| Show IGNITION OF FIREDAMP BY EXPOSED FILAMENTS OF ELECTRIC MINE LAMP BULBS by R D leitch A B hooper and W P yant tests have recently been conducted by the bureau of mines on the ignition hazard of exposing heating filaments filament of electric mine lamp bulbs in an explosive mixture of methane and air this investigation was undertaken in order to settle a question that had arisen ity in connection with the safety of miners electric lamps for several years in view of former studies made by rale rhe bureau and reported in bulletin 52 the jact fact that the heated filaments of even low voltage low candlepower candle power bulbs cons constitute titu te a danger was generally accepted by the bureaus engineers ngi these early tests as well as subsequent tests were conducted with pittsburgh natural gas as the testing medium in nearly all coal mines the explosive Z gas 11 as found is is methane this 6 gas as is known to be somewhat less sensitive tu to ignition than natural gas which contains in addition to methane one or more of the higher hydrocarbons therefore the question naturally arose whether heated filaments which regularly ignited natural gas would also ignite methane if not then perhaps the bureau had taken unnecessary precautions in requiring all permissible electric lamps designed for use in mines to be equipped with a safety device the present study conclusively settles this question bulbs that had previously proved dangerous when unprotected in natural gas atmospheres were used in the investigation and methane was substituted for natural gas as testing medium also a few check tests were made using 1 natural 1 gas three types of mine lamp bulbs were tested namely BM 19 2 volt 07 to 09 ampere bulbs the methane used was prepared by on and fractional distillation of natural gas at approximately C the natural gras gas used was that which is supplied to the city of pittsburgh I 1 this summary shows that the results obtained with methane and natural casare gas are practically the same and that any difference in sensitiveness to ignition between these thee two gases cannot be shown within the abc acc accuracy bracy of tests of this nature I 1 judged by the large percentage of ignitions obtained in in methane the bure bureau is amply justified in including among its safety requirements lamps the th requirement 1 that be protect edby some effi efficient type of safety s tf ay device jn in fact the bureau burean would f feel eel justi justified fied in requiring 1 such arafet a safety y device devi ceif if only one ignition had bad been obtained iid J |
