ASTM D7154 Test Method for Freezing Point of Aviation Fuels (Automatic Fiber Optical Method)
4. Summary of Test Method
4.1 After insertion of 25 mL of the test specimen into a test chamber, the test specimen is cooled while being continuously stirred and monitored by a fiber optical system. The temperature of the specimen is measured with an electronic temperature measuring device. When crystal formation is detected in the specimen, the temperature is recorded and the specimen in the test chamber is warmed, while being continuously stirred and monitored by the optical system, until the crystals in the specimen completely disappear. The temperature of the specimen when the last crystals disappear is recorded as the freezing point (automatic fiber optical method).
5. Significance and Use
5.1 The freezing point of an aviation fuel is an index of the lowest temperature of its utility for certain applications. Solid hydrocarbon crystals can restrict the flow of fuel in the fuel system of the aircraft. The temperature of the fuel in the aircraft tank normally decreases during flight depending on aircraft speed, altitude, and flight duration. The freezing point of the fuel must always be lower than the minimum operational fuel temperature.
5.2 Petroleum blending operations require precise measurement of the freezing point.
5.3 This test method expresses results with a resolution of 0.1 °C.
5.4 This test method eliminates most of the operator time and judgment required by Test Method D2386.
5.5 When the specification requires the use of Test Method D2386, do not substitute this test method or any other method.
