IhTDUXTRIAL A N D ENGINEERING CHEMISTRY
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oughly for liquid as well as gas at all points. This can be done simultaneously if desired, utilizing the light of the safety lamp. It must also be emphasized that the lower limit of 0.5 per cent detectable by this method is somewhat above the safe
Vol. 16, No. 11
limit for breathing for more than a few minutes. Ordinarily the tank repairs do not require men to remain inside the tank for any considerable period, but if this is necessary, gas mask protection might still be required for complete safety.
How Coal-Handling Costs Were Cut $5000 a Year‘ By J. J. Hartley LINK-BELT Co , CHICAGO, ILL
NE of the most interesting examples of the reduction of overhead through the employment of mechanical means is that accomplished by a prominent Chicago concern. For a number of years all the coal for their power plant was handled by hand. Under this method it was necessary to employ six firemen, in addition to drafting three or four men from other work, when there were cars of coal to unload. About six years ago it was decided that this method was too costly and the boiler room and power plant were completely automatized through the installation of a coal-handling system. This system consists of a track hopper, apron conveyor, gravity discharge elevator, overhead bunker, and weigh larry. Of course, net savings cannot be calculated without first considering operation and maintenance costs. For this
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this investment a t 6 per cent and depreciation at the rate of 5 per cent a year totals $2200. The items of repair, oil, attention, and so forth can be figured a t 1per cent of the total cost, which $200, when added to the annual operation charge, totals $2400. This last item is a very conservative figure, for, truth to tell, they have had only $51 worth of repairs in the entire time of this machinery’s operation-about six years. Only about 50 gallons of oil are used annually, and a half hour of one man’s time once each week is all that is necessary to keep the entire equipment in first-class working condition. Now for the brighter side of the calculations. The equipment has reduced the number of firemen necessary from six to one, and the elimination of five firemen a t $1500 a year means lopping off the pay roll a total of $7500 annually. Furthermore, the coal can be dumped into the track hopper (from bottom dump cars) without the necessity of extra men from the plant, and this eliminates considerable labor and cost. Not alone this, but the men in the plant did not relish leaving their regular work to shovel coal for a half day, and the installation of the track hopper and apron conveyor has completely done away with the old grumbling and complaint on the part of these men. But considering only the major item of $7500 a year through the elimination of the five firemen, the net annual saving would be in excess of $5000--after having subtracted from the gross saving the operating and maintenance costs.
APRONCONVEYOR CARRYING COALFROM TRACK HOPPER TO ELEVATOR GSNERALV I E W
OF
BOILERROOMSHOWING OVERHEAD BUNKER AND TRAVELING WEIGHLARRY
reason, the “dark” side of the installation will first be considered. The entire installation cost about $20,000. Interest on 1
Received August 13, 1924.
Thus the equipment pays for itself every four years. This may seem a long period in comparison with the performance of some other machines, but it is an excellent example of what mechanical means can do to overcome labor difficulties and reduce overhead. The installation would probably be considered profitable if it saved only half the annual amount.
