ISTOCK/ANDRII ATANOV
WORK SAFE By Walter P. Chartrand
Ensure Fuel Purity with Soak Testing The performance and safety of your aircraft depend on this procedure.
A
T MY FIRM, AVIATION MARKETING SERVICES, we’re often asked about soak testing, which is used to verify the purity of aviation fuel.
If you’re responsible for—or depend on—fuel in your work, you likely know how important it is to perform a
Fuel Systems, Storage Tanks, and Related Equipment A soak test consists of filling a fuel system (stainless steel, aluminum, epoxy lined, or rubber bladder) with an adequate volume of the appropriate-grade fuel and, after following the recommended recirculation procedures, allowing it to soak for a period of time recommended by ASTM or the specific fuel supplier. Before putting the fuel in the system, be sure to retain a sample to serve as a control batch should testing reveal off-specification product. By following the stringent requirements of Energy
soak test after completing new construction or major repairs to tanks or piping. This applies to both fuel stor- age systems and servicing vehicles. Afterward, a labora- tory evaluation of the fuel samples used in the soak test can detect any potential contaminants—from solvents used in coatings and linings, welding flux, preservative oils (corrosion inhibitors), valve grease, and other debris—that could compromise the performance and safety of the fuel. Because soak testing is such an important step in
purchasing fuel, any acquisition or modification contracts for new fuel systems or servicing vehicles should include a clause that requires the manufacturer or con- tractor to provide evidence that a proper soak test has been performed. The clause should also require that the test results verify the fuel meets the appropriate ASTM International specifications. Let’s review how to conduct a soak test and the vari- ous lab tests involved.
64 ROTOR 2020 Q4
Institute (EI) Standard 1541, Requirements for Internal Protective Coating Systems Used in Aviation Fuel Handling Systems, you’ll dramatically reduce the risk of fuel contamination. Adherence to this industry standard ensures that the proper coating materials were correctly applied and allowed to fully cure as recommended by the manufacturer, and that storage tanks (including pip- ing, pumps, valves, meters, filter vessels, and so on) are filled to the normal level and the fuel recirculated com- pletely at least once and allowed to soak for a minimum of four days and a maximum of seven. At the end of the designated soak period, obtain a 1 gallon sample from the new or repaired system and send it off for laboratory evaluation. The best location from which to obtain a sample is the low-point drain. Remember to displace an adequate volume in the sam- pling piping to ensure a truly representative sample of the tank bottom.
Fuel-Servicing Vehicles and Hoses All fuel-servicing vehicles with tanks and piping made of aluminum or stainless steel should have the appropriate fuel circulated throughout the system. Fueling vehicles (whether new, repaired, or those that have undergone an extended period out of service) should be filled to the normal level and the fuel recirculated completely at least once and allowed to soak for at least an hour. You may obtain 1 gallon representative samples of fuel from any combination of multiple low-point drains and combine them into a single sample. For proper soak testing, every fueler loading hose and
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