Historical
ASTM E681-09(2015)
Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases)
1.1 This test method covers the determination of the lower and upper concentration limits of flammability of chemicals having sufficient vapor pressure to form flammable mixtures in air at atmospheric pressure at the test temperature. This test method may be used to determine these limits in the presence of inert dilution gases. No oxidant stronger than air should be used.
1.2 This test method is based on electrical ignition and visual observations of flame propagation. Users may experience problems if the flames are difficult to observe (for example, irregular propagation or insufficient luminescence in the visible spectrum), if the test material requires large ignition energy, or if the material has large quenching distances.
1.3 Annex A1 provides a modified test method for materials (such as certain amines, halogenated materials, and the like) with large quenching distances which may be difficult to ignite.
1.4 In other situations where strong ignition sources (such as direct flame ignition) is considered credible, the use of a test method employing higher energy ignition source in a sufficiently large pressure chamber (analogous, for example, to the methods in Test Method E2079 for measuring limiting oxygen concentration) may be more appropriate. In this case, expert advice may be necessary.
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