. The street railway review . it may be due to the tilling of an empty boiler, or the blowing offof an economizer. In any case, whenever the pressure in the feedmain is lower than the steam pressure, the steam if not checkedwill force the feed water back and cause very serious damage. Anautomatic pimip between the steam and feed lines is no barrier 298 STREET RAILWAY REVIEW. [Vol. XV. No. 5- , because llic >.l<;;im al lioilcr pressure will open and passthrough the pump valves, even when the pump is not nnniing. Forthe same reason an automatic drip pnmp cannot be used to dis-cha
. The street railway review . it may be due to the tilling of an empty boiler, or the blowing offof an economizer. In any case, whenever the pressure in the feedmain is lower than the steam pressure, the steam if not checkedwill force the feed water back and cause very serious damage. Anautomatic pimip between the steam and feed lines is no barrier 298 STREET RAILWAY REVIEW. [Vol. XV. No. 5- , because llic >.l<;;im al lioilcr pressure will open and passthrough the pump valves, even when the pump is not nnniing. Forthe same reason an automatic drip pnmp cannot be used to dis-charge into an open heater or another receptacle which is underless than boiler pressure. The discharge pressure must always be be obtained in case the discharge pipe is closed. Unless the linesand pumps be built for such pressures breakdowns must occur, be-cause when shuttiuK down the boiler il is quite a simple oversightfor an operator to close the automatic pump discharge and notnotice that there is no other way of riG. 40. greater than the suction, even though it be caused by only a shortcolumn of water additional. The discharge line from the automaticpump should have a relief valve placed between the pump and anyvalve that may be placed in this line and the discbarge should thenbe piped to a catch basin where the end of the pipe is open so thatany discharge which is taking place may be seen. This relief valve Another method of returning drips to the boilers is illustratedin Fig. 39. This arrangement can only be used in connection withsingle acting pumps and in systems where there is but one pumpon the line and the header is not less than 5 ft. above the waterline of the boilers. The operation of this system is made possibleby the pulsating pressure which is present during the operation of r/^yrw Srf^/v /^f/fOS/?
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
