April 2006

OEM INTRINSIC SAFE WATER IN JET FUEL SENSOR

Water can occur in three different forms in jet fuel: dissolved in the fuel, as a separate liquid phase (free water), and as a fuel-water emulsion. Some amount of dissolved water is present in all fuels. Free water or a water emulsion are potentially hazardous and must be avoided. The EASZ-1 is an instrument that will measure water contamination in a dissolved, emulsion or free water state below 100ppm with a resolution of +/- 35ppm and up to 250,000 ppm. The advantage of the EASZ-1 is it’s ability to measure below and above saturation levels with a remarkable response time of 1 second. No matter how accurate an instrument claims to be, the problem is real time immediate response measurements that can be considered representative of the liquid in the flowing stream. The JX version of our measurement cell has been modified to sense the total volume of Jet Fuel through a 1 inch line . For a 3 inch line, it may be necessary to use a mixing device designed to mix the fluid to a homogeneous condition before drawing sample through a probe into the EASZ-1 .Whatever the situation, it is important to conduct independent laboratory tests which will prove the viability of a moisture in oil measurement device through representative and reliable composite samples. Since laboratory analysis will report values in ppm, it is necessary to correlate ppm lab reports with ppm reports from the EASZ-1 sensor. The standard OEM sensor can be manufactured out of stainless steel but is not limited to this material. Special applications which require exotic materials such as Duplex, Monel, Hastelloy, Titanium or gold plating can be accommodated. Please contact our corporate headquarters for special requirements.

EASZ-1 measures dissolved water in Jet Fuel. Water is very slightly soluble in jet fuel, and conversely, jet fuel is very slightly soluble in water. The amount of water that jet fuel can dissolve increases with the aromatics content of the fuel and temperature. Fuel in contact with free water is saturated with water, i.e., the fuel has dissolved all the water it can hold. A typical water-saturated kerosene-type fuel contains between 40 and 80 ppm dissolved water at 21°C (70°F). If the temperature of the fuel increases, it can dissolve more water. Conversely, if the temperature of water-saturated fuel decreases, some of the water dissolved in the fuel will separate as free water. The EASZ-1 has a built in temperature sensor which connects to the electronic PCB and internal software compensates for changes in dielectric due to temperature change. The change is normally small but for some clients this small difference may have greater value than others.

Fuel close to a fuel-water or fuel-air interface will reach water equilibrium in a matter of minutes. However, if the volume of fuel is large and the area of the interface is limited – conditions that exist in a large fuel storage tank – some of the fuel will be many feet from the interface. In the absence of mixing, it will take a lot longer for this portion to reach water equilibrium. In fact, fuel in a large tank may never come to complete water equilibrium since ambient temperature and relative humidity are constantly changing.

EASZ-1 measures Free Water in Jet Fuel In jet fuel, free water exists as a separate liquid phase. Since water is denser than jet fuel, free water, under the influence of gravity, forms a lower layer and the jet fuel an upper layer. If jet fuel and water are mixed, normally they will quickly separate again. The speed of the separation and the sharpness of the fuel-water interface are indications of the fuel’s water separability. Free water could appear at any time and happen so fast that it is possible that it may go unnoticed. The EASZ-1 measures once a second and none of the fuel is missed while it passes through the sensor chamber. When water-saturated jet fuel cools, free water separates out, taking the form of many very small droplets sometimes called dispersed water. Even if they are not stabilized by surfactants the droplets coalesce slowly because of their small size. The suspended droplets give the fuel a hazy appearance. The haze will disappear if the fuel is warmed enough to redissolve the water. The EASZ-1 will measure water content if the fuel is warmed. Although it may be safe to use such and oil in a warmer process, the water content is a valuable piece of information to clients wishing to trace their water level history.

Contact us with your OEM applicaton.

Common Knowledge

AVIATION TURBINE FUEL (JET FUEL)

CIVIL JET FUELS

Aviation turbine fuels are used for powering jet and turbo-prop engined aircraft and are not to be confused with Avgas. Outside former communist areas, there are currently two main grades of turbine fuel in use in civil commercial aviation : Jet A-1 and Jet A, both are kerosene type fuels. There is another grade of jet fuel, Jet B which is a wide cut kerosene (a blend of gasoline and kerosene) but it is rarely used except in very cold climates.

JET A-1

Jet A-1 is a kerosene grade of fuel suitable for most turbine engined aircraft. It is produced to a stringent internationally agreed standard, has a flash point above 38°C (100°F) and a freeze point maximum of -47°C. It is widely available outside the U.S.A. Jet A-1 meets the requirements of British specification DEF STAN 91-91 (Jet A-1), (formerly DERD 2494 (AVTUR)), ASTM specification D1655 (Jet A-1) and IATA Guidance Material (Kerosine Type), NATO Code F-35.

JET A

Jet A is a similar kerosene type of fuel, produced to an ASTM specification and normally only available in the U.S.A. It has the same flash point as Jet A-1 but a higher freeze point maximum (-40°C). It is supplied against the ASTM D1655 (Jet A) specification.

JET B

Jet B is a distillate covering the naphtha and kerosene fractions. It can be used as an alternative to Jet A-1 but because it is more difficult to handle (higher flammability), there is only significant demand in very cold climates where its better cold weather performance is important. In Canada it is supplied against the Canadian Specification CAN/CGSB 3.23

MILITARY

JP-4

JP-4 is the military equivalent of Jet B with the addition of corrosion inhibitor and anti-icing additives; it meets the requirements of the U.S. Military Specification MIL-DTL-5624U Grade JP-4. (As of Jan 5, 2004, JP-4 and 5 meet the same US Military Specification). JP-4 also meets the requirements of the British Specification DEF STAN 91-88 AVTAG/FSII (formerly DERD 2454),where FSII stands for Fuel Systems Icing Inhibitor. NATO Code F-40.

JP-5

JP-5 is a high flash point kerosene meeting the requirements of the U.S. Military Specification MIL-DTL-5624U Grade JP-5 (as of Jan 5, 2004, JP-4 and 5 meet the same US Military Specification). JP-5 also meets the requirements of the British Specification DEF STAN 91-86 AVCAT/FSII (formerly DERD 2452). NATO Code F-44.

JP-8

JP-8 is the military equivalent of Jet A-1 with the addition of corrosion inhibitor and anti-icing additives; it meets the requirements of the U.S. Military Specification MIL-DTL-83133E. JP-8 also meets the requirements of the British Specification DEF STAN 91-87 AVTUR/FSII (formerly DERD 2453). NATO Code F-34.

AVIATION FUEL ADDITIVES

Aviation fuel additives are compounds added to the fuel in very small quantities, usually measurable only in parts per million, to provide special or improved qualities. The quantity to be added and approval for its use in various grades of fuel is strictly controlled by the appropriate specifications.

A few additives in common use are as follows:

1. Anti-knock additives reduce the tendency of gasoline to detonate. Tetra-ethyl lead (TEL) is the only approved anti-knock additive for aviation use and has been used in motor and aviation gasolines since the early 1930s.
   
2. Anti-oxidants prevent the formation of gum deposits on fuel system components caused by oxidation of the fuel in storage and also inhibit the formation of peroxide compounds in certain jet fuels.
   
3. Static dissipater additives reduce the hazardous effects of static electricity generated by movement of fuel through modern high flow-rate fuel transfer systems. Static dissipater additives do not reduce the need for `bonding' to ensure electrical continuity between metal components (e.g. aircraft and fuelling equipment) nor do they influence hazards from lightning strikes.
   
4. Corrosion inhibitors protect ferrous metals in fuel handling systems, such as pipelines and fuel storage tanks, from corrosion. Some corrosion inhibitors also improve the lubricating properties (lubricity) of certain jet fuels.
   
5. Fuel System Icing Inhibitors (Anti-icing additives) reduce the freezing point of water precipitated from jet fuels due to cooling at high altitudes and prevent the formation of ice crystals which restrict the flow of fuel to the engine. This type of additive does not affect the freezing point of the fuel itself. Anti-icing additives can also provide some protection against microbiological growth in jet fuel.
   
6. Metal de-activators suppress the catalytic effect which some metals, particularly copper, have on fuel oxidation.
   
7. Biocide additives are sometimes used to combat microbiological growths in jet fuel, often by direct addition to aircraft tanks; as indicated above some anti-icing additives appear to possess biocidal properties.
   
8. Thermal Stability Improver additives are sometimes used in military JP-8 fuel, to produce a grade referred to as JP-8+100, to inhibit deposit formation in the high temperature areas of the aircraft fuel system.

POWER BOOSTING FLUIDS

It used to be commonplace for large piston engines to require special fluids to increase their take-off power. Similar injection systems are also incorporated in some turbo-jet and turbo-prop engines. The power increase is achieved by cooling the air consumed, to raise its density and thereby increase the weight of air available for combustion. This effect can be obtained by using water alone but it is usual to inject a mixture of methanol and water to produce a greater degree of evaporative cooling and also to provide additional fuel energy.

For piston engines, methanol/water mixtures are used and these may have 1 percent of a corrosion inhibiting oil added. The injection system may be used to compensate for the power lost when operating under high temperature and/or high altitude conditions (i.e. with low air densities) or to obtain increased take-off power under normal atmospheric conditions, by permitting higher boost pressure for a short period.

Both water alone and methanol/water mixtures are used in gas turbine engines, principally to restore the take-off power (or thrust) lost when operating under low air density conditions. Use of a corrosion inhibitor in power boost fluids supplied for these engines is not permitted.