AvCount Particle Counter news…

1/1/2008

AvCount IP 565 included in DEF STAN 91-91

The Seta Avcount Particle Counter, IP 565, has been agreed for inclusion in DEF STAN 91-91 as a more precise rapid alternative for checking particulate contamination of jet fuels……

Because of the critical nature of aviation fuel and the potential hazards posed by fuel contaminated with particulate, the industry operates to stringent quality control guidelines. These are designed to help ensure that only clean, dry and uncontaminated fuel is delivered to aircraft. The guidelines recommend approved practices for receiving fuel into airport storage and delivering it to aircraft; they also include recommended equipment for use by airport fuelling facilities, system checks and field tests.

Contamination
On its journey from refinery to aircraft fuel tank, aviation fuel is likely to spend time in storage tanks and also be transferred one or more times. Each time a transfer occurs there is a potential for contamination of the fuel to occur. Particulate matter and water are the most common fuel contaminants. A primary source of particulate matter is the solid corrosion products that form inside steel pipes and tanks (rust and scale). Other sources of particulate matter are refinery processing materials (catalyst fines and salts); airborne solids that enter through tank vents or slip past the seals of floating roof tanks (dust and pollen); solids from damaged hoses and filters (rubber particles and fibers); and solids from microbial infestation (cellular debris and microbial by-products).

Filtration
A very important stage in fuel distribution is receipt into airport storage facilities. As fuel is received here, tests are conducted to confirm the identity of the fuel and also to check for water and particulate contamination. Fuel is typically filtered both going into airport storage tanks and also at the tank outlet. Filtration also occurs during refueling to ensure that clean fuel is being uplifted to the aircraft. Unknown contaminants or harsh operating conditions may however lead to a reduction in filter efficiency and therefore monitoring filter performance is of great importance.

DEF STAN 91-91 Jet A-1 Particulate Measurement
The current guidelines and test methods for aviation fuels were developed in the late 1950’s and have severe limitations regarding detection of particulate. DEF STAN 91-91 currently specifies a contamination limit of 1mg/l at point of manufacture. The aviation fuel suppliers and jet engine industry are striving to improve fuel quality, enabling enhanced engine reliability and reduced maintenance. However, the capability of providing the levels of accuracy for this specification limit with the existing methods is highly questionable.

Current testing - IP 423 & ASTM D545
Refinery or QC lab based testing will typically use filtration tests in accordance with IP 423 or ASTM D5452 to determine particulate contamination at point of manufacture. Field based testing is based around the traditional ‘Clear & Bright’ or the ‘line sampling method’ (IP 216 or ASTM D2276)’. Clear & Bright is a simple visual test but can be subjective, it is limited by the ability of the human eye to only detect particles greater than 40 microns. The filtration and line sampling methods require laboratory based analysis so real time analysis is not possible. Of key importance is that all these ‘traditional tests’ suffer from poor resolution and cannot provide information regarding particle size or distribution.

Industry Change
Current restrictions have prompted the need for a more objective, quantitative assessment of the cleanliness of jet fuel and hence the development of the Seta ‘AvCount’ analyser.

IP & ASTM Particulate Measurement
Following a successful European laboratory round robin the Energy Institute (IP) in London has now published two new test methods for the Particulate Measurement of Aviation fuels.

IP 565
“Determination of the level of cleanliness of aviation turbine fuels – portable automatic particle counter method”

The Avcount from Seta Analytics is a fully automatic Particle counter which complies with the new method, IP 565.

Improving quality control & process efficiency with AvCount – IP 565
AvCount is an easy to use, rugged, portable instrument specifically designed for testing the particulate content of fuel and lubricants. It incorporates the latest measuring technology to provide a unique, innovative and low-maintenance test instrument.

‘AvCount’ features a high precision laser measurement system capable of identifying particle sizes from 4 µm to >70 µm. Test operation is easy - once a test is started an integral pump draws the sample into the measurement chamber. The flushing and measurement sequence runs automatically, the complete test sequence takes under 4 minutes and uses only 80ml of sample. Results are displayed in real time on the LCD display and printed on the integral printer. Test results can be saved to memory for trend analysis of samples, or downloaded to a PC in various formats using a “Log and Show” software option.

Def Stan 91-91 - Issue 6
During the December 2007 ASTM D02 meeting of aviation fuel/engine/airframe experts, it was announced by the UK QinetiQ Group (responsible to the UK CAA/MOD for DEF STAN 91-91 Jet A-1 specification), that there is a commitment to include new particle counting methods, including IP 565 in the forthcoming release of DEF STAN 91-91 Issue 6.

Who should use Avcount?
Aviation Fuel QA personnel in laboratory and field testing environments benefit from a far superior means of ensuring fast and reliable particulate test results than is currently available.
Fuel suppliers can provide customers with a more comprehensive and secure ‘fuel cleanliness’ report whilst significantly reducing the effort needed for testing.
Fuel filter maintenance personnel can more easily identify and isolate any potential problem, supporting reduced maintenance costs and downtime.

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