1.1 This test method covers the procedure for rating the tendencies of gas turbine fuels to deposit decomposition products within the fuel system. 1.2 The differential pressure values in mm Hg are defined only in terms of this test method. 1.3 The deposition values stated in SI units shall be regarded as the referee value. 1.4 The pressure values stated in SI units are to be regarded as standard. The psi comparison is included for operational safety with certain older instruments that cannot report pressure in SI units. 1.5 No other units of measurement are included in this standard.