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
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
相关考题：
Throttling in the _____ line of a centrifugal pump involves the risk of the pump cavitation.A.suctionB.exhaustC.pressureD.discharge
While on watch in the engine room, you hear a continuous sounding of the general alarm. Which of the following actions should you take?A.Make an entry in the official logbookB.Open the master control valves on the fixed CO2 systemC.Start the fire pump and check discharge pressureD.Secure auxiliary condenser overboard discharge
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
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
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
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
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
单选题Which of the following statements is correct with regards to the operation of a centrifugal cargo pump?（）AOil is discharged from the impeller through the outletBGravity causes the oil to flow toward the dischargeCThe self-priming feature of the centrifugal pump enables it to draw its own suction as it startsDThe discharge capacity varies directly with the speed of the impeller
单选题If you heard a ‘crackling’ noise in centrifugal pump, the most probable cause of the problem would be（）Ainsufficient speedBcavitationCexcess discharge pressureDexcessive net positive suction head B
单选题A centrifugal bilge pump requires priming （）.Aprimarily to lubricate the shaft sealsBdue to the inability of this type of pump to lift water to cover the suction (eye) of the impellerCto initially unload the pump by having its head pressure equal to discharge pressureDin order to overcome the potential energy of water in the discharge line
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
单选题Most pump manufacturers recommended that the discharge piping for centrifugal pumps be （）.Aone size larger than the pump discharge nozzleBthe same size as the pump discharge nozzleCone size smaller than the pump discharge nozzleDinstalled with a short radius elbow at the pump
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 （）.Adiameter of the discharge piping, with all other factors remaining the sameBdiameter of the suction piping, with all other factors remaining the sameCwidth of the impeller onlyDdiameter of the impeller
单选题All of the following steps are taken in starting a centrifugal pump，EXCEPT to（）.Aset the relief valveBcheck the lubrication systemCvent the pump casingDopen the pump suction and discharge valves
单选题The usual symptoms of cavitation in a centrifugal pump is （）.Anoise and vibrationBan increase in discharge pressureCan increase in suction pressureDlifting of the relief valve
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（）.Aexcessive pump speedBexcessive suction headCworn wearing ringsDgross pump misalignment
单选题To operate a centrifugal fire pump at reduced capacity, you should （）.Areadjust the relief valveBthrottle the suction lineCthrottle the discharge valveDopen the priming line
单选题The purpose of the wearing rings used in a centrifugal pump is to （）.Aprevent an internal explosion in the pump when it is overheatedBenable a visual inspection of the pump while it is runningCinsure a proper alignment of the pump coupling to the driverDaccommodate for friction between the impeller and the easing
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（）.Abooster pump coming on the line and discharging properlyBbooster pump failing to startCbooster pump being lined up in the wrong directionDship's pump speeding up
单选题A relief valve for a cargo pump is generally installed（）.Aafter the discharge valveBbetween the pump and discharge valveCafter the suction valveDbetween the pump and suction valve
单选题To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）.Ashaft and impellerBmotor and pump shaftCcasing and impeller wearing ringsDlantern ring and impeller
单选题When starting a centrifugal pump, the discharge valve should be （）.AclosedBopened fullyCcracked openDpartly open
单选题The valve on the discharge side of a cargo pump on a tanker will usually be a（）.Abutterfly valveBspectacle valveCcheck valveDglobe valve
单选题One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.Amotor overload will openBrelief valve will openCpump will overheatDmotor will overheat
单选题The simplest method to use for determining if a centrifugal pump is operating as designed, is to （）.Aclosely observe the pump discharge temperatureBclose off the discharge valve, and watch for a rise in pressureCmomentarily close off the suction valve, and watch for a rise in pressureDuse a clamp on ammeter and compare the readings to past records
单选题The combined fan discharge rate in an inert gas system is related to the（）.Ashoreside loading rateBmaximum cargo pump discharge rateCboiler forced draft fan rateDsize of the largest cargo tank
单选题The valve on the discharge side of a cargo pump on a tank vessel will usually be a（）.Abutterfly valveBspectacle valveCcheck valveDglobe valve