网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）.
A
shaft and impeller
B
motor and pump shaft
C
casing and impeller wearing rings
D
lantern ring and impeller
参考答案
参考解析
解析：
暂无解析
更多 “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” 相关考题
考题
Throttling in the _____ line of a centrifugal pump involves the risk of the pump cavitation.A.suctionB.exhaustC.pressureD.discharge
考题
Software design is a(71)process .It requires a certain(72)of flair on the part of the designer. Design can not be learned from a book .It must be practiced and learnt by experience and study of existing systems .A well(73)software system is straightforward to implement and maintain ,easily(74)and reliable .Badly(73)software systems ,although they may work are(75)to be expensive to maintain ,difficult to test and unreliable.A．createB．createdC．creatingD．creative
考题
Software design is a(46) process. It requires a certain amount of fl air on the part of the(47). Design can not be learned from a book . It must be practiced and learnt by experience and study of existing systems. A well(48) software system is straightforward to implement and maintain , easily(49) and reliable. Badly(48) software systems, although they may work are(50) to be expensive to maintain , difficult to test and unreliable.A．createB．creativeC．creatingD．created
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
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
考题
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
What is the purpose of pressure-vacuum relief valves ________．A.Regulation of discharge pressure from cargo pumpsB.Maintaining constant velocity in cargo linesC.Regulation of suction head on cargo pumpsD.To maintain a tank or void at atmospheric pressure
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What is the purpose of pressure-vacuum relief valves? （）A
Regulation of discharge pressure from cargo pumpsB
Maintaining constant velocity in cargo linesC
Regulation of suction head on cargo pumpsD
To maintain a tank or void at atmospheric pressure
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If a large difference exists between the compressor discharge pressure and the pressure corresponding to the existing condensing temperature in a refrigeration system, you should（）.A
increase the flow of the cooling water through the condenserB
adjust the high pressure cutout to maintain the desired pressureC
open the hot gas bypass temporarily to reduce capacityD
purge non-condensable gases to reduce the excess pressure
考题
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
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CO2 cylinders equipped with pressure actuated discharge heads will discharge automatically when（）.A
the discharge valve is openB
the control box glass is brokenC
pressure from the control cylinders is detectedD
the control cylinders have been completely discharged
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In （） pumps a closed discharge valve will cause bursting discharge pressure.A
centrifugalB
plungerC
injectorD
water
考题
单选题Which of the following pumps will build up a bursting pressure or stall their motors if the discharge valves are closed?（） (1) gear (2) centrifugal (3) screwA
（1）and（2）B
（1），（2）and（3）C
（1）and（3）D
（2）and（3）
考题
单选题The design of for a flash type evaporator is of critical importance because it must provide an optimum feedwater spray pattern that facilitates the flashing process, and it must also maintain a pressure differential between successive stages（）A
condenserB
flashing deviceC
lashing deviceD
vacuum pump
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The purpose of the refrigeration system low pressure cutout switch is to （）A
protect the compressor from liquid flood backB
protect the compressor from low discharge pressureC
start and stop the compressor upon system demandD
start the compressor after a drop in the evaporator pressure
考题
单选题The basic function of the centrifugal pump impeller is to （）.A
directly increase the pressure of the liquid being pumpedB
directly increase the velocity of the liquid being pumpedC
convert the potential energy of the liquid to kinetic energyD
separate air from the liquid being pumped
考题
单选题The advantage of a centrifugal pump as compared with a reciprocating pump is that （）.A
discharge is continuousB
it has no internal valvesC
upon accidental closing of discharge valve, excessive pressure will not build upD
all of the above are true
考题
单选题Bad valves operation of the reciprocating air compressors can be detected by observation of （）.A
the discharge temperature lowB
the discharge temperature highC
the discharge pressure riseD
the inter-stage pressure low
热门标签
最新试卷