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Overlap probability for short-period-delay detonators used in underground coal mining.

Authors
Bajpayee-T; Mainiero-R; Hay-JE
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8888, 1985 Jan; :1-18
NIOSHTIC No.
10004523
Abstract
The Bureau of Mines investigated coal-mine-type short-delay electric detonators marketed by three domestic manufacturers to determine the accuracy of delays and the probability of overlap between adjacent delay periods. The Winzer index was computed and compared with the probability of overlap. A close agreement between the winzer criterion and overlap probability was demonstrated. A permissible blasting unit capable of delivering a maximum firing energy of 4.0 J and a digital oscilloscope were used to measure the delay time with an accuracy of plus or minus 0.25 Ms. Another oscilloscope and a pulse transformer were used to record firing current. Experimental data indicated negligible overlap probability in detonators of shorter delay periods: periods 1 to 4, which correspond to 25 to 250 ms. However, a significant probability of overlap was detected in some detonators of longer delay periods: periods 5 to 9, which correspond to 300 to 500 ms.
Keywords
Mining-industry; Underground-mining; Coal-mining; Explosive-devices; Explosives; Explosive-hazards
Contact
NIOSH, Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Publication Date
19850101
Document Type
Report of Investigations
Fiscal Year
1985
NTIS Accession No.
PB86-112513
NTIS Price
A02
Identifying No.
RI-8888
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8888
State
PA
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