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
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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
A.frosting of the liquid line
B.higher than normal head pressure
C.a clear sight glass
D.abnormally cold reefer boxes
A.The hose should not be twisted
B.The hose should be protected with a sleeve if it is subjected to rubbing
C.There should be some slack in the hose
D.All of the above
A.acid
B.fuel oil
C.sediment
D.water
最新試題
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
Thermostatic expansion valves can be adjusted for （）.
A pressure drop through the refrigerant liquid line may cause （）.
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 （）.
Which of the following statements is correct concerning heat transfer?（）
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）