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单选题
The function of a centrifugal pump double volute casing is to （）.
A
reduce radial thrust to the impeller
B
double the liquid velocity through the pump when compared to a single volute
C
reduce hydraulic end thrust
D
provide the effect of multi-staging
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考题
Throttling in the _____ line of a centrifugal pump involves the risk of the pump cavitation.A.suctionB.exhaustC.pressureD.discharge
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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 improveB.discharge to be reversedC.efficiency to decreaseD.slippage to decrease
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单选题With respect to centrifugal pump impellers, which of the following descriptions represents the correct centrifugal pump classification? （）A
Single stage or multistageB
High pressure or low pressureC
Open or close coupledD
Horizontal or vertical
考题
单选题While flowing through the volute in a centrifugal pump, part of the （） energy of the liquid is converted to （） energy.A
kinetic；pressureB
kinetic；essentialC
pressure；kineticD
pressure；height
考题
单选题What is a function of the wearing rings used in most centrifugal pumps?（）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the discharge side from the suction sideD
Dampen the turbulent discharge flow
考题
单选题The volute pump is one in which the impeller （）.A
discharges into a gradually widening channelB
has stationary diffuser vanesC
produces no kinetic energyD
All of the above are true
考题
单选题A double suction centrifugal pump impeller has been installed in the reverse direction, and will （）.A
have a greater head capacityB
operate with increased impeller efficiencyC
discharge through the suction side of the pump casingD
require more power to run the shaft
考题
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
a single stepped impeller mounted in a progressively staged casingC
a large radial clearance between the impeller and casing to prevent overheating due toD
an increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stages
考题
单选题Most pump manufacturers recommended that the discharge piping for centrifugal pumps be （）.A
one size larger than the pump discharge nozzleB
the same size as the pump discharge nozzleC
one size smaller than the pump discharge nozzleD
installed with a short radius elbow at the pump
考题
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
diameter of the suction piping, with all other factors remaining the sameC
width of the impeller onlyD
diameter of the impeller
考题
单选题All of the following steps are taken in starting a centrifugal pump，EXCEPT to（）.A
set the relief valveB
check the lubrication systemC
vent the pump casingD
open the pump suction and discharge valves
考题
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
考题
单选题Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and （） or regenerative types.A
reciprocatingB
hydraulicC
turbineD
vane
考题
单选题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 speedB
excessive suction headC
worn wearing ringsD
gross pump misalignment
考题
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
head capacity to improveB
discharge to be reversedC
efficiency to decreaseD
slippage to decrease
考题
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
accommodate for friction between the impeller and the easing
考题
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
考题
单选题The basic function of the centrifugal pump impeller is to （）.A
directly increase the pressure of the liquid being pumpedB
directly increase the velocity of the liquid being pumpedC
convert the potential energy of the liquid to kinetic energyD
separate air from the liquid being pumped
考题
单选题Most pump manufacturers recommend that the suction piping dimension for centrifugal pumps be （）.A
one size smaller than the pump suction nozzleB
the same size as the pump suction nozzleC
one size larger than the pump suction nozzleD
installed with a short radius elbow at the pump
考题
单选题Which of the following pumps belongs to centrifugal pump?（）A
Piston pumpB
Screw pumpC
Diffuser pumpD
Water-ring pump
考题
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
the size of centrifugal pump with same capacity is smaller than that of reciprocating pumpC
centrifugal pump makes maintenance easier than reciprocating pump doesD
all of the above
考题
单选题A centrifugal pump can’t supply water after startingYou should check （）.A
priming waterB
power supplyC
packing glandD
bearing lubrication
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
Heavy fluid in the flow stream
考题
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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