. Railway mechanical engineer . ing rings at-tached to the diaphragms in the stages. Where gases other thanair are handled, double carbon rings are placed at each end ofthe casing, in addition to the labyrinth rings surrounding the ini-lieller suction inlets and the packing rings on the shaft. Thediaphragms stages are separate from the casing and aredivided on a horizontal plane so that they may be removed with-out removing the shaft and impellers. When cooling is em-l>loyed, the diaphragms are hollow, the water entering throughthe bottom of the casing and escaping at the top. The
. Railway mechanical engineer . ing rings at-tached to the diaphragms in the stages. Where gases other thanair are handled, double carbon rings are placed at each end ofthe casing, in addition to the labyrinth rings surrounding the ini-lieller suction inlets and the packing rings on the shaft. Thediaphragms stages are separate from the casing and aredivided on a horizontal plane so that they may be removed with-out removing the shaft and impellers. When cooling is em-l>loyed, the diaphragms are hollow, the water entering throughthe bottom of the casing and escaping at the top. The impellers are of the single-suction shrouded type, and arebuilt up on heat-treated chrome-nicUel steel disks, the bladesor vanes being riveted to the disks and to side plates, turnedtapering to give strength and lightness. That part of the diskwhich is within the circle of the suction opening is subjected onthe inlet side to the suction pressure and on the back to thedischarge pressure of the individual stage, which gives a re-. -Stage Compresso ith Top Casing Removed sultant thrust equal to the area <if the suction opening multipliedby the pressure generated. The accumulated thrust of all thestages is overcome by a balancing disk at the discharge end. soarranged that one side receives the total discharge pressure in adirection opposite to that acting upon the impeller disk, whilethe chamber upcn the opposite side of the balancing disk is con-nected to the suction inlet, thus completely neutralizing {he un-balanced pressure on all of the wheels. As in the case of single-stage blowers, the head-delivery char-acteristic can be varied considerably to meet different require-ments. Generally where compressed air is used in tools, a fairlyconstant pressure over a wide range of delivery is desired. Thecappcities in such cases range between 2,000 and cu. nun., and the pressures from 75 to 120 lb. per sq. in. Less than 2,000 cu. ft. per min, is usually not practicable.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
