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You start a centrifugal cargo pump to discharge cargo．The pump works for a while and then loses suction．This could be caused by ______．
A.The pump running backwards
B.Incomplete priming
C.The discharge head being too high
D.All of the above
参考答案
更多 “ You start a centrifugal cargo pump to discharge cargo．The pump works for a while and then loses suction．This could be caused by ______．A.The pump running backwardsB.Incomplete primingC.The discharge head being too highD.All of the above ” 相关考题
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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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If it becomes necessary to pump bilges while a vessel is in port, which of the following procedures should be followed?A.Pump only if the discharge is led to a shore tank or bargeB.Pump only during the hours of darknessC.Pump only on the outgoing tideD.Pump only as much as is necessary
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If you must pump bilges while a vessel is in port，you should pump only ______．A.If discharge is led to a shore tank or bargeB.During the hours of darknessC.On the outgoing tideD.As much as is necessary
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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
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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
The self-priming feature of the centrifugal pump enables it to draw its own suction as it startsD
The discharge capacity varies directly with the speed of the impeller
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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 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
width of the impeller onlyD
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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
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单选题The usual symptoms of cavitation in a centrifugal pump is （）.A
noise and vibrationB
an increase in discharge pressureC
an increase in suction pressureD
lifting of the relief valve
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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
excessive pump speedB
excessive suction headC
worn wearing ringsD
gross pump misalignment
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单选题To operate a centrifugal fire pump at reduced capacity, you should （）.A
readjust the relief valveB
throttle the suction lineC
throttle the discharge valveD
open the priming line
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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
accommodate for friction between the impeller and the easing
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单选题The terminal indicates to you that they are going to use a booster pump to assist the discharging operation. You start the discharge，and in a few minutes the pressure drops sharply. This could be a result of the（）.A
booster pump coming on the line and discharging properlyB
booster pump failing to startC
booster pump being lined up in the wrong directionD
ship's pump speeding up
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单选题A relief valve for a cargo pump is generally installed（）.A
after the discharge valveB
between the pump and discharge valveC
after the suction valveD
between the pump and suction valve
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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When starting a centrifugal pump, the discharge valve should be （）.A
closedB
opened fullyC
cracked openD
partly open
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单选题The valve on the discharge side of a cargo pump on a tanker will usually be a（）.A
butterfly valveB
spectacle valveC
check valveD
globe valve
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单选题One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.A
motor overload will openB
relief valve will openC
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motor will overheat
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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 combined fan discharge rate in an inert gas system is related to the（）.A
shoreside loading rateB
maximum cargo pump discharge rateC
boiler forced draft fan rateD
size of the largest cargo tank
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单选题The valve on the discharge side of a cargo pump on a tank vessel will usually be a（）.A
butterfly valveB
spectacle valveC
check valveD
globe valve
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