Do not change a regulator... ... ... .... Note the condition of curtains and line brattices. Doors to be closed unless ordered left open.. Be careful when entering rise workings.. Precautions in entering dip workings.. By J. J. RUTLEDGE. INTRODUCTION. No feature of coal mining is more important than proper ventilation at the face, for on it the safety and health of the miner depend. Moreover, every man in a mine has a direct interest in its proper ventilation, and in case the mine is gaseous his life, as well as the lives of all other men in the mine, may be lost if poor ventilation permits inflammable gas to collect in the workings. It is the duty, therefore, of everyone in a mine to see that the ventilation is always good. Probably no feature of coal mining in the United States has advanced more during the last 20 years than has mine ventilation, but to equip a mine with expensive ventilating machinery is useless unless the management of the mine has the hearty cooperation of everybody in the mine, especially the miner. Much of the recent progress in mine ventilation has been in compliance with laws meant to protect especially the lives and health of miners, and miners, above all persons, should do their part in keeping the ventilating devices in proper condition. The carelessness of any man in a mine at any time, for example, in leaving trapdoors open, may render useless the best ventilating system and thus lead to loss of life and damage to property. The purpose of this circular is to impress on mine officials and employees the necessity of keeping the ventilation good in all parts of a mine, especially in working places and in workings that are gaseous; and to point out the more important precautions to be observed. A brief review of the laws on mine ventilation that are in force in some of the more important coal-mining States is included. CHANGES IN AIR IN THE MINE. After air enters a mine the breathing of men and animals, the burning of lamps, the decay of mine timbers, and the firing of shots take oxygen from the air and add carbon dioxide to it, but in well-ventilated mines the changes caused in these ways are very small. Much more important changes are those caused by oxygen being taken from the air by the coal and by gases from the coal, the roof, or the floor being added to the air. The most important gas given off in many mines is methane, or marsh gas, which most miners call "gas." COMPOSITION OF AIR. In 100 cubic feet of ordinary normal air there are 79 cubic feet of a gas called nitrogen, which will not support life, nearly 21 cubic feet of another gas called oxygen, which does support life, and about 0.03 cubic feet of a suffocating gas called carbon dioxide. When an explosion takes place in a mine the proportion of oxygen in the mine air is greatly reduced, that of carbon dioxide is increased, carbon monoxide, a very poisonous gas, is usually formed, and the proportion of nitrogen may be increased or decreased. The resulting mixture of gases is called afterdamp. The most efficient ventilating system for a mine is the one that, with the least velocity through the main air courses, furnishes at the working faces a current containing almost as much oxygen (over 19 per cent) as normal air, very little carbon dioxide and methane (gas), and no carbon monoxide. An efficient ventilating system must supply fresh air enough for all the men and stock in the mine, and must dilute, render harmless, and quickly remove all dangerous gases in the workings. LAWS OF DIFFERENT STATES REGARDING MINE VENTILATION. Most, if not all, countries and States have passed laws requiring that the volume of air circulated through a mine in a certain time shall be not less than a certain quantity for each person employed underground, and some laws require an additional quantity for each animal employed. The important features of the laws of a number of States are given here. PENNSYLVANIA LAWS. ANTHRACITE MINING LAW OF 1891. The Pennsylvania anthracite mining law of 1891 requires: * * The minimum quantity of air * shall not be less than 200 cubic feet per minute for each and every person employed in any mine, and as much more as the circumstances may require. * * * Not more than 75 persons shall be employed at the same time in any one split or current of air. The measurement shall be made at the inlet and outlet airways and also at or near the face of each gangway. BITUMINOUS MINING LAW OF 1911. * * * The Pennsylvania bituminous mining law of 1911 requires: In a nongaseous mine the minimum quantity of air shall be not less than 150 cubic feet per minute for each person employed. In a mine wherein explosive gas is being generated in such quantities that it can be detected by an approved safety lamp, the minimum quantity of air shall be not less than 200 cubic feet per minute for each person employed therein, and as much more in either case as one or more of the inspectors may deem requisite. The mine foreman or his assistant shall at least once every week measure the air current at or near the main inlet and outlet airway, and also in the last cut-through, in the last room, and in the entry beyond the last room turned in each entry, and make a record of said measurements. * * * Said measurements shall be taken on days when the men are at work, and for making said measurements an anemometer shall be provided and kept in good condition by the superintendent of the mine. OHIO LAW OF 1912. The coal-mining law (code of 1912) of Ohio requires: The owner, lessee, or agent of a mine * * * shall maintain a sufficient volume of air, not less per minute than 150 cubic feet for each person, and 500 cubic feet per minute for each animal working therein, measured at the intake and distributed so as to expel or dilute and render harmless explosive, poisonous, and noxious gases. [When a mine generates fire damp, 50 cubic feet per minute must be added to the 150 cubic feet for each person working in the mine.] WEST VIRGINIA LAW OF 1907. The West Virginia coal-mining law (1907) requires that there shall be provided 100 cubic feet of air per minute for each and every person employed in the mine, and as much more as the district mine inspector may require; which shall be circulated around the main headings and cross headings and working places to an extent that will dilute, render harmless, and carry off the noxious and dangerous gases generated therein. In mines generating fire damp, and where there is every reason to believe that gas will be encountered in the future workings and developments of the mine, the minimum ventilation shall be 150 cubic feet per minute for each and every person employed therein. * * * ILLINOIS LAW OF 1913. The coal-mining law (1913) of Illinois requires that at every coal mine there shall be provided, supplied, and maintained an amount of air which shall not be less than 100 cubic feet per minute for each person and not less than 500 cubic feet per minute for each animal in the mine, measured at the foot of the downcast and of the upcast; except that in gaseous mines there shall be not less than 150 cubic feet of air per minute for each person in the mine. The inspector shall have power by order in writing to require these quantities to be increased. The main current of air shall be so split or subdivided as to give a separate current of reasonably pure air to every 100 men at work, and the inspector shall have authority to order, in writing, separate currents for smaller groups of men if, in his judgment, special conditions render it necessary. INDIANA LAW OF 1913. The coal-mining law (1913) of Indiana requires: The operator of any mine shall provide and maintain hereafter for every such mine a sufficient amount of ventilation, affording not less than 100 cubic feet of air per minute for each and every person employed and 300 cubic feet per minute for each mule, horse, or other animal used in said mine, measured at the foot of the downcast, and as much more as the circumstances require. It shall be forced and circulated around the main entries, cross entries, and working places throughout the mine so that said mine shall be free from standing gas of whatsoever kind to such an extent that the entire mine shall be in a fit state at all times for men to work therein, and will render harmless all noxious or dangerous gases generated therein. Every place where fire damp is known, or supposed to exist, shall be carefully examined with a safety lamp by a competent fire boss immediately before each shift, and in making said examinations it shall be the duty of the fire boss, at each examination, to leave at the face of every place examined evidence of his presence, and it shall be unlawful for any person to enter the mine, or part of mine, generating fire damp until it has been examined by the fire boss and reported by him to be safe. PRECAUTIONS TO BE OBSERVED IN REGARD TO VENTILATION. Most miners are aware of the dangers mentioned in this circular, and therefore they may be inclined to think little of the warnings given, but the only way in which all persons in a mine can be led to avoid accidents is by repeatedly warning them against danger. At mines where the management provides for efficient ventilation there are certain things that the miners, drivers, bosses, and others should and must do in order to keep the ventilation at the highest standard of safety. The following hints are offered in the hope that they may be of aid in reducing accidents in coal mines: HINTS TO THE MINE SUPERINTENDENT. Be sure that the engineer or fireman keeps the ventilating fan running at its regular speed all the time. The fan should run 24 hours a day, whether men are in the mine or not. There is always a chance that gas may accumulate if the fan is idle while the men are out of the mine. If the fan is driven by steam, do not permit the engineer or firemen to allow the steam pressure to become low so that the fan slackens speed while men are in the mine. If the fan is driven by electricity, see that the current is not reduced nor shut off while men are underground; if the current must be shut off, the men should be withdrawn. It is well to have the fan motor on a separate line so that the motor will not be affected by a short circuit on any other machine. In the purchase of supplies for the ventilating system be as liberal as possible, while exercising proper economy. If the foreman or mine manager requests canvas for curtains, wood for doors, or material for stoppings, rest assured that he needs it or he would not ask for it. If he does not get the supplies he needs, and the ventilation is not as good as it should be, the inspector and the miners hold him alone responsible. KEEPING AIR OR ESCAPE SHAFT CLEAR OF ICE. In cold weather the air or escape shaft should be carefully watched to see that it does not become choked with ice. Masses of ice in the air shaft will prevent the free passage of air and may greatly reduce or entirely cut off the ventilating current so that black damp or fire damp will accumulate in the mine workings. Disastrous explosions have resulted from ice choking the intake shaft. Exhaust steam may |