. Operation of trains and station work and telegraphy . rvesas an expansion chamber to secure free circulation. Theair freed from the pipes after the water is heated risesand gathers in the upper half of the drum. There aretwo tapped holes in the bottom of the drum, a and b;the upper pipe from the heater enters one and from theother runs the circulating or down-flow pipe which car-ries the hot water through the car. Should the fire be allowed to burn unchecked or the 44 RULES FOR MOVEMENT OF TRAINS water circulation be impeded the pressure in the heatermight become dangerously high. To provide
. Operation of trains and station work and telegraphy . rvesas an expansion chamber to secure free circulation. Theair freed from the pipes after the water is heated risesand gathers in the upper half of the drum. There aretwo tapped holes in the bottom of the drum, a and b;the upper pipe from the heater enters one and from theother runs the circulating or down-flow pipe which car-ries the hot water through the car. Should the fire be allowed to burn unchecked or the 44 RULES FOR MOVEMENT OF TRAINS water circulation be impeded the pressure in the heatermight become dangerously high. To provide for such acontingency an appliance of cast iron called a safetyvent, indicated at v in Figure 2, is screwed into the topof the circulating drum. It is a single casting withoutjoints; at the top it is thinned down to a specified thick-ness which serves as a weak spot to yield, allowing thetop to be blown off when the pressure reaches a certainpoint. More or less water is lost when a top blows off,which should be renewed. As soon as a safety vent blows. PIG. 2. CIRCULATING DRUM, OR WATER RESERVOIR AND EX-PANSION —Safety Vent, C—Oock. a b—Tapped Holes for the Upflow and Downflow Pipes. out the fire should be put out to protect the coil. Ofcourse, when a safety vent top is blown out it should bereplaced with a new one, although the bushing may beused again. The piping arrangement is shown in Figure 3. Theexpansion drum D is placed horizontally upon the roof,the heater being upon the floor of the car immediatelybeneath, as indicated by the coil A. The inflow pipe orriser R conveys the heated water to drum D from which HEATING AND LIGHTING CARS 45
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Keywords: ., bookcentury1900, bookdecade1910, bookidopera, booksubjecttrainmen
