A.hydraulic fluid contamination
B.excessive fluid friction
C.turbulent fluid flow
D.fluid pressure surges
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A.yearly
B.quarterly
C.monthly
D.daily
A.evaporator pressure decrease
B.evaporator coil over-feed
C.evaporator capacity increase
D.expansion valve diaphragm rupture
A.head capacity to improve
B.discharge to be reversed
C.efficiency to decrease
D.slippage to decrease
A.gums, acids, and varnishes
B.removed by cellulose type filters
C.neutralized by oil additives
D.not removed by absorbent filters
A.repack all valve stems
B.lubricate it prior to use
C.replace the foundation bolts
D.balance the warping heads
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)
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最新试题
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?()
Low compressor head pressure in a refrigeration system can be caused by().
If the head pressure of a reciprocating refrigeration compressor is excessive, ().
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?()
Which of the following statements is correct concerning heat transfer?()
The rate of heat transfer from a hot region to a cold region is affected most by the ().
A grease gun is generally used to lubricate a ().
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will ().
The control mode in which the final control element is moved from one of two flexed positions to the other is known as ().
The usual symptoms of cavitation in a centrifugal pump is ().