ASTM D3523 Test Method for Spontaneous Heating Values of Liquids and Solids (Differential Mackey Test)
4. Summary of Test Method
4.1 The sample is supported on surgical gauze and placed in a heated chamber which is open to the air at the top. The temperature of the sample, thus prepared, is compared to that of an equal reference quantity of surgical gauze contained in an identical chamber. The amount by which the temperature of the sample exceeds that of the reference is taken as an index of the spontaneous heating value of the sample. Tests may be conducted for durations of 4 to 72 h or longer if desired.
4.1.1 Any convenient, inert, fibrous substrate of adequate absorbency may be substituted for surgical gauze as required. Any such substitution shall be reported with the spontaneous heating value so obtained.
5. Significance and Use
5.1 The spontaneous heating value of a substance is a measure of the ability of that substance to undergo self-heating reactions while supported by cellulosic or other fibrous material in air. It is an index of the autoignition tendency of the substance under such conditions.
