单项选择题
If the electric motor driving an air compressor fails to start, the cause may be a （）.
A.leaking unloader
B.tripped circuit breaker
C.control line leak
D.defective pop valve
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相关考题
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单项选择题
The refrigerant gas returning to the compressor should be （）.
A.superheated
B.saturated
C.dense
D.flooded -
单项选择题
The vacuum maintained in the salt water feed heater shell of a flash-type evaporator is generally accomplished by （）.
A.a separate air ejector unit
B.a direct unimpeded connection between second stage and salt water feed heater
C.either by vacuum drag or an external line from the first stage via a fixed orifice
D.the fixed orifice provided in the steam supply line -
单项选择题
In which of the listed refrigeration system components does superheating of the refrigerant take place?（）
A.Expansion valve
B.Evaporator
C.Drier
D.Receiver
