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What is the function of wearing rings found on some centrifugal pumps ________．
A.Absorb erosion of high velocity discharge stream
B.Seal pump shaft against entry of air
C.Isolate the outlet side from the inlet side
D.Dampen the turbulent discharge flow
参考答案
更多 “ What is the function of wearing rings found on some centrifugal pumps ________．A.Absorb erosion of high velocity discharge streamB.Seal pump shaft against entry of airC.Isolate the outlet side from the inlet sideD.Dampen the turbulent discharge flow ” 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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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
考题
The discharge flow of a reciprocating pump is ______.A.steadyB.in pulsationC.continuousD.large
考题
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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What causes cavitation in a centrifugal pump ________．A.Vapor pockets in the flow streamB.Rough impeller surfacesC.Worn wearing ringsD.Heavy fluid in the flow stream
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What prevents water running along the shaft of a leaking centrifugal pump from entering the shaft bearing ________．A.Shaft sealB.Water flingerC.Drain holeD.Lantern ring
考题
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
考题
单选题What is the function of wearing rings found on some centrifugal pumps? （）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the outlet side from the inlet sideD
Dampen the turbulent discharge flow
考题
单选题Which of the following statements is true concerning centrifugal pumps?（）A
They are particularly suited for pumping high viscosity fluidsB
They are started with the discharge valve openedC
The flow of liquid is developed by imparting energy due to the rotation of an impellerD
They are always mounted in a horizontal position
考题
单选题A centrifugal pump attempting to develop flow against a closed discharge valve has a/an （）.A
capacity of 0%B
efficiency of 100%C
internal slippage of 0%D
shut off horsepower rating of 100%
考题
单选题One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.A
maintain radial alignment between the pump impeller and casingB
absorb all impeller shaft end thrustC
prevent water leakage to the atmosphereD
prevent wear of the pump casing and/or impeller
考题
单选题Which of the following statements represents the advantage of rotary pumps as compared to reciprocating pumps?（）A
The high discharge pressure of the rotary pumps permits a larger volume of fluid per unit time than the reciprocating pumpB
Rotary pumps are capable of pumping more fluid than reciprocating pumps of the same weightC
Rotary pumps occupy only one-half the space of reciprocating pumpsD
Rotary pumps eliminate discharge slippage of the pumped liquid, while this does not hold true for a reciprocating pump
考题
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
考题
单选题What is a characteristic of all centrifugal cargo pumps? （）A
They are self-primingB
Decreasing the speed of rotation will decrease the discharge pressureC
Opening the discharge valve wider will increase the discharge pressureD
All of the above
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
installed with a short radius elbow at the pump
考题
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
考题
单选题In a diesel engine cooling system, the high temperature alarm contact maker will be activated on excessively high water discharge temperature from the （）A
raw water pump dischargeB
expansion tank outletC
cooling water heat exchangerD
outlet engine jacket water outlet
考题
单选题Which of the following problems will occur if a disk-type centrifugal lube oil purifier is not properly primed prior to admitting oil flow to the bowl?（）A
Contamination of the lube oil by emulsification will resultB
The lube oil will not be subjected to the proper centrifugal forceC
The lube oil will overheat and flashD
Oil will discharge from the heavy phase discharge port and be wasted
考题
单选题Which of the listed statements is correct concerning the starting of centrifugal pumps?（）A
They should always be started with the discharge valve closedB
They should always be started with the discharge valve openedC
A priming pump is always required to flood the impeller suctionD
They should always be started with the sealing line valves closed
考题
单选题If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）A
The wearing rings are excessively wornB
The suction strainer is cloggedC
The discharge valve is cloggedD
The shaft is worn
考题
单选题Which method should be used to warm up the pump turbines prior to discharge（）.A
Lock the turbine rotor and slowly bleed in steam until operating temperature is reachedB
Run the pump at high speed with the discharge valves closedC
Run the turbine at slow speed with the pump disconnectedD
Shut the discharge valve and run the pump at slow speed
考题
单选题As to the low speed diesel engine, if you want to change the coolant flow for a certain cylinder, you can regulate （）.A
the inlet valveB
the outlet valveC
both the inlet valve and the outlet valveD
the pump inlet valve
考题
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
考题
单选题The discharge flow of a reciprocating pump is （）.A
steadyB
in pulsationC
continuousD
large
考题
单选题What is a function of the wearing rings used in most centrifugal pumps?（）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the discharge side from the suction sideD
Dampen the turbulent discharge flow
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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