propeller
impeller
circumference
screw
第1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2题：
Single stage or multistage
High pressure or low pressure
Open or close coupled
Horizontal or vertical
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：
（1），（2）
（2），（3）
（1），（2），（3）
（2）only
第5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：
kinetic；pressure
kinetic；essential
pressure；kinetic
pressure；height
第8题：
Before performing any maintenance on a hydraulic system storing energy in an accumulator, you should
A.pressurize the system to test for leaks
B.bleed off all pressure within the system
C.operate the machine until it reaches normal temperature
D.disconnect the pump pressure control switch
第9题：
supply clean air to the measuring compartment of the units for more accuracy
generaate the pressure required for the extraction of the oil mist from the
generate the pressure required for the extraction of the oil mist from the crankcase
supply clean air to the measuring track of the units for more accuracy
第10题：
one size larger than the pump discharge nozzle
the same size as the pump discharge nozzle
one size smaller than the pump discharge nozzle
installed with a short radius elbow at the pump