1.1 The purpose of this standard is to describe the test method used to evaluate the tendency of gas turbine fuels to deposit decomposition products within the combustion system. 1.2 The test results are representative of the behavior of the fuel during the operation of a gas turbine and can be used to evaluate the level of deposits formed when the liquid fuel is brought into contact with a hot surface at a specified temperature. 2 RATIONALE OF THE METHOD With this method, the high temperature stability of gas turbine fuels is measured; using the "Jet Fuel Thermal Oxidation Tester" (JFTOT) (Control Test of Thermal Oxidation of Turbine Fuels), which subjects the fuel to be tested to conditions that can be related to those that occur in the turbine system. gas. The fuel is pumped at a preset flow rate through a heater after which it enters a stainless steel precision filter where degradation products can be retained. 2.1.1 The device needs 600 mI of fuel sample for a 2 h 30 min test. The essential data derived are the sum of deposits or sediments on an aluminum heating tube and the evaluation of the clogging of a precision filter of nominal porosity of 1 7 //m located downstream of the heating tube.