ASTM D5306 Standard Test Method for Linear Flame Propagation Rate of Lubricating Oils and Hydraulic Fluids
8. Procedure
8.1 Tie small loops in each end of a 500 mm section of ceramic fiber support (string). Place a few millilitres of the sample to be studied in an evaporating dish. Immerse the ceramic fiber support (string) in the liquid sample for 60 s. Avoid immersion of the loops at the end of the string.
8.2 While the ceramic fiber support (string) is immersed in the sample, carefully wrap an absorbent paper wiper around the 15 mm diameter chrome plated rod. Leave one end of the rod uncovered by the wiper.
8.3 Remove the ceramic fiber support (string) section from the liquid sample and attach a 50 g weight to the loop at each end. Fix the chrome-plated rod with its absorbent paper wrapping in a horizontal position and hang the soaked string section with attached weights over the unwrapped section of the rod. Press down gently on the uppermost weight to cause the soaked string to pass over the bare rod, flexing gently as it moves. When the lower weight has been drawn up to the rod, reverse the process until the first weight has again been drawn up the rod. Repeat the cycle four times to work the sample thoroughly into the string.
8.4 Transfer the string with attached weights to the covered portion of the chrome-plated rod. Pass the string over the absorbent paper in the manner described in 8.3. After each complete double cycle, lift the string from the paper, rotate it through 180° as it is held taut in a vertical position and then replace it on a fresh area of the absorbent medium. Again pass the string over the paper in the manner described in 8.3. Repeat until four double cycles have been completed.
8.5 Place the string support and thermocouple holder in a draft-free hood with the ventilation turned off. Level the apparatus with a spirit level. Place the prepared string on the string supports. The attached weights should be left in place to provide tension in the string. Adjust the differential thermocouple junctions so that they are exactly 2 mm directly above the string. Connect the differential thermocouple pair to the fast-response, zero-centered strip chart recorder.
8.6 Start the recorder chart after an appropriate warm-up period. With an ignition source, ignite the sample on the string near its support at one end of the apparatus. Permit the flame to advance along the string past each thermocouple until it extinguishes itself upon reaching the opposite string support. Stop the recorder and start the hood ventilator to exhaust the combustion products of the sample.
NOTE 1 - Warning: Take extreme care to avoid inhalation of the combustion products as extremely toxic substances are formed during the combustion of some synthetic materials, especially halogenated and phosphorus-based compounds.
8.7 Measure the horizontal distance between the thermocouples and interval between the first thermal effects as shown in Fig. 2. From the measured interval, the chart speed of the recorder and the known horizontal distance between thermocouples in the test apparatus, calculate and report the horizontal linear flame propagation rate in millimetres per second. If the flame does not advance during the experimental run, or if it extinguishes itself before passing both thermocouples, record that fact. Replicate runs shall be made as required.
