ASTM International

Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants
 N G125

Annotation

This test method covers a procedure for measuring the threshold-limit conditions to allow equilibrium of combustion of materials in various oxidant gases under specific test conditions of pressure, temperature, flow condition, fire-propagation directions, and various other geometrical features of common systems.

This test method is patterned after Test Method D 2863-95 and incorporates its procedure for measuring the limit as a function of oxidant concentration for the most commonly used test conditions. Sections 8, 9, 10, 11, 13, and 14 for the basic oxidant limit (oxygen index) procedure are quoted directly from Test Method D 2863-95. Oxygen index data reported in accordance with Test Method D 2863-95 are acceptable substitutes for data collected with this standard under similar conditions.

This test method has been found applicable to testing and ranking various forms of materials. It has also found limited usefulness for surmising the prospect that materials will prove "oxygen compatible" in actual systems. However, its results do not necessarily apply to any condition that does not faithfully reproduce the conditions during test. The fire limit is a measurement of a behavioral property and not a physical property. Uses of these data are addressed in Guides G 63 and G 94.

NOTE 1—Although this test method has been found applicable for testing a range of materials in a range of oxidants with a range of diluents, the accuracy has not been determined for many of these combinations and conditions of specimen geometry, outside those of the basic procedure as applied to plastics.

NOTE 2—Test Method D 2863-95 has been revised and the revised Test Method has been issued as D 2863-97. The major changes involve sample dimensions, burning criteria and the method for determining the oxygen index. The aim of the revisions was to align Test Method D 2863 with ISO 4589-2. Six laboratories conducted comparison round robin testing on self-supporting plastics and cellular materials using D 2863-95 and D 2863-97. The results indicate that there is no difference between the means provided y the two methods at the 95 % confidence level. No comparison tests were conducted on thin films. The majority of ASTM Committee G4 favors maintaining the D 2863-95 as the backbone of G 125 until comprehensive comparison data become available.