. The street railway review . raft is concerned,is only of a length sufficient to deliver the gases above theroof. The stack is supported on an entablature, whichin turn is carried on • I beams over the these I beams is a large, slow-running exhaust fanwhose outlet discharges directly up into the bottom ofthe stack. The waste gases from the furnace passthrough a Lowcock economizer, which opens into thesuction of the fan. The economizer is carried on ironcolumns, and the whole system is overhead and out of theway. leaving a clear floor space below. A by-passdamper is provided on
. The street railway review . raft is concerned,is only of a length sufficient to deliver the gases above theroof. The stack is supported on an entablature, whichin turn is carried on • I beams over the these I beams is a large, slow-running exhaust fanwhose outlet discharges directly up into the bottom ofthe stack. The waste gases from the furnace passthrough a Lowcock economizer, which opens into thesuction of the fan. The economizer is carried on ironcolumns, and the whole system is overhead and out of theway. leaving a clear floor space below. A by-passdamper is provided on each side of the economizer, so roo that the draft can be direct to the stack in case the econ-omizer is temporarily out of service for repairs. Asteam-cone nozzle maj be set in the base of the stack asa relay in the remote contingency of any necessity foroverhauling the fan. The probability of repairs is bestjudged by the fact that the usual speed of the fan in ordi-nary service is from forty to fifty turns per minute, and. SECTION THROUGH ECONOMIZER. when driven at the slow speed of eighty turns per min-ute it is sufficient to cause a draft adequate to the mostintense combustion. The motive power of the fan is asmall Westinghouse engine, nominally of lO-horse power,but in fact running at so slow a speed and under such aclose throttle as to develop only a fraction of that draft is automatically controlled by a pressure regu-lator in the steam pipe to the engine, so that the speedof the fan is varied according to the steam pressure inthe boilers, being in this respect the equivalent of themost sensitive steam damper. This scheme of mechani-cal draft is capable of producing a draft pressure equal tothat of a 200-foot chimney costing ten times as much tobuild, and additionally possesses the feature which nonatural draft enjoys, of absolute flexibility in meetingsudden demands of steam. The fireman is thus renderedindependent of weather conditions, and has nothing tofe
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
