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单选题
The usual symptoms of cavitation in a centrifugal pump is （）.
A
noise and vibration
B
an increase in discharge pressure
C
an increase in suction pressure
D
lifting of the relief valve
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单选题Increasing the speed of a centrifugal pump will result in an increase in its capacity Another means of increasing the capacity of a centrifugal pump is to increase the （）.A
diameter of the discharge piping, with all other factors remaining the sameB
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单选题All of the following steps are taken in starting a centrifugal pump，EXCEPT to（）.A
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单选题One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.A
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absorb all impeller shaft end thrustC
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单选题Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to（）A
facilitate bi-directional operationB
provide the greatest pump efficiencyC
prevent pump clogging from marine growthD
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单选题The usual symptoms of cavitation in a centrifugal pump is （）.A
noise and vibrationB
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lifting of the relief valve
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increase the size of the cardent assemblyC
reduce wearing ring clearancesD
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impellerC
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单选题When starting a centrifugal pump, the discharge valve should be （）.A
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cracked openD
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单选题On modern ships, centrifugal pump with a self-primer has replaced reciprocating pump as bilge pump because（）A
centrifugal pump is cheaper than reciprocating pumpB
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centrifugal pump makes maintenance easier than reciprocating pump doesD
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考题
单选题Which of the listed conditions can lead to cavitation气穴in a centrifugal pump?（）A
Vapor pockets formed in the suction flow streamB
Rough easing volute surfacesC
Worn wearing ringsD
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