trbidi="on">
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In many process control applications in industry, it is sometimes desirable to have multiple control valves respond to the output of a single common controller. <b>Control valves configured in this way to follow the command of a single controller are said to be split-ranged, or sequenced</b>.</div>
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Split-ranged control valves may assume different forms of sequencing. Common modes of control valve sequencing seen in the process industry are: complementary, exclusive, and progressive.</div>
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<b>Complementary Split-Range Control</b></div>
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With this form of split-ranging, there is never a condition in the controller’s output range where both valves are fully open or fully shut. Rather, each valve complements the other’s position. A typical example of complementary split-range control is a situation where two valves serve to proportion a mixture of two fluid streams, such as where base and pigment liquids are mixed together to form colored paint as shown below:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1fr2tiAqkf1umMF3Ae-HGu26pV754VvpgU92pB5QfxT3En6YdADlIPd3aCWd07cuYy8WHLAt3cmXnr0T7V3yuA26wlgL4-5t8-bk3x4s5r-fdT7azqRdx8CpZc4gD0LGh3TB72sbUdwEO/s1600/Complementary+Split-Range+Control.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="366" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1fr2tiAqkf1umMF3Ae-HGu26pV754VvpgU92pB5QfxT3En6YdADlIPd3aCWd07cuYy8WHLAt3cmXnr0T7V3yuA26wlgL4-5t8-bk3x4s5r-fdT7azqRdx8CpZc4gD0LGh3TB72sbUdwEO/s640/Complementary+Split-Range+Control.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Example of complementary split-range control.<br />
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<span style="font-size: small;">Both base and pigment valves operate from the same controller output signal. While the pigment valve is Air-To-Open, the base valve is Air-To-Close. The following table shows the relationship between valve opening for each control valve and the </span><span style="font-size: small;">controller’s output:</span></div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Controller Output (%)</b></div>
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<b>I/P Output (PSI)</b></div>
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<b>Pigment Valve (Stem position)</b></div>
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<b>Base Valve (Stem position)</b></div>
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<td><div style="text-align: center;">
0</div>
</td>
<td><div style="text-align: center;">
3</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
</tr>
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<td><div style="text-align: center;">
25</div>
</td>
<td><div style="text-align: center;">
6</div>
</td>
<td><div style="text-align: center;">
25% Open</div>
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<td><div style="text-align: center;">
75% Open</div>
</td>
</tr>
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<td><div style="text-align: center;">
50</div>
</td>
<td><div style="text-align: center;">
9</div>
</td>
<td><div style="text-align: center;">
Half-Open</div>
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<td><div style="text-align: center;">
Half - Open</div>
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<td><div style="text-align: center;">
75</div>
</td>
<td><div style="text-align: center;">
12</div>
</td>
<td><div style="text-align: center;">
75% Open</div>
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<td><div style="text-align: center;">
25% Open</div>
</td>
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<td><div style="text-align: center;">
100</div>
</td>
<td><div style="text-align: center;">
15</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
</tbody></table>
</center>
</div>
<br />
<div style="text-align: justify;">
<b>Exclusive Split-Range Control</b></div>
<div style="text-align: justify;">
The nature of valve sequencing in this type of split-range control is to have an “EITHER OR” throttled path for process fluid. That is, either process fluid flows through one valve or through the other, but never through both at the same time.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
This type of split-ranged control valves call for a form of valve sequencing where both valves are fully closed at a 50% controller output signal, with one valve opening fully as the controller output drives toward 100% and the other valve opening fully as the controller output goes to 0%.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
A practical example of this form of split-ranging is in reagent feed to a pH neutralization process, where the pH value of process liquid is brought closer to neutral by the addition of either acid or caustic:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItJB_z_-xaNc1OZ5kCAKQhF7AB9c0UVd13tHCmRpQjCH6OVa8kX0UgxnxMF2bhwIf1ayEXEk63zoChtU4XM6ikhKuqFcZth8YNsPVGhpBZbnyWvV98tjmDF6ye2x3tmupL7FNoLLwNMgE/s1600/Exclusive+Split-Range+Control.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="416" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItJB_z_-xaNc1OZ5kCAKQhF7AB9c0UVd13tHCmRpQjCH6OVa8kX0UgxnxMF2bhwIf1ayEXEk63zoChtU4XM6ikhKuqFcZth8YNsPVGhpBZbnyWvV98tjmDF6ye2x3tmupL7FNoLLwNMgE/s640/Exclusive+Split-Range+Control.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Exclusive Split-Range Control</td></tr>
</tbody></table>
<div style="text-align: justify;">
<br /></div>
<div>
<div>
The basic operating principle of the above process is:</div>
<div>
<ol>
<li>A pH analyzer monitors the pH value of the mixture and a single pH controller commands two reagent valves to open when needed.</li>
<br />
<li>If the process pH begins to increase, the controller output signal increases as well (direct action) to open up the acid valve.</li>
<br />
<li>The addition of acid to the mixture will have the effect of lowering the mixture’s pH value.</li>
<br />
<li>Conversely, if the process pH begins to decrease, the controller output signal will decrease as well, closing the acid valve and opening the caustic valve.</li>
<br />
<li>The addition of caustic to the mixture will have the effect of raising the mixture’s pH value.</li>
</ol>
</div>
<div>
The Air-To-Open acid valve has an operating range of 9 to 15 PSI, while the Air-To-Close caustic valve has an operating of 9 to 3 PSI. The table below shows the relationship between valve opening for each control valve and the controller’s output:</div>
<div>
<br /></div>
<center>
<table border="1" cellpadding="3" cellspacing="3" style="background-color: white; border-collapse: collapse; border: 1px solid black; color: #222222; width: 90%;">
<tbody>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Controller Output (%)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>I/P Output (PSI)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Acid Valve (Stem position)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Caustic Valve (Stem position)</b></div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
0</div>
</td>
<td><div style="text-align: center;">
3</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
25</div>
</td>
<td><div style="text-align: center;">
6</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
<td><div style="text-align: center;">
Half - Open</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
50</div>
</td>
<td><div style="text-align: center;">
9</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
75</div>
</td>
<td><div style="text-align: center;">
12</div>
</td>
<td><div style="text-align: center;">
Half - Open</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
100</div>
</td>
<td><div style="text-align: center;">
15</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
</tbody></table>
</center>
<br />
<div style="text-align: justify;">
<b>Progressive Split-Range Control</b></div>
<div style="text-align: justify;">
This form of split-range control for control valves is used to expand the operating range of flow control for some fluid beyond that which a single control valve could deliver. In this type of control, one of the valve usually a small valve opens gradually and becomes fully open at 50% of controller output while the large valve will remain shut at until the controller output goes beyond 50% when it starts opening. Both valves become fully open when controller output is 100%.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
An example of progressive split-range control is a pH control process where the incoming liquid always has a high pH value, and must be neutralized with acid as shown below:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij8yVnml45JmWFddzkwDjHEyQ3hRj7-dbGOAKy_-Pa3Uh572dz7uugBciIXRSPC4yw55o6obY7hqxfNdiQm44UbuX6rs6xKvXz3HrN96C3Asvw1NycP8nyQ7A0X1VlQVZ2WD-38LQNeCm_/s1600/Progressive+Split-Range+Control.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="412" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij8yVnml45JmWFddzkwDjHEyQ3hRj7-dbGOAKy_-Pa3Uh572dz7uugBciIXRSPC4yw55o6obY7hqxfNdiQm44UbuX6rs6xKvXz3HrN96C3Asvw1NycP8nyQ7A0X1VlQVZ2WD-38LQNeCm_/s640/Progressive+Split-Range+Control.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An example of progressive split-range control</td></tr>
</tbody></table>
<div>
<div style="text-align: justify;">
<br />The PH of the incoming water to be treated is measured by the analyzer, AT. As the output of controller AIC increases, the small acid valve starts to open and becomes fully open at 50% of controller output. Meanwhile the large acid valve will remain shut until controller output goes beyond 50%. At 100%, both small and large acid valves are fully open to ensure that the PH of the incoming water is neutralized.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Controller output and valve status for proper sequencing of the small and large acid control valves is shown below:<br />
<br /></div>
</div>
<center>
<table border="1" cellpadding="3" cellspacing="3" style="background-color: white; border-collapse: collapse; border: 1px solid black; color: #222222; width: 90%;">
<tbody>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Controller Output (%)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>I/P Output (PSI)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Small Acid Valve (Stem position)</b></div>
</td>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Large Acid Valve (Stem position)</b></div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
0</div>
</td>
<td><div style="text-align: center;">
3</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
25</div>
</td>
<td><div style="text-align: center;">
6</div>
</td>
<td><div style="text-align: center;">
Half Open</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
50</div>
</td>
<td><div style="text-align: center;">
9</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
<td><div style="text-align: center;">
Fully Closed</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
75</div>
</td>
<td><div style="text-align: center;">
12</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
<td><div style="text-align: center;">
Half Open</div>
</td>
</tr>
<tr>
<td><div style="text-align: center;">
100</div>
</td>
<td><div style="text-align: center;">
15</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
<td><div style="text-align: center;">
Fully Open</div>
</td>
</tr>
</tbody></table>
</center>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-17565915234704513732017-04-20T21:08:00.000+01:002017-04-20T21:08:16.527+01:00How a Self Operated Pressure Reducing Regulator Works<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: justify;">
A self operated pressure reducing regulator is a mechanical device that is used to control and reduce pressure especially in natural gas plants. A pressure regulator is essentially a force balanced device that adjusts to changes in the system it is controlling. There are two types of pressure reducing regulators used in natural gas systems:</div>
<div style="text-align: justify;">
1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Self operated regulators</div>
<div style="text-align: justify;">
2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Pilot operated regulators</div>
<div style="text-align: justify;">
Both types of regulators are very common in the gas industry the self-operated regulators are general used in lower flow and lower pressure system, and are less expensive regulators. While the pilot operated regulators are generally use in higher flow situation, like city gates, large customers, industrial accounts etc and where you have higher pressure to control.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>Basic Parts of a Self Operated Pressure Reducing Regulators</b></div>
<div style="text-align: justify;">
Self Operated regulators consist of three basic components:</div>
<div style="text-align: justify;">
1.<span class="Apple-tab-span" style="white-space: pre;"> </span>A loading element. </div>
<div style="text-align: justify;">
2.<span class="Apple-tab-span" style="white-space: pre;"> </span>A measuring element and </div>
<div style="text-align: justify;">
3.<span class="Apple-tab-span" style="white-space: pre;"> </span>A restrictive element as shown below</div>
<div style="text-align: justify;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjULbzXiiGeyTNhyphenhyphenNhjm3Ep2sLIULEpEcSThCB2XPeKd5X-j9A3J60A4Q9-FOMRrAFEhExKKO7rt1mnXQd4F3j2hzpIkTdsd8kAVBrfolV3s7dXGLA10diIhYhtmU5JW0bTAG-kJ4_HXoSV/s1600/Self+Operated+Pressure+Reducing+Regulator.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjULbzXiiGeyTNhyphenhyphenNhjm3Ep2sLIULEpEcSThCB2XPeKd5X-j9A3J60A4Q9-FOMRrAFEhExKKO7rt1mnXQd4F3j2hzpIkTdsd8kAVBrfolV3s7dXGLA10diIhYhtmU5JW0bTAG-kJ4_HXoSV/s640/Self+Operated+Pressure+Reducing+Regulator.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Self Operated Pressure Reducing Regulator</span></td></tr>
</tbody></table>
<div style="text-align: justify;">
<br />As seen above, the loading element is typically a spring but it can also be a weight or pressure from some external source. When the spring is compressed, it exerts a loading force. The measuring element or diaphragm is connected to the process fluid (gas) that is being controlled and creates a force opposing the loading force. The restricting element or valve is connected to the spring and diaphragm assembly and regulates the flow through the regulator.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>Operating Principle of Self Operated Pressure Reducing Regulators</b></div>
<div style="text-align: justify;">
In a self operated pressure regulator, as downstream system pressure decreases the spring force overcomes the force of the gas acting on the effective area of the diaphragm and the valve opens increasing flow into the system. When system pressure increases, the measuring force (the force of the system gas acting on the effective area of the diaphragm) overcomes the loading force (spring force) and closes the valve reducing flow into the system.</div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-75437247087259861482017-04-05T22:02:00.000+01:002017-04-05T23:21:02.245+01:00What is Damping in Process Transmitters<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: justify;">
A process transmitter typically ”measures” a process variable – flow, level, temperature, pressure - and produces an output in response to changes in the input variable. Most transmitters incorporates a sensor which measures the input variable and gives out an output of which 4 – 20m A is common.</div>
<div style="text-align: justify;">
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnduQbtMl6xkAgiY8SalCxWrF9bkKapLTgk0war7Ebkl1hUXS72eDkeocFuEM7jgTxUYbARcuAJ_tGkKrmKpfCUY4taC8xiwhdFnRErFOs1ovCQx4toKZUmIpC4fzucI9W7eD3CAppk1xk/s1600/Damping+in+Process+Transmitter.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnduQbtMl6xkAgiY8SalCxWrF9bkKapLTgk0war7Ebkl1hUXS72eDkeocFuEM7jgTxUYbARcuAJ_tGkKrmKpfCUY4taC8xiwhdFnRErFOs1ovCQx4toKZUmIpC4fzucI9W7eD3CAppk1xk/s640/Damping+in+Process+Transmitter.png" width="640" /></a></div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Of critical importance in the performance of a transmitter is a concept called damping. As the input variable changes, the transmitter output must update and change accordingly. Damping is the amount of time required, in addition to the update time, for the output of the transmitter to reach 63.2% of its final value after a step change has been applied to the input. A typical damping response curve of a process transmitter is shown below:</div>
<div style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTJbl1aRjzTuMYJbKtiHDKxKFUJyCp44q3Bh4PkHoP6_Zkwb7V0p0fTefHXNgmksNOY1ljpLslDLLAAXZbHf6ZF6je77EUchpZxwJL_mBMiZbcV4SU9cWDOPPoR4YhyphenhyphenbG0RjLCtUJJJQHH/s1600/Process+Transmitter+Damping.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTJbl1aRjzTuMYJbKtiHDKxKFUJyCp44q3Bh4PkHoP6_Zkwb7V0p0fTefHXNgmksNOY1ljpLslDLLAAXZbHf6ZF6je77EUchpZxwJL_mBMiZbcV4SU9cWDOPPoR4YhyphenhyphenbG0RjLCtUJJJQHH/s640/Process+Transmitter+Damping.png" width="640" /></a></div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Transmitter damping is adjustable from 1 to 32 seconds. Damping reduces the effects of electrical noise and any other insignificant transient noise that may influence the transmitter output signal. It is often used to stabilize control loops and prevent false trips. In the absence of electrical or transient noise, damping may not be required in processes that are slow and have inherent lag time e.g temperature control loops. Damping should be minimized in fast changing process conditions.</div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-4556836252175496522017-04-02T22:36:00.001+01:002017-04-02T22:42:42.166+01:00ANSI B16.5 - Maximum Pressure and Temperature Ratings of Flanges and Flange Fittings<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: justify;">
The Maximum allowable non-shock pressure (psig) and temperature ratings for steel pipe flanges and flanged fittings according the American National Standard ANSI B16.5 are given in the table below. </div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Flanges and their Fittings are a common feature in the process plants. The need to accurately determine their pressure rating and corresponding temperature ratings is important for personnel and plant safety and overall plant performance and reliability:</div>
<div style="text-align: justify;">
<br /></div>
<style type="text/css">.nobrtable br { display: none }</style>
<br />
<div class="nobrtable">
<div class="tg-wrap">
</div>
<center>
<table border="1" cellpadding="3" cellspacing="3" style="background-color: white; border-collapse: collapse; border: 1px solid #222222; color: #222222; width: 90%;">
<tbody>
<tr>
<td bgcolor="98FB98" colspan="8"><div style="text-align: center;">
<b>Maximum Allowable Non-Shock Pressure (Psig)</b></div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA" rowspan="4"><div style="text-align: center;">
<b>Temperature (<span style="color: black; text-align: justify;">°F</span>)</b></div>
</td>
<td bgcolor="00FF7F" colspan="7"><div style="text-align: center;">
<b>Pressure Class (lb)</b></div>
</td>
</tr>
<tr>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>150</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>300</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>400</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>600</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>900</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>1500</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>2500</b></div>
</td>
</tr>
<tr>
<td bgcolor="00FF7F" colspan="7"><div style="text-align: center;">
<b>Hydrostatic Test Pressure (Psig)</b></div>
</td>
</tr>
<tr>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>450</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>1125</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>1500</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>2225</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>3350</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>5575</b></div>
</td>
<td bgcolor="98FB98"><div style="text-align: center;">
<b>9275</b></div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>-20 to 100</b></div>
</td>
<td><div style="text-align: center;">
285</div>
</td>
<td><div style="text-align: center;">
740</div>
</td>
<td><div style="text-align: center;">
990</div>
</td>
<td><div style="text-align: center;">
1480</div>
</td>
<td><div style="text-align: center;">
2220</div>
</td>
<td><div style="text-align: center;">
3705</div>
</td>
<td><div style="text-align: center;">
6170</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>200</b></div>
</td>
<td><div style="text-align: center;">
260</div>
</td><td><div style="text-align: center;">
675</div>
</td><td><div style="text-align: center;">
900</div>
</td><td><div style="text-align: center;">
1350</div>
</td><td><div style="text-align: center;">
2025</div>
</td><td><div style="text-align: center;">
3375</div>
</td><td><div style="text-align: center;">
5625</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>300</b></div>
</td>
<td><div style="text-align: center;">
230</div>
</td><td><div style="text-align: center;">
655</div>
</td><td><div style="text-align: center;">
875</div>
</td><td><div style="text-align: center;">
1315</div>
</td><td><div style="text-align: center;">
1970</div>
</td><td><div style="text-align: center;">
3280</div>
</td><td><div style="text-align: center;">
5470</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>400</b></div>
</td>
<td><div style="text-align: center;">
200</div>
</td><td><div style="text-align: center;">
635</div>
</td><td><div style="text-align: center;">
845</div>
</td><td><div style="text-align: center;">
1270</div>
</td><td><div style="text-align: center;">
1900</div>
</td><td><div style="text-align: center;">
3170</div>
</td><td><div style="text-align: center;">
5280</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>500</b></div>
</td>
<td><div style="text-align: center;">
170</div>
</td><td><div style="text-align: center;">
600</div>
</td><td><div style="text-align: center;">
800</div>
</td><td><div style="text-align: center;">
1200</div>
</td><td><div style="text-align: center;">
1795</div>
</td><td><div style="text-align: center;">
2995</div>
</td><td><div style="text-align: center;">
4990</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>600</b></div>
</td>
<td><div style="text-align: center;">
140</div>
</td><td><div style="text-align: center;">
550</div>
</td><td><div style="text-align: center;">
730</div>
</td><td><div style="text-align: center;">
1095</div>
</td><td><div style="text-align: center;">
1640</div>
</td><td><div style="text-align: center;">
2735</div>
</td><td><div style="text-align: center;">
4560</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>650</b></div>
</td>
<td><div style="text-align: center;">
125</div>
</td><td><div style="text-align: center;">
535</div>
</td><td><div style="text-align: center;">
715</div>
</td><td><div style="text-align: center;">
1075</div>
</td><td><div style="text-align: center;">
1610</div>
</td><td><div style="text-align: center;">
2685</div>
</td><td><div style="text-align: center;">
4475</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>700</b></div>
</td>
<td><div style="text-align: center;">
110</div>
</td><td><div style="text-align: center;">
535</div>
</td><td><div style="text-align: center;">
710</div>
</td><td><div style="text-align: center;">
1065</div>
</td><td><div style="text-align: center;">
1600</div>
</td><td><div style="text-align: center;">
2665</div>
</td><td><div style="text-align: center;">
4440</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>750</b></div>
</td>
<td><div style="text-align: center;">
95</div>
</td><td><div style="text-align: center;">
505</div>
</td><td><div style="text-align: center;">
670</div>
</td><td><div style="text-align: center;">
1010</div>
</td><td><div style="text-align: center;">
1510</div>
</td><td><div style="text-align: center;">
2520</div>
</td><td><div style="text-align: center;">
4200</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>800</b></div>
</td>
<td><div style="text-align: center;">
80</div>
</td><td><div style="text-align: center;">
410</div>
</td><td><div style="text-align: center;">
550</div>
</td><td><div style="text-align: center;">
825</div>
</td><td><div style="text-align: center;">
1235</div>
</td><td><div style="text-align: center;">
2060</div>
</td><td><div style="text-align: center;">
3430</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>850</b></div>
</td>
<td><div style="text-align: center;">
65</div>
</td><td><div style="text-align: center;">
270</div>
</td><td><div style="text-align: center;">
355</div>
</td><td><div style="text-align: center;">
535</div>
</td><td><div style="text-align: center;">
805</div>
</td><td><div style="text-align: center;">
1340</div>
</td><td><div style="text-align: center;">
2230</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>900</b></div>
</td>
<td><div style="text-align: center;">
50</div>
</td><td><div style="text-align: center;">
170</div>
</td><td><div style="text-align: center;">
230</div>
</td><td><div style="text-align: center;">
345</div>
</td><td><div style="text-align: center;">
515</div>
</td><td><div style="text-align: center;">
860</div>
</td><td><div style="text-align: center;">
1430</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>950</b></div>
</td>
<td><div style="text-align: center;">
35</div>
</td><td><div style="text-align: center;">
105</div>
</td><td><div style="text-align: center;">
140</div>
</td><td><div style="text-align: center;">
205</div>
</td><td><div style="text-align: center;">
310</div>
</td><td><div style="text-align: center;">
515</div>
</td><td><div style="text-align: center;">
860</div>
</td>
</tr>
<tr>
<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>1000</b></div>
</td>
<td><div style="text-align: center;">
20</div>
</td><td><div style="text-align: center;">
50</div>
</td><td><div style="text-align: center;">
70</div>
</td><td><div style="text-align: center;">
105</div>
</td><td><div style="text-align: center;">
155</div>
</td><td><div style="text-align: center;">
260</div>
</td><td><div style="text-align: center;">
430</div>
</td>
</tr>
</tbody></table>
</center>
</div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-71800680621813671242017-04-02T13:54:00.001+01:002017-04-02T13:55:16.001+01:00Control Valve Selection Requirements<div dir="ltr" style="text-align: left;" trbidi="on">
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Control valves abound in every area of industrial process control. Control valves handle all kinds of fluids at temperatures from the cryogenic range to well over 1000<span style="background-color: white;">°F</span> (538<span style="background-color: white;">°C</span>). Selection of a control valve body assembly requires particular consideration to provide the best available combination of valve body style, material, and trim construction design for the intended service. Capacity requirements and system operating pressure ranges also must be considered in selecting a control valve to ensure satisfactory operation without undue initial expense.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUjvBMtkYULXY0l7BPXqlFr06zJw7JwHw1Y-ztk43uxb3_IupqFBR63jIyjDqHwEgBjXt7Ke0jf3-kRMS-3yaMvk2VTQMce-cAcmsDmJIJ323sd7hUh95_PlOjeyYFIpFjoZwmp6tSPY40/s1600/Control+Valve+Selection+Information.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUjvBMtkYULXY0l7BPXqlFr06zJw7JwHw1Y-ztk43uxb3_IupqFBR63jIyjDqHwEgBjXt7Ke0jf3-kRMS-3yaMvk2VTQMce-cAcmsDmJIJ323sd7hUh95_PlOjeyYFIpFjoZwmp6tSPY40/s640/Control+Valve+Selection+Information.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Information required to select a control valve. Photo Credit : Fisher</span></td></tr>
</tbody></table>
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The numbers in the orange colored circles in the above control valve diagram corresponds to the serial numbers in the table below where we have given the typical information required to select the right control valve. For example serial numbers 1, 2, 3, 4, 5 represents fluid properties corresponding to serial numbers 1, 2, 3, 4,5 in the table below.<br />
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To have a clear understanding of the information required to select a control valve which we have discussed in this article, please read the following:</div>
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<a href="http://www.instrumentationtoolbox.com/2014/04/how-to-specify-control-valves.html" target="_blank">How control valves are specified</a></div>
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<a href="http://www.instrumentationtoolbox.com/2014/04/control-valve-body-materials.html" target="_blank">Control valve body materials</a><br />
<a href="http://www.instrumentationtoolbox.com/2014/03/common-terms-used-with-control-valves.html" target="_blank">Common terms used in control valve applications</a><br />
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Because of the tendency to get the selection of control valves wrong, most control valve manufacturers and their representatives have dedicated themselves to helping their clients select the control valve most appropriate for the existing service conditions. To aid in selecting the right control valve, the following information must be provided before the actual sizing and selection process:</div>
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<b>S/N </b></div>
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<b>CONTROL VALVE SELECTION INFORMATION</b></div>
</td>
</tr>
<tr>
<td>1</td>
<td>Type of fluid to be controlled</td>
<td>What fluid will you be controlling? Water?, natural gas? </td>
</tr>
<tr>
<td>2</td>
<td>Temperature of fluid</td>
<td>State the worst scenario temperature of the fluid in degree Fahrenheit or Celsius</td>
</tr>
<tr>
<td>3</td>
<td>Viscosity of fluid</td>
<td><br /></td>
</tr>
<tr>
<td>4</td>
<td>Specific gravity of fluid</td>
<td><br /></td>
</tr>
<tr>
<td>5</td>
<td>Flow capacity of the control valve</td>
<td>State the maximum and minimum flow rates.</td>
</tr>
<tr>
<td>6</td>
<td>Inlet pressure at valve</td>
<td>State maximum and minimum inlet pressures expected to be handled by the control valve</td>
</tr>
<tr>
<td>7</td>
<td>Outlet pressure at valve</td>
<td>State maximum and minimum outlet pressures expected to be handled by the control valve</td>
</tr>
<tr>
<td>8</td>
<td>Pressure drop during normal flowing conditions</td>
<td><br /></td>
</tr>
<tr>
<td>9</td>
<td>Pressure drop at shut off</td>
<td><br /></td>
</tr>
<tr>
<td>10</td>
<td>Noise level</td>
<td>State the maximum permissible noise level if required and the measurement reference point e.g 55 dBA</td>
</tr>
<tr>
<td>11</td>
<td>Degrees of superheat or existence of flashing if known</td>
<td><br /></td>
</tr>
<tr>
<td>12</td>
<td>Inlet and outlet pipeline size and schedule</td>
<td><br /></td>
</tr>
<tr>
<td>13</td>
<td>State whether any special tagging information is required for the control valve</td>
<td><br /></td>
</tr>
<tr>
<td>14</td>
<td>Body material of the control valve</td>
<td>State the required body material of the control valve - ASTM A216 grade WCC, ASTM A217 grade WC9, ASTM A351 CF8M, etc.)</td>
</tr>
<tr>
<td>15</td>
<td>End connections and valve ratings</td>
<td>Is it going to be screwed? Class 600 RF flanged? Class 1500 RTJ flanges? etc</td>
</tr>
<tr>
<td>16</td>
<td>Valve action desired when instrument air fails</td>
<td>Is the valve to fail open, close or retains its last controlled position?</td>
</tr>
<tr>
<td>17</td>
<td>Instrument Air Availability</td>
<td>State whether the valve require instrument air</td>
</tr>
<tr>
<td>18</td>
<td>Valve type number</td>
<td>Only when required by manufacturer</td>
</tr>
<tr>
<td>19</td>
<td>Valve size</td>
<td><br /></td>
</tr>
<tr>
<td>20</td>
<td>Valve body construction</td>
<td>Is the valve body going to be angle? double-port? Butterfly? etc.</td>
</tr>
<tr>
<td>21</td>
<td>Valve port size</td>
<td>State whether the valve port size is going to be full or restricted</td>
</tr>
<tr>
<td>22</td>
<td>State the desired valve trim materials required</td>
<td><br /></td>
</tr>
<tr>
<td>23</td>
<td>Flow action</td>
<td>State whether flow will tend to open valve or close valve</td>
</tr>
<tr>
<td>24</td>
<td>Actuator size</td>
<td>State the size of actuator required for the control valve.</td>
</tr>
<tr>
<td>25</td>
<td>Bonnet Style</td>
<td>Is the bonnet style going to be plain, extension,<br />
bellows seal, etc.<br />
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<br /></div>
</td>
</tr>
<tr>
<td>26</td>
<td>Valve packing materials</td>
<td>State the type of valve packing material - PTFE V-ring, laminated graphite, environmental<br />
sealing systems, etc.<br />
<div>
<br /></div>
</td>
</tr>
<tr>
<td>27</td>
<td>Valve accessories</td>
<td>State the control valve accessories required – positioner, handwheel etc</td>
</tr>
</tbody></table>
</center>
</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-1552787894734699292017-03-31T22:12:00.000+01:002020-02-26T19:23:13.537+01:00How to Calibrate a Fisher 3582 Pneumatic Valve Positioner<div dir="ltr" style="text-align: left;" trbidi="on">
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The valve positioner is a critical component in the control valve loop as it helps to accurately position the valve during the control process. However, failure to calibrate the positioner accurately could lead to wrong valve positioning which could in turn have significant impact on the process where the control valve is being used. Imagine supplying a customer natural gas at 5barg through a control valve controlled by a controller taking signal from the supply to the customer. If pressure suddenly goes to 7barg and the controller gives a signal to the control valve to close more to bring the pressure to 5barg, if the control valve is wrongly positioned and fails to close more, we could be giving the customer more than 5barg! This could be catastrophic and lead to undesirable consequences.</div>
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In view of the importance of a positioner in accurately positioning the control valve plug, the need to accurately calibrate the valve positioner cannot be over emphasized. The set up below illustrates the basic components required to calibrate a control valve positioner:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSytnRZDJSwAuJPII47vyDfec51G4BBT6bCSeXJ9Vv1mYTDbztStAsVgozEEX2zASz1X2HkbMRPBF1EcQG4GeIJ-BO-0lcTsQVo8bzFWXFEnLgsKSj11vsXY1AFR0IqFd08p9rA492TL17/s1600/How+to+Calibrate+a+Valve+Positioner.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSytnRZDJSwAuJPII47vyDfec51G4BBT6bCSeXJ9Vv1mYTDbztStAsVgozEEX2zASz1X2HkbMRPBF1EcQG4GeIJ-BO-0lcTsQVo8bzFWXFEnLgsKSj11vsXY1AFR0IqFd08p9rA492TL17/s640/How+to+Calibrate+a+Valve+Positioner.png" width="640" /></a></div>
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Before studying this procedure, read : <a href="http://www.instrumentationtoolbox.com/2016/10/how-pneumatic-valve-positioner-works.html" target="_blank">How a Pneumatic Valve Positioner Works </a></div>
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<b>Procedure for Calibrating a Pneumatic Valve Positioner</b></div>
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<b>Step 1</b></div>
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Shut off the supply pressure to the valve positioner. Connect or reconnect the necessary tubing from the valve positioner output to the actuator supply connection. Connect the input to the valve positioner and set the input signal value at mid-range.</div>
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<b>Step 2</b></div>
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Move the flapper assembly to approximately position 6 in the proper operating quadrant of the beam (direct or reverse acting), and apply supply pressure to the valve positioner. The <b>0 degree index marks</b> on the rotary shaft arm should align with the<b> case index marks</b> as shown in diagram below and the actuator should be at its mid-travel position. If not, first check for loose linkage or improper cam installation. A minor nozzle height adjustment might be necessary to make the desired input signal value correspond to the starting point of travel.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYCn7H-st4j2IzsV5rLjATeMubkaje4s0Z0IWNCVbRrmOxvGWU5bG48v37sBhSCDPQ18EWo5OuPchbLrOwjYQ2zSd2tTfesJsTyHEQPX0kk4Mykb89iutI8EMRN_ZBARRbBpVmA-O-xrfo/s1600/calibrating+a+Valve+positioner.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="272" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYCn7H-st4j2IzsV5rLjATeMubkaje4s0Z0IWNCVbRrmOxvGWU5bG48v37sBhSCDPQ18EWo5OuPchbLrOwjYQ2zSd2tTfesJsTyHEQPX0kk4Mykb89iutI8EMRN_ZBARRbBpVmA-O-xrfo/s640/calibrating+a+Valve+positioner.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Positioner Beam and Arm Index Marks. Photo Credit: Fisher</td></tr>
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<b><br />Step 3</b></div>
<div style="text-align: justify;">
Apply an input signal equal to the low value of the input signal range. If your positioner is a 0.2bar – 1.2 bar range (3 to 15psig) input range, set the input to 3psig. Loosen the nozzle locknut and adjust the nozzle until the actuator moves to the proper end of its travel. Changing the nozzle position is intended only as a means of zero trim adjustment. Whenever nozzle position is changed, the zero reference point is changed. </div>
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<b>Step 4</b></div>
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Apply an input signal equal to the high value of the input signal range (15psig, if using a 3 to 15psig positioner) and observe the actuator stem travel. If the stem travel is short of its expected range, increase the travel by moving the flapper assembly to a higher number on the beam. If the desired stem travel occurs before the input signal reaches the high value of the input signal range, decrease the travel by moving the flapper assembly toward a lower number on the beam.</div>
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<b>Step 5</b></div>
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Repeat steps 3 and 4 until the correct travel is achieved. Each time the flapper assembly position is changed in step 4, repeat step 3 to provide proper zero. Note that Moving the flapper assembly toward zero on the beam scale decreases stem travel.</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-22283544683724739012017-03-25T00:46:00.000+01:002017-03-31T22:13:23.633+01:00How An Air Pressure Regulator Works<div dir="ltr" style="text-align: left;" trbidi="on">
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In pneumatic instrumentation systems, instrument air is required to power valve actuators and other instruments - transmitters, controllers, control valves etc. A key component of the instrument air supply system is an air pressure regulator. The air pressure regulator is a simple device. It is used to lower the main instrument air supply of a plant to a pressure suitable for an air-operated instruments; eg, a transmitter, control valve, etc. </div>
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Normally, each air operated instrument has its own regulator. So an air regulator is one of the most common devices in the plant. There are various manufacturers of air regulators, eg Masoneilan and Fisher. However, they all work in much the same way. The schematic of a Fisher air pressure regulator is shown below:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgflnBHX0jYKRoA-4I0-z-1IjgkPLTLV56uHs4p2zefjMhUOMUlHGAouIse3O9FRRcp2p6Y7rOYIjRA8fzByahRyf67BUYXeVjJLMnpVk037SHWb1BKjGIEcqw4xKG9rmo32Mjwtfnq4-h2/s1600/Working+Principle+of+Fisher+Pressure+Regulator.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="248" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgflnBHX0jYKRoA-4I0-z-1IjgkPLTLV56uHs4p2zefjMhUOMUlHGAouIse3O9FRRcp2p6Y7rOYIjRA8fzByahRyf67BUYXeVjJLMnpVk037SHWb1BKjGIEcqw4xKG9rmo32Mjwtfnq4-h2/s640/Working+Principle+of+Fisher+Pressure+Regulator.png" width="640" /></a></div>
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<b>Principle of Operation of the Air Pressure Regulator</b></div>
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<ol>
<li>The main air supply is connected to the <b>AIR INLET PORT</b>. Air passes into the filtering chamber at the bottom of the regulator.</li>
<li>Air passes through the filter which removes dirt particles in the incoming air which may block nozzles etc. It then goes into the valve assembly.</li>
<li>The valve assembly is moved by the range spring pressing on the diaphragm.</li>
<li>The range spring will hold the valve assembly down until the output pressure is high enough to lift the diaphragm (via the air passage shown). At this point the small spring in the valve assembly closes the valve.</li>
<li>Air is allowed to pass through a hole at the center of the diaphragm and out of the vent. This maintains balanced pressure across the diaphragm.</li>
<li>If the outlet pressure is above the pressure set by the range spring, the air will go out through the vent above the diaphragm. When the outlet pressure is correct, the valve assembly opens to set the correct pressure. This pressure exits the regulator through the <b>OUTLET AIR PORT</b></li>
<li>If the outlet pressure is below the pressure set by the range spring the valve assembly will stay open until the set pressure is reached.</li>
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</ol>
<div>
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</div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-60997302344384527362017-03-24T21:41:00.000+01:002017-03-25T00:19:12.192+01:00Process Performance of Correctly Sized, Undersized and Oversized Control Valves<div dir="ltr" style="text-align: left;" trbidi="on">
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In the process of sizing and selecting control valves, there is one of three possible outcomes:</div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>The valve is correctly sized or </div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>The valve is oversized or</div>
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>The valve is undersized</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1oDvrIBLGv7IOmIcJuwpRcwQLPfwx1p_fJ3n5yxFfU67MPveauEqWWwpI375xStVDNrkuvXWGg2dRcBjowWUvjfpUEHwduSnKaT5FSTgIF06zqzQFkY2TcYpbVTykpSXUKO3PkBajEfiL/s1600/Control+Valve+Performance.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="416" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1oDvrIBLGv7IOmIcJuwpRcwQLPfwx1p_fJ3n5yxFfU67MPveauEqWWwpI375xStVDNrkuvXWGg2dRcBjowWUvjfpUEHwduSnKaT5FSTgIF06zqzQFkY2TcYpbVTykpSXUKO3PkBajEfiL/s640/Control+Valve+Performance.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Characteristics of Correctly Sized, Under-sized and Over-sized Control Valves</td></tr>
</tbody></table>
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<b>A Correctly Sized Control Valve (The right valve Cv)</b></div>
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A correctly sized valve has the required capacity to deliver the right flow rate at minimum, normal and maximum flows and helps to safeguard optimal control both as far as comfort and economy are concerned.</div>
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<b>Oversized Control Valves (Large Cv)</b></div>
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An oversized valve has poor controllability. An oversized control valve implies that all normal operations will be confined to small openings of the valve with great risk of variable sensitivity and aggravation of any uneven movement of the valve. Poor accuracy and unstable control often result.</div>
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The smallest change in stroke in an oversized valve will result in large flow variations. As the valve opens or closes, large flow speeds and a powerful turbulence are created between the plug and seat. This both erodes the valve and causes noise. </div>
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<b>Undersized Control Valves (Small Cv)</b></div>
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If the control valve is undersized (Cv - too small), the required flow rate will not be achieved even when the valve is fully opened. If a higher pressure is applied to force a higher flow rate across the undersized valve; not only the pump energy will be excessive but also the valve may cavitate or develop flashing.</div>
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</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-32208074795455157342017-03-23T20:44:00.000+01:002017-03-23T20:44:20.585+01:00How a Pneumatic Displacer level sensor is used to Control Liquid Level<div dir="ltr" style="text-align: left;" trbidi="on">
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Although we have covered the <a href="http://www.instrumentationtoolbox.com/2013/03/operating-principle-of-displacer-level.html" target="_blank">principle of operation of the displacer level sensor</a> before, here we attempt to introduce you how a pneumatic displacer level sensor is applied in liquid level control in a process plant. The anatomy of a typical pneumatic displacer level sensor is exemplified by the fisher 25000 controller/displacer level sensor assembly:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx5J0UcqM1eMhu32-AgwB0P8WnO8iF2dPBHhOa_HUD5PaUuU8cWS52k6EYD1jhBbOCPj-pv7y6EiSuCTxJ6VmkM75o101mIEG4sMn9QGZLt_xO0jvv37iJoS_uwctNjd2Z0-vNLyowSsTh/s1600/Fisher+Pneumatic+Level+Controller.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="339" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhx5J0UcqM1eMhu32-AgwB0P8WnO8iF2dPBHhOa_HUD5PaUuU8cWS52k6EYD1jhBbOCPj-pv7y6EiSuCTxJ6VmkM75o101mIEG4sMn9QGZLt_xO0jvv37iJoS_uwctNjd2Z0-vNLyowSsTh/s640/Fisher+Pneumatic+Level+Controller.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fisher 2500 Pneumatic Level Sensor. Photo Credit : Fisher</td></tr>
</tbody></table>
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<b>Principle of Operation of the Displacer Level Sensor/Controller </b></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIdsQM31puyPSbIidHyEGPGzSAnbqY8px5DSwD-LoWEbb0JfMvYaOVzNbwHwaCPYQEg6Dr-mXryJ_CHUdN4_auo5qn9I_-hHL5dv62KhtnkSakb73o79zATDULPRmgL7PxmdYeIoeSfhY6/s1600/How+a+pneumatic+level+controller+works.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="370" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIdsQM31puyPSbIidHyEGPGzSAnbqY8px5DSwD-LoWEbb0JfMvYaOVzNbwHwaCPYQEg6Dr-mXryJ_CHUdN4_auo5qn9I_-hHL5dv62KhtnkSakb73o79zATDULPRmgL7PxmdYeIoeSfhY6/s640/How+a+pneumatic+level+controller+works.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Liquid Level Controller Using a Displacer Level Sensor</td></tr>
</tbody></table>
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As shown above, changes in the level of liquid in the vessel whose level is being controlled exerts a buoyant force on a displacer which causes the rotation of a torque tube shaft. The rotation of the torque tube shaft is converted into a proportional pneumatic output signal by the pneumatic controller attached to the displacer level sensor. Typically, this pneumatic output is 3 – 15psig. The output signal from the controller drives a dump valve open to evacuate liquid from the vessel. When liquid level rises, the buoyant force on the displacer increases leading to increasing output from the controller if it is a direct acting controller. When the liquid level falls, the buoyant force on the displacer decreases resulting in decreasing output to the controller. If the controller is set at 25% of vessel level for example, then as soon as liquid in the vessel reaches 25%, the controller outputs a signal to completely open the dump control valve to release the liquid to a dump or safe area in the case of a hazardous liquid e.g hydrocarbon condensate.</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-87625180238597803012017-03-16T22:04:00.001+01:002017-03-31T22:13:23.640+01:00How the Foxboro 43AP Pneumatic Controller Works<div dir="ltr" style="text-align: left;" trbidi="on">
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The Foxboro 43AP pneumatic controller is a versatile process instrument controller that can be used to control pressure, temperature , flow and level. As with all process controllers, the Foxboro 43AP pneumatic controller continuously detects the difference between a process measurement and its set point, and produces an output air signal that is a function of this difference and the type of control. </div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcYJwCrqRdysyW5m7v20f3wUtksgEXvrJKt2TVJu62qELuOQxUslC5MrSH-Lypz1Z7HvqiK4387Z7sP-ikUh14j7cHIG3gwzZeN1BiOwKF8B5LULopwSsHpI-deNte_7udZY69kLZuplFy/s1600/Controller+Loop+Basics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="443" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcYJwCrqRdysyW5m7v20f3wUtksgEXvrJKt2TVJu62qELuOQxUslC5MrSH-Lypz1Z7HvqiK4387Z7sP-ikUh14j7cHIG3gwzZeN1BiOwKF8B5LULopwSsHpI-deNte_7udZY69kLZuplFy/s640/Controller+Loop+Basics.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Controller Loop for a Pneumatic Controller</td></tr>
</tbody></table>
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The output signal is transmitted to a control valve or other control device. The process measurement, set point, and output signal are indicated on the controller.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-Z5wkA6NT48EvF2ucJTQJUy6LXjlzLutajPi92sqLMZ1zumdVxV12AFQLEltmW_megTBPVubdc_qHXdLJAEofEK4Jt26gevHJaRi5O5_Jql4urrHkDvGJBrADemTAXoPSHchHq91yIMEF/s1600/How+Foxboro+43AP+Pneumatic+Controller+Works.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-Z5wkA6NT48EvF2ucJTQJUy6LXjlzLutajPi92sqLMZ1zumdVxV12AFQLEltmW_megTBPVubdc_qHXdLJAEofEK4Jt26gevHJaRi5O5_Jql4urrHkDvGJBrADemTAXoPSHchHq91yIMEF/s640/How+Foxboro+43AP+Pneumatic+Controller+Works.png" width="611" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Foxboro Pneumatic Controller with Proportional, Reset and Derivative Actions and Automatic Manual Transfer System. Photo Credit: Foxboro</td></tr>
</tbody></table>
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<b>Principe of Operation of the 43AP Pneumatic Controller</b></div>
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The above schematic shows the basic internal parts of the mechanism of operation of a Foxboro 43AP pneumatic controller. The principle of operation of the device is explained below:</div>
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<br />
<ol>
<li>A differential linkage measures difference between measurement pointer and setting index positions as shown in the schematic above. This error signal moves proportioning lever.</li>
<li>The proportioning lever pivots at its center on the end of a flat spring.</li>
<li>This motion of the proportioning lever changes flapper nozzle relationship, causing relay to establish an output pressure.</li>
<li>This output pressure is fed back to the proportioning bellows, which acts through the proportioning lever to re-balance flapper nozzle.</li>
</ol>
</div>
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As shown above, this particular controller model has reset bellows as well as a derivative tank. The reset bellows and tank assembly are used when measurement must be maintained exactly at control point -that is without “offset”. The derivative tank assembly is used to improve system response to a slow process.</div>
</div>
<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-9158483729536383122017-02-25T23:27:00.000+01:002017-02-25T23:28:07.517+01:00Pressure Drop Regimes Across a Control Valve<div dir="ltr" style="text-align: left;" trbidi="on">
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Control valves are critical elements in industrial process control. They are used for controlling various types of fluid. However as fluid passes across a control valve, the pressure regimes across the valve especially pressure drop changes with flow. A basic understanding of the pressure regimes across a control valve will help in the valve sizing process.</div>
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To accurately size a control valve, we must correctly predict the pressure drop across the valve from minimum flow to normal to maximum flow.</div>
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Typically as flow increases across a valve, the pressure drop across the valve reduces until it gets to the minimum allowable pressure drop across the valve at maximum fluid flow. As flow decreases, the pressure drop across the valve increases commensurately. These variations are illustrated in the diagram below:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHcsQuLH2trRMt7FjGBuoKuMSRyuozSXJpQirXyrTzonIkDYQq5LDK3iaRjW1Bn8JOiSoH4RsLcp1uIbnZRkypD2kes4tkXC0xKMVO5iNskiSAyFLvHZAyBA5u-4QOjCuG-p5-fQbjaQfg/s1600/Pressure+Drop+Regimes+Across+a+Control+Valve.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="364" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHcsQuLH2trRMt7FjGBuoKuMSRyuozSXJpQirXyrTzonIkDYQq5LDK3iaRjW1Bn8JOiSoH4RsLcp1uIbnZRkypD2kes4tkXC0xKMVO5iNskiSAyFLvHZAyBA5u-4QOjCuG-p5-fQbjaQfg/s640/Pressure+Drop+Regimes+Across+a+Control+Valve.png" width="640" /></a></div>
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As shown in the diagram above:</div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>As flow increases across the valve , upstream pressure P1 drops</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>The pressure drop across the valve, ∆P, decreases as flow increases</div>
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>At zero flow, ∆P is maximum and the downstream pressure P2 = 0</div>
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>As flow increases, downstream pressure, P2 increases.</div>
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5.<span class="Apple-tab-span" style="white-space: pre;"> </span>At maximum flow across the valve, ∆P is minimum</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-54558592809941386902017-02-22T23:57:00.000+01:002020-02-14T21:47:19.337+01:00How to Select the Adjustable Range of a Pressure Switch<div dir="ltr" style="text-align: left;" trbidi="on">
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The adjustable range of a pressure switch is also known as the working range of the switch. It is the pressure range a switch may see under normal working conditions.</div>
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In the process of adjusting a pressure switch, accuracy and the service life could be compromised. Efforts should therefore be made when adjusting a pressure switch to ensure that the desired accuracy can be achieved while at the same time ensuring that the switch lasts long by choosing the right adjustable or working range of the pressure switch.</div>
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For the greatest accuracy, the set point of the pressure switch should be adjusted such that the set point fall in the upper 65% of the adjustable range. For a long service life, the switch set point should be adjusted to fall in the lower 65% of the adjustable range. </div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5Vib9W27bKGeT88WXuNW-ephm5GRUVoFryVespX_BiVha9oqCeyfHcned7vAxMLFTK_s0dIPAzbTcbbFCtRqI-3oAgNZ8ocf__NayQBPwpqtUH_rsqDZSis5bIrfM9ILi7diNZLRabMFD/s1600/Adjustable+Range+of+a+Pressure+Switch.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="438" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5Vib9W27bKGeT88WXuNW-ephm5GRUVoFryVespX_BiVha9oqCeyfHcned7vAxMLFTK_s0dIPAzbTcbbFCtRqI-3oAgNZ8ocf__NayQBPwpqtUH_rsqDZSis5bIrfM9ILi7diNZLRabMFD/s640/Adjustable+Range+of+a+Pressure+Switch.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adjustable Range of a Pressure Switch</td></tr>
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The best combination of accuracy and long service life lies in the middle 30% of the adjustable range as shown above. This rule applies to diaphragm as well as bourdon tube pressure switches.</div>
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As shown in the schematic diagram above depicting the various operating zones of the pressure switch, we can see that :</div>
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1. For optimum accuracy and long service life, select Zone A</div>
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2. For long service life, select Zone C</div>
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3. For accuracy, select Zone B</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-72433523646719130982017-02-19T13:46:00.000+01:002017-02-19T13:51:00.644+01:00Operating Principle of Variable Area Flow Meters<div dir="ltr" style="text-align: left;" trbidi="on">
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The variable area flowmeter is a reverse differential pressure meter used to accurately measure the flow rate of liquids and gases. The flow meter generally comprises a vertical, tapered glass tube and a weighted float whose diameter is approximately the same as the tube base.</div>
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How the Variable Area Flow Meter Works</div>
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The schematic below shows the basic design of a variable area flow meter:</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTOiWwQw3e_UxT7rl743-HmhxTIMvr4ArYFeh2I6BHnq-EqA96GISY4ucwxiDv8NUG7BKqAbpN2MVLzk-jIEHC-rqBiSyLpzBH8SGYWpO_wDgdacGR0lI5gteew4BVxib8l6kdfqa9sE6j/s1600/Basic+construction+of+a+variable+area+flow+meter.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="347" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTOiWwQw3e_UxT7rl743-HmhxTIMvr4ArYFeh2I6BHnq-EqA96GISY4ucwxiDv8NUG7BKqAbpN2MVLzk-jIEHC-rqBiSyLpzBH8SGYWpO_wDgdacGR0lI5gteew4BVxib8l6kdfqa9sE6j/s400/Basic+construction+of+a+variable+area+flow+meter.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Basic Design of a Variable Area Flow Meter : Photo Credit Brooks Instrument</span></td></tr>
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During operation, the fluid or gas flows through the inverted conical tube from the bottom to the top, carrying the float upwards as indicated by the arrow in our schematic above. Since the diameter of the tube increases in the upward direction, the float rises to a point where the upward force on the float created by differential pressure across the annular gap, between the float and the tube, equals the weight of the float.</div>
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As shown in the schematic above, three forces are seen acting on the float:<span style="white-space: pre;"> </span></div>
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(a) A constant gravitational force, <b>W</b>.<br />
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(b) A buoyancy force, <b>A</b>, which is constant if the fluid density is constant (According to Archimedes principle)<br />
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(c) Flow resistance force <b>S</b>, the upward force of the fluid flowing past the float.</div>
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Two of these forces are acting in an upward direction as indicated by the arrows in the schematic above. They are the buoyancy force <b>A</b> and the flow resistance force <b>S</b>. The gravitational force <b>W</b>, acts downward.</div>
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When the float is stationary, <b>W</b> and <b>A</b> are constant and <b>S</b> must also be constant. In a position of equilibrium (floating state) the sum of forces <b>S</b> + <b>A</b> is opposite and equal to W and the float position corresponds to a flow rate that can be read off a scale. </div>
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A major advantage of the variable area flowmeter is that the flow rate is directly proportional to the orifice area that, in turn, can be made to be linearly proportional to the vertical displacement of the float. Thus, unlike most differential pressure systems, it is unnecessary to carry out square root extraction.</div>
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<b>Flow Rate Equation for the Variable Area Flow Meter</b></div>
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In a typical variable area flow meter, the flow Q can be shown to be approximately given by:</div>
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$Q = CA\sqrt{ρ}$</div>
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where:</div>
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Q = flow</div>
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C = constant that depends mainly on the float</div>
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A = cross-sectional area available for fluid flow past the float</div>
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ρ = density of the fluid</div>
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As shown by the flow equation above, indicated flow depends on the density of the fluid which, in the case of gases, varies strongly with the temperature, pressure and composition of the gas.</div>
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<b>Floats Used in Variable Area Flow Meters</b></div>
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A wide variety of float shapes are available for use in variable area flow meters. The weight, shape and materials of these floats are adapted to the individual installations. The common floats used are:</div>
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A.<span class="Apple-tab-span" style="white-space: pre;"> </span>Ball float</div>
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B.<span class="Apple-tab-span" style="white-space: pre;"> </span>Viscosity-immune float</div>
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C.<span class="Apple-tab-span" style="white-space: pre;"> </span>Viscosity-dependent float</div>
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D.<span class="Apple-tab-span" style="white-space: pre;"> </span>Float for low pressure drop</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_IIf14hyo-X-qVm5gxKPF5Ya_7gPD3aBfvZe3tHYl7fI7ZlnvhKF4ICwnlovP054F-SDghF4o6fNKkfSrROUvSGusm7pVJMmcEDNBlW2g4j1KhuJ_Vu9krNIaWb8yiUrIJp30v-q6L-k8/s1600/Floats+for+Variable+Area+Flow+Meters.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_IIf14hyo-X-qVm5gxKPF5Ya_7gPD3aBfvZe3tHYl7fI7ZlnvhKF4ICwnlovP054F-SDghF4o6fNKkfSrROUvSGusm7pVJMmcEDNBlW2g4j1KhuJ_Vu9krNIaWb8yiUrIJp30v-q6L-k8/s640/Floats+for+Variable+Area+Flow+Meters.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Different Shapes of Floats used for Variable Area Flow Meters. Photo Credit: ABB Flow</span></td></tr>
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The ball float (A) is mainly used as a metering element for small flowmeters. The viscosity-immune float (B) is used in applications where viscosity change is a critical factor. The viscosity-dependent (C) float is used in larger sized variable area flowmeters. Floats for low pressure drop (D) applications are very light in weight with relatively low pressure drops. Its design requires minimum upstream pressures and is usually preferred for gas flow measurement.</div>
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<b>Flow Metering Tubes</b></div>
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The meter tube of a variable area meter is normally manufactured from borosilicate glass that is suitable for metering process medium temperatures up to 200 °C and pressures up to about 2 - 3 MPa. Because the glass tube is vulnerable to damage from thermal shocks and pressure hammering, it is often necessary to provide a protective shield around the tube.</div>
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Variable area meters are inherently self-cleaning since the fluid flow between the tube wall and the float provides a scouring action that discourages the build-up of foreign matter. Nonetheless, if the fluid is dirty, the tube can become coated – affecting calibration and preventing the scale from being read. This effect can be minimised through the use of an inline filter.</div>
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The temperature and pressure range may be considerably extended (for example up to 400 °C and 70 MPa) through the use of a stainless steel metering tube. Again, the float can incorporate a built-in permanent magnet that is coupled to an external field sensor that provides a flow reading on a meter.</div>
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<b>Floats Centering Methods in Variable Area Meters</b></div>
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An important requirement for accurate metering is that the float is exactly centered in the metering tube. One of three methods is usually used:</div>
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(a) Slots in the float head cause the float to rotate and center itself and prevent it sticking to the walls of the tube. Slots cannot be applied to all float shapes and, further, can cause the indicated flow to become slightly viscosity dependent.<br />
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(b) Three molded ribs within the metering tube cone, parallel to the tube axis, guide the float and keep it centered. This principle allows a variety of float shapes to be used and the metering edge remains visible even when metering opaque fluids.<br />
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(c) A fixed center guide rod within the metering tube is used to guide the float and keep it centered. The use of guide rods is confined mainly to applications where the fluid stream is subject to pulsations likely to cause the float to ‘chatter’ and possibly, in extreme cases, break the tube. It is also used extensively in metal metering tubes.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPqe46GIXqP_Dudtqj8QFE16bGIWPBfV8rVewYXvwHMEITlNolAV3W0xtwsto63E_cp27fdDD1UzskIo4pdZ9qz_TjTvpTRfU3rmPzQWZDnZ5h37kxsi5eezZGr9a3MlbDIJpWUBNHiiRu/s1600/Float+Centring+Methods+in+Variable+Area+Flow+Meters.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPqe46GIXqP_Dudtqj8QFE16bGIWPBfV8rVewYXvwHMEITlNolAV3W0xtwsto63E_cp27fdDD1UzskIo4pdZ9qz_TjTvpTRfU3rmPzQWZDnZ5h37kxsi5eezZGr9a3MlbDIJpWUBNHiiRu/s640/Float+Centring+Methods+in+Variable+Area+Flow+Meters.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Floats Centering Methods in Variable Area Flow Meter Design</span></td></tr>
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<b>Materials Used in Construction of Floats</b></div>
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The float material is largely determined by the medium and the flow range and includes: stainless steel, titanium, aluminium, black glass, synthetic sapphire, polypropylene, Teflon, PVC, hard rubber, Monel, nickel and Hastelloy C.</div>
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<b>Advantages of Using a Variable Area Flow Meter</b></div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>It has wide range of applications.</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>It has a linear float response to flow rate change.</div>
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>It has a 10 to 1 flow range or tum-down rate.</div>
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Easy sizing or conversion from one particular service to another.</div>
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5.<span class="Apple-tab-span" style="white-space: pre;"> </span>Ease of installation and maintenance.</div>
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6.<span class="Apple-tab-span" style="white-space: pre;"> </span>Simplicity and low cost.</div>
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7.<span class="Apple-tab-span" style="white-space: pre;"> </span>High low-flow accuracy (down to 5 cm3/ min). </div>
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8.<span class="Apple-tab-span" style="white-space: pre;"> </span>Easy visualisation of flow</div>
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<b>Disadvantages of Using a Variable Area Flow Meter</b></div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>It has limited accuracy.</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>It is susceptibility to changes in temperature, density and viscosity.</div>
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Fluid medium must be clean, no solids content.</div>
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Erosion of device (wear and tear).</div>
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5.<span class="Apple-tab-span" style="white-space: pre;"> </span>It can be expensive for large diameters application.</div>
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6.<span class="Apple-tab-span" style="white-space: pre;"> </span>It operates in vertical position only.</div>
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7.<span class="Apple-tab-span" style="white-space: pre;"> </span>It requires accessories for data transmission.</div>
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-3777794220780775032017-02-10T19:58:00.000+01:002017-02-19T10:10:27.545+01:00How a Coriolis Mass Flow Meter Works<div dir="ltr" style="text-align: left;" trbidi="on">
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The vast majority of flow meters in use today are volumetric. However, there are a few other applications where what is required is a mass flow meter. One of such mass flow meters is the Coriolis Mass Flowmeter that can measure both the mass of liquids and gases.</div>
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Today, commercial Coriolis flowmeters are gradually gaining prominence in flow measurement applications. Steady technical improvements on these meters since they first came into the markets in the 1970s have greatly increased their accuracy and acceptance in the process industries. Currently in the process industries, direct mass flow measurements represent a substantial and fast-growing percentage of worldwide flowmeter applications (15 to 20%). The diagram below shows the construction a U-shaped Coriolis mass flow meter:</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrft-z5oHVXAwYNZlGQVhq-7CkBhZy_SivXNxNGQzqyQ7yJlo1UIkKcsJgU8NPIt_nESjJb8Dk9pW5RrktdF5-X7pv3c6PyxmTKh-wSHijd7Q-H1WHAyNklAVJ2jBwSgBe8PCkfcYbPjT3/s1600/Construction+of+a+Commercial+Coriolis+Mass+Flow+Meter.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrft-z5oHVXAwYNZlGQVhq-7CkBhZy_SivXNxNGQzqyQ7yJlo1UIkKcsJgU8NPIt_nESjJb8Dk9pW5RrktdF5-X7pv3c6PyxmTKh-wSHijd7Q-H1WHAyNklAVJ2jBwSgBe8PCkfcYbPjT3/s640/Construction+of+a+Commercial+Coriolis+Mass+Flow+Meter.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Construction a Commercial Coriolis Mass Flow Meter. Photo Credit: Micro Motion</span></td></tr>
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<b>How a Coriolis Mass Flow Meter Works</b></div>
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A Coriolis flowmeter requires a force acting on a tube carrying a flowing fluid. This force deforms tubes through which the fluid flows. The amount of deformation depends directly on the mass flow rate through the tubes. Signals from sensors measuring this deformation provide a direct indication of the mass flowrate.</div>
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In a Coriolis meter measuring process mass flow rates, the flowmeter must rotate the fluid. In practice they rotationally oscillate the fluid, which produces equivalent Coriolis forces. Tube designs are U-shaped, S-shaped, or straight. </div>
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<b>Design and Working Principle of a Commercial Coriolis Meter</b></div>
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Inside U-shaped sensor housing, the U-shaped flow tube is vibrated at its natural frequency by a magnetic device located at the bend of the tube. The vibration is like that of a tuning fork, covering less than 0.1 in. and completing a full cycle about 80 times/sec. As the liquid flows through the tube, it is forced to take on the vertical movement of the tube as shown in the diagram below. When the tube is moving upward during half of its cycle, the liquid flowing into the meter resists being forced up by pushing down on the tube.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpQ0WXYXyiAO4X21HLVZZr7DfLkFhxZ1S_zrjBwyMd7ZFjObcSbxOh0FurT9Hf_2NPlFYlEl0LbRIovkFbctqXX6blblWBlT6LEpwUaO8BlPKQm47ec4xzpi98OdM_oK_knBwpy9op_f6N/s1600/How+a+Coriolis+Mass+Flow+Meter+Works.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="448" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpQ0WXYXyiAO4X21HLVZZr7DfLkFhxZ1S_zrjBwyMd7ZFjObcSbxOh0FurT9Hf_2NPlFYlEl0LbRIovkFbctqXX6blblWBlT6LEpwUaO8BlPKQm47ec4xzpi98OdM_oK_knBwpy9op_f6N/s640/How+a+Coriolis+Mass+Flow+Meter+Works.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Operating Principle of the Coriolis Mass Flow Meter. Photo Credit : Micro Motion</td></tr>
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Having been forced upward, the liquid flowing out of the meter resists having its vertical motion decreased by pushing up on the tube. This action causes the tube to twist. When the tube is moving downward during the second half of its vibration cycle, it twists in the opposite direction.</div>
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Having been forced upward, the liquid flowing out of the meter resists having its vertical motion decreased by pushing up on the tube. This action causes the tube to twist. When the tube is moving downward during the second half of its vibration cycle, it twists in the opposite direction. The amount of twist is directly proportional to the mass flow rate of the liquid flowing through the tube. Magnetic sensors located on each side of the flow tube measure the tube velocities, which change as the tube twists. The sensors feed this information to the electronics unit, where it is processed and converted to a voltage proportional to mass flow rate. The meter has a wide range of applications from adhesives and coatings to liquid nitrogen.</div>
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Commercial Coriolis flowmeters design incorporate identical dual tubes oscillating in opposite directions. The flow from process piping splits in two as it enters the flow meter. This provides a more balanced design, making the meter more resistant to external vibrations and temperature swings. Sensors mounted on the tubes measure their relation to each other rather than to a fixed plane.<br />
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Straight tube designs operate in a similar manner. The vibrating tube is fixed at its ends, creating two rotating reference frames. The rotations at the inlet and outlet sides are in opposite directions, creating opposing Coriolis forces that distort the tube.</div>
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<b>Merits of Using a Coriolis Mass Flow meter</b><br />
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Used for direct, in-line and accurate mass flow measurement of both liquids and gases.<br />
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Can achieve accuracies as high as 0.1% for liquids and 0.5% for gases.<br />
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Mass flow measurement ranges cover from less than 5 g/m to more than 350 tons/hr.<br />
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Flow measurement is independent of temperature, pressure, viscosity, conductivity and density of the medium. <br />
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5.<span class="Apple-tab-span" style="white-space: pre;"> </span>Can be used for direct, in-line and accurate density measurement of both liquids and gases.<br />
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6.<span class="Apple-tab-span" style="white-space: pre;"> </span>Multi-variable capability as mass flow, density and temperature can be accessed from the one sensor.<br />
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7.<span class="Apple-tab-span" style="white-space: pre;"> </span>Can be used for almost any application irrespective of the density of the process.<br />
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<b>Demerits of Using a Coriolis Mass Flow Meter</b><br />
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>They are very expensive.<br />
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Many models are affected by vibration.<br />
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Current technology limits the upper pipeline diameter to 150 mm (6 inches).<br />
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Secondary containment can be an area of concern.<br />
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<div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-14526865365467388132017-02-07T21:44:00.000+01:002017-02-07T21:45:11.988+01:00How to Become a Highly Skilled Instrument Engineer and Instrument Technician<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAPSN647FmgKBYTi8GZ_LCrMC0LZ3OkCz_e0rwW_qbjcl2zmsnIjWtqeBfT294vPSvxHC2rgWjv5PDbt64XLs2vBuwnnNnW69k-jjM84zuMw2gOGJWqkm1qC0YPFF55RqHm0k11A7FCwgj/s1600/How+to+Become+a+Highly+Skilled+Instrument+Engineer+and+Technician.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAPSN647FmgKBYTi8GZ_LCrMC0LZ3OkCz_e0rwW_qbjcl2zmsnIjWtqeBfT294vPSvxHC2rgWjv5PDbt64XLs2vBuwnnNnW69k-jjM84zuMw2gOGJWqkm1qC0YPFF55RqHm0k11A7FCwgj/s400/How+to+Become+a+Highly+Skilled+Instrument+Engineer+and+Technician.png" width="400" /></a></div>
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We have already seen the knowledge areas you require to become a successful instrument engineer and technician. However, the process of acquiring the skills that will make you a competent instrument engineer and technician requires a lot of hard work on your part. There are not shortcuts. On the road to becoming a highly skilled instrument engineer and technician, you must possess certain habits and or skills some of which are listed below:</div>
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<b>Know Your Plant/Process</b></div>
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Knowing the process is one of the most important habit for highly skilled instrument engineers and technicians. To be effective in your job, you must have a thorough understanding of the process and how the various instruments in the plant/process interact to produce the desired outcome. One starting point in knowing your plant is learning how to read <a href="http://www.instrumentationtoolbox.com/2011/03/piping-and-instrumentation-diagrams-6-p.html" target="_blank">P&IDs and Process Flow Diagrams (PFDs)</a>.</div>
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<b>Develop Competence in Using Available Engineering Tools</b></div>
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Every instrument engineer and technician is required to be able to use available engineering tools to interrogate the process to get all kinds of results to diagnose problems with the instrumentation installation. Tools like meters, calibrators and other necessary troubleshooting instruments should be leveraged upon by a good instrument engineer and technician to solve problems that occur in instrumentation installations.</div>
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<b>Have a Mentor</b></div>
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Nobody will likely succeed in any endeavour without a mentor. Mentors are key building blocks in acquiring necessary engineering skills in the field of instrumentation. Mentorship will help to sharpen the skills of engineers and technicians and possibly shape their careers. Every instrument engineer and technician aspiring to become highly skilled and successful needs a mentor. Many companies run different kinds of mentorship programme to help to instil the necessary skills in their instrument engineers and technicians.</div>
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<b>Engage in Continuous Learning</b></div>
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Learning in engineering is a continuous process. Continuous learning and training will help to horn your skills as an instrument engineer and technician. In a world that has been redefined by the advent of the internet, training in anything has been made easy because of the multiplicity of materials everywhere. In fact today, you have a huge number of training resources available. You can take training courses in your plant, at a training center, or over the web. You can quickly find <a href="http://www.instrumentationtoolbox.com/2017/02/instrumentation-engineering-books-for.html" target="_blank">instrumentation books</a> and articles on the web just be doing a google search! </div>
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One other quick way to learning is curiosity. You must have a natural curiosity to be able to learn new things and ask questions especially when you don’t know. There will always be someone, somewhere in your plant or company ready to share knowledge.</div>
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<b>Share Your Knowledge</b></div>
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In the field of instrumentation and control, knowledge is king. A thorough knowledge of your process/plant will make you solve many problems in instrumentation and control. However, sharing your knowledge with others can help to make you and them more effective in your given tasks. It is therefore imperative that you strive to share whatever knowledge you have gained with colleagues and co-workers.</div>
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<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-78713217084199052452017-02-05T22:33:00.000+01:002020-02-14T22:17:43.269+01:00Knowledge Areas Required to Become a Successful Instrument Engineer and Instrument Technician<div dir="ltr" style="text-align: left;" trbidi="on">
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The instrumentation and control engineering field is a very broad arena. Often instrument engineers and technicians are required to have sufficient knowledge in many areas of engineering to enable them function competently as well as efficiently.</div>
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These knowledge areas can be broadly divided into two:</div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>General Knowledge</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Specialized knowledge</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSw8r7qyvg9zhhuhkrr0R6WZgIiqDm5ApXsDWptZ_69HR2aIVfOpilmlLWOcHrLl5IKp3mxLbCQ7Xjfcv6HfeCAv69W6Gdxf898nkGwI3wRWWe1Vb5L_1l6ZIw-o3-cdMYahzhGW8PTmre/s1600/Instrument++Engineers+and+Technicians+Knowledge+Areas.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSw8r7qyvg9zhhuhkrr0R6WZgIiqDm5ApXsDWptZ_69HR2aIVfOpilmlLWOcHrLl5IKp3mxLbCQ7Xjfcv6HfeCAv69W6Gdxf898nkGwI3wRWWe1Vb5L_1l6ZIw-o3-cdMYahzhGW8PTmre/s400/Instrument++Engineers+and+Technicians+Knowledge+Areas.png" width="400" /></a></div>
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<b>General Knowledge Areas</b></div>
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The key knowledge areas are:</div>
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(a)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Mathematics</b> – Proficiency in mathematics is mandatory to understand and carry out almost any technical job.</div>
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(b)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Physical Sciences</b> – Knowledge of physical science is necessary to understand basic electricity, electronics and manufacturing processes. Pressure, level, flow and temperature principles utilize physical science knowledge. Understanding the physical sciences makes a good instrument technician. A good instrument technician must be able to read and interpret P&IDs drawings and even help to develop some when the need arises.</div>
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(c)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Electricity and Electronics</b> – This knowledge is required to for the newer electronic and microprocessor based instruments and controllers. An understanding of both analog and digital electronics is necessary to maintain modern instruments and control systems. Electrical/Electronic maintenance and repair as well as pneumatic maintenance techniques are crucial knowledge areas required in the field of instrumentation and control engineering.</div>
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(d)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Primary Elements</b> – Knowledge of primary elements such as pressure, level, flow and temperature is required by instrument engineers and technicians. A primary element is the part of a measuring or sensing device in direct contact with the process whose attributes or characteristics are being measured. A primary element performs the initial conversion of measurement of energy and a thorough knowledge of the primary elements is extremely necessary.</div>
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(e)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Signal Processing and Conditioning Equipment</b> – Signal conditioning and processing equipment helps to convert signals from one form to another such as analog-to-digital or current-to-pressure. Signal conditioning is necessary to convert a signal to usable energy that is compatible with devices that perform mathematical functions such as sum, integration, counting and square-root.</div>
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(f)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Process Control Instrumentation Knowledge</b> – Knowledge of basic automatic control theory and feedback control loop is mandatory. The concept of gain, proportional band, integral action, manual bias etc must be understood in both analog and digital control circuits in addition to those in pneumatic and electronic systems. Knowledge of final control elements such as valve positioners and actuators is necessary to know how the control valve affects the process control loop.</div>
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(g)<span class="Apple-tab-span" style="white-space: pre;"> </span><b>Procedures and Documentation</b> – Knowing how to follow correct formal procedures in performing and documenting maintenance tasks is required in order to properly maintain instrumentation and control systems. National, or industry – wide codes, standards and recommended practice as well as plant procedures must be understood and followed.</div>
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<b>Specialized Knowledge Areas</b></div>
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Specialized knowledge covers many areas of engineering. The key specialized knowledge areas required by instrument engineers and technicians are listed below:</div>
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1.<span class="Apple-tab-span" style="white-space: pre;"> </span>Emergency Shutdown Systems</div>
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2.<span class="Apple-tab-span" style="white-space: pre;"> </span>Programmable Logic Controllers (PLC) -operation and programming ability.</div>
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3.<span class="Apple-tab-span" style="white-space: pre;"> </span>Distributed Control Systems (DCS)</div>
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4.<span class="Apple-tab-span" style="white-space: pre;"> </span>Communication Systems such as Local Area Networks (LAN) and Telemetry.</div>
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5.<span class="Apple-tab-span" style="white-space: pre;"> </span>Manufacturing Control Systems</div>
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6.<span class="Apple-tab-span" style="white-space: pre;"> </span>Heating, Ventilating and Air Conditioning Systems (HVAC)</div>
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7.<span class="Apple-tab-span" style="white-space: pre;"> </span>Configuration/Programming of both instrument devices and computers.</div>
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8.<span class="Apple-tab-span" style="white-space: pre;"> </span>Process Control Applications – Feedback, Cascade, Feed forward etc.</div>
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9.<span class="Apple-tab-span" style="white-space: pre;"> </span>Codes, Standard and Recommended Practices.</div>
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10.<span class="Apple-tab-span" style="white-space: pre;"> </span>Nuclear Power Plant Systems.</div>
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11.<span class="Apple-tab-span" style="white-space: pre;"> </span>Basic Plant Operations.</div>
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12.<span class="Apple-tab-span" style="white-space: pre;"> </span>Advanced Plant Instrumentation.</div>
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13.<span class="Apple-tab-span" style="white-space: pre;"> </span>Pneumatic Control Systems.</div>
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14.<span class="Apple-tab-span" style="white-space: pre;"> </span>Analytical Systems</div>
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15.<span class="Apple-tab-span" style="white-space: pre;"> </span>Metallurgy</div>
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16.<span class="Apple-tab-span" style="white-space: pre;"> </span>Boilers/Turbines</div>
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17.<span class="Apple-tab-span" style="white-space: pre;"> </span>Distillation processes</div>
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18.<span class="Apple-tab-span" style="white-space: pre;"> </span>Wastewater Treatment processes.</div>
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19.<span class="Apple-tab-span" style="white-space: pre;"> </span>Fibre Optics</div>
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20.<span class="Apple-tab-span" style="white-space: pre;"> </span>Maintenance Management Systems</div>
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21.<span class="Apple-tab-span" style="white-space: pre;"> </span>Computer Integrated Manufacturing</div>
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22.<span class="Apple-tab-span" style="white-space: pre;"> </span>Batch Control Systems</div>
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23.<span class="Apple-tab-span" style="white-space: pre;"> </span>Industrial Robotics</div>
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<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-84047359789098291402017-02-02T16:12:00.001+01:002017-02-05T22:34:11.547+01:00Instrumentation Engineering Books for Instrument Engineers and Technicians<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG2feihuGK6StxFVqBiNsbnpEi6HqLk6xVETiEdUwaX93v931l8DRuEoNlFYtZrT0u2Ki_T-dF8OSx3Da8NQW-ULE0FbBfbi3Pr8LZ0uCcQDURj_pPX0hVSEm92sAlVykYsw-YR49nD9iR/s1600/Instrumentation+Books+for+Instrument+Engineers+and+Technicians.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG2feihuGK6StxFVqBiNsbnpEi6HqLk6xVETiEdUwaX93v931l8DRuEoNlFYtZrT0u2Ki_T-dF8OSx3Da8NQW-ULE0FbBfbi3Pr8LZ0uCcQDURj_pPX0hVSEm92sAlVykYsw-YR49nD9iR/s320/Instrumentation+Books+for+Instrument+Engineers+and+Technicians.png" width="247"></a></div>
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In every field of human endeavour learning never ceases. In fact, lifelong learning is a must for anyone who wants to succeed in their chosen career. We must always be at the edge of the ever changing technological tide.</div>
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Instrument engineers and technicians are no exception to this rule of lifelong learning. Continuous education and learning is a must for all engineers. You may be sitting on many years of experience; you may have gone through many professional courses or you maybe just starting out in the field of instrumentation and control, continuous learning will improve your knowledge and reinforce your professional skills</div>
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One key tool for continuous learning and education is to possess quality instrumentation and control books which will serve as valuable reference anytime any day. Although technology is now changing the way we learn, given that the internet has completely revolutionized everything we do, we still need quality reference instrumentation books. These can be in electronic format (e-books) or “the good old” hard copy. Engineering books by reputable authors and practioners are a good reference for engineering practice</div>
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Given the importance of reference books to instrument engineers and technicians, here are five good books you should have in your library<br>
</div></div><a href="http://www.instrumentationtoolbox.com/2017/02/instrumentation-engineering-books-for.html#more">Read more »</a><div class="blogger-post-footer"><p> © copyright 2022 – All rights reserved </p>
<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-56761670896058511692016-12-17T22:58:00.000+01:002016-12-17T22:59:20.790+01:00How to Calibrate a Thermocouple Transmitter<div dir="ltr" style="text-align: left;" trbidi="on">
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To calibrate a thermocouple transmitter will require a thermocouple simulator with an accuracy of at least four times greater than the thermocouple sensor we desire to calibrate. </div>
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<b>Equipment and Materials Required</b></div>
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The following equipment/materials are required to successfully calibrate a thermocouple transmitter:</div>
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<li>Thermocouple Simulator (of at least four times the accuracy of sensor)</li>
<li>Two Digital Voltmeters (Five-digit readout) with accuracy of at least ±0.01% with resolution 1mV</li>
<li>24 VDC Power Supply of at least 35 – 40mA current output</li>
<li>Thermocouple wire of the same type of wire the thermocouple transmitter is constructed of.</li>
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<b>Equipment Setup</b></div>
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Below is the equipment set up for the calibration</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVsFz53SvegSQSd6XsF24JJqpnhjvEnbE-S4pNsuIHm3V_SbGzw1zy89QZfUoAG-o_g9Kr1lqIPG196rzmNO9f3n4OZZd-MkLOg9x_gxpL6hfTdFBBFtXFSlfrTgpw9cnAfrAT2-PoOa7y/s1600/Thermocouple+Transmitter+Calibration+Diagram.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="297" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVsFz53SvegSQSd6XsF24JJqpnhjvEnbE-S4pNsuIHm3V_SbGzw1zy89QZfUoAG-o_g9Kr1lqIPG196rzmNO9f3n4OZZd-MkLOg9x_gxpL6hfTdFBBFtXFSlfrTgpw9cnAfrAT2-PoOa7y/s640/Thermocouple+Transmitter+Calibration+Diagram.png" width="640" /></a></div>
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<b>Calibration Procedure</b></div>
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<li>Remove the thermocouple transmitter terminal housing cover</li>
<li>If the transmitter is already connected, remove all the thermocouple lead connections.</li>
<li>Determine the base and full scale temperatures. Read: <u><a href="http://www.instrumentationtoolbox.com/2011/05/converting-thermocouple-milivolts-to.html" target="_blank">How to convert thermocouple millivolt to temperature.</a></u></li>
<li>Turn power supply on.</li>
<li>Consult the thermocouple simulator manual for instructions on setting the thermocouple type and engineering units.</li>
<li>Set the simulator to the base (zero) temperature and adjust the zero pot until the output is 4mA or 40mV at the test terminals</li>
<li>Set the simulator to the full scale temperature and adjust the span pot until the output is 20mA</li>
<li>Repeat steps (1-7) above until both the 4 and 20mA readings are obtained without re-adjusting the span and zero pots.</li>
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<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-18527583635743650682016-12-12T22:31:00.001+01:002016-12-12T22:47:38.927+01:00How to Specify a Digital Pressure Gauge<div dir="ltr" style="text-align: left;" trbidi="on">
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCRib9qBaFFbrjjIggB915TNpeAQtmcJYSb79xSCzNE9GoTdRbD414k2Rw_k5YxdnGCcvQJto3TymACoDoNvP7QVu51_MOxBSPsdVBnsEBhw6tPHd5UHCoPylkhPW5mrSqxDgJSXyb5SCx/s1600/Digital+Pressure+Gauge.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCRib9qBaFFbrjjIggB915TNpeAQtmcJYSb79xSCzNE9GoTdRbD414k2Rw_k5YxdnGCcvQJto3TymACoDoNvP7QVu51_MOxBSPsdVBnsEBhw6tPHd5UHCoPylkhPW5mrSqxDgJSXyb5SCx/s320/Digital+Pressure+Gauge.png" width="286" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Digital Pressure Gauge (Photo Credit: ASHCROFT)</td></tr>
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With the advancement in gauge technology, digital pressure gauges are becoming more popular. With their superior accuracy and functionality, most new plants are increasingly employing digital gauges especially in industrial processes where accuracy is paramount.</div>
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Although we probably all know the key parameters required to purchase a regular dial gauge, we may be at a loss when it comes to digital gauges. This is because in addition to the regular features of a typical pressure gauge, digital gauges are equipped with other functionalities that need to be specified. </div>
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<span style="text-align: justify;">Digital pressure gauges are specified in much the same way a typical pressure gauge will be specified except for few specification items that are specific to digital pressure gauges. The table below shows the key parameters that must be taken into consideration for a general purpose digital pressure gauge to be accurately specified.</span></div>
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<b>Parameters to Specify</b></div>
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<b>Details of Specification</b></div>
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<td><b>Accuracy</b></td><td>Typical accuracies include ±0.1% FS, ±0.25% FS, ±0.5% FS etc </td></tr>
<tr><td><b>Case Size</b> </td>
<td>Standard case sizes include 3’’, 41/2’’,6’’ etc. </td>
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<td><b>Case Material</b></td><td>Depending on your application, typical ones include 300 series stainless steel, fiberglass reinforced thermoplastic, black painted aluminium etc</td></tr>
<tr><td><b>Wetted Materials</b></td>
<td>Specify materials that will resist corrosion. Typical materials include 17 – 4 PH stainless steel sensor, stainless steel socket etc</td>
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<td><b>Socket Size</b></td>
<td>Typical socket sizes include 1/8’’ , ¼’’ , ½’’ etc. </td>
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<td><b>Connection</b></td>
<td>Specify whether process connection will be lower (6 o’clock), top or side</td>
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<td><b>Measuring Range</b></td>
<td>Specify the measuring range of gauge in the desired unit. For example 15 psi through 20,000 psi, 0 – 100 bar etc</td>
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<td><b>Power Source</b></td>
<td>For digital pressure gauges, they could be powered through:<br />
1. Alkaline batteries (two pieces of size AA typically)<br />
2. C Alkaline batteries (two pieces)<br />
3. Loop powered by a 4 – 20mA source<br />
4. Line powered (specify voltage and current)<br />
Specify the desired power source you desire for the digital gauge</td>
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<td><b>Battery Life</b></td>
<td>Battery life is specified in hours. Typical battery life include 500hrs, 1000hrs, 2000hrs etc</td>
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<td><b>Battery Indicator</b></td>
<td>Specify the battery indicator levels</td></tr>
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<td><b>Cycle Life</b></td>
<td>Specify the cyle life of the digital pressure gauge. e.g 5million cycles, 10 million cycles etc</td></tr>
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<td><b>Operating Temperature</b></td>
<td>Operating temperature of gauge is critical for accurate performance. Specify the operating temperature of gauge depending on temperature regime of the environment where the gauge is to be used.</td>
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<td><b>Storage Temperature</b> </td>
<td>Specify storage temperature of gauge</td>
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<td><b>LCD Display</b></td>
<td>Specify the type of LCD display</td></tr>
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<td><b>Character Height</b></td>
<td>Specify the character height of the LCD display - specify height of upper character and that of lower character</td></tr>
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<td><b>Engineering Units</b></td>
<td>Specify the engineering units you want your digital gauge to display - psi, bar, mmHg etc</td></tr>
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<td><b>Backlight</b></td>
<td>Specify whether the LCD display should have a backlight especially in applications where illumination could be a problem especially at night</td></tr>
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<td><b>Enclosure Rating</b></td>
<td>Specify the enclosure rating. Common enclosure rating for gauges is IP 67</td></tr>
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<td><b>Keypad Functions</b></td>
<td>Specify the keypad functions of the gauge. Three key with multi press functionality are typical. </td></tr>
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<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.comtag:blogger.com,1999:blog-5624717864455829484.post-31778192846209958122016-12-11T23:56:00.000+01:002016-12-12T20:14:37.341+01:00Process Safety – Basics of UEL & LEL of Hazardous Gases<div dir="ltr" style="text-align: left;" trbidi="on">
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In today’s highly complex industrial environment, process safety is a key consideration in the maintenance and sustenance of very expensive and complex process facilities. Furthermore, the classification of a plant environment into various classes – Class I, II, III – according to the degree or probability of occurrence of hazards has greatly simplified the management of process safety. However, despite these classifications and the abundance of a lot of knowledge on hazardous gases, accidents still occur in process plants in the most bizarre manner. These are largely due to a lack of basic knowledge about the nature of the hazardous gases themselves and what constitute an explosive atmosphere for example.</div>
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The objective of this piece is to explain the concept of explosive limits in hazardous atmospheres in a plant.</div>
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<b>Fire Triangle and Explosive Limits</b></div>
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To have combustion in a hazardous atmosphere, there must be sufficient fuel, sufficient oxidizer (commonly Oxygen) and sufficient energy for ignition. These three elements make up what we call the FIRE TRIANGLE. Please read: <u><a href="http://www.instrumentationtoolbox.com/2014/05/electrical-hazardous-area.html" target="_blank">Hazardous Area Classification</a></u> for more detail.</div>
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The fire triangle does not give sufficient information to tell us if the necessary conditions exist to support a fire or explosion. For a fire or explosion to occur, we need an adequate mixture of fuel and oxidizer in the correct proportions, and a source of ignition energy exceeding a certain minimum threshold. The thresholds required for combustion to take place with fuels are referred to as the Lower Explosive Limits (LEL) and the Upper Explosive Limits (UEL). While the threshold for energy is referred to as the Minimum Ignition Energy (MIE)</div>
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<b>Ignition Curve of a Typical Combustible Fuel</b></div>
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The ignition curve for a gas or flammable vapor shows all the conditions -fuel, air(oxidizer), minimum energy – required for an explosion or combustion to take place in a flammable atmosphere. It is specific and typical for any fuel and oxidizer combination. Most ignition curves are published with the assumed conditions of air as the oxidizer, at room temperature and at atmospheric pressure.. Below is a typical ignition curve for a combustible gas.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheDX1VIsDsN5qg2bOQaQNG2TAfXbd7juFtwRvrjDJLq1c5vqs_AWbDJRsJuAXXoV4NUJ2an5eSbOXeYQfIML9JU1L7tZLoKI7Iw-qhTPSctm8mLDELQZ0rHloyt8olklOO_eeZO4hf5Rop/s1600/Ignition+Curve+of+a+Typical+Gas.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="346" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheDX1VIsDsN5qg2bOQaQNG2TAfXbd7juFtwRvrjDJLq1c5vqs_AWbDJRsJuAXXoV4NUJ2an5eSbOXeYQfIML9JU1L7tZLoKI7Iw-qhTPSctm8mLDELQZ0rHloyt8olklOO_eeZO4hf5Rop/s640/Ignition+Curve+of+a+Typical+Gas.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Typical Ignition Curve of a Gas</span></td></tr>
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There are three critical values on the ignition curve above:</div>
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(a) The Lower Explosive Limit (LEL) of a gas</div>
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(b) The Upper Explosive Limit (UEL) of a gas</div>
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(c) The Minimum Ignition Energy (MIE) of a gas</div>
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<b>Lower Explosive Limit (LEL)</b></div>
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The LEL of a gas is the lowest concentration (percentage) of a gas or vapor in air capable of producing combustion in the presence of an ignition source (flame, heat etc). It can also be referred to as the Lower Flammable Limit (LFL).</div>
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<b>Upper Explosive Limit (UEL)</b></div>
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The UEL of a gas is the maximum concentration(percentage) of gas or vapor that will burn in air in the presence of an ignition source. Above the UEL, the mixture is too “rich” to burn. The range between the LEL and the UEL as shown in the graph above is known as the flammable range of the gas. The larger the flammability range, the greater the potential for an explosive mixture of the gas with air.</div>
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<b>Minimum Ignition Energy (MIE) of a Gas</b></div>
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As the name implies, the MIE of a gas is the minimum energy required for the gas – air mixture to burn in air in the presence of an ignition source. It is specific for each type of gas.</div>
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<b>Variation of LEL, UEL and MIE</b></div>
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The critical values of LEL, UEL and MIE differ for every type of fuel and oxidizer combination and they change with ambient temperature and pressure. They may be rendered irrelevant in the presence of a catalyst.</div>
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<b>LEL and UEL of Some Common Combustible Substances</b></div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
<b>Substance</b></div>
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<b>LEL (% Volume)</b></div>
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<b>UEL (% Volume)</b></div>
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<td><div style="text-align: center;">
Acetylene</div>
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<td><div style="text-align: center;">
2.5</div>
</td><td><div style="text-align: center;">
100</div>
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Acetone</div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
2.5</div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
12.8</div>
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<td><div style="text-align: center;">
Butane</div>
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<td style="text-align: center;">1.5</td><td style="text-align: center;">8.5</td></tr>
<tr><td bgcolor="E6E6FA"><div style="text-align: center;">
Carbon Disulfide</div>
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<td bgcolor="E6E6FA" style="text-align: center;">1.3</td><td bgcolor="E6E6FA" style="text-align: center;">50</td></tr>
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Carbon Monoxide</div>
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<td><div style="text-align: center;">
12.5</div>
</td><td style="text-align: center;">74</td>
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Ether </div>
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<td bgcolor="E6E6FA" style="text-align: center;">1.9</td><td bgcolor="E6E6FA" style="text-align: center;">36</td></tr>
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Gasoline</div>
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<td><div style="text-align: center;">
1.4</div>
</td><td style="text-align: center;">7.6</td>
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Kerosene</div>
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<td bgcolor="E6E6FA" style="text-align: center;">0.7</td><td bgcolor="E6E6FA" style="text-align: center;">5</td></tr>
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Hydrazine</div>
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<td><div style="text-align: center;">
2.9</div>
</td><td style="text-align: center;">98</td>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
Hydrogen</div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
4.0</div>
</td><td bgcolor="E6E6FA" style="text-align: center;">75</td>
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<td><div style="text-align: center;">
Methane</div>
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<td><div style="text-align: center;">
4.4</div>
</td><td style="text-align: center;">17</td>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
Propane</div>
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<td bgcolor="E6E6FA"><div style="text-align: center;">
2.1</div>
</td><td bgcolor="E6E6FA" style="text-align: center;">9.5</td>
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<a href=”http://www.instrumentationtoolbox.com“>Learning Instrumentation and Control Engineering</a></div>Alliakhue Mhttp://www.blogger.com/profile/13134822626088782059noreply@blogger.com