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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 casing
B
Low rotational speed of impeller
C
Removable end plate
D
Replaceable impeller and casing wearing rings
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Throttling in the _____ line of a centrifugal pump involves the risk of the pump cavitation.A.suctionB.exhaustC.pressureD.discharge
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Single stage or multistageB
High pressure or low pressureC
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单选题Which of the following statements is correct with regards to the operation of a centrifugal cargo pump?（）A
Oil is discharged from the impeller through the outletB
Gravity causes the oil to flow toward the dischargeC
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单选题Which of the following will be the advantage of a centrifugal pump as compared with a reciprocating pump?（） (1) Its discharge is continuous (2) It has no internal valves (3) Upon accidental closing of discharge valve, excessive pressure will not build upA
（1），（2）B
（2），（3）C
（1），（2），（3）D
（2）only
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
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单选题Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.A
cavitationB
electrolysisC
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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
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
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check the lubrication systemC
vent the pump casingD
open the pump suction and discharge valves
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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
prevent water leakage to the atmosphereD
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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
increase speedB
increase the size of the cardent assemblyC
reduce wearing ring clearancesD
change the pump to a close coupled arrangement
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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
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head capacity to improveB
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单选题The purpose of the wearing rings used in a centrifugal pump is to （）.A
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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Excessive air leakage into the suction side of a centrifugal pump would be indicated by which of the following operational problems?（）A
The pump delivers full capacity when started, but gradually slackens off toan abnormally low flowB
The pump packing gland overheats after short operating periodsC
The motor over-current protective device continually shuts the pump downD
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单选题Most pump manufacturers recommend that the suction piping dimension for centrifugal pumps be （）.A
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the same size as the pump suction nozzleC
one size larger than the pump suction nozzleD
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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
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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
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考题
单选题Which of the following actions should be taken if during a routine maintenance inspection of a centrifugal pump, localized scoring on a pump shaft sleeve is detected?（）A
Correct the cause of the scoring and repair the sleeve or replace with a new oneB
Reassemble the unit and provide more water leak off for proper lubricationC
Check for parallel alignment of the sleeve radial faces to the sleeve boresD
Reassemble the unit and adjust the governor to obtain a slower speed
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Which of the following centrifugal pump components converts the liquid kinetic energy of velocity to the potential energy of pressure?（）A
ImpellerB
Electric motorC
VoluteD
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