. American stationary engineering; a practical work which begins at the boiler room and takes in the whole power plant. een in the figure. Thesteam pressure is thus assisted in holding the valve open, aswell as raising it much higher, giving a larger opening thanwould be the case if the valve were lifted by the pressure loaded valves are mostly used on marine boilers,locomotives and portable boilers, and wherever outside disturb-ances interfere with the action of a weight. A pop safety valve is a com-mon form of safety valve and takesits name from the fact that it takesa little mo
. American stationary engineering; a practical work which begins at the boiler room and takes in the whole power plant. een in the figure. Thesteam pressure is thus assisted in holding the valve open, aswell as raising it much higher, giving a larger opening thanwould be the case if the valve were lifted by the pressure loaded valves are mostly used on marine boilers,locomotives and portable boilers, and wherever outside disturb-ances interfere with the action of a weight. A pop safety valve is a com-mon form of safety valve and takesits name from the fact that it takesa little more pressure to raise it offits seat than what it is set at, conse-quently it releases itself with apop. Fig. 95 shows a form of deadweight safety valves when a is thevalve which rests on the seating b. The valve is attached to the cir-cular casting A, A, A, so that bothrise and fall together. The weightsW, W, etc., are disposed on thecasting in rings, which can beadjusted to the desired blow off pres-sure. Owing to the center of gravityof the casting and weight being belowFig. 95. the valve, the latter requires no. Maxims and Instructions. i8g THE SAFETY VALVE. requires no guides to keep it in position. This is a great ad-vantage as guides frequently sticli, and prevent tlie valvefrom acting. Another advantage of this form ,of valve is,that it is difficult to tamper with. For instance, a four inchvalve, intended to blow off at 100 lbs. per square inch wouldrequire weight of over 1,200 lbs., which require a considerablebulk. An unauthorized addition of a few pounds to such amass would make no appreciable addition to the blowing offpressure, while any effectual amount added to the weightwould be immediately noticed. It is quite different with thelever safety valve about to be described, a small addition to theweight at the end of the lever is multiplied several times atthe valve. U. S. Rules Eelating to Safety Valves. Extract from rules and regulations passed and approvedFeb. 25,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectsteamen, bookyear1917
