A.repack all valve stems
B.lubricate it prior to use
C.replace the foundation bolts
D.balance the warping heads
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A.blue
B.green
C.orange
D.purple
A.blue
B.green
C.orange
D.purple
A.excessive condenser cooling water
B.warm food in the refrigerator
C.a shortage of refrigerant
D.s shortage of compressor oil
A.either all the way open or all the way closed
B.normally open
C.throttled depending on load
D.controlled by suction pressure
When a hydraulic vane pump is working, which of the following is in contact with the vanes?()
(1) the rotor
(2) the internal surface of the housing
(3) the external surface of the housing
A.(1) only
B.(2) only
C.(1) and (2)
D.(1), (2) and (3)
A.Control of evaporation
B.A separate means to prevent feed-water contamination
C.Power circulating pump
D.Super-heater
A.check and regulate the water level
B.close the air cock once fires are lit
C.blowdown the gage glass
D.crack the steam stop to assure protective steam flow
A.furnace to be re-purged
B.electric charge to buildup in the igniter
C.fuel pump to restart
D.drum level to stabilize
A.The blow down valve
B.The scum valve
C.The air release cock
D.Scot-blower
A.acid
B.alkali
C.salt
D.None of the above
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最新试题
The rate of heat transfer from a hot region to a cold region is affected most by the ().
The usual symptoms of cavitation in a centrifugal pump is ().
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump ().
When the steering gear is in operation, you should ().
A pressure drop through the refrigerant liquid line may cause ().
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by ().
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?()
The general purpose of a heat exchanger is to ().
Which of the following statements is correct concerning heat transfer?()
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().