Aircraft fuel

Two significant chemical exchange reactions useful for the concentration of deuterium are 

ACS Symposium Series American Chemical Society Washington, DC, 1975. 

In the hotter column, at 130°C, the exchange equilibrium constant Is 1.69, and deuterltmi Is returned from the aqueous phase to the gaseous phase. Thus, dual-temperature operation avoids the need for a chemical reaction to return the desired Isotope from the phase In which It enriches to the phase In which it Is depleted. 

In operation, feed water at the natural deuterium abundance of 145 ppm Is fed to the top of the cold column, depleted water at 120 ppm deuterium Is discarded from the bottom of the hot column, and enriched D2O Is withdrawn between the cold and hot columns. 

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Super slurper Supersonic aircraft fuel Supertarget Super three SUPERTRAP Supplies... 

Combustion. The primary reaction carried out in the gas turbine combustion chamber is oxidation of a fuel to release its heat content at constant pressure. Atomized fuel mixed with enough air to form a close-to-stoichiometric mixture is continuously fed into a primary zone. There its heat of formation is released at flame temperatures deterruined by the pressure. The heat content of the fuel is therefore a primary measure of the attainable efficiency of the overall system in terms of fuel consumed per unit of work output. Table 6 fists the net heat content of a number of typical gas turbine fuels. Net rather than gross heat content is a more significant measure because heat of vaporization of the water formed in combustion cannot be recovered in aircraft exhaust. The most desirable gas turbine fuels for use in aircraft, after hydrogen, are hydrocarbons. Fuels that are liquid at normal atmospheric pressure and temperature are the most practical and widely used aircraft fuels kerosene, with a distillation range from 150 to 300 °C, is the best compromise to combine maximum mass —heat content with other desirable properties. For ground turbines, a wide variety of gaseous and heavy fuels are acceptable. 

Exhaust emissions of CO, unbumed hydrocarbons, and nitrogen oxides reflect combustion conditions rather than fuel properties. The only fuel component that degrades exhaust is sulfur the SO2 concentrations ia emissions are directly proportional to the content of bound sulfur ia the fuel. Sulfur concentrations ia fuel are determined by cmde type and desulfurization processes. Specifications for aircraft fuels impose limits of 3000 —4000 ppm total sulfur but the average is half of these values. Sulfur content ia heavier fuels is determined by legal limits on stack emissions. 

Water plays a primary role in corrosion of the metal walls of tanks and pipes (17), and increases the tendency for high speed pumps to produce wear particles and to exhibit shortened life. Formation of corrosion products can be controlled by addition of corrosion inhibitors, a mandatory additive in military fuels. However, corrosion inhibitors may also degrade other fuel properties and adversely affect ground filtration equipment. Thus they are not generally acceptable in commercial fuels where rigorous attention is given to clean and dry fuels upon aircraft fueling. 

Aircraft Fuels. Demand for aviation gas turbine fuels has been growing more rapidly than demand for other petroleum products since 1960, about 3—5% per year compared with 1% for all oil products. This strong demand reflects a current and predicted growth in worldwide air traffic of 4—7% annually until the end of the century. Total world oil demand will be up by 15% by the year 2000, but aviation fuel demand will increase by 50—125%. However, the fraction of the oil barrel devoted to aviation, now about 8%, will increase only slightly. 

H. C. Barnett and R. R. Hibbard, Properties of Aircraft Fuels, NASA TN 3276, NASA, Lewis Research Center, Qeveland, Ohio, Aug. 1956. 

Chemical Resistance. Fluorocarbon elastomer compounds show excellent resistance to automotive fuels and oils, hydrocarbon solvents, aircraft fuels and oils, hydrauHc fluids, and certain chlorinated solvents, and may be used without reservation. 

For gasoline and aircraft fuels see Hibhard, NACA Res. Mem. E56I21 (declassified 1958). 

In recent years it has become apparent that widespread microbial infections of materials in the manufacturing industries can lead to corrosion for the reason briefly outlined above. Examples include the instant rusting of machined parts, corrosion of machine tools, aircraft fuel tanks, hydraulic systems, strip steel etc. 

Uses. n-Pentane has found use as an anesthetic an expl suppressant when mixed with a halogen-ated hydrocarbon and included in aircraft fuel (Ref 13) a jet engine fuel (Ref 16a) as a base for synthetic rubbers and plastics a parent compd for the formation of nitropentanes and azido nitro pentanes used as expls and propints (Refs 15a, 15b 21a) also, as a parent compd for fluorine-contg resin binders which impart both thermal stability and, in conjunction with metal hydrides, high impulse to solid propints (Ref 15b)... 

Selden A, Ahlborg G, Jr. 1991. Mortality and cancer morbidity after exposure to military aircraft fuel. Aviat Space Environ Med 62(8) 789-794. 

Uses. JP-4 and JP-7 (jet propellant-4 and jet propellant-7) are used by the US Air Force as aircraft fuels. 

JP-5 F-44 High-flash/high-freeze-point, kerosene-based Naval carrier aircraft fuel will not corrode copper and will not emulsify with salt water... 

JP-7 — Low-volatility kerosene very high performance aircraft fuel... 

Jet fuels are blended primarily from straight-run distillate components and contain virtually no olefins. Aromatics in jet fuel are also limited. High aromatic content can cause smoke to form during combustion and can lead to carbon deposition in engines. A total aromatic content >30% can cause deterioration of aircraft fuel system elastomers and lead to fuel leakage. 

The electrical conductivity of fuel must be maintained at a minimum and maximum level. Fuel must have adequate conductivity to ensure that static charge does not build up in the fuel. However, if fuel is too highly conductive, some capacitance-type aircraft fuel gauges can be disrupted. 

Bomb Igniter, Ml5 is designed to be attached to a jettison-type aircraft fuel tank to adapt it for use as a fire bomb. 

What follows is a summary of the props requirements of the most common jet-aircraft fuels (JP series) and a list of recent review articles on these and other jet fuels of special interest... 

Theoretically, use of fuel as a coolant is convenient. But, it is well known that heating oils for even short periods of time accelerates gum and sediment formation. (In fact, this is the basis for many stability prediction tests in the petroleum industry.) It was not unexpected then, that when fuels are heated in aircraft fuel systems, temperatures would be high enough to cause some fuel degradation... 

The term "aviation gasoline indicates the gasoline which becomes the base of the aircraft fuel. It is either "straight-tun" or "cracked gasoline , prepd by the Houdry process. Its boiling range, 100°F(37.78°C) to 249°F(120.56°C), is lower than that for std gasoline... 

Field Sampling. An opportunity arose where actual field samples could be analyzed by both the infrared and gas chromatographic methods. At Robins AFB, Georgia, workers were inspecting and repairing the interior and exterior of C-141 aircraft fuel tanks. They were exposed only to JP-4 fuel fumes. Duplicate charcoal tubes or vapor monitors were attached to each worker, one on each lapel. Samples were drawn through the charcoal tubes at 0.20 to 0.26 1pm by portable pumps attached to the worker s belt. Because of slight variations, the total volumes collected for the duplicates were close, but not exactly the same in all cases. Samples were then labeled and shipped to our Laboratory for analysis by both methods. 

In the event of another major war, it is probable that all existing isomerization units would be reactivated and pushed to capacity. Although production of Grade 115/145 aviation fuel required by newer aircraft engines may place somewhat greater emphasis on aromatics, there would still be a demand for maximum alkylate production, and butane isomerization would again play an important role. Expansion of pentane and naphtha isomerization is somewhat less certain and would depend on future developments in aircraft fuels. 

Effect of Petroleum Fuel Properties. Three primary requirements must be met by practical fuels for aircraft turbojets. These requirements are They must be available in large quantities at low cost, they must produce satisfactory performance in all types of engines, and they must be suitable for aircraft fuel systems. Petroleum fuels vary in volatility, chemical composition, and concentrations of minor nonhydrocarbon compo-... 

Aircraft canopies Aircraft engines Aircraft fittings Aircraft fuels Aircraft sealants... 

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