DISCRIMINATION BETWEEN FLAMMABILITY RATINGS: ASTM D6668
EXPLANATION
This test method covers a means for the discrimination between solid and liquid materials which will not burn in air when exposed to a temperature of 1500° F for a period of 5 min and those which will ignite and burn under the same conditions. This test method can be applied to any substance which is solid or liquid at ambient temperature and pressure. This test method provides a means for the classification of flammability hazard of material of hazard degrees (F = 0) and (F = 1) or both, in accordance with the definitions of degrees of flammability hazard as defined by NFPA 704 para, 3.2.1.

This test method should be used subject to the limitations that no single fire hazard property such as flash point, ignition temperature, or the performance under the conditions of this test method shall be used to describe or appraise the fire hazard or fire risk of a material, product, assembly or system under actual fire conditions. Fire hazard properties measured under controlled laboratory conditions may, nevertheless, be employed to describe properly the response of materials, products, assemblies or systems under said controlled conditions. Properties measured under controlled laboratory conditions may be used as elements of hazard or risk assessment only when such assessment takes into account all of the factors that are pertinent to the evolution of the fire hazard of a given situation.

TEST SUMMARY
Small, measured amounts of the sample are placed on a stainless steel surface heated to 1500° F. Reactions which occur during the 5 min interval, thereafter, are observed and recorded. A material which does not exhibit any evidence of burning as defined herein under the conditions of the test procedure may be classified as Flammability Degree of Hazard Zero material (F = 0) provided other properties of the material are not such as to require a higher degree of classification.

TEST PRECISION
No information is available about either precision or bias of this test method since the results are nonquantitaive.