JET FUEL

PPM

2011-06-21T10:33:00.000-07:00

Parts Per Million (PPM)

A unit of concentration often used when measuring levels of pollutants in air, water, body fluids, etc. One ppm is 1 part in 1,000,000. The common unit mg/liter , is equal to ppm. Four drops of ink in a 55-gallon (208 liters) barrel of water would produce an "ink concentration" of 1 ppm.

Parts per million - ppm - is commonly used as a measure of small levels of pollutants in air, water, body fluids, etc. Parts per million is the mass ratio between the pollutant component and the solution and ppm is defined as

ppm = 1,000,000 mc / ms

where
mc = mass of component (kg, lbm)
ms = mass of solution (kg, lbm)

In the metric system ppm can be expressed in terms of milligram versus kg where
1 mg/kg = 1 part per million

Alternatively mass related units to measure very small concentration levels used are
ppb - parts per billion (1 / 1,000,000,000)
ppt - parts per trillion (1 / 1,000,000,000,000)

An alternatively mass related unit to measure larger concentration levels are weight percent which can be expressed like
weight percent = 100 mc / ms
Volume related Concentration Units
Mass per Unit Volume

The concentration of a component can be measured as mass per unit volume as mg/liter, mg/cm3, etc.

Weight of substance added to one unit volume of water to give one part per million (ppm)

1 ppm
= 2.72 pounds per acre-foot

= 1,233 grams per acre-foot

= 1.233 kilograms per acre-foot

= 0.0283 grams per cubic foot

= 0.0000624 pounds per cubic foot

= 0.0038 grams per US gallon

= 0.058419 grains per US gallon

= 0.07016 grains per Imperial gallon

= 1 milligram per liter

= 1 microlitre ( μL ) per liter

= 0.001 gram per litre

= 8.345 pounds per million gallons of water

Percent by Volume
Volume percent can be expressed as volume per unit volume as
percent by volume = 100 vc /(vc + vs)
where
vc = volume component
vs = volume solvent

Molarity
Molarity is the number of moles of solute (substance of interest - pollution, etc.) dissolved in one liter (volume) of the solution.

Molality
Molality is the number moles of solute dissolved in one kg (mass) of the solution.

Parts per Million by Weight in Water

The concentration in ppm of gas in water is meanly meant by weight. To express this concentration with metric units the density of water is needed.

The density of pure water has to be by definition 1000.0000 kg/m3 at a temperature of 3.98°C and standard atmospheric pressure, till 1969. Till then this was mean definition for the kilogram. Today's the kilo is defined as being equal to the mass of the international prototype of the kilogram. Water with a high purity (VSMOW) at a temperature of 4°C (IPTS-68) and standard atmospheric pressure has a density of 999.9750 kg/m3.

The density of water is effected by the temperature, pressure and impurities, i.e. dissolved gasses or the salinity of the water. Even the concerning concentration of gas dissolved in the water is affecting the density of the solution. By nature there's a chance that water contains a certain concentration of Deuterium which influences the density of the water. This concentration is also called the isotopic composition.

Accurate calculations on these conversions are only possible when the density of the water is measured. In practice the density of water is therefore set to 1.0 ·103 kg/m3. When calculating the conversion with this value you gets:

Jet Fuel Testing and Inspection.

2011-04-12T09:00:00.000-07:00

Jet aviation fuel tests:

Acidity, Aniline Point, Anti-icing Additives
API Gravity, API Density
Color (Saybolt Method)
Aromatics, Appearance
Burning Quality
Water Reaction
Vapor Pressure (RVP Method)
Viscosity
Distillation, Doctor Test
Explosiveness
FAME in Jet Fuel
Carbon Residue (Ramsbottom)
Smoke Point
Particle Count and ISO Coding
Gum Existent Steam
Flash-point, Freeze-point
Olefins Content, Naphthalenes Content
Conductivity, Corrosion, Copper ContentA
Engine Damage Testing for Dust and Volcano Particles
Heat of Combustion, Hydrogen Content
Lubricity (BOCLE)A
Fuel Degradation Storage Problems
Sulfur
MSEP (Micro-separarometer Index)

Aviation Gasoline Fuel Testing

2011-04-12T08:58:00.000-07:00

JET Fuel Laboratories handles full ASTM-910 specification testing for aviation fuel gasoline, also known as AVGAS. Super-Charge Octane performance test engine testing for ASTM D-909 is also carried out.

Test Specification for AVGAS: ASTM D-910

Avgas Fuel Test with ASTM Method:

Sulfur (ASTM D2622)
Vapor Pressure (ASTM D5191)
Water Reaction - Volume change (ASTM D1094)
Electrical Conductivity (ASTM D2624)
Octane Number (ASTM D2700)
Net Heat of Combustion (ASTM D3338)
Potential Gum (ASTM D873)
Color (ASTM D2392)
Density (ASTM D4052)
Distillation (ASTM D86)
Copper Corrosion (ASTM D130)
Tetraethyl Lead (ASTM D5059)
Lean Rating (ASTM D2700)
Freezing Point (ASTM D2386)
Performance Number (ASTM D909)

AVIATION FUEL TESTING EQUIPMENT

2011-04-12T08:14:00.000-07:00

TURBINE ENGINES

2011-04-11T11:13:00.000-07:00

A gas turbine, or a combustion turbine, is a rotary engine that produce energy from a flow of combustion gas.

It has a compressor coupled to a downstream turbine, and a combustion chamber in-between.

Gas turbine also called just the turbine component.

Air is sucked in by the intake portion of the engine and added to compressor which compress this air to a high potential.

The compressed air is subjected to combustion chamber where it is mixed with fuel spray and ignition source. The high potential burning mixture flow is directed througha nozzleover the turbine's blades, spinning the turbine which powers the compressor (turbine & compressor are coupled togather by a shaft) and, for some turbines, drives their mechanical output. when the hot gases exhuasts, it produce a thrust for the engine which pushes the A/C in forward direction.

The following diagram shows how air enters, compresses and after combustion produce thrust from the exhaust gases.

Aromaticity

2011-04-11T10:45:00.000-07:00

Definition: "Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone."

According to organic chemistry, the structures of some rings of hydrocarbons atoms are unexpectedly stable. It is usually considered to be because electrons are free to move around circular paths of atoms which are alternately "single" and "double-bonded" to one another. These bonds may be seen as a hybrid of a single bond and a double bond, each bond in the ring identical to every other. Such generaly-seen model of aromatic rings ( namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds (cyclohexatriene). The model for benzene consists of two resonance forms, which corresponds to the double and single bonds superimposing to give rise to six one-and-a-half bonds. Benzene is a more stable molecule than would be expected without accounting for charge delocalization.

Significance:

Key aromatic hydrocarbons are benzene, toluene, ortho-xylene and para-xylene. They are extracted from complex mixtures obtained by the refining of oil or by distillation of coal tar, and are used to produce a range of important chemicals and polymers,

MILITARY JET FUELS

2011-04-11T10:09:00.000-07:00

CHEMICAL COMPOSITION OF AVIATION FUEL:

Aviation fuels consist of blends of over a thousand chemicals, primarily Hydrocarbons (paraffins,olefins, naphthenes, and aromatics) as well as additives such asantioxidants and metal deactivators, and impurities.

The main components include n-octane and isooctane. Like other fuels, blends of aviation fuel used in piston engined aircraft are often described by their Octane rating.

CIVIL AVIATION FUEL

They are classified as A, B, TS-1, A1

MILITARY AVIATION FUEL

They are classified as jet propellant-1 (JP-1), (JP-4), (JP-5), (JP-8), (JP-8)+100 and 100LL (low lead)

JP-8

JP-8, (Jet Propellant-8) is a kerosene based jet fuel, converted by the U.S. government from JP-4 fuel. It is a less flammable, less hazardous fuel for better safety. Its NATO code is F-35, with FSII is F-34. JP-8 has a flash point of 46 °C (100 °F) compared to -18 °C (0 °F) for JP-4.

Commercial aviation uses a similar mixture under the name Jet-A.

JP-8 is formulated with icing inhibitor, corrosion inhibitors, lubricants, and antistatic agents, and less benzene (a carcinogen) and less n-hexane (a neurotoxin) than JP-4. However, it also smells stronger than JP-4. JP-8 has an oily feel to the touch, while JP-4 feels more like a solvent. As JP-8 is less volatile, it remains on the contaminated surfaces for longer time, increasing the risk of exposure.

JP-8+100

It is a version of JP-8 with an additive that increases its thermal stability by 56°C (a difference of 100°F). The additive is a combination of a surfactant, metal deactivator, and an antioxidant, and was introduced in 1994 to reduce cocking and fouling in engine fuel systems.

FSII

Fuel system icing inhibitor (FSII) is an additive to aviation fuels that prevents the formation of ice crystals and microbiological growth in fuel tanks and lines.
When the aircraft goes to higher altitude, the temperature drops and Jet fuel's capacity to hold water is diminished. Particulate water can separate out and could become a serious problem if it freezes in fuel lines or filters, blocking the flow of fuel and shutting

down an engine.

FSII is an agent that is mixed with jet fuel as it is pumped into the aircraft. The mixture of FSII must be between 0.10% and 0.15% by volume for the additive to work correctly, and the FSII must be distributed evenly throughout the fuel. Simply adding FSII after the fuel has been pumped is therefore not sufficient.

Large aircraft do not require FSII as they are usually equipped with electric fuel line heaters that keep the fuel at an appropriate temperature to prevent icing. However, if the fuel heaters are inoperable, the aircraft may be still be declared fit to fly, if FSII is added to the fuel.

WATER IN THE FUEL

It is very important that jet fuel be free from water contamination. During flight,the temperature of the fuel in the tanks decreases, due to the low temperatures in the upper atmosphere.

This causes precipitation of the dissolved water from the fuel. The separated water then drops to the bottom of the tank, because it is denser than the fuel. From this time on, as the water is no longer in solution, it can freeze, blocking fuel inlet pipes. Removing all water from fuel is impractical, therefore fuel heaters are usually used on commercial aircraft to prevent water in fuel from freezing.

There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30ppm (parts per million) free water.

Viscosity, Specific gravity & API Gravity

2011-04-11T10:06:00.000-07:00

Viscosity:
A Viscosity is a measure of the resistance of a fluid which is being deformed by either shear, stress or tensile stress. For (fluids only), viscosity is the measure of "thickness" or "internal friction".

Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. in short, the less viscous the fluid is, the greater its ease of movement (fluidity) will be.

Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. All real fluids have some resistance to stress and therefore are viscous, but a fluid which has no resistance to shear stress is known as an ideal fluid or inviscid fluid.

Specific gravity:

Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density (mass of the same unit volume) of a reference substance.
Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance.
The reference substance is usually water for liquids or air for gases
Temperature and pressure must be specified for both the sample and the reference.
Pressure is nearly always 1 atm equal to 101.325 kPa.

API Gravity:

The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks. API gravity is thus an inverse measure of the relative density of a petroleum liquid and the density of water, but it is used to compare the relative densities of petroleum liquids. For example, if one petroleum liquid floats on another and is therefore less dense, it has a greater API gravity. Although mathematically, API gravity has no units (see the formula below), it is nevertheless referred to as being in "degrees". API gravity is graduated in degrees on a hydrometer instrument. The API scale was designed so that most values would fall between 10 and 70 API gravity degrees.

The formula to obtain API gravity of petroleum liquids, from specific gravity (SG), is:

Direct Measurement of API gravity (Hydrometer method) = This method is detailed in ASTM D287.

Crude oil is classified as light, medium or heavy, according to its measured API gravity.
Light crude oil is defined as having an API gravity higher than 31.1 °API. (less than 870 kg/m3)
Medium oil is defined as having an API gravity between 22.3 °API and 31.1 °API. (870 to 920 kg/m3)
Heavy oil is defined as having an API gravity below 22.3 °API. (920 to 1000 kg/m3)
Extra heavy oil is defined with API gravity below 10.0 °API. (greater than 1000 kg/m3)