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An increase in rotor clearances in a rotary pump will ______.
A.increase discharge pressure
B.decrease pump capacity
C.decrease pump cavitation
D.decrease reaction ring clearance
参考答案
更多 “ An increase in rotor clearances in a rotary pump will ______.A.increase discharge pressureB.decrease pump capacityC.decrease pump cavitationD.decrease reaction ring clearance ” 相关考题
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Which of the following terms is used to identify the pressure of the liquid entering a pump?A.Suction headB.Pump headC.Discharge headD.Total head
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Which statement is NOT true?A.While displacement pump works, volume of the working chamber will increase and decrease alternatelyB.A gear pump always has two gearsC.Any vane pump will have a rotor within a ringD.A balanced vane pump has two outlet ports and they are positioned symmetrically
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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
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Which statement is NOT true?A.In a simple vane pump, the rotor and cam ring are exactly concentricB.Balanced vane pump has an elliptical cam ringC.Liquid in both gear pump and vane pump are forced out to the outlet.D.Balanced vane pumps can work at a higher pressure than the simple vane pump
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An increase in the fuel injection pump discharge pressure can be caused by a/an _______.A.leaking delivery valveB.excessive bearing end playC.plugged injector spray holeD.increased plunger stroke
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The pressure of a liquid leaving the pump can be referred to as the ______.A.total headB.discharge headC.net positive suction headD.suction head
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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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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
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单选题In （） pump a closed discharge valve will not cause excessive pressure to build up.A
gearB
vaneC
screwD
centrifugal
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单选题A multistage centrifugal pump can be BEST described as having （）.A
two or more impellers housed together in one casing and mounted on a single shaftB
a single stepped impeller mounted in a progressively staged casingC
a large radial clearance between the impeller and casing to prevent overheating due toD
an increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stages
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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 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
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单选题If a hydraulic pump is overheating, the cause may be （）.A
excessive internal leakage in the pumpB
low discharge pressure and fluid flowC
excessive fluid level in the hydraulic reservoirD
operation of the pump at 100% efficiency
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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
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If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.A
capacity will increaseB
capacity will decreaseC
suction pressure will increaseD
suction pressure will decrease
考题
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
diameter of the impeller
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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
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
考题
单选题Operating a rotary pump at speeds in excess of design requirements could cause（）.A
decreased clearances between rotating partsB
decreased slippage to the suction side of the pumpC
air binding in the discharge portsD
erosion and excessive wear
考题
单选题If a bilge pump failed to build up discharge pressure, you should check for （）.A
excessive water in the bilgesB
a clogged suction strainerC
oil in the bilgesD
All of the above
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The （） discharge a nearly constant amount of liquid regardless of pressure.A
mixed-flow pumpB
axial-flow pumpC
centrifugal pumpD
displacement pump
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单选题The pump discharge pressure will be considerably higher than the pressure at the （）.A
pump entry branchB
outlet pipeC
impellerD
None of the above is true
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单选题The boiler feed pump discharge pressure is higher than the steam drum pressure to （）.A
ensure feed water flow into the boilerB
keep the steam drum pressure highC
prevent water hammer in the feed lineD
help the feed water flash to steam
考题
单选题An increase in rotor clearances in a rotary pump will （）.A
increase discharge pressureB
decrease pump capacityC
decrease pump cavitationD
decrease reaction ring clearance
考题
单选题An increase in the fuel injection pump discharge pressure can be caused by a/an （）A
leaking delivery valveB
excessive bearing end playC
plugged injector spray holeD
increased plunger stroke
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