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)
最新試題
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Which of the listed pumps is NOT a positive displacement pump?（）
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The major source of chemical contaminants in hydraulic fluid is （）.
A pressure drop through the refrigerant liquid line may cause （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.