Engineering Pedia

2017-05-09T08:19:00.001+02:00

How do Wind Turbines work ?

2017-05-02T09:17:00.005+02:00

Types Of Gears

2017-04-24T09:56:00.001+02:00

Topping Tulips | John Deere 6R on Soucy Tracks

2017-04-22T20:50:00.001+02:00

Topping tulips during the spring in Holland using a John Deere 6130R op Soucy tracks with a triple topper unit witch tops three beds of 1.80mtr wide in one pass.

These tulips are growing for the bulbs not for the flowers. The flowers are topped so that the plant is putting all his energy into the development of the bulbs. The bulbs are harvest in the summer where after they been put in storage, in the fall the small bulbs are planted back in the field and the large ones are sold to greenhouse growers where they grown to beautiful tulips for the consumer market.

How does an Induction Motor work ?

2017-04-22T20:35:00.000+02:00

Working of 3 Phase Induction motor is explained in this video with help of animation. They are the most commonly used electric motors. Here basic operation principle of an induction motor is introduced in a logical manner. Concepts of rotating magnetic field, synchronous speed and slip is well introduced in this video.

Automatic Transmission, How it works ?

2017-04-22T20:26:00.003+02:00

The operation of an automatic transmission is explained here with help of animation. Allison-1000 transmission model, which has 6 speed and reverse is used for this purpose. The video starts with an explanation of planetary gear set. Just by engaging few clutch packs different output speed can be achieved in automatic transmission. A brief introduction of the torque converter is also given here

The little about Nuclear Power Plant :

2017-04-19T11:32:00.001+02:00

In a nuclear power plant, heat energy is generated by a nuclear reaction called as nuclear fission. Nuclear fission of heavy elements such as Uranium or Thorium is carried out in a special apparatus called as a nuclear reactor. A large amount of heat energy is generated due to nuclear fission. Rest parts of a nuclear power plant are very similar to conventional thermal power plants. It is found that fission of only 1 Kg of Uranium produces as much heat energy as that can be produced by 4,500 tons of high grade coal. This considerably reduces the transportation cost of fuel, which is a major advantage of nuclear power plants. Also, there are large deposits of nuclear fuels available all over the world and, hence, nuclear power plants can ensure continued supply of electrical energy for thousands of years. About 10% of the total electricity of the world is generated in nuclear power plants.

How does a nuclear power plant work?

Heavy elements such as Uranium (U²³⁵) or Thorium (Th²³²) are subjected to nuclear fission reaction in a nuclear reactor. Due to fission, a large amount of heat energy is produced which is transferred to the reactor coolant. The coolant may be water, gas or a liquid metal. The heated coolant is made to flow through a heat exchanger where water is converted into high-temperature steam. The generated steam is then allowed to drive a steam turbine. The steam, after doing its work, is converted back into the water and recycled to the heat exchanger. The steam turbine is coupled to an alternator which generates electricity. The generated electrical voltage is then stepped up using a transformer for the purpose of long distance transmission.

The image below shows basic components and layout of a nuclear power station.

Basic components of a nuclear power plant

Nuclear Reactor

A nuclear reactor is a special apparatus used to perform nuclear fission. Since the nuclear fission is radioactive, the reactor is covered by a protective shield. Splitting up of nuclei of heavy atoms is called as nuclear fission, during which huge amount of energy is released. Nuclear fission is done by bombarding slow moving neutrons on the nuclei of a heavy element. As the nuclei break up, it releases energy as well as more neutrons which further cause fission of neighboring atoms. Hence, it is a chain reaction and it must be controlled, otherwise, it may result in an explosion. A nuclear reactor consists of fuel rods, control rods, and moderator. A fuel rod contains small round fuel pallets (uranium pallets). Control rods are of cadmium which absorbs neutrons. They are inserted into the reactor and can be moved in or out to control the reaction. The moderator can be graphite rods or the coolant itself. Moderator slows down the neutrons before they bombard on the fuel rods.

Two types of nuclear reactors that are widely used -

Pressurized Water Reactor (PWR) -
This type of reactor uses regular water as coolant. The coolant (water) is kept at very high pressure so that it does not boil. The heated water is transferred through heat ex-changer where water from secondary coolant loop is converted into steam. Thus the secondary loop is completely free from radioactive stuff. In a PWR, the coolant water itself acts as a moderator. Due to these advantages, pressurized water reactors are most commonly used.
Boiling Water Reactor (BWR) -
In this type of reactor only one coolant loop is present. The water is allowed to boil in the reactor. The steam is generated as it heads out of the reactor and then flows through the steam turbine. One major disadvantage of a BWR is that, the coolant water comes in direct contact with fuel rods as well as the turbine. So, there is a possibility that radioactive material could be placed on the turbine.

Heat ex-changer

In the heat ex-changer, the primary coolant transfers heat to the secondary coolant (water). Thus water from the secondary loop is converted into steam. The primary system and secondary system are closed loop, and they are never allowed to mix up with each other. Thus, heat ex-changer helps in keeping secondary system free from radioactive stuff. Heat ex-changer is absent in boiling water reactors.

Steam Turbine

Generated steam is passed through a steam turbine, which runs due to pressure of the steam. As the steam is passed through the turbine blades, the pressure of steam gradually decreases and it expands in volume. The steam turbine is coupled to an alternator through a rotating shaft.

Alternator

The steam turbine rotates the shaft of an alternator thus generating electrical energy. Electrical output of the alternator is the delivered to a step up transformer to transfer it over distances.

Condenser

The steam coming out of the turbine, after it has done its work, is then converted back into water in a condenser. The steam is cooled by passing it through a third cold water loop.

Cast Iron Frame AC Motors

2017-04-16T19:46:00.000+02:00

Products Manufactured at the Athens Plant: Cast Iron Frame AC Motors, Fixed and Adjustable Speed, NEMA 360T - 5800 Frames

YouTube dark mode how to activate?

2017-04-16T14:16:00.000+02:00

Here's how to activate YouTube dark mode on Google chrome

Fire up YouTube and sign into your account
Access Chrome DevTools by opening the Chrome menu (directly below the browser’s Close key) and selecting Developer Tools in the More Tools section
Click on Console
Paste document.cookie="VISITOR_INFO1_LIVE=fPQ4jCL6EiE" into the text box and hit enter
Close DevTools and refresh the page (sign in again if this logs you out)
Click your Google profile picture in the top right corner of the screen, select Dark Mode and activate it

Diesel Engine, How it works ?

2017-04-16T13:59:00.002+02:00

Diesel engines are the most versatile IC Engines. With help of animation working of Diesel engine is elaborately explained in this video. Here the basic construction of diesel engine, its working and mechanical design aspects are covered. Starting from working of single cylinder diesel engine, working of a four cylinder engine is logically explained here.

Automatic Transmission, How it works

2017-04-16T12:59:00.001+02:00

The working of an automatic transmission is best understood with help of a 2D animation. This video demonstrates working of Allison 6 speed transmission in a step by step logical manner. Working of reverse gear is also explained here. A good introduction of planetary gear (epicyclic) set is also given at the introduction.

All You Need To Know About Potentiometer

2017-04-16T09:57:00.003+02:00

The potentiometer is a handy little component that you really should know how to use.

It’s used in circuits a lot, such as to control the volume of music equipment, control the brightness of a light, and much more.

If you’re not familiar with it, it can seem complicated to use in a circuit. But once you see how it’s built, you’ll quickly understand how it’s done. Check out the wiring examples at the end to see it in action.

What Is A Potentiometer ?

It is like the resistor. But while the resistance value of a resistor stays the same, you can change the resistance value of a potentiometer by turning it’s shaft.

It has three pins and the schematic symbol looks like this:

Between the two side pins of the potentiometer there is a strip of resistive material. For example as carbon. This material creates resistance.

We call the middle pin the wiper. It is connected somewhere on the strip between the two ends.

You can move the point where the wiper connects to the carbon strip by turning the shaft of the potentiometer.

When you move the wiper to the left side, the resistance between the middle pin and the left pin decreases. And the resistance between the middle pin and the right pin increases.

Move the wiper to the right, and the opposite happens.

When you buy a potentiometer, you have to choose a value. For example 100k. This value is the resistance between the two end pins. And it’s the largest resistance value you can get from it.

Potentiometer Wiring

Wiring a pot can be confusing at times. I’m often asked:

“What does the third potentiometer pin do?”

Well, the pins doesn’t really “do” anything actively.

As explained above, the two pins on the side connect to the ends of a carbon strip. The middle one connects somewhere between the ends of this strip.

Keep that in mind, and have a look at the following three examples on how to wire a potentiometer.

Wiring Example #1: Variable Resistor

If you need a simple resistor that you can change the resistance of, you only need two pins: the middle pin and one of the side pins.

The above image shows a simple circuit to dim an LED. The extra resistor is there to make sure you don’t destroy the LED even if you change the potentiometer resistance to zero.

Turn the shaft of the potentiometer one direction and the resistance increases. Turn it the other direction and the resistance decreases.

Wiring Example #2: Strange Connection

Sometimes you’ll see a potentiometer in a circuit diagram, connected like this:

The middle and bottom pin are connected. Why?

And how does that affect the resistance?

This way of connecting is actually equal to connecting only two pins. Connecting the third pin to the middle pin does not affect the resistance at all.

So why do it?

Some people prefer it this way. Some may argue it’s a bit messy with an unconnected pin, so they connect it like this. You’ll also avoid warnings in some circuit design softwares.

Wiring Example #3: Volume Input

This example uses all three pins of the potentiometer to create a simple way of adjusting the volume of an amplifier.

By connecting it like this, you’ll get a voltage divider that decreases the voltage of the input signal. The more you turn the shaft, the more you decrease the volume.

This potentiometer wiring is very common in audio equipment.

Centrifugal pumps

2017-04-15T10:11:00.003+02:00

Centrifugal pumps

Centrifugal pumps are the most commonly used kinetic-energy pump. Centrifugal force pushes the liquid outward from the eye of the impeller where it enters the casing. Differential head can be increased by turning the impeller faster, using a larger impeller, or by increasing the number of impellers. The impeller and the fluid being pumped are isolated from the outside by packing or mechanical seals. Shaft radial and thrust bearings restrict the movement of the shaft and reduce the friction of rotation

Basic classifications

Centrifugal pumps are designed with respect to the:

Number of suctions (single or double)
Number of impellers (single, double, or multistage)
Output
Impellers (type, number of vanes, etc.)

Most impellers are arranged from one side only and are called single-suction design. High-flow models use impellers that accept suction from both sides and are called double-suction design.

Impeller types

The efficiency of a centrifugal pump is determined by the impeller. Vanes are designed to meet a given range of flow conditions. Fig. 1 illustrates the basic types of impellers.

Fig. 1—Basic types of impellers.

Open impellers

Vanes are attached to the central hub, without any form, sidewall, or shroud, and are mounted directly onto a shaft. Open impellers are structurally weak and require higher NPSHR values. They are typically used in small-diameter, inexpensive pumps and pumps handling suspended solids. They are more sensitive to wear than closed impellers, thus their efficiency deteriorates rapidly in erosive service.

Partially open or semi closed impellers

This type of impeller incorporates a back wall (shroud) that serves to stiffen the vanes and adds mechanical strength. They are used in medium-diameter pumps and with liquids containing small amounts of suspended solids. They offer higher efficiencies and lower NPSHR than open impellers. It is important that a small clearance or gap exists between the impeller vanes and the housing. If the clearance is too large, slippage and re-circulation will occur, which in turn results in reduced efficiency and positive heat buildup.

Closed impellers

The closed impeller has both a back and front wall for maximum strength. They are used in large pumps with high efficiencies and low NPSHR. They can operate in suspended-solids service without clogging but will exhibit high wear rates. The closed-impeller type is the most widely used type of impeller for centrifugal pumps handling clear liquids. They rely on close-clearance wear rings on the impeller and on the pump housing. The wear rings separate the inlet pressure from the pressure within the pump, reduce axial loads, and help maintain pump efficiency.

Number of impellers

Single stage pumps

The single-stage centrifugal pump, consisting of one impeller, is the most widely used in production operations. They are used in pumping services of low-to-moderate TDHs. The TDH (total dynamic head) is a function of the impeller’s top speed, normally not higher than 700 ft/min. Single-stage pumps can be either single or double suction. The single-stage pump design is widely accepted and has proved to be highly reliable. However, they have higher unbalanced thrust and radial forces at off-design flow rates than multistage designs and have limited TDH capabilities.

Multistage pumps

The multistage centrifugal pump consists of two or more impellers. They are used in pumping services of moderate-to-high TDHs. Each stage is essentially a separate pump. All the stages are within the same housing and installed on the same shaft. Eight or more stages can be installed on a single horizontal shaft. There is no limit to the number of stages that can be installed on a vertical shaft. Each stage increases the head by approximately the same amount. Multistage pumps can be either single or double suction on the first impeller.

Impeller axial loading

A single-suction, enclosed or semienclosed impeller is inherently subject to continual end thrust. The thrust is directed axially toward the suction because of the low pressures that exist in the impeller eye during pump operation. This thrust is handled with a thrust bearing. The larger the TDH and the larger the impeller-eye diameter, the larger the thrust. Excessive thrust results in bearing and seal damage.
Thrust can be reduced by designing a single-stage impeller for a double suction. In multistage pumps, thrust can be reduced by facing half the impellers in one direction and half in the other. Balancing holes can be used in single-suction, single-stage pumps. The impeller is cored at the rear shroud to allow high-pressure liquid to flow back to the impeller eye.

Impeller radial loading

As the fluid leaves the top of the rotating impeller, it exerts an equal and opposite force on the impeller, shaft, and radial bearings. At the best-efficiency point (BEP), the sum of all radial forces nearly cancels each other out. At capacities below or above the BEP, forces do not cancel out completely because the flow is no longer uniform around the periphery on the impeller. Radial forces can be significant. Heavy-duty radial bearings may be required in lieu of the manufacturer’s standard when pump operation departs significantly from the BEP.

Pump specific speed

Pump specific speed is the speed in revolutions per minute required to produce a flow of 1 gal/min with a TDH of 1 ft, with an impeller similar to the one under consideration but reduced in size. The pump specific speed links the three main components of centrifugal-pump performance characteristics into a single term. It is used to compare two centrifugal pumps that are geometrically similar. Pump specific speed can be calculated from
................(1)
where
N_s = pump specific speed
N = pump rotative speed
q = pump capacity
H_td′ = TDH per stage at the BEP.
The pump specific speed is always calculated at the pump’s point of maximum efficiency. The number is used to characterize a pump’s performance as a function of its flowing parameters. Normally, it is desirable to select the impeller with the highest specific speed (smallest diameter). This may be offset by the higher operating cost associated with higher speeds and greater susceptibility to cavitation damage.
Impellers With Low Specific Speeds (500 to 4,000). Radial-flow impellers typically have low specific speeds. Radial-flow impellers are narrow and relatively large in diameter and are designed for high TDHs and low flow capacity. The pumped fluid undergoes a 90° turn from inlet to outlet of the impeller.
Impellers With Median Specific Speeds (4,000 to 10,000). Mixed-flow impellers typically have medium specific speeds and are wider and smaller in diameter than radial-flow impellers. They exhibit medium TDH and medium flow capability. They are typically used in vertical multistage pumps and downhole electrical submersible pumps, which require small diameters.
Impellers With High Specific Speeds (10,000 to 16,000). Axial-flow impellers typically have high specific speeds. In these impellers, the liquid flow direction remains parallel to the axis of the pump shaft. Axial-flow impellers are used for high flow and low TDH applications. They are most commonly used for water irrigation, flood control, pumped storage power-generation projects, and as ship impellers.

Pump performance curves

When a pump manufacturer develops a new pump, the new pump is tested for performance under controlled conditions. The results are plotted to show flow rate vs. head, efficiency, and power consumption. These graphs are known as performance curves. Under similar operating conditions, an installed pump is expected to demonstrate the same performance characteristics as shown on the performance curves. If it does not, this indicates that something is wrong with the system and/or pump. Comparison of actual pump performance with rated performance curves can help determine pump malfunction.

Curve performance

The impeller shape and speed is the primary determinant of pump performance. Fig. 2 illustrates a generalized centrifugal-pump curve. Head, NPSHR, efficiency, horsepower, and brake-horsepower (BHP) requirements vary with flow rate. The TDH is greatest at zero capacity (shutoff head) and then falls off with increasing flow rates. The horsepower curve starts out at some small value at zero flow, increases moderately up to a maximum point, and then tapers off slightly. The pump efficiency curve starts out at zero, increases rapidly as flow increases, levels off at the BEP, and decreases thereafter. The NPSHR is a finite value at zero flow and increases as the square of the increase in flow rate.

Fig. 2—Characteristic pump-performance curve.

Curve parameters

It is best to operate the pump at the BEP, but this is not normally feasible. Alternatively, the pump should operate only in the area of the curve closest to the BEP and only in the moderately sloping portion of the head curve. Operating in the flat or steeply sloping portions of the curve results in wasted energy and flow control instability. Pumps that run at or near BEP run smoother and have better run lives. Any time the actual flow drops to less than 50% of the BEP flow, it is wise to consult the manufacturer because shaft deflections may increase dramatically (especially with single-stage overhung-design pumps), which could lead to higher maintenance costs and to failures.

Pumps in parallel

Fig. 3 illustrates the shape the TDH-vs.-capacity curve assumes when identical pumps are operated in parallel and series. Parallel operation occurs where multiple pumps are piped to the same suction and discharge lines. The combined flow rate is the total of the individual pump flows at the TDH. In most cases, the head capacity curves of the parallel pumps are the same, or nearly so. It is not necessary for the curves to be the same as long as each pump operating in parallel can put out the desired TDH.

Fig. 3—Head capacity curve for parallel and series pump operation.

All centrifugal pumps discharging to an elevated or pressurized vessel and all centrifugal pumps operating in parallel should have check valves in the event of a pump shutdown to keep the pump from spinning backwards. (The danger is a sheared shaft on restart attempt.)
Driver size should be selected so that overloading does not occur at any point across the entire pump curve. Flow orifices or meters should be provided in each pump’s discharge line for verification of flow rates. Suction and discharge piping should be arranged as symmetrically as practical so that all pumps have the same NPSHA.

Series operation

Series operation is used when a single pump cannot develop the total TDH required. It is also used when a low NPSHR is used to feed a larger pump that requires an NPSHR that cannot be provided from an atmospheric tank or vessel operating at its bubblepoint. In series operation, the combined head is the sum of the individual-pump TDHs at the same flow.

System head curves

The system head curve is a graphical representation of TDH required to be furnished by the pump vs. the flow rate through the piping system. It consists of a constant (static) and an increasing (variable) portion. Fig. 4 illustrates an example of a typical system head curve.

Fig. 4—Example of a typical system head curve.

The constant portion represents the static head difference between the suction and the discharge at zero flow and is equal to
................(2)
The variable portion represents the head required to overcome friction as a result of flow. It varies as the square of the flow and is equal to
................(3)
where
p_f1 = pressure drop resulting from friction in the suction piping
p_f2 = pressure drop resulting from friction in the discharge piping
P_c = discharge flow-control-valve losses.

Regulation of flow rate

It is unusual for a system to require operation at a single fixed flow rate. A pump will deliver only the capacity that corresponds to the intersection of the TDH capacity and system head curves. To vary the capacity, one must change the shape of one or both curves. The head-capacity-curve shape can be changed by altering the pump speed or impeller diameter. The system-head-curve shape can be changed by the use of a backpressure throttling valve (see Backpressure Valves in this page).
The effects of operating at significantly reduced capacity may lead to:

Operating at much less than the BEP
Higher energy consumption per unit capacity
High bearing loads
Temperature rise
Internal circulation

These results can be minimized with the use of a variable-speed driver or with the use of several parallel pumps for the total capacity and sequentially shutting down individual units as demand requires.
Higher bearing loads will exist for any flow that departs from the BEP, especially for single-stage, single-suction pumps. This can be anticipated by specifying certain types of heavy-duty and long-life bearings. If the temperature of the pumped fluid rises and the flow rate through the pump decreases, minimum-flow recirculation can be used (see Minimum-Flow Recirculation Valve in this page). The manufacturer generally provides the minimum continuous required flow rate for any pump selection. Operating between the BEP and minimum required flow rate generally avoids all the problems discussed.

Back-pressure valves

The difference between the TDH developed by the pump and the head required by the system head curve represents lost energy. Because most centrifugal pumps are driven by constant-speed electric motors, throttling is the only practical method of regulating capacity. The backpressure valve imposes a variable amount of loss on the system head curve. Closing the valve increases control losses and causes the system head curve to slope up more steeply to intersect the TDH capacity curve at the desired capacity. Opening the valve decreases the control losses and causes the system head curve to slope downward and intersect the TDH capacity curve at a higher capacity. With the valve completely open, the capacity is governed only by the intersection of the two curves.

Minimum flow re-circulation valve

The re-circulation valve prevents the buildup of excessive amounts of heat within the casing. A minimum-flow re-circulation valve should be installed if the pump piping system contains a back-pressure valve that could close and result in less than the minimum continuous flow at which the pump can safely operate. A re-circulation valve is often used in installations in which the pump piping contains an automatic shutdown discharge valve that could fail in the closed position, or a discharge block valve that can be inadvertently closed. The re-circulation valve should be upstream of the first block valve or control valve downstream of the pump. On small pumps, an orifice is usually installed on the re-circulation, which continuously recirculates a fixed flow of liquid back to the suction. A control valve costs more but will modulate the re-circulation to assure only minimum flow and thus result in less energy loss.

Changing performance

The maximum head that a centrifugal pump can develop is determined by speed, impeller diameter, and number of stages. Thus, to change the head of a pump, one or more of these factors must be changed. Speed can be changed with different gears, belts, or pulleys, or by installing a variable-speed driver. The impeller diameter can be altered for large permanent changes. The number of impellers can be changed by replacing existing impellers with spacers or dummy impellers.

Variable speed control

Most motor-driven centrifugal pumps are operated at constant speed. A direct-current or variable-frequency alternating-current motor control can maintain nearly the same pump efficiency over a larger speed range. Variable-speed control makes it possible to eliminate the backpressure throttling requirements to adjust system head.
Fig. 5 illustrates the head-capacity-curve relationship of a constant-speed and variable-speed pump. The pump is operating at 100% of its capacity, and the TDH is represented by Point 1 on the graph. If it becomes desirable to reduce the capacity to 80% of the rated capacity, the constant-speed-pump operation will move to Point 3. Point 3 requires 110% of the head and 92% of the BHP required at Point 1, and thus, additional back-pressure would be required to force the system curve to intersect the pump curve at this point.

Fig. 5—Head/capacity-curve comparison of constant- and variable-speed pump.

A variable-speed driver could, in effect, find a TDH capacity curve that intersects the system curve at Point 2. Point 2 requires only 70% of the head and 73% of the power required at Point 1. Thus, at 80% capacity, the constant-speed pump would operate at Point 3 and the variable-speed pump at Point 2. The potential energy savings is represented by the difference between 92 and 73% of horsepower, or 19%.

Affinity laws

The affinity laws are used to predict what effect speed or impeller-diameter changes have on centrifugal-pump performance. The laws are based on dimensional analysis of rotating machines that shows, for dynamically similar conditions, certain dimensionless parameters remain constant. These relationships apply to all types of centrifugal and axial machines.
For a change in pump speed, the following changes in pump performance can be determined:
................(4)
................(5)
................(6)
where
N₁ = old speed
N₂ = new speed.
For a change in diameter, the following performance changes can be determined:
................(7)
................(8)
................(9)
where
D₁ = old diameter
D₂ = new diameter.
For a change in both diameter and speed, the following changes in pump performance can be determined:
................(10)
................(11)
................(12)
Predictions for speed changes are fairly accurate throughout the range of speed changes. However, predictions for diameter changes tend to be accurate for diameter change of only ± 10% because changing the diameter also changes the relationship of the impeller to the pump casing. Thus, for a 10% increase in either diameter or speed, the flow will increase by 10%, TDH by 21%, and the BHP by 33%.
The efficiency is assumed to be constant in all the previous calculations. Fig. 6 illustrates a graphic example of reduced operating parameters because of speed reducers.

Fig. 6—Example of reduced operating parameters as a result of speed reducers.

Pump priming

Most centrifugal pumps have a flooded suction. The source is above the pump suction, and atmospheric pressure is sufficient to maintain fluid at the pump inlet at all times. Sometimes the pump must take suction from a source that is below the centerline of the pump. Atmospheric pressure alone will not always keep the suction flooded. Conventional centrifugal pumps are not self-priming. Thus, they are not capable of evacuating vapor from the casing so that fluid from the suction line can replace the vapor. Self-priming pumps are designed so that an adequate fluid volume for repriming is always retained within the pump casing, even if fluid drains back to the source.

Installation considerations

A centrifugal pump is a piece of precision machinery that must not be subjected to external strains beyond those it was designed to encounter. It must be installed in the intended position, carefully aligned, and free from piping forces and moments.

Foundations

Generally, foundation design is not critical. Vibration in a centrifugal pump is minimal unless an engine driver is used. As a general rule of thumb, the foundation should be able to handle three times the weight of the pump, driver, and skid assembly. The manufacturer is the best source for determining the required foundation size.

Piping design

Poor piping design and installation is a common cause of poor centrifugal-pump performance or failure. Poor piping can result in:

Cavitation
Performance dropout
Impeller failure
Bearing and mechanical seal failures
Cracked casings
Leaks
Spills
Fires

Suction piping

Suction piping is more important than discharge piping.

Fluid source inlet

When the fluid source is above the pump (static head), the source vessel should contain a weir to minimize turbulence, a vortex breaker to eliminate vortexing and vapor entrainment, and a nozzle sized to limit exit velocity to 7 ft/sec or, preferably, less. When the fluid source is below the pump (static lift), the sump, basin, or pit should be designed to provide even velocity distribution in the approach or around the suction inlet and should be sufficiently submerged to prevent vortexing.

Pipe size and elimination of air pockets

Piping should be at least one nominal pipe size larger than the pump suction flange. Velocities should be less than 2 to 3 ft/sec, and the head loss as a result of friction should be less than 1 ft per 100 ft of equivalent piping length. Suction lines should be short and free of all unnecessary turns. For flooded suctions, piping should be continuously sloping downward to the pump suction so that any vapor pockets can migrate back to the source vessel. For static lifts, the piping should be continuously sloping upward with no air pockets (install gate valves in horizontal position). Where air pockets cannot be avoided, the use of automatic vent valves is recommended.

Upstream elbow considerations

When making upstream orientation changes, only long-radius elbows should be used. They should not be connected directly to the pump suction flange, and a minimum of at least two to five pipe diameters of straight pipe should be between the suction flange and the elbow and between successive elbows. This reduces swirl and turbulence before the fluid reaches the pump. Otherwise, separation of the leading edges may occur, with consequent noisy operation and cavitation damage.

Basket strainers

Conditions may dictate that permanent strainers be installed in the suction piping. If permanent strainers are not required, temporary cone-type strainers should be installed at least for initial startups. Basket strainers should have at least 150% flow-area screens.

Eccentric reducers

Reducers are required when making a transition from one pipe size to another and in going from the suction-pipe size to the pump flange. Reduction at the pump should be limited to one nominal size change (e.g., 8 to 6 in.). If two or more nominal pipe size reductions are required, it is best to locate any remaining changes several pipe diameters away from the pump inlet. Eccentric reducers should be used, if possible, and should be installed with the flat side up. Concentric reducers should not be used for horizontal suction lines because they could trap vapor that can be pulled into the pump and cause cavitation or vapor lock. Concentric reducers can be used for vertical suction lines and horizontal lines with flooded suction.

Discharge piping

Minimum Flow Bypass. The minimum-flow bypass (or “recirculation”) protects the pump from temperature buildup when the pumping rates are low. They should be designed to handle the pump’s minimum flow capacity at minimum discharge pressure with a line restrictor to adjust flow. Small pumps are usually controlled by an orifice or choke tube. For large pumps in which a continuous bypass would consume excessive power, a control valve actuated (opened) by low flow is used.

Check valves

Check valves are essential to minimize backflow, which can damage the pump. Selection should take into account the effect of water hammer. Water hammer is the transient change in static line pressure as a result of a sudden change in flow. Items that can start the sudden change in flow include the starting or stopping of a pump or the opening or closing of a check valve.
Slow-closing check valves are acceptable on systems with a single pump and long lengths of pipe. Fast-closing check valves are required with multiple pumps operating in parallel and at high heads. As a general guideline, lift (“swing”) check valves are slow unless they are spring loaded. Tilting-disk check valves are fast closing but are more expensive and have a higher pressure drop than swing check valves. When fast-reacting check valves are required, pressure-drop considerations should be secondary.

Nomenclature

N_s	=	pump specific speed
N	=	pump rotative speed
q	=	pump capacity
H_td	=	TDH per stage at the BEP
p_f1	=	pressure drop resulting from friction in the suction piping
p_f2	=	pressure drop resulting from friction in the discharge piping
P_c	=	discharge flow-control-valve losses
N₁	=	old speed
N₂	=	new speed
D₁	=	old diameter
D₂	=	new diameter

12 INSANE WATCHES You Won’t Believe Exist

2017-04-14T23:08:00.002+02:00

pumps types

2017-04-14T19:50:00.002+02:00

Pump Types Guide - Find the right pump for the job

There are lots of pump types available, but which one is right for you? Understanding which pump type is right for your application is critical to reduce costs and increase the life of your pump and system. We've worked with leading pump experts to put together this comprehensive guide to the most popular pump types. The individual pump types are listed in the left column and are grouped by either centrifugal pumps or positive displacement pumps.

Pump Type

	Basic Description	Key Features	Applications Used	Recommended Media (Fluid)	Advantages	Flow Rate Ranges	Total Head (Pressure) Ranges	Horse Power Ranges
Centrifugal Pumps	General name for pumps with one or more impellers. Many types and configurations for different applications. See below for specific centrifugal pump types.	One or more impellers. Casing is volute or diffuser type. Normally electric motor driven, but other drive types available.	All sorts of liquids can be pumps with centrifugal pumps. Highest flow rates of all pump types. Handles clean or dirty liquids, and liquids with low viscosity. Liquid should not contain air or vapors.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	Best pump choice for lower viscosity (thin) liquids and high flow rates. No pulsations that may be found in some positive displacement pumps.	5 - 200,000 gpm -------- 19 - 757,080 lpm	10 - 7,500 ft -------- 3 - 2,286 m	0.125 - 5,000 hp
ANSI Process Pumps	ANSI Process pumps are the only dimensionally standard pump type in the U.S. pump industry (e.g., comparable sizes of all manufacturers have identical envelope and interface dimensions.) ANSI process pumps are, by definition, a horizontal, end suction, single stage pump. The pump meets ANSI B73.1 (ASME B73.1).	Considered an end suction pump, frame mounted. Normally supplied with open impellers. Dimensionally standard sizes supplied by all manufacturers. Available in a wide variety of alloys and non-metals for many corrosive services.	Transfer and process applications in chemical plants, pulp and paper mills, refineries, food processing plants, and general services in manufacturing plants of all types.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	Dimensional standardization allows the complete piping, foundation, and building design to be completed before the pump supplier is chosen. Also, this permits the pump brand to be switched in the field without having to re-pipe or modify the motor, coupling, or bedplate. This pump type has more material options than other types.	10 - 5,000 gpm -------- 38 - 18,927 lpm	50 - 750 ft -------- 22 - 325 psi	1 - 250 hp
API Process Pumps	The API pump type applies to pumps built to the API 610 standard for pumps for refineries, pipelines, and other hydrocarbon processing applications. It includes end suction, horizontal split case, vertical turbine, and other types.	Meets API 610 standard for hydrocarbon services. Includes closed impellers, with locked wearing rings. Normally centerline mounted to minimize thermal movement.	Hydrocarbon transfer and processing services in refineries, pipelines, and hydrocarbon processing plants.	Crude oil and all types of hydrocarbons.	Meets API 610 requirements, assuring safety and reliability for high pressure, high temperature hydrocarbon services.	10 - 10,000 gpm -------- 38 - 37,854 lpm	50 - 7,500 ft -------- 22 - 3251 psi	1 - 5,000 hp
Axial Flow Pumps	Axial Flow pumps are a very high flow, low head type of pump. Also called a propeller pump.	Single stage, high specific speed impeller for high flow low head.	Flood dewatering, power plant circulating water pump, evaporator services, and irrigation.	Water and relatively thin liquids. Can pump liquids with or without solids if proper impeller type is chosen.	This pump type is the best type to achieve very high flow rate with very low head, a hydraulic requirement needed for certain applications such as flood dewatering.	5,000 - 200,000 gpm -------- 18,927 - 757,08 lpm	10 - 30 ft -------- 4 - 13 psi	10 - 1,500 hp
Booster Pumps	Booster pumps are used to further boost the pressure in a system. It may be an end suction, in-line circulator, horizontal split case, or vertical turbine in a can type of pump.	Booster pumps are almost always a multi-stage pump (has more than one impeller). All other features are quite specific to the application.	Potable water distribution, irrigation booster, cooling water booster, process booster service	Water and relatively thin liquids (won't pump thicker oils). Normally not used for liquids containing solids. Available in alloys for corrosive services.	Allows the building up of additional pressure that is required to move liquid a long distance or to use the high pressure for spraying or other services.	5 - 10,000 gpm -------- 19 - 37,854 lpm	200 - 7,500 ft -------- 87 - 3,251 psi	1 - 5,000 hp
Canned Motor Pumps	Canned Motor pumps are sealless centrifugal pumps. The impeller is directly attached to the motor rotor, with a can separating the wetted rotor from the motor stator.	Pump and motor are close coupled, so no mechanical seal. Pump rotor includes a circulating path of pumped liquid to lubricate sleeve bearings and thrust surfaces. These wear areas are made of ceramic, silicon carbide, or tungsten carbide.	Pumping chemicals, hydrocarbons, or other liquids that are difficult to seal, or where the consequences of leakage are serious. Pumping heat transfer fluids which are high temperature or which are prone to costly evaporative losses with traditional mechanical seals.	All types of thin (non-viscous liquids).	Eliminates the mechanical seal, one of the largest components of pump maintenance cost. Plus, the pump is assured to be leak-free.	5 - 1,500 gpm -------- 19 - 5,678 lpm	25 - 400 ft -------- 11 - 173 psi	0.5 - 300 hp
Chopper Pumps	Chopper Pumps are a type of centrifugal pump that is designed to chop up solids and stringy material as it pumps. It is available in a vertical column and end suction configuration.	Pump impeller contains heavy duty grinding teeth, and many have replaceable wear plates in the casing, to allow chopping of solids as the pump operates.	Chopper pumps are used in applications that plug conventional solids handling wastewater pumps in industrial, chemical, and fool processing facilities.	Liquids containing solids and stringy material that would otherwise be difficult to pump.	Able to pump liquids containing long stringy materials or other solids that would plug up in other pump types.	50 - 10,000 gpm -------- 189 - 37,854 lpm	15 - 200 ft -------- 7 - 87 psi	1 - 500 hp
Circulator Pumps	Circulator pumps is generally a pump with in-line suction and discharge flanges.	In-line suction and discharge piping connections. Pump may be equipped with a traditional motor and coupling, or may have a wetted rotor motor that eliminates the seal.	Circulator pumps are used in HVAC systems in buildings (chilled water circulation, hot water circulation, potable water circulation). Also circulation of cooling water in plants.	Water and relatively thin liquids.	In-line design saves on floor space.	5 - 750 gpm -------- 19 - 2,839 lpm	20 - 180 ft -------- 9 - 78 psi	1 - 50 hp
Cryogenic Pumps	Cryogenic pumps are used to handle very low temperature liquids.	Special materials, seals, and clearances to tolerate very low temperatures.	Low temperature applications in process industries, LNG supply, and semiconductor manufacturing.	Ideal for very low temperature liquids.	Able to tolerate the low temperatures found in certain applications.	5 - 1,000 gpm -------- 19 - 3,785 lpm	25 - 1,000 ft -------- 11 - 434 psi	0.5 - 500 hp
Drum Pumps	Drum pumps are used to pump small quantities of liquid out of drums and carboys. Pump is very slim to fit in drum opening. Normally supplied as centrifugal pump, but positive displacement pump types are available for thicker liquids and pastes.	Small diameter tube surrounding the shaft fits into the opening of a 55 gallon drum. Normally has a hand-trigger controlled motor.	Pumping small quantities of liquids out of 55 gallon drums and larger carboys.	Wide variety of thin and thick liquids, including corrosive liquids.	Very practical way to pump small amounts of various fluids that are stored in drums or carboys.	0.5 - 70 gpm -------- 2 - 265 lpm	20 - 75 ft -------- 9 - 33 psi	0.25 - 1 hp
End Suction Pumps	End suction pumps are the common type of centrifugal pump. Has horizontal shaft with overhung impeller. Flow goes in the end of the casing, and out the top.	Horizontal shaft, single impeller (see multi-stage category for pumps with more impellers). Various impeller types for clean and dirty services, many material options	Any transfer or circulation of liquid. Handles clean or dirty liquids, and liquids with low viscosity. Liquid should not contain air or vapors.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	Lowest first cost option for most applications. Stocked by most distributors in common sizes.	5 - 7,000 gpm -------- 19 - 26,498 lpm	10 - 750 ft -------- 4 - 325 psi	0.125 - 250 hp
Fire Pumps	Centrifugal pump used for fire fighting in buildings, plants, and other locations. May meet UL/NFPA standards for fire pumps. Normally this is a horizontal split case or vertical turbine pump for UL/FM services. Non listed pumps may be end suction type.	Listed pumps meet the requirements of UL/FM for firefighting services.	Fire fighting services of all types, both UL/FM listed and unlisted.	Water	Meets requirements of UL/FM for fire fighting pumps. Suppliers often include complete system, including engine and controls.	20 - 5,000 gpm -------- 76 - 18,927 lpm	100 - 1,200 ft -------- 43 - 520 psi	10 - 800 hp
Grinder Pumps	Grinder pumps are a type of submersible sewage pump that has cutting teeth incorporated onto the impeller, to grind the sewage for pressure sewer applications. Also available in progressing cavity pump positive displacement type.	Grinding teeth on the inlet of the impeller, submersible motor.	Residential pressure sewer systems.	Sewage and other wastewater.	This type of sewage pump allows smaller diameter sewage lines than typical gravity drain sewers. Also, the sewer lines can follow the contour of the land since they don’t have to continuously drain to the collection point.	5 - 50 gpm -------- 19 - 189 lpm	50 - 150 ft -------- 22 - 65 psi	0.5 - 5 hp
Horizontal Split Case Pumps	Horizontal Split Case pumps are a types of centrifugal pump type has a single double suction impeller supported between bearings. Casing is split horizontally for maintenance. Suction and discharge flanges are opposed to each other.	Double suction impeller gives better NPSH and lower axial thrust. Casing is normally double volute, to reduce radial bearing loads. Pump has two seals, both sealing suction pressure.	Usually higher flow rate applications than end suction pumps. Used for cooling water, plant make-up water, potable water distribution, fire pumps, pipelines, and other main process flows.	Water and relatively thin liquids (won't pump thicker oils). Normally not used for liquids containing solids. Available in alloys for corrosive services.	This pump type permits much higher flow rates than end suction pumps. The double suction impeller has no axial thrust loads, and is less likely to cavitate.	100 - 100,000 gpm -------- 379 - 378,540 lpm	50 - 1,500 ft -------- 22 - 650 psi	3 - 5,000 hp
Jet Pumps	Jet pumps are a type of home water well pump that is used for lower flow rates than vertical turbine types. It is a horizontal end suction pump, put makes use of an ejector to assist the flow.	Horizontal end suction pump with ejector either mounted on the pump (for shallow well services), or located down in the well.	Domestic water wells	Water	Lower cost domestic well pump than submersible.	1 - 70 gpm -------- 4 - 265 lpm	20 - 200 ft -------- 9 - 87 psi	0.5 - 5 hp
Magnetic Drive Pumps	Magnetic drive pumps are a type of sealless centrifugal pump. It transmits the torque from the motor to the impeller by means of a rotating outer magnet which transmits the magnetic flux through a can to an inner magnet that is attached to the impeller. The inside of the can is thus isolated, with no shaft penetration, and the seal is eliminated.	Magnets are typically made of ceramic, samarium cobalt, or neodymium. Bushings and thrust surfaces inside the can are made of silicon carbide or tungsten carbide, or ceramic, to handle the potentially abrasive liquid that circulates inside the can. Most must be protected against loss of flow, which could seriously damage the pump due to temperature build-up due to the magnetic flux.	Pumping chemicals, hydrocarbons, or other liquids that are difficult to seal, or where the consequences of leakage are serious. Pumping heat transfer fluids which are high temperature or which are prone to costly evaporative losses with traditional mechanical seals.	All types of thin (non-viscous liquids).	Eliminates the mechanical seal, one of the largest components of pump maintenance cost. Plus, the pump is assured to be leak-free.	5 - 4,000 gpm -------- 19 - 15,142 lpm	25 - 1,000 ft -------- 11 - 434 psi	0.5 - 300 hp
Multistage Pumps	Multistage pumps use multiple impellers with either diffusers or volutes generate more head than single stage (single impeller) pumps. Available in horizontal and vertical orientations.	Casing may be split radially or axially. Axial thrust may or may not be balanced out, depending on design. Impellers are enclosed design with diffuser or volute casing.	Higher pressure services such as boiler feed water, condensate, pipelines, reverse osmosis, and decaling.	Water and relatively thin liquids (won't pump thicker oils). Normally not used for liquids containing solids. Available in alloys for corrosive services.	Best ways to get high pressure with a centrifugal pump. Thrust loads may be lower than single stage designs.	5 - 10,000 gpm -------- 19 - 37,854 lpm	200 - 7,500 ft -------- 87 - 3,251 psi	1 - 5,000 hp
Regenerative Turbine Pumps	Regererative turbine pumps are not considered a true centrifugal, but works on the same kinetic principal as a centrifugal pump.Instead of an impeller with vanes, the turbine impeller has blades similar to turbines, which generate the head. Normally it is end suction, single stage, though multi-stage versions are available.	Normally single stage, though multi-sage is available. Pump has very tight internal clearances, so liquid pumped must be quite clean. Pump has very steep head-capacity curve, so pump must be protected against possibly operating against closed valve.	Small boiler feed pumps for dry cleaners, bakeries, and similar small commercial boilers. Also used in OEM applications such as chiller and laser cooling.	Thin, clear liquids.	Very compact pump for low flow, high head applications. This may result in space savings and reduced cost for small boiler feed pumps. This pump type handles vapor and air mixed in with the liquid better than traditional centrifugal pumps.	1 - 200 gpm -------- 4 - 757 lpm	50 - 1,200 ft -------- 22 - 520 psi	0.5 - 75 hp
Slurry Pumps	Slurry pump is a general term for a pump that handles an abrasive slurry. They may be considered an end suction pump, vertical column pump, or submersible pump.	Pumps are constructed either of high nickel cast iron (white iron) to withstand the abrasive wear of slurries, or the pump is lined with rubber for more round-edged slurries. Pumps often have replaceable wear plates on one or both sides of the impeller.	Mining, minerals processing, transportation of slurries for processing, and dredging. Also pumps used in slurry applications in coal fired power plants, steel mills, cement mills, etc.	Very abrasive liquids of all types.	Ordinary pumps wouldn't withstand the abrasive wear that slurries cause on pump parts. Slurry pumps are designed to handle abrasive slurries and give pumps the longest life possible.	10 - 30,000 gpm -------- 38 - 113,560 lpm	30 - 250 ft -------- 13 - 108 psi	1 - 2000 hp
Self-Priming Pumps	Self-Priming pumps are a type of centrifugal that can be located above the suction reservoir without an external priming system. End suction configuration, but enlarged case to support priming.	No need for external priming or foot valves.	Sump pumps and dewatering applications. Transfer services where pump must be located above the suction vessel.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	No need for external priming	5 - 7,000 gpm -------- 19 - 26,498 lpm	10 - 350 ft -------- 4 - 152 psi	1 - 150 hp
Submersible Pumps	Submersible pumps involve a submersible motor with a close coupled to single stage pump that allows the entire assembly to operated submerged.	Submerged motor, either air-filled or oil-filled. Different impellers are designed to accommodate solids of various sizes.	Sump pump services, effluent and sewage services ranging in size from products for homes to main sewage treatment plants.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen.	Eliminates column shaft and bearings found in column sump pump. More compact, reduced sump installation cost. May be located in areas prone to flooding.	5 - 7,500 gpm -------- 19 - 28,391 lpm	10 - 200 ft ........ 4 - 87 psi	0.25 - 250 hp
Trash Pumps	Trash pumps are a type of self-priming centrifugal or submersible centrifugal pump designed to handle rocks and other solids while dewatering.	Open or non-clog enclosed impellers, designed to pass rocks and other debris. Pumps may be self-priming. Seals usually have hardened faces.	Dewatering construction sites, mines, and utility pits.	Dirty water containing mud, rocks, stone, and other debris.	Designed to pump the solids and abrasives found in many dewatering applications.	5 - 1,000 gpm ........ 19 - 3,785 lpm	25 - 150 ft -------- 11 - 65 psi	0.25 - 50 hp
Vertical Sump Pumps	Vertical sump pumps involve a vertical shaft supported in a center column. Single impeller, open or enclosed, pumps through a volute casing and then out a discharge column pipe.	Various impeller types for clean and dirty services. Sleeve bearings in the column pipe need to be lubricated by the sump water, or externally with water or grease.	Sump pump services.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	Relatively low cost sump pump. Most designs need no shaft seal, since shaft column not pressurized.	5 - 7,500 gpm -------- 19 - 28,391 lpm	15 - 150 ft -------- 7 - 65 psi	0.5 - 250 hp
Vertical Turbine Pumps	Vertical turbine pumps are a vertical shaft pump that is designed to fit in a bore-hole well. Can also pump out of open reservoir, river, intake structure, or tank, or can be mounted in barrel for booster pump applications. Pump can have one or more impellers and diffuser bowls, depending on total head requirement.	Available with open and enclosed impellers. Sleeve bearings in pump diffuser bowls are lubricated by liquid pumped. Vertical high thrust motor mounted on top for product lubricated lineshaft bearings, or submersible motor mounted below pump to eliminate lineshaft and lineshaft bearings.	Irrigation, potable water supply, plant make-up water, cooling water, fire pumps, potable water distribution, booster pumps, process pumps.	Water and relatively thin liquids (won't pump thicker oils). Can pump liquids with or without solids if proper impeller type is chosen. Available in alloys for corrosive services.	Only practical way to pump from a deep well. Wide flow and head ranges. Low floor space usage. Immersed pump eliminates priming. Canned pump version excellent for low NPSH services	50 - 150,000 gpm -------- 189 - 567,810 lpm	15 - 2,000 ft -------- 7 - 867 psi	1 - 5,000 hp
Well Pumps	A type of vertical turbine pump designed especially for use in a drilled bore-hole well. Also, for lower flow rates refer to jet pump type above.	Available with open and enclosed impellers. Sleeve bearings in pump diffuser bowls are lubricated by liquid pumped. Vertical high thrust motor mounted on top for product lubricated lineshaft bearings, or submersible motor mounted below pump to eliminate lineshaft and lineshaft bearings.	Irrigation, potable water supply, plant make-up water, cooling water, fire pumps, potable water distribution	Water and relatively thin liquids. Can pump liquids with or without solids if proper impeller type is chosen.	Only practical way to pump from a deep well. Wide flow and head ranges. Low floor space usage. Immersed pump eliminates priming.	50 - 20,000 gpm -------- 189 - 75,708 lpm	20 - 1,000 ft -------- 9 - 434 psi	1 - 3,000 hp
Positive Displacement Pumps	A positive displacement (PD) pump is a general name for a pump type that does not have impellers, but rather relies on rotating or reciprocating parts to directly push the liquid in an enclosed volume, until enough pressure is built up to move the liquid into the discharge system. This includes many specific types for specific applications, as described below.	Pump works on positive displacement principal, either rotary or reciprocating type. See below for features of specific types.	All types of services in many industries where positive displacement pumps are favored over centrifugal pumps due to high viscosity, presence of fragile or shear sensitive solids, or need for low flow and high pressure.	High viscosity fluids, some thinner fluids, fluids containing solids, especially fragile solids, and shear sensitive liquids.	Best choice for higher viscosity services, and to move liquids gently. May also be needed for low flow, high pressure combination, or other application niches. Some types are inherently self-priming, and several types are sealless.	0.1 - 15,000 gpm -------- .38 - 56,781 lpm	10 - 100,000 psi -------- .7 - 6,895 bar	0.5 - 5,000 hp
AODD Pumps	AODD pumps are any type of reciprocating diaphragm pump containing two diaphragms and driven by air instead of by electric motor.	Air section with shuttle valve applies air alternately to the two diaphragms. Each diaphragm has a set of check valves.	Many applications in general plant service where electricity isn't available, or where the liquid being pumped has high solids content or high viscosity.	Wide range of liquids, including liquids containing solids, and corrosive liquids.	Can be used where no electricity is available, if compressed air is available. Available in a variety of metal and non-metallic materials depending on the fluid pumped. Able to pump liquids containing large solids. Pump is sealless and can run dry.	0.25 - 300 gpm -------- 1 - 1,136 lpm	10 - 125 psi -------- .7 - 9 bar	0.25 - 30 hp
Concrete Pump	Concrete pumps are a type of reciprocating positive displacement pump that is specially designed to pump concrete and other mixed aggregate solutions.	High pressure discharge for pumping concrete long distances or up high elevations. Materials of construction that can handle the abrasive aggregate.	Concrete pouring, construction projects.	Concrete and other aggregate solutions.	Best way to move concrete long distances and up heights during pour.	10 - 1,000 gpm -------- 38 - 3,785 lpm	25 - 1,000 psi -------- 2 - 69 bar	10 - 500 hp
Diaphragm Pumps	Diaphragm pumps are a type of reciprocating positive displacement pump in which liquid is pumped by a reciprocating diaphragm, which is driven by a solenoid, a mechanical drive, or a fluid drive. Other versions are air operated (see AODD type below). Pump has inlet and outlet check valves.	Pump contains reciprocating diaphragm and inlet and outlet check valves.	Many applications in general plant service where the liquid being pumped has high solids content or high viscosity.	Wide range of liquids, including liquids containing solids, and corrosive liquids.	Handles a wide range of liquids, including liquids containing solids. Pump is sealless, and can run dry without damaging the pump.	1 - 1,800 gpm -------- 4 - 6,814 lpm	25 - 15,000 psi -------- 2 - 1,034 bar	0.5 - 2,000 hp
Flexible Impeller Pumps	Flexible impeller pumps are a type of rotary positive displacement pump that has a rotating rubber impeller with vanes that bend and then straighten as the impeller rotates to conform to the internal cam in the pump casing.	Various rubber materials available for correct compatibility with the fluid pumped.	Used as bilge and ballast pumps in small and medium marine services. Also found in other applications in plants where fluids contain some solids.	Water, seawater, and other thin liquids, including liquids containing some solids.	Relatively low cost way to move liquids containing some amounts of solids.	5 - 150 gpm -------- 19 - 568 lpm	10 - 60 psi -------- .7 - 4 bar	0.25 - 10 hp
Gear Pumps	Gear pumps are a type of rotary positive displacement pump in which liquid is pumped by passing between two meshing gears and the surrounding casing. There are internal and external gear types.	Internal and external gear types. Typically doesn't handle solids or abrasive liquids.	Most common pump for clean oils and other viscous liquids.	Oils and other high viscosity liquids. Usually only suited for clean liquids (no solids).	Most widely used for clean oil services. Few moving parts, simple construction.	1 - 1,500 gpm -------- 4 - 5,678 lpm	10 - 2,500 psi -------- .7 - 138 bar	0.5 - 2,000 hp
Lobe Pumps	Lobe pumps involve two shafts drive lobes which mesh with each other, but do not touch due to the use of timing gears. This allows gentle pumping of liquids containing soft or fragile solids, or viscous liquids.	Pump has timing gears so that lobes don't contact each other while pumping. Available in sanitary options for food, pharmaceutical, and biotech services.	Available in sanitary options for food, beverage, pharmaceutical, and biotech applications.	Liquids which are viscous or which contain fragile solids or are shear sensitive.	This is the normal pump of choice for sanitary applications pumping viscous liquids or liquids containing fragile solids. No metal to metal contact inside the pump.	25 - 3,000 gpm -------- 95 - 11,356 lpm	50 - 450 psi -------- 3 - 31 bar	1 - 500 hp
Metering Pumps	Metering pumps are a type of reciprocating positive displacement diaphragm pump that has a very low flow rate (typically measured in gallons per hour or per day, rather than per minute). Flow rate is adjustable.	Pump is typically a diaphragm style, though older designs are plunger type. Diaphragm is driven by solenoid, mechanical actuation, or hydraulic actuation. Pump includes inlet and outlet check valves. Normally contains stroke length adjustment to vary flow rate, and some pumps can also control flow rate with speed control.	Used to meter or dose very low flow rates with high accuracy. Most common application is chemical treatment of water in boilers, cooling towers, potable water, etc.	Wide variety of thin and thick liquids, including corrosive liquids.	Accurate, repeatable volumetric flow measurement. Ability to easily adjust the flow rate by adjusting stroke length or speed.	.01 - 20 gpm -------- .038 - 76 lpm	10 - 30,000 psi -------- .7 - 2,068 bar	0.125 - 60 hp
Peristaltic Pumps (Hose Pump)	Peristaltic pumps or hose pumps are a type of rotary positive displacement pump that has a roller or shoe that squeezes a tube or hose as it rotates. The squeezing action moves the liquid along the tube.	Includes replaceable hose that must be compatible with the pumped liquid. This hose is typically able to be replaced when worn.	This pump type is used to handle chlorine and other disinfectants in commercial swimming pools, in wineries, in sewage treatment plants, and in many OEM applications where sealless pumping is a plus.	Wide range of liquids, including liquids containing solids, and corrosive liquids.	This pump type requires no seal, and keeps the liquid inside the tube, so zero leakage.	0.2 - 200 gpm -------- .78 - 757 lpm	10 - 250 psi -------- .7 - 17 bar	0.125 - 40 hp
Piston Pumps	Piston pumps are a type of reciprocating positive displacement pump that has, double acting reciprocating pistons.	Pump includes one or more double acting pistons, sealed with o-rings against cylinder walls. Pump has an inlet and outlet check valve for each piston.	Used in oil production, in wash down services, pressure washing, car washes, reverse osmosis, and other applications where high pressure is needed.	Water and other thin liquids, including liquids containing abrasives.	May be better alternative than plunger pump in certain applications, such as abrasive liquids. Slower speeds may mean less maintenance.	5 - 700 gpm -------- 19 - 2,650 lpm	50 - 5,000 psi -------- 3 - 345 bar	1 - 500 hp
Plunger Pumps	Plunger pumps are a type of reciprocating positive displacement pump that has, typically, three or five single acting reciprocating plungers.	Pump includes one or more single acting plungers, sealed with packing against cylinder walls. Pump has an inlet and outlet check valve for each plunger.	Used in oil production, in wash down services, pressure washing, car washes, reverse osmosis, and other applications where high pressure is needed.	Water and other thin liquids, crude oils.	Best way to achieve very high pressures when pumping.	5 - 1,200 gpm ........ 19 - 4,543 lpm	50 - 100,000 psi ........ 3 - 6,895 bar	1 - 5,000 hp
Progressive Cavity Pumps	Progressive cavity pumps are a type of rotary positive displament pump that has a single-threaded helically shaped rotor turning inside of a double-threaded helically shaped rubber stator. This produces a progressing cavity that moves the liquid through the pump and pressurizes it.	Rotor is an interference fit inside the electrometric stator to minimize leakage (slip). Starting torque may be higher than running torque because of this.	Used to pump polymers and dewatered sludge in sewage treatment applications, and in pumping liquids which are viscous or contain solids in industrial plants such as pulp mills, petrochemical, and chemical plants.	Wide variety of thin and thick liquids, including corrosive liquids and liquids containing solids.	Sometimes considered the pump of last resort, as it will handle difficult liquids which are viscous or contain solids and which other pump types cannot accommodate.	10 - 2,400 gpm -------- 38 - 9,085 lpm	50 - 2,000 psi -------- 3 - 138 bar	1 - 500 hp
Screw Pumps	Screw pumps use two intermeshing screws, driven by timing gears, move oils and other viscous liquids. Also available with three screws, one driving the other.	Two screw pumps make use of timing gears so that meshing screws don't drive each other. Triple screw types have one screw driving the other two and don't include timing gears.	Fuel transfer, elevators, and other applications requiring relatively high flow rates of viscous liquids.	Oils, fuels, and other high viscosity liquids. Also handles two-phase liquid/gas mixtures.	Highest flow rate of positive displacement pumps.	50 - 15,000 gpm -------- 189 - 56,781 lpm	50 - 4,500 psi -------- 3 - 310 bar	5 - 5,000 hp
Vane Pumps	Vane pumps use a rotor with vanes located in slots, rotating inside an eccentrically shaped casing. As the rotor turns, the vanes move in and out of the slots.	Sliding vanes are often made of carbon.	An alternative to a gear pump for transferring oils and other viscous liquids. Also good for thinner liquids.	Oils and other high viscosity liquids. Usually only suited for clean liquids (no solids). Also good for thin liquids like gasoline and water.	Good for both thick and thin liquids, so often chosen for terminals and truck unloading where many types of liquids are handled.	5 - 2,500 gpm -------- 19 - 9,464 lpm	20 - 200 psi -------- 1 - 14 bar	1 - 300 hp

US Just Dropped Mother Of All Bombs In Afghanistan. This Is How It Explodes

2017-04-14T11:09:00.001+02:00

step up and step down transformer

2017-04-14T08:47:00.001+02:00

What is the different between step up and step down transformer?

pump cavitation

2017-04-13T19:43:00.001+02:00

What is pump cavitation?

Simply defined, cavitation is the formation of bubbles or cavities in liquid, developed in areas of relatively low pressure around an impeller. The imploding or collapsing of these bubbles trigger intense shockwaves inside the pump, causing significant damage to the impeller and/or the pump housing. If left untreated, pump cavitation can cause:

Failure of pump housing

Destruction of impeller

Excessive vibration - leading to premature seal and bearing failure

Higher than necessary power consumption

Decreased flow and/or pressure

There are two types of pump cavitation: suction and discharge.

Suction Cavitation

When a pump is under low pressure or high vacuum conditions, suction cavitation occurs. The pump is being "starved" or is not receiving enough flow. When this happens, bubbles or cavities will form at the eye of the impeller. As the bubbles carry over to the discharge side of the pump, the fluid conditions change, compressing the bubble into liquid and causing it to implode against the face of the impeller.
An impeller that has fallen victim to suction cavitation will have large chunks or very small bits of material missing, causing it to look like a sponge.
Possible causes of suction cavitation:

Clogged filters or strainers
Blockage in the pipe
Pump is running too far right on the pump curve
Poor piping design
Poor suction conditions (NPSH requirements)

Discharge Cavitation

When a pump's discharge pressure is extremely high, or runs at less than 10% of its best efficiency point (BEP), discharge cavitation occurs. The high discharge pressure makes it difficult for the fluid to flow out of the pump, so it circulates inside the pump. Liquid flows between the impeller and the housing at very high velocity, causing a vacuum at the housing wall and the formation of bubbles.
As with suction cavitation, the implosion of those bubbles trigger intense shockwaves, causing premature wear of the impeller tips and pump housing. In extreme, discharge cavitation can cause the impeller shaft to break.
Possible causes of discharge cavitation:

Blockage in the pipe on discharge side
Clogged filters or strainers
Running too far left on the pump curve
Poor piping design

Cavitation Prevention

If your pumps are experiencing cavitation, check these things to troubleshoot the problem on your own:

Check filters and strainers - clogs on the suction, or discharge side can cause an imbalance of pressure inside the pump
Reference the pump's curve - Use a pressure gauge and/or a flowmeter to understand where your pump is operating on the curve. Make sure it is running at its best efficiency point
Re-evaluate pipe design - Ensure the path the liquid takes to get to and from your pump is ideal for the pump's operating conditions

For more information about how to detect and prevent pump cavitation, be sure to check out our post: Technologies To Detect and Prevent Pump Cavitation.
Cavitation is a common problem in pumping systems, but with proper pump sizing, pipe design, and care of filters and strainers, damage to pumps and their impellers can be largely avoided.

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pump cavitation

What is pump cavitation?

Failure of pump housing Destruction of impeller Excessive vibration - leading to premature seal and bearing failure Higher than necessary power consumption Decreased flow and/or pressure

Suction Cavitation

Discharge Cavitation

Cavitation Prevention

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Failure of pump housing

Destruction of impeller

Excessive vibration - leading to premature seal and bearing failure

Higher than necessary power consumption

Decreased flow and/or pressure