Science for beginners . Fig. 90.—Ball and lever,safety valve. Fig. 91.—Pop safetyvalve. ball and lever type, Fig. 90, the valve is held clown by the weight of the ball upon the lever. The pressure is increased by slipping the ball farther out on the lever. Explain why. The principle of the pop valve is shown in Fig. 91. The 124 THE PRODUCTION AJMD USE OF HEAT valve in this case is held down by a spiral spring. The topof the spring rests against a metal washer. This plate maybe forced farther down by turning down the screw. Thespring then holds the valve down against a greater each
Science for beginners . Fig. 90.—Ball and lever,safety valve. Fig. 91.—Pop safetyvalve. ball and lever type, Fig. 90, the valve is held clown by the weight of the ball upon the lever. The pressure is increased by slipping the ball farther out on the lever. Explain why. The principle of the pop valve is shown in Fig. 91. The 124 THE PRODUCTION AJMD USE OF HEAT valve in this case is held down by a spiral spring. The topof the spring rests against a metal washer. This plate maybe forced farther down by turning down the screw. Thespring then holds the valve down against a greater each type, the valve opens and allows some steam to escapeas soon as the pressure within the boiler exceeds the amountfor which the valve is set. 135. The Water Gage.—The purpose of the water gage isto enable the operator or engineer to see exactly how high thewater stands in the boiler. The gage is merely a strongglass tube mounted on the side of the boiler at the height atwhich the water should stand. This glass tube
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscience, bookyear1921
