ASTM D3523 Test Method for Spontaneous Heating Values of Liquids and Solids (Differential Mackey Test)
8. Procedure
8.1 Determination of Instrumental Blank:
8.1.1 Assemble the spontaneous heating apparatus and place 2000 mL of distilled water in the boiling chamber. Heat the apparatus until continuous refluxing occurs.
8.1.1.1 When test temperatures higher than that obtained by the refluxing of water in the test apparatus are desired, reagent grade ethylene glycol or any other suitable pure compound may be substituted for water. Report any such substitutions with the test data.
8.1.2 Pack the sample and reference containers (screen baskets) with 20 g of rolled cotton gauze. Insert a thermocouple in the center of the gauze mass in each container and place both in the apparatus.
NOTE 1 - When considerable variation in temperature from the norm exists, an additional thermocouple may be necessary to measure the temperature of the bath.
8.1.3 Allow the system to attain thermal equilibrium and then continue heating for 4 h. Record temperature readings, BR and BS. Determine the average instrumental blank TB, found over the duration of the test from measurements of BS and BR made at 1/2-h intervals after establishment of thermal equilibrium.
8.2 Measurement of Spontaneous Heating Value:
8.2.1 Assemble the spontaneous heating apparatus and place 2000 mL of distilled water in the boiling chamber. Heat the apparatus until continuous refluxing occurs.
8.2.2 Pack the reference container (screen basket) with 20 g of freshly rolled cotton gauze.
8.2.3 For a liquid sample, saturate 20 g of freshly rolled cotton gauze with 10 g of liquid. For a solid sample record the particle size if appropriate, and roll 10 g of a solid sample in 20 g of fresh cotton gauze. Locate the sample as near as possible to the position of the thermocouple tip. Pack the sample and gauze in the sample container (screen basket).
NOTE 2 - For simulation of self heating of oily wastes and similar materials, it may be necessary to use the sample to gauze ratios as high as 2:1.
NOTE 3 - The SHV will tend to vary with the particle size of solid samples.
8.2.4 Samples that contain volatile components such as solvents in paint or coating materials may be conditioned to remove such solvents before being placed in the test apparatus. Conditioning will of necessity be determined by the nature of the sample and shall be described in the report.
8.2.5 Insert thermocouples in the sample and reference containers.
8.2.6 Allow the system to attain equilibrium (within 1.5 K (1.5°C)) and then continue heating for 4 h. Record temperature readings, tR and tS.
8.2.6.1 While the minimum duration shall be 4 h, extended test durations may be employed as required. The test duration shall be reported if a duration other than 4 h is employed.
