单项选择题
If a bilge pump is able to develop vacuum, but is unable to sufficiently pump out the bilges, you would check for all of the following EXCEPT （）.
A.the circuit breaker
B.for leaks in the suction piping
C.relief valve is not properly seated
D.the suction strainer
相关考题
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单项选择题
The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.
A.increase the refrigerating effect, by decreasing the amount of flash gas
B.allow the refrigerant to enter the throttling device in a saturated condition
C.increase the refrigerating effect by increasing the amount of flash gas
D.minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side -
单项选择题
Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to （）.
A.maintain adequate coil back pressure
B.prohibit flashing in the liquid line
C.reduce refrigerant volume in the system
D.reduce compressor discharge line loading -
单项选择题
An advantage of a helical gear pump over a simple gear pump is that the helical gear pump is capable of （）.
A.maintaining a steadier speed
B.delivering liquids over greater distances
C.operating for longer periods of time
D.producing a smoother discharge flow
