Sold only by the Superintendent of Documents, U. S. Government Printing Office UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON PREFACE This handbook, Safety in Coal Mining, has been prepared at my request by the chairman of the mine safety board of the Bureau of Mines. The purpose of the handbook is to make available in convenient form a concise statement of practices and methods recommended by the bureau for the increase of safety in coal mining. Rapid growth in the use of machinery for cutting and loading coal, longer haulage ways, and the wider use of mechanical haulage have contributed toward economy in mining by making possible a larger output of coal without a corresponding increase in the number of workers. At the same time this mechanicalization of the mines has been accompanied by increased hazards from falls of roof and coal and from accidents in transporting the coal from the face to the tipple. Incidentally, also, the machines have introduced new hazards peculiar to themselves, although these hazards can not be classed among the major causes of mine accidents. Progress in accident prevention is indicated by either a larger output per accident or fewer accidents per employee; double progress is realized when increased production per accident accompanies a reduction in the accident rate per employee. It is hoped that this publication will prove helpful to safety engineers, mine owners, mine employees, and others in their endeavor to obtain the Nation's necessary fuel at a minimum cost in life and limb. The bureau plans to revise the handbook from time to time as developments in the industry, and further study and research, seem to warrant. SCOTT TURNER, Director. Detailed description of principal methods and instruments Notes on classification of mines by gas content___ Measuring the volume of mine air_. Methods of ventilating coal mines_- Arrangements for ventilation in shafts, slopes, or drifts_ Summary of facts regarding coal-dust explosions and their prevention_ Coal-dust explosions in tipples and shafts__ Conditions prescribed for use of permissible explosives---- Explosions caused through ignition of gas by open lights--- Underground power, lighting, and miscellaneous circuits____ Liability of electrical machinery and circuits to ignite gas.. Explosions caused by electric circuits in haulage ways___ Limiting use of trolley locomotives to avoid ignition of gas and Combination trolley locomotives, including trolley---- Permissible storage-battery locomotives__ Explosions and fires from leakage of natural gas and oil wells |