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单选题
The discharge head of a centrifugal pump will vary directly with the （）.
A
change in impeller diameter
B
square of the impeller diameter
C
cube of the impeller diameter
D
impeller efficiency for large changes in the size of the impeller
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单选题What is the function of wearing rings found on some centrifugal pumps? （）A
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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
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单选题If you heard a ‘crackling’ noise in centrifugal pump, the most probable cause of the problem would be（）A
insufficient speedB
cavitationC
excess discharge pressureD
excessive net positive suction head B
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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
operate with increased impeller efficiencyC
discharge through the suction side of the pump casingD
require more power to run the shaft
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单选题If a centrifugal bilge pump were continually operated with the discharge valve closed the （）.A
motor overload would openB
relief valve would openC
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单选题A centrifugal bilge pump requires priming （）.A
primarily to lubricate the shaft sealsB
due to the inability of this type of pump to lift water to cover the suction (eye) of the impellerC
to initially unload the pump by having its head pressure equal to discharge pressureD
in order to overcome the potential energy of water in the discharge line
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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
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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
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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
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diameter of the impeller
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set the relief valveB
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noise and vibrationB
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lifting of the relief valve
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单选题What does the term head mean when applied to a fire pump?（）A
Length of the discharge pipeB
Height of the discharge pipeC
Difference between the discharge and suction pressuresD
Sum of discharge and suction pressures
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worn wearing ringsD
gross pump misalignment
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单选题A centrifugal pump produces flow with a resulting discharge head by energy conversionIt is typical for the energy conversion to follow the order of （）.A
mechanical energy to kinetic energy to potential energyB
mechanical energy to potential energy to kinetic energyC
potential energy to mechanical energy to kinetic energyD
kinetic energy to mechanical energy to potential energy
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
lantern ring and impeller
考题
单选题When starting a centrifugal pump, the discharge valve should be （）.A
closedB
opened fullyC
cracked openD
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考题
单选题The discharge rate or capacity of a centrifugal pump will vary directly as the （）.A
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square of the impeller radiusC
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motor overload will openB
relief valve will openC
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单选题The simplest method to use for determining if a centrifugal pump is operating as designed, is to （）.A
closely observe the pump discharge temperatureB
close off the discharge valve, and watch for a rise in pressureC
momentarily close off the suction valve, and watch for a rise in pressureD
use a clamp on ammeter and compare the readings to past records
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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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