Comparative initiating strength primary explosives

The comparative initiating strength of different types of primary explosives may be obtained in a similar way—on the basis of the dent depth produced in the steel witness plate after the detonation of the primary explosive alone. For this, 300 mg of primary explosive alone is press-loaded at 1115 kp/cm into a PMMA sample holder, wliich is then placed on the steel witness plate. The initiation of the primary explosive is performed by means of the safety fuse. The depth of the dent produced in the steel witness plate after the detonation of the primary explosive is connected with its initiating performance and serves for the comparative evaluation of the initiating strength of different types of primary explosives. 

Initiating Efficiency(ar Strength) af Primary Explosives by Sand Teat. Using 0.400 g charges of tetryl and 0.400 g of the initiating explosive under test, dec the wts of sand crushed by initiator alone and by initiator + tetryl. Subtract from the last value, the amt crushed by 0.400 g of initiator and record this as the value crushed by tetryl. Repeat the test with initiator + tetryl a total of 5 times and compare the.results. If the values for tetryl do not vary hy more than 3.0 g and the av of these is within 2.0 g of the av value for tetryl obtained with 0.300 g of LA aa an initiator, consider it ae the maximum. Repeat the test using smaller amts (0.350 g, 0.300 g etc) of initiator(and always 0.400 of tetryl) until the minimum is reached. (Compare with Sensitiveness to Initiation by Detonators, etc). Refs l)L.V.Clark, IEC 25, 666(1933) 2)PATR 1401,... 

It should be pointed out that the initiating strength of primary explosives depends on several factors, such as explosive purity, leading density, confinement conditions, etc. Thus, the results obtained by different testing methods are not directly comparable. 

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