A.gate valve
B.globe valve
C.check valve
D.plug cock
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A.At the designed operating temperature, the liquid refrigerant charge has changed to a vapor
B.The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivity
C.The sensing bulb is empty of liquid refrigerant charge at the designed operating temperature
D.The sensing bulb is never emptied of liquid refrigerant under normal operating conditions
A.diaphragm type gage
B.pressure transducer
C.manometer
D.All of the above
A.reduce radial thrust to the impeller
B.double the liquid velocity through the pump when compared to a single volute
C.reduce hydraulic end thrust
D.provide the effect of multi-staging
A.dirt will cause corrosion of bearing
B.bearings will leak oil excessively
C.dirt is very abrasive when mixed with grease
D.grease will become inflammable
A.promote refrigerant dehydration
B.be absorbed in the receiver
C.cause low condensing pressure
D.carry moisture and lead to corrosion
最新試題
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
The major source of chemical contaminants in hydraulic fluid is （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
A salinity indicator is used to determine the （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.