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
When the steering gear is in operation, you should （）.
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?（）
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
The general purpose of a heat exchanger is to （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.