Show ame features of coal and metal mine ventilation As disclosed in the study of mine disasters by D harrington and M W von zt in studying the mine disaster files of the bureau of abines amines a mines for preparation of a bulletin on coalmine coal mine explosions a table was compiled covering various features of fan installations and the handling of air currents at the time of and after the disasters As a sidelight on this discussion there were tabulated the loss of life and number of men injured of the disasters tabulated were explosions 14 were fires and 2 involved both fire and explosion the total loss of life was and were injured there were disasters in bituminous coal mines 13 in anthracite mines mines 2 in lignite mines 1 in a cannel coal mine and 3 in in metal mines by states 35 took place in pennsylvania in west virginia 16 in oklahoma and alabama 15 in kansas and illinois 12 in indiana 7 in colorado 6 in kentucky 3 each in ohio tennessee and wyoming 2 each in m arkansas montana washington virginia new mexico and utah and I 1 each in iowa missouri maryland and california driving and reversing Fea features tires of fans fans rans at forty seven of the mines were steam driven thirty airty six six were driven by electricity four by either steam or electricity and two by gas and one by either gas or elec Iri city ity information is lacking as to the method of driving the ne fans ians at the remaining seventy five of the total of anines tabulated of the method of ventilating fans I 1 vre vere operated aerated Pe rated exhausting and sixty four were blower or I 1 i pressure for fans in forty two instances the fans were equipped 4 quick rev fe versal of air currents in case of necessity and nineteen deteen were nonreversible non reversible while information is lac lacking king 11 to reversing reversa reve rsm mature feature mines some som at fans of the remaining fans fan mines specially especially in the anthracite region had several ns and single fan capacity varied up to cubic feet per P mil minute lut value of reversibility of air currents there were ten disasters where the air currents were iv n ul 1 m reverse these ed after the faster disaster by use of the fan and in five of saved aved there was saving ng of life the total number of lives I 1 amounting to over in one instance itce prompt re ersal isal of the air officials after an currents by the mine explosion saved about eighty lives in another and com Para 1 Y recent 1924 instance stance the direction of air was promptly nine mine reversed by action at the fan at the time of a fire fir instance stance a nd over twenty IY lives were saved in still another re reverse vers a t the e time of a coalmine coal mine fire through ability to the i saved air currents promptly numerous lives were and a 1 the reversing feature was used frequently in it perlor ter lor no ly mining engineer bureau of mines department of the mining W practicing his profession in salt lake city utah 6 and a nu metallurgical engineer bureau of mines fighting the fire in at least one probably two instances reversal of the ai air r drew methane over fires and explosions occurred but without loss of life in the above list involving most of the major disasters in in the united states since 1907 there is not a single instance of loss of life directly or indirectly by reversal of direction of air currents by fans How veer in a number of instances in recent years in our mines there has been loss of life by reversal of air by a fire there being no fan available to control direction of the air and in some instances there has undoubtedly been loss of life because the fan was nonreversible non reversible and reversing currents could not be effected without serious loss of time an incident at one mine is worth recording as being a point worth watching at the time of the explosion the explosion doors on oil the fan housing opened and thus saved the fan but my some means the reversing door was forced halfway half way over the air duct and remained jammed until discovered and moved back value of reserve fans in at least two cases after the fan was put out of commissio commis commission n by coalmine coal mine explosions a reserve fan was used and in at least one instance many lives probably over were undoubtedly saved by having a reserve fan in one case at time of a disaster the fan was stopped and the methane which accumulated came in contact with burning feeders and caused an explosion in one coal mine an underground fan was driven by a gas engine and when a fire started the gas tank exploded and thirteen men lost their lives in another case underground in a metal mine a fire started at the motor of an electrically driven fan and awen tyone ty one lives were lost in connection with the latter case it may be stated that many fires have been started in recent in metal mines at electric motors at underground fan years installations these being chiefly small temp temporary orar y units for the ventilation of blind ends where tubing is used to carry the air general observations on fan installations modern practice in fan installations at coal mines seems to favor electrically electrical ly driven high speed fans falls in fireproof housing at the surface and while fans are usually operated as exhausting units they are equipped with doors so that reversed if necessary the air currents may be quickly to date properties have a second seconder or auxiliary fan many up drive the fan one of to second source power or at least a successful instance of this is in alabama where the electric cut off by an explosion but a kerosene for the fan wa was s power engine with jaw clutch attachment to the fan shaft was put into commission within fifteen minutes with circulation while many lives 1 ves cally no interruption of air were saved here an genius in small capacity compressed pa immediate starting of the air installation allowed almost kerosene engine frequently there is is considerable delay and difficulty in starting gas engines which are only occasionally sio nally used r present day practice at coal mines mines is is to have the tan fan well out of direct line of the air course leading to the tan fan and with suitable outward opening and easily operated doors in the direct line to allow of quick relief of pressure in case of explosion thus saving the fan the record shows that in at least eight instances the relief doors operated and saved the fan in two severe explosions during the past few years the fan approach was made purposely of flimsy material yet it was made tight by means pi of this saved the fan by readily collapsing and mine ventilation ti was readily restored by temporary repair in each case within an hour coal and metal mine ventilating systems contrasted in ventilating installations at metal mines the main fan is frequently placed underground this is a practice which would not be tolerated in coal mines and it has definite dangers in metal mines though undoubtedly advisable in in sonic some cases exhaust fans predominate at coal mines and are fairly common at metal mines drawing from air shafts and so making the hoisting shafts downcast pressure fans are also common at metal mines and there are good reasons for each practice which might b be discussed as follows at metal mines it is frequently necessary to force back into the surrounding workings heated air or harmful gases from strata or from timber and to do this it is advisable to place the air in working places under slightly increased pressure on the other hand it seems adiv sable to pull exhaust as much as possible of the methane the principal gas found in coal mines out of the worked out or abandoned sections and into the circulating air to render it non explosive moreover it is felt that should the methane in coal mines be kept back into the or abandoned sections by pressure ventilation hence with extra air pressure within the mine as soon as there is any relief of that pressure s such as by change of barometer or slight or total i interruption n ter of the air circulation excessive quantities of gas would be released due to the decreased pressure which would be dangerous however sonic some coal mins have pressure ventilation and some metal mines have the exhaust system in one metal mining district where many of the main main fans were blowers blowe rs causing the main haulage trav elway to be the return air course at time of fire the gases cut off the trav elway but afterwards the main fans of this district were changed to exhaust units with intake on the main haulage and trav elway while hazardous in any mine the placing of small lans fans boosters boasters bo underground to assist in air distribution is decidedly dangerous and inefficient in coal mines yet is considered good practice in metal mines in any underground tan fan installation the workings should be thoroughly fireproofed fire proofed even if the fan is but temporarily in one position and in coal mines the greatest any should be betoken betaken taken against ignition of methane possible at fans care by bv short circuiting or after fan stoppage or otherwise what to do at the fan in case of disaster there is a diversity of opinion as to what should be done at the fan at time of disaster as a matter of fact set rule can be given e except that if damaged by the no harington 0 D coal 0 and metai ami mining coal age vol 23 1923 p methods contrasted fire the fan should be sion or certainly immediately placed il in running order all mines whether coal or metal should have the ventilating system arranged so that the direction direct io of air travel may be controlled at the fan hence in case of 5 Peces necessity sity direction of air currents may be reversed with wiehl in I 1 a few minutes no change should be made in the usual 0 coursing of air unless available information indicates that fo advantage may be secured either by stopping the fan or by reversing the air many mining men advocate stopping the fan immediately ft upon learning of trouble underground this maybe I 1 good policy in sonic some instances but there are others in which z it would certainly result in disaster in the first place merely stopping the fan does not ensure that the air w cur r rents will stop and if it is desired to stop the air flow other definite steps such as placing brattices bratt ices or the opening or idt closing of doors are necessary moreover even if the air circulation is stopped at or near the fan an underground fire quickly establishes its own circulation and especially if f the mine is gaseous is there grave danger of explosion sion due to local circulation of methane accumulations due to fan stoppage over fires ignited gas blowers etc again in case of mine fire the fumes will have been carried through the mine in the usual direction of air flow until the fan is stopped and frequently upon stopping the fan the fire reverses the direction of air flow and so fills the remainder of the mine with deadly gases reversal of direction of the air at or near the fan will not necessarily cause change of direction of air currents in in the interior of the mine unless dunles provision has been made to hold doors closed even where pressure against the door beco becomes mes suction or vice versa hence to make air reversia reversing 9 installations at mine fans effective they should be tested at intervals to determine their probable efficiency in case of emergency immediately taking suitable remedial action as to defects defect s shown bithe by the trial observations by bureau of mines engineers after dis asters indicate that underground workmen are prone a at time of disaster to try to follow their accustomed travel 4 roads irrespective of condition as to falls gases etc there fore about as good Z a general practice as can be followed follo wedis far is to try to supply fresh air to the usual travel roads as la ir cur as this can be done by causing the fan to continue a rents in the usual direction or to reverse their direction to it is obviously desera desirable accomplish the latter operation to have fan installation of such nature that reversal rever maybe other lep accomplished with minimum loss of time oni on the made hand it is equally obvious that no change should be den under in the usual coursing of the mine air currents except t orders from a responsible mine official who has ca considered the various phases of the existing conditions condition j |