A.excessive drive motor speed
B.excessive pump discharge pressure
C.too low of a tilting box angle
D.insufficient drive motor speed
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A.high pressure liquid
B.low pressure vapor
C.high pressure vapor
D.low pressure liquid
A.propeller hub
B.lignum vitae
C.shaft packing
D.labyrinth seal
A.liquid
B.dry saturated gas
C.wet saturated gas
D.superheated vapor
A.closed, and no leakage permitted across the shaft packing
B.closed, and only slight leakage permitted across the shaft packing
C.open, and no leakage permitted across the shaft packing
D.open, and only slight leakage permitted across the shaft packing
A.freezing point
B.floc point
C.condensing temperature
D.compression temperature
最新試題
Low compressor head pressure in a refrigeration system can be caused by（）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
A pressure drop through the refrigerant liquid line may cause （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The output volume of a positive fixed displacement pump can be changed only by （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Which of the following statements is correct concerning heat transfer?（）
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.