change in the impeller diameter
square of the impeller radius
cube of the impeller diameter
impeller efficiency for large changes in its size
第1题：
It is possible to mount a double suction centrifugal pump impeller with the vanes facing in the wrong direction. This would cause the pump ______.
A.head capacity to improve
B.discharge to be reversed
C.efficiency to decrease
D.slippage to decrease
第2题：
You start a centrifugal cargo pump to discharge cargo．The pump works for a while and then loses suction．This could be caused by ______．
A.The pump running backwards
B.Incomplete priming
C.The discharge head being too high
D.All of the above
第3题：
Throttling in the _____ line of a centrifugal pump involves the risk of the pump cavitation.
A.suction
B.exhaust
C.pressure
D.discharge
第4题：
primarily to lubricate the shaft seals
due to the inability of this type of pump to lift water to cover the suction (eye) of the impeller
to initially unload the pump by having its head pressure equal to discharge pressure
in order to overcome the potential energy of water in the discharge line
第5题：
Oil is discharged from the impeller through the outlet
Gravity causes the oil to flow toward the discharge
The self-priming feature of the centrifugal pump enables it to draw its own suction as it starts
The discharge capacity varies directly with the speed of the impeller
第6题：
All of the following steps are taken in starting a centrifugal pump，EXCEPT to ______．
A.Set the relief valve
B.Check the lubrication system
C.Vent the pump casing
D.Open the pump suction and discharge valves
第7题：
Absorb erosion of high velocity discharge stream
Seal pump shaft against entry of air
Isolate the outlet side from the inlet side
Dampen the turbulent discharge flow
第8题：
If a centrifugal pump is driven by a constant speed electric motor and produces a discharge pressure less than designed, the cause is probably ______.
A.excessive pump speed
B.excessive suction head
C.worn wearing rings
D.gross pump misalignment
第9题：
Absorb erosion of high velocity discharge stream
Seal pump shaft against entry of air
Isolate the discharge side from the suction side
Dampen the turbulent discharge flow
第10题：
cavitation
water hammer
fluid friction
steam knock