3-9.3–l0.3–11.3–12.What instrument is best formeasuring pressure differences inan atmosphere of air where thepressure ranges between 31 and 32inches of mercury?1.Bourdon gauge2.Schrader gauge3.Manometer4.Diaphragm gaugeA barometer is used to measure1.absolute temperature2.atmospheric pressure3.relative humidity4.steam pressureThe forces in an aneroid barometerthat balance each other are the1.2.3.4.Theresistance of a metal box tostretching or compression plusthe tension in a spring andatmospheric pressureresistance of a metal box tostretching or compression plusthe force exerted by the air inthe box, and the force exertedby the atmosphereforce exerted by steam underpressure and the tension in aspringforce resulting from expansionin a metal bar and the tensionin a springforces in a mercurial barometerwhich balance each other are the1.2.3.4.weight of a column of mercuryplus the force exerted by theair in the tube above themercury, and the force exertedby the atmosphere plus 14.7 psiforce exerted by steam underpressure and the force exertedby the weight of a column ofmercuryforces exerted by theatmosphere and the weight of acolumn of mercuryweight of a column of mercury,and the pressure of the vacuumaboveforcethe mercury plus theexerted by the atmosphere3–13.If an airtight container is filledwith steam and then cooled so thatthe steam condenses, the pressureinside the container is reducedbecause1.2.3.4.a volume of steam weighs lessthan an equal volume of waterthe pressure on the surface ofa liquid is always zerothe water resulting from thecondensation of the steamcannot be compresseda partial vacuum results fromthe condensation of the steam3–14.Which of the following instrumentsis used for measuring pressures inthe condenser for a steam turbine?1.Barometer2.Schrader gauge3.Manometer4.Bourdon tube gaugeInformation for items 3–15 ando3–16:Pressure measurements aregenerally classified as absolute pressureor gauge pressure.Absolute pressure isthe total pressure, including that of theatmosphere; it is the pressure measuredabove zero pressure as a reference level.Gauge pressure is the difference betweenabsolute pressure and the pressure of theatmosphere; it is pressure measured aboveatmospheric pressure as a reference level.3–15.At sea level, the pressure in atire is 24 psi gauge pressure.Theabsolute pressure in the tire isapproximately1.39 psi2.33 psi3.24 psi4.9 psi3–16.At sea level, the pressure in anair tank as measured by an aneroidbarometer is 31 inches of mercury.How much greater or less thanatmospheric pressure is thepressure in the air tank?1.1 inch more2.1 inch less3.2 inches less4.2 inches more23
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