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Evaluation of a sheathed permissible explosive charge for open shooting in flammable atmospheres.

Authors
Mainiero-RJ; Hay-JE
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, TPR-118, :1-9
NIOSHTIC No.
10002327
Abstract
The Bureau of Mines has developed a prototype nonincendive explosive rock-breaker charge that can be fired unconfined in underground bituminous coal mines without the danger of igniting a flammable atmosphere that might be present. At present, unconfined shooting in underground coal mines is prohibited, but there are situations where the use of such shots would yield an overall improvement in safety. The charge consists of 1-1/2 lb of permissible water gel explosive in the form of a short cylinder 7 inches in diameter and 7/8 inches high, surrounded by a 1/2-inch-thick layer of damp salt, and encased in latex rubber reinforced with cheese cloth. The latex rubber housing provides a charge package that is strong enough to resist rough handling yet is pliable enough to conform to an irregular stone surface. A charge of this shape was found to be more effective at breaking rock than charges with lined or unlined cavities. Incendivity tests in a gallery have shown that the prototype charge will not ignite a flammable methane-air atmosphere when fired. In cooperation with the Mine Safety and Health Administration (MSHA), a test protocol for the certification of these charges as "permissible" for use in flammable atmospheres is being developed.
Keywords
Explosions; Materials-testing; Construction-materials; Coal-mining; Explosion-prevention; Explosion-protection; Equipment-design; Structural-analysis; Ignition-sources
Publication Date
19820101
Document Type
IH
Fiscal Year
1982
NTIS Accession No.
NTIS Price
Identifying No.
TPR-118
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, TPR-118
State
PA
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