The following tests are used to determine the Bureau of Alcohol, Tobacco, and Firearms (BATF) storage compatibilities and quantity-distance separations for a given substance. The internal ignition test is performed as a screening test to determine whether a material is an explosive substance. If the material is an explosive substance, the No.8 cap test is used to characterize the material into the categories of either high explosive (cap sensitive) or low explosive (not cap sensitive).
This test is designed to determine the response of an explosive to rapidly rising temperatures and pressures. The sample, with an initial temperature of 25°C, is loaded into a schedule 80 pipe with forged steel end caps. A black powder bag igniter is inserted into the center of the pipe and the leads are sealed with epoxy resin. The igniter is fired and the results are assessed. Either the pipe or at least one of the end caps must be fragmented into at least two distinct pieces for a positive result.
The test is considered negative (the material passes) if the pipe is merely split open or the caps are blown off in one piece. Three trials are performed unless a positive result occurs earlier. The test determines if a material will explode or detonate when ignited under confinement.
No. 8 Cap Test
The No. 8 cap test is used to determine susceptibility of explosives to detonation from the energy delivered by a No. 8 electric blasting cap. The test consists of a sample approximately 60 in3 in size placed in a cardboard tube (liquid samples are placed in a polypropylene bottle). The tube is placed on top of a steel witness plate with a No. 8 cap inserted at the top of the cardboard tube. Sample detonation is determined by examining the witness plate the criteria for detonation is that the witness plate is torn or penetrated.
The explosive is considered a high explosive if it fails the No. 8 cap test and a low explosive if it passes.