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Priming with Multiple Delays with the Same Timing

Paper by:  David P. Lilly

Explosives Technologies International, Inc.; Pawleys Island, South Carolina, USA

Abstract:

The introduction of electronic caps with significantly more precise timing is forcing an examination into the practical effects of timing precision upon vibration, air blast, fragmentation and crusher productivity.  These investigations have produced suggestions that techniques using multiple delays of the same period with conventional detonators might approximate electronic high precision.

This paper is an attempt to quantify the implications of multiple priming with conventional detonators and to provide a tool to those who are interested in further investigation.  The paper examines the effect of multiple priming with the same delay to reduce scatter.  The results are shown in both graphical and tabular examples.

A typical initiator (100 MS) has a normal distribution of firing times with a 50% chance that the initiator will fire less than 100 MS.  By adding a second initiator with the same 100 MS delay, the probability of firing less than 100 MS is increased to 75%, the median firing time is shifted, and the scatter is reduced.  As more delays with the same period are added, the probability of firing less than 100 MS is increased and the timing scatter is further reduced.

To simplify the analysis and have a practical tool to evaluate many different situations and types of initiators, this paper presents a technique involving the random number generator for normal curves, histogram generation, minimum function generator, and other functions in Microsoft Excel.

 
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