  the safety testing of explosives involves the determination of various properties of the different energetic materials that are used in commercial, mining, and military applications. it is highly desirable to measure the conditions under which explosives can be set off for several reasons, including: * safety in handling * safety in storage * safety in use it would be very difficult to provide an absolute scale for sensitivity with respect to the different properties of explosives. therefore, it is generally required that one or more compounds be considered a standard for comparison to those compounds being tested. for example, petn is considered to be a primary explosive by some individuals, and a secondary explosive by others. as a general rule, petn is considered to be either a relatively insensitive primary explosive, or one of the most sensitive secondary explosives. petn may be detonated by striking with a hammer on a hard steel surface (a very dangerous thing to do), and is generally considered the least sensitive explosive with which this may be done. for these facts and other reasons, petn is considered one standard by which other explosives are gauged. another explosive that is used as a calibration standard is tnt, which was afforded the arbitrary figure of insensitivity of 100. other explosives could then be compared against this standard. because there are different ways to set off explosives, there are several different components to the safety testing of explosives: * impact testing. the impact testing of explosives is performed by dropping a fixed weight onto a prepared sample of the explosive to be tested from a given distance. the weight is released, impacts upon the sample, and the result is noted. the impact distances are determined and the results are analyzed by the sensitivity test and analysis methods selected. the two most common sensitivity test and analysis methods are the bruceton analysis and neyer d-optimal test. these methods allow the user to determine the 50% initiation level (the distance at which 50% of the samples will "go"), and a standard deviation. impact testing may also be performed with liquid samples confined in special cells. * friction testing. there are several techniques through which explosives may be tested to determine their sensitivity to friction. one of the most popular is the abl friction test, which uses a line of explosives on a prepared metal plate, placed in front of a specially prepared metal wheel that is forced down upon the plate with a hydraulic press. the metal plate is then struck with a pendulum to move it, squeezing the explosives between plate and wheel as the plate moves. initiation is determined, and analyzed by the bruceton analysis or neyer d-optimal test, as above. bam friction testing is similar, except that the sample is placed on a ceramic 
Explosives Explosives_engineering Safety