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Emerald Group Publishing Limited
Copyright © 2009, Emerald Group Publishing Limited
Parker's laser-based particle counter
Article Type: Equipment and software From: Aircraft Engineering and Aerospace Technology: An International Journal, Volume 81, Issue 6
Parker Hannifin, a major company in motion and control technologies, introduces the Parker icountACM20, a portable particle counting system specifically designed for use with aviation and diesel fuels that provides airport and aviation operations professionals with a quick and easy 2 min, economical fuel condition test.
There are a number of reasons why airport operators should use particle counting over current methods. Particle counting data are available in real time, and regulated by ISO11171. It provides both on- and off line testing, connects to existing sample points, and has inbuilt alarms. Furthermore, it is portable and suitable for high-pressure systems, so laboratory cost is reduced.
Particle counting based on the principle of light obscuration is otherwise known as light blockage or light extinction, where an object passing in front of a light source creates a shadow of a particle suspended in a fluid and is measured by voltage drop across a light sensitive diode. The signal generated as a result of the shadow is dependent on the size of the particle and the speed at which it passes through the light.
Light obscuration is the most common and accurate method. Now for the first time, fuel suppliers from the refineries through distribution hubs, to the final delivery of fuel into the aircraft can be sure that the fuel being delivered is clean and dry.
Dispersed solids in fuels causes blockage of fuel ways, additive depletion, deposition in storage, equipment failure from wear, and premature filter blocking. Furthermore, microbial contamination occurs anywhere there is water. Fuel contaminants in aviation fuel can take the form of water, particulate and microbiological organisms.
Problems arising from dispersed water in fuel that has entered a jet engine include the fact that water will not burn, leading to flameout or reduced power, and corrosion. Jet fuels have a marginal solubility for water, and one that is very temperature dependent, potentially resulting in water forming at the bottom of the tank and/or pipelines in cold conditions. Water encourages microbiological infestations, and free-water cooling produces ice which can block engine filters.
In a recent study carried out at a major international airport, icountACM20, the portable monitor for Aviation fuel applications, was used to monitor refuelling activities around the airport. The icountACM20 results clearly indicated that there were levels of solid contamination present throughout the underground hydrant system that were previously undetected by other tried monitoring methods.
As a result the hydrant was flushed and readings reduced to acceptable levels. “The ease of use of the icountACM20, being able to connect directly to existing sampling points on vehicles and around the airport, combined with real time, accurate and repeatable monitoring has lead to a further programme of monitoring for other airports operated by the oil company” stated the aviation operations manager.
The Joint Inspection Group (JIG), comprising representatives from all the major oil companies, has published the Defstan standard with particle detection being required as the approved method of determining the quality of aviation fuel at each stage of the manufacturing and distribution process, from refinery to fuel farm and refuelling points.
The JIG actually compiles the individual test requirements and limits drawn from the contributory JetA-1 specifications and publishes the list in cooperation with IATA.
Following the Defstan accreditation, the icountACM20 can now be used in place of traditional and often subjective methods of measuring jet fuel contamination levels, such as Clear and Bright. The unit can discern moisture and contaminant particles as low as 4 μm in size, which can contaminate fuel during the distribution process, as well as through installation and maintenance, or through degradation of components. It can be used effectively with minimum training.
Complementing the ACM20, the icountPD online particle detector features independent monitoring of system contamination trends, early warning LED or digital display indicators for low-, medium- and high-contamination levels. The laser-based technology helps prolong fluid life and reduce machine downtime. Icount PD has visual indicators with power and alarm output warnings, providing continuous performance for dependable analysis with self diagnostic software, and full PC/PLC integration technology using digital interfaces, such as RS232, and analogue interfaces, such as 0-5 V or 4-20 mA.
Parker Hannifin has also introduced the world's first online Zone 2 classified ATEX-approved particle counter, for use with hydrocarbon and aviation turbine fuels. The icountACM20 Z2 allows quick, accurate and safe detection PF contaminants at refineries, pipeline distribution terminals, storage depots and airports (Figure 2).