4.1 Most organic liquids and solids will ignite in a pressurized oxidizing gas atmosphere if heated to a sufficiently high temperature and pressure. This procedure provides a numerical value for the temperature at the onset of ignition under carefully controlled conditions. Means for extrapolation from this idealized situation to the description, appraisal, or regulation of fire and explosion hazards in specific field situations, are not established. Ranking of the ignition temperatures of several materials in the standard apparatus is generally in conformity with field experience.

4.2 The temperature at which material will ignite spontaneously (AIT) will vary greatly with the geometry of the test system and the rate of heating. To achieve good interlaboratory agreement of ignition temperatures, it is necessary to use equipment of approximately the dimensions described in the test method. It is also necessary to follow the described procedure as closely as possible.

4.3 The decomposition and oxidation of some fully fluorinated materials releases so little energy that there is no clear-cut indication of ignition. Nor will there be a clear indication of ignition if a sample volatilizes, distilling to another part of the reaction vessel, before reaching ignition temperature.

1.1 This test method covers the determination of the temperature at which liquids and solids will spontaneously ignite. These materials must ignite without application of spark or flame in a high-pressure oxygen-enriched environment.

1.2 This test method is intended for use at pressures of 2.1 to 20.7 MPa [300 to 3000 psi]. The pressure used in the description of the method is 10.3 MPa [1500 psi], and is intended for applicability to high pressure conditions. The test method, as described, is for liquids or solids with ignition temperature in the range from 60 to 500 °C [140 to 932 °F].

Note 1: Test Method G72/G72M normally utilizes samples of approximately 0.20 +/- 0.03-g mass, a starting pressure of 10.3 MPa [1500 psi] and a temperature ramp rate of 5 °C/min. However, Autogenous Ignition Temperatures (AIT) can also be obtained under other test conditions. Testing experience has shown that AIT testing of volatile liquids can be influenced by the sample pre-conditioning and the sample mass. This will be addressed in the standard as Special Case 1 in subsection 8.2.2. Testing experience has also shown that AIT testing of solid or non-volatile liquid materials at low pressures (i.e., < 2.1 MPa) can be significantly influenced by the sample mass and the temperature ramp rate. This will be addressed in the standard as Special Case 2, in subsection 8.2.3. Since the AIT of a material is dependent on the sample mass/configuration and test conditions, any departure from the standard conditions normally used for Test Method G72/G72M testing should be clearly indicated in the test report.

1.3 This test method is for high-pressure pure oxygen. The test method may be used in atmospheres from 0.5 % to 100 % oxygen.

1.4 An apparatus suitable for these requirements is described. This test method could be applied to higher pressures and materials of higher ignition temperature. If more severe requirements or other oxidizers than those described are desired, care must be taken in selecting an alternative safe apparatus capable of withstanding the conditions.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.