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
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 improve
B.discharge to be reversed
C.efficiency to decrease
D.slippage to decrease
相关考题：
第二组Displacement pumps are those where the volume of the pump chamber is alternately increased to draw the liquid in from the suction pipe and then decreased to force the liquid out into the delivery pipe. Centrifugal pumps are those wherein an impeller rotating at high speed throws the liquid by centrifugal force from the center to the periphery of the impeller where the liquid is discharged through the delivery outlet.Gear pump consists of two or more meshing gears (spur, single or double helical teeth) enclosed m a close-fitted housing. These are used extensively for pumping fuel oil, lubricating oil and hydraulic oil. When gears are unmeshed on the inlet side, a pressure drop occurs that helps the atmospheric pressure acting on the surface of the oil in the reservoir to force it up the pipe to fill the void, the oil is then transferred around the periphery of the pump housing. As the gear teeth mesh again on the outlet side, they form. a seal that prevents oil from backing up to the inlet, the oil in the void is then be forced out into the discharge line.All vane pumps have a rotor driven within a ring (cam ring) by a drive shaft coupled to a prime mover. A cylindrical rotor with sliding vanes, generally in radial slots, rotates within the ring. The center of the rotor is offset from the center of the ring. In a simple vane pump, as the rotor turns, the vanes are forced outward against the inner surface of the cam ring by centrifugal force. This outward radial movement of the vanes and turning of the rotor causes the chamber between the vanes to increase as the vanes pass further away from the inlet port. This increase in volume results in a lowering of pressure until the atmospheric pressure is sufficient to force oil from the reservoir into the inlet chamber. Oil from the inlet is swept away by the vanes toward the outlet port through a decreasing series of chambers until it is forced through the outlet port. A vane pump of balanced design has an elliptical cam ring so that two pumping chambers are formed. This pump is in hydraulically balance, since the two intake and two outlet ports are diametrically opposed to each other. Therefore the side loads exerted on the rotor cancel out, thereby increasing bearing lift and permitting high operating pressure.According to the last sentence of paragraph 1, from where the liquid is discharged through the delivery outlet?A.from the eye of the impellerB.from passage of impellerC.from the periphery of the impellerD.from the impeller
A centrifugal pump may fail to deliver water when first started if the ______.A.water seal pipe is pluggedB.pump is not primedC.seal ring is properly locatedD.impeller is flooded
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A double suction centrifugal pump impeller has been installed in the reverse direction, and will （）.Ahave a greater head capacityBoperate with increased impeller efficiencyCdischarge through the suction side of the pump casingDrequire more power to run the shaft
单选题Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump is a result of （）.AcavitationBwater hammerCfluid frictionDsteam knock
单选题Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.AcavitationBelectrolysisCabrasionDcorrosion
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Increasing the speed of a centrifugal pump will result in an increase in its capacity in its capacityAnother means of increasing the capacity 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One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.Amaintain radial alignment between the pump impeller and casingBabsorb all impeller shaft end thrustCprevent water leakage to the atmosphereDprevent wear of the pump casing and/or impeller
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A centrifugal impeller consists of a number of vanes curving （） from the direction of rotation.AbackwardsBforwardsCupwardDdownwards
单选题Attempts are made to eliminate axial thrust in centrifugal pump by （）.Aproviding the impeller with balancing holesBthe use of symmetrical impellerCneither A nor BDeither A or B
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 （）.Aincrease speedBincrease the size of the cardent assemblyCreduce wearing ring clearancesDchange the pump to a close coupled arrangement
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 absorb the wear resulting from impeller rotation and abrasives in the liquid, a centrifugal pump is usually fitted with （）.Alantern ringsBbearingsCeasing volutesDwearing rings
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 （）.Ahead capacity to improveBdischarge to be reversedCefficiency to decreaseDslippage to decrease
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In order to properly remove air from the casing of a centrifugal pump when starting, the pump should have a （）.Apositive headBnegative suction headCmechanical sealDvent valve attached to the casing at the top of the volute
单选题Most pump manufacturers recommend that the suction piping dimension for centrifugal pumps be （）.Aone size smaller than the pump suction nozzleBthe same size as the pump suction nozzleCone size larger than the pump suction nozzleDinstalled with a short radius elbow at the pump
单选题A centrifugal pump produces the required pressure energy by means of a rotating （） provided with vanes.ApropellerBimpellerCcircumferenceDscrew
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Which features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）AClose radial clearance between impeller hub and casingBLow rotational speed of impellerCRemovable end plateDReplaceable impeller and casing wearing rings
单选题The discharge head of a centrifugal pump will vary directly with the （）.Achange in impeller diameterBsquare of the impeller diameterCcube of the impeller diameterDimpeller efficiency for large changes in the size of the impeller
单选题The discharge rate or capacity of a centrifugal pump will vary directly as the （）.Achange in the impeller diameterBsquare of the impeller radiusCcube of the impeller diameterDimpeller efficiency for large changes in its size
单选题A centrifugal pump vibrates excessively during operationUpon disassembling the pump it is found that the impeller is out of balanceWithout an available spare, you should （）.Adrill holes through the heavy side of the impeller until it balancesBweld counterweights to the light side of the impellerCremove metal from the heavy side by machining in a latheDacid wash and serape the heavy side until it balances