. The street railway review . s-sary to compound it, possibly six to one, and use it as a compoundpump for the low pressure work only. By operating the portchanging slide valve the pump would be immediately changed totwo high pressure cylinders for fire service or boiler feeding. In many ways the gravity storage tank is very desirable, as it pro-vides a storage for water while changing over the pumps and italso helps to maintain a steady pressure of water. If gravitytank water is to be used for cooling engine journals, it will neces-sitate the use of a much larger amount of water than otherwis
. The street railway review . s-sary to compound it, possibly six to one, and use it as a compoundpump for the low pressure work only. By operating the portchanging slide valve the pump would be immediately changed totwo high pressure cylinders for fire service or boiler feeding. In many ways the gravity storage tank is very desirable, as it pro-vides a storage for water while changing over the pumps and italso helps to maintain a steady pressure of water. If gravitytank water is to be used for cooling engine journals, it will neces-sitate the use of a much larger amount of water than otherwise,due to the tank becoming heated. If the tank be of metal andlocated near the roof, much trouble will be experienced from itssweating and, in order to avoid dripping, it will be necessary touse a water-tight pan under it. In order to maintain a steadypressure with a small amount of storage, it would be preferableto use a small closed expansion tank in the basement. The three pumps would ordinarily use different water for the. A^Sl^^^/? /^^^^ ^,V FIG. 14. suctions, the boiler feed pump using hot water from tlie heater andthe other pumps using cold water. The pumps must therefore havetheir suctions so piped that any one of the three can use the heaterwater or intake water. Before laying out the piping for this pumping system it isnecessary to consider what to do in regard to the heater. Shallone or two heaters be used? Before attempting to determine thisquestion, it is necessary to consider how essential the heater isin securing continuous operation. There are condensing plantsusing economizers and electrically driven auxiliaries that takewater from the hot well and feed directly into the economizerswithout having any heater at all. Now if the economizers canoperate continuously without a heater, why must we provide areserve heater for the two hours or so that it takes to clean themout? The only directly appreciable loss is the heat dischargedfrom the exhaust pipe while clea
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
