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)
11. Procedure
11.1 Preparation of Fuel Test Sample:
11.1.1 Filter and aerate sample using standard operating conditions (see A2.2.9). (Warning - All jet fuels must be considered flammable except JP5 and JP7. Vapors are harmful (see A3.3, A3.6, and A3.7).)
NOTE 3 - Before operating, see Warning in 6.1.1.
NOTE 4 - Test method results are known to be sensitive to trace contamination from sampling containers. For recommended containers, refer to Practice D4306.
11.1.2 Maintain temperature of sample between 15°C and 32°C during aeration. Put reservoir containing sample into hot or cold water bath to change temperature, if necessary.
11.1.3 Allow no more than 1 h to elapse between the end of aeration and the start of the heating of the sample.
11.2 Final Assembly:
11.2.1 Assemble the reservoir section (see User Manual).
11.2.2 Install reservoir and connect lines appropriate to the model JFTOT being used (see User Manual).
11.2.3 Remove protective cap and connect fuel outlet line to heater section. Do this quickly to minimize loss of fuel.
11.2.4 Check all lines to ensure tightness.
11.2.5 Recheck thermocouple position at 39 mm.
11.2.6 Make sure drip receiver is empty (Models 230 and 240 only).
11.3 Power Up and Pressurization:
11.3.1 Turn POWER to ON.
11.3.2 Energize the ΔP alarms on models with manual alarm switch (Models 202, 203, and 215).
11.3.3 Pressurize the system slowly to about 3.45 MPa as directed in the User Manuals for Models 202, 203, and 215 (see also A2.2.5).
11.3.4 Inspect the system for leaks. Depressurize the system as necessary to tighten any leaking fittings.
11.3.5 Set controls to the standard operating conditions.
11.3.6 Use a heater tube control temperature as specified for the fuel being tested. Apply any thermocouple correction from the most recent calibration (see A2.2.8).
NOTE 5 - The JFTOT can be run to a maximum tube temperature of about 350°C. The temperature at which the test should be run and the criteria for judging results are normally embodied in fuel specifications.
11.4 Start Up:
11.4.1 Use procedure for each model as described in the appropriate User Manual.
11.4.2 Some JFTOT models may do the following steps automatically, but verify that:
11.4.2.1 No more than 1 h maximum elapses from aeration to start of heating.
11.4.2.2 The manometer bypass valve is closed as soon as the heater tube temperature reaches the test level, so fuel flows through the test filter (see A2.2.6).
11.4.2.3 Manometer is set to zero (see A2.2.6).
11.4.3 Check fuel flow rate against Standard Operating Conditions by timing flow or counting the drip rate during first 15 min of test. (See X1.5.)
NOTE 6 - When counting drop rate, the first drop is counted as drop 0, and time is started. As drop 20 falls, total time is noted.
11.5 Test:
11.5.1 Record filter pressure drop every 30 min minimum during the test period.
11.5.2 If the filter pressure drop begins to rise sharply and it is desired to run a full 150-min test, a bypass valve common to all models must be opened in order to finish the test. See appropriate User Manual for details on operation of the bypass system (see A2.2.2).
11.5.3 Make another flow check within final 15 min before shutdown (see 11.4.3 and accompanying note). (See X1.5.)
11.6 Heater Tube Profile - If a heater tube temperature
profile is desired, obtain as described in X1.4.
11.7 Shutdown:
11.7.1 For Models 202, 203, and 215 only:
11.7.1.1 Switch HEATER, then PUMP to OFF.
11.7.1.2 Close NITROGEN PRESSURE VALVE and open MANUAL BYPASS VALVE.
11.7.1.3 Open NITROGEN BLEED VALVE slowly, if used, to allow system pressure to decrease at an approximate rate of 0.15 MPa/s.
11.7.2 Models 230 and 240 shut down automatically.
11.7.2.1 After shutdown, turn FLOW SELECTOR VALVE to VENT to relieve pressure.
11.7.2.2 Piston actuator will retreat automatically.
11.7.2.3 Measure effluent in drip receiver, then empty.
11.8 Disassembly:
11.8.1 Disconnect fuel inlet line to the heater section and cap to prevent fuel leakage from reservoir.
11.8.2 Disconnect heater section.
11.8.2.1 Remove heater tube from heater section carefully so as to avoid touching center part of tube, and discard test filter.
11.8.2.2 Flush tube with recommended general cleaning solvent (see 7.2) from top down. If the tube is grasped from the top, do not wash solvent over gloves or bare fingers. Allow to dry, return tube to original container, mark with identification and hold for evaluation.
11.8.3 Disconnect reservoir.
11.8.3.1 Measure the amount of spent fluid pumped during the test, and reject the test if the amount is less than 405 mL.
11.8.3.2 Discard fuel to waste disposal.
12. Heater Tube Evaluation
12.1 Visually rate the deposits on heater tube in accordance with Annex A1.
12.2 Return tube to original container, record data, and retain tube for visual record as appropriate.
