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AvCount - Precise Particulate measurement


and its importance in Jet Fuel…

Particulate in Jet Fuels – why is measurement so important?

Small particles of insoluble composition present in jet fuel can agglomerate to form particulate material that may effect or wear fuel nozzles and ducts within the engine; in addition particulate contamination in the fuel may affect the quality of spray produced by the fuel injection system reducing combustion efficiencies. It is therefore important to identify and remove particulate before the fuel is pumped onto an aircraft to maximise fuel economy and minimise maintenance down time.

Particulate material contamination typically originates from tanks, pipelines, hoses, pumps, people, and even the environment – such as construction work near or on the airport. The most common sediments found in aviation fuels are pieces of rust, paint, metal, rubber, dust, and sand.

For quality control purposes particulate material is classified by particle size.

The US Aviation Fuel Handling Handbook states that ‘particles of coarse sediment, that is 10 microns in size or larger, may clog nozzle and other fine screens throughout the aircraft fuel system, and most dangerously, the fuel orifices of aircraft engines. Particles of this size can also become wedged in sliding valve clearances and valve shoulders where they cause excessive wear in the fuel controls and fuel injection equipment’.

A technical review of fuels by Chevron states:
“While the fuel filters recommended by engine manufacturers have a nominal pore size of 10 microns, studies by Southwest Research Institute reveal that the critical particle size for initiating significant abrasive wear in rotary injection fuel pumps and in high-pressure fuel injection systems is as small as 6-7 microns.”

For many years the Aviation industry has relied upon visual checks, known as ‘the clear and bright test’ to identify the presence of particulate which is identified as a haze or suspension in the fuel sample.

The problem is that to be visible to the naked eye, sediment particles must be larger than 30-40 microns whereas the primary particles that may be present in fuel are typically only 1-5 micron in size.

Recently the development of high precision engine technology, together with greater emphasis on fuel efficiency, has lead to the demand for a more precise method of determining the presence of particulate in fuels.

A new test method IP 565 has recently been included in International Fuel specification DEF STAN 91-91. This uses the latest laser technology as a way of checking and managing the quality of fuel from the refinery to wing tip. The Seta AvCount particle analyser is a rugged, automatic portable instrument which strictly conforms to this method. It is easy to use and specifically designed for testing the particulate content of fuel and lubricants from 4-70 microns. It incorporates the latest measuring technology to provide a unique, innovative and low-maintenance test instrument.

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Magnified 10 micron fuel particle

Copyright Stanhope–Seta Limited 2014