One of the authors, Murakado, has reported that changes of delay time, incomplete blastings, and misfires seen in M.S. delay detonators set in charge holes, which accompany so often combustion of explosives, are caused due to detonation of explosives in nearby holes. In this work, to obtain some information about mechanisms of such phenomena, we attempted to examine the effects of compressive deformation on M.S. delay detonators.
An M.S. delay detonator was set in a steel-container, which was filled with imitation explosives, and then compressed by an external pressure before blasting. It was found that the delay time of the detonators came to change at the external pressures of 60 and 204kg/cm
2in powdery explosives and gelative dynamite, respectively. It was also found that the detonators started to be deformed at these pressures, above which the degree of deformation increased nearly linearly with increasing the pressure. The lead plate tests showed that the incomplete blasting occured at pressures of 330 and 280kg/cm
2in powdery explosives and gelative dynamite, respectively, and above these pressures, the curves of the degree of deformation vs. pressure leveled off.
The results in this work clearly indicated that M.S. delay detonators were considerably deteriorated by compressive deformation., Our unpublished work showed that in fact, considerable deformation by adjacent blasting was seen in M.S. delay detonators, which was detected with a strain gauge attached directly to M.S. delay detonators.
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