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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
have a greater head capacityB
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单选题A multistage centrifugal pump can be BEST described as having ().A
two or more impellers housed together in one casing and mounted on a single shaftB
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单选题Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by ().A
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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
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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
maintain radial alignment between the pump impeller and casingB
absorb all impeller shaft end thrustC
prevent water leakage to the atmosphereD
prevent wear of the pump casing and/or impeller
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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
prevent cavitation at the pump outlet
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单选题Attempts are made to eliminate axial thrust in centrifugal pump by ().A
providing the impeller with balancing holesB
the use of symmetrical impellerC
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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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单选题To absorb the wear resulting from impeller rotation and abrasives in the liquid, a centrifugal pump is usually fitted with ().A
lantern ringsB
bearingsC
easing volutesD
wearing rings
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单选题It is possible to mount a double suction centrifugal pump impeller with the vanes facing in the wrong directionThis would cause the pump ().A
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discharge to be reversedC
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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
accommodate for friction between the impeller and the easing
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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
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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
positive headB
negative suction headC
mechanical sealD
vent valve attached to the casing at the top of the volute
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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
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单选题The discharge head of a centrifugal pump will vary directly with the ().A
change in impeller diameterB
square of the impeller diameterC
cube of the impeller diameterD
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单选题The discharge rate or capacity of a centrifugal pump will vary directly as the ().A
change in the impeller diameterB
square of the impeller radiusC
cube of the impeller diameterD
impeller efficiency for large changes in its size
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one fixed power pump and one portable hand pumpB
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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