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单选题
The volute pump is one in which the impeller （）.
A
discharges into a gradually widening channel
B
has stationary diffuser vanes
C
produces no kinetic energy
D
All of the above are true
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单选题A double suction centrifugal pump impeller has been installed in the reverse direction, and will （）.A
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单选题A multistage centrifugal pump can be BEST described as having （）.A
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a single stepped impeller mounted in a progressively staged casingC
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diameter of the discharge piping, with all other factors remaining the sameB
diameter of the suction piping, with all other factors remaining the sameC
width of the impeller onlyD
diameter of the impeller
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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
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单选题Attempts are made to eliminate axial thrust in centrifugal pump by （）.A
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单选题The capacity of a centrifugal pump can be increased by the installation of a larger diameter impeller Another means of increasing the pump capacity is to （）.A
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change the pump to a close coupled arrangement
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lantern ringsB
bearingsC
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wearing rings
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单选题The purpose of the wearing rings used in a centrifugal pump is to （）.A
prevent an internal explosion in the pump when it is overheatedB
enable a visual inspection of the pump while it is runningC
insure a proper alignment of the pump coupling to the driverD
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单选题Which of the listed statements is correct concerning the starting of centrifugal pumps?（）A
They should always be started with the discharge valve closedB
They should always be started with the discharge valve openedC
A priming pump is always required to flood the impeller suctionD
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单选题In order to properly remove air from the casing of a centrifugal pump when starting, the pump should have a （）.A
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negative suction headC
mechanical sealD
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单选题To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）.A
shaft and impellerB
motor and pump shaftC
casing and impeller wearing ringsD
lantern ring and impeller
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单选题Which features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）A
Close radial clearance between impeller hub and casingB
Low rotational speed of impellerC
Removable end plateD
Replaceable impeller and casing wearing rings
考题
单选题The discharge head of a centrifugal pump will vary directly with the （）.A
change in impeller diameterB
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impeller efficiency for large changes in its size
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one fixed hand pump and one portable hand pumpC
two portable hand pumpsD
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单选题A centrifugal pump vibrates excessively during operationUpon disassembling the pump it is found that the impeller is out of balanceWithout an available spare, you should （）.A
drill holes through the heavy side of the impeller until it balancesB
weld counterweights to the light side of the impellerC
remove metal from the heavy side by machining in a latheD
acid wash and serape the heavy side until it balances
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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
Heavy fluid in the flow stream
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单选题The volute of centrifugal pump also acts as a diffuser converting （）into pressure head.A
mechanical energyB
heat energyC
potential energyD
kinetic head
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