ASTM D3241 Method for Thermal Oxidation Stability of Aviation Turbine Fuels
ASTM D3241 Standard Test Method for Thermal Oxidation Stability of Aviation Turbine Fuels (JFTOT Procedure)
8. Standard Operating Conditions
8.1 Standard conditions of the test method are as follows:
8.1.1 Fuel Quantity, 450-mL minimum for test + about 50 mL for system.
8.1.2 Fuel Pre-Treatment - Filtration through a single layer of general purpose, retentive, qualitative filter paper followed by a 6-min aeration at 1.5 L/min air flow rate for a maximum of 1000 mL sample using a coarse 12-mm borosilicate glass gas dispersion tube.
8.1.3 Fuel System Pressure, 3.45 MPa (500 psi) ±10 % gauge.
8.1.4 Thermocouple Position, at 39 mm.
8.1.5 Fuel System Prefilter Element, filter paper of 0.45-µm pore size.
8.1.6 Heater Tube Control Temperature, preset as specified in applicable specification.
8.1.7 Fuel Flow Rate, 3.0 mL/min ± 10 %.
8.1.8 Minimum Fuel Pumped During Test, 405 mL.
8.1.9 Test Duration, 150 ± 2 min.
8.1.10 Cooling Fluid Flow, approximately 39 L/h, or center of green range on cooling fluid meter.
8.1.11 Power Setting, approximately 75 to 100 on non-computer models; internally set for computer models.
9. Preparation of Apparatus
9.1 Cleaning and Assembly of Heater Test Section:
9.1.1 Clean the inside surface of the heater test section using a nylon brush saturated with trisolvent material to remove all deposits.
9.1.2 Check the heater tube to be used in the test for surface defects and straightness by referring to the procedure in Annex A1.10. Be careful, also, to avoid scratching tube shoulder during the examination, since the tube shoulder must be smooth to ensure a seal under the flow conditions of the test.
9.1.3 Assemble the heater section using new items: (1) visually checked heater tube, (2) test filter, and (3) three O-rings. Inspect insulators to be sure they are undamaged.
NOTE 1 - Heater tubes must not be reused. Tests indicate that magnesium migrates to the heater tube surface under normal test conditions. Surface magnesium may reduce adhesion of deposits to reused heater tube.
9.1.4 During assembly of heater section, handle tube carefully so as not to touch center part of tube. IF CENTER OF HEATER TUBE IS TOUCHED, REJECT THE TUBE SINCE THE CONTAMINATED SURFACE MAY AFFECT THE DEPOSIT-FORMING CHARACTERISTICS OF THE TUBE.
9.2 Cleaning and Assembly of Remainder of Test Components:
9.2.1 Perform the following steps in the order shown prior to running a subsequent test.
NOTE 2 - It is assumed that the apparatus has been disassembled from previous test (see Annex A2 or appropriate user manual for assembly/disassembly details).
9.2.2 Inspect and clean components that contact test sample and replace any seals that are faulty or suspect especially the (1) lip seal on piston, and (2) O-rings on the reservoir cover, lines, and prefilter cover.
9.2.3 Install prepared heater section (as described in 9.1.1-9.1.4).
9.2.4 Assemble pre-filter with new element and install.
9.2.5 Check thermocouple for correct reference position, then lower into standard operating position.
9.2.6 On Models 230 and 240, make sure the water beaker is empty.
10. Calibration and Standardization Procedure
10.1 Perform checks of key components at the frequency indicated in the following (see Annexes or user manual for details).
10.1.1 Thermocouple - Calibrate a thermocouple when first installed and then normally every 30 to 50 tests thereafter, but at least every 6 months (see A2.2.8).
10.1.2 Differential Pressure Cell - Standardize once a year or when installing a new cell (see A2.2.6).
10.1.3 Aeration Dryer - Check at least monthly and change if color indicates significant absorption of water (see 7.3).
10.1.4 Metering Pump - Perform two checks of flow rate for each test as described in Section 11.
10.1.5 Filter Bypass Valve - For Models 202, 203, and 215, check for leakage at least once a year (see X1.6).
