单选题A （） pump is that where the volume of the pump chamber is alternately increased to draw the liquid in and then decreased to force the liquid out.AinjectorBpositive displacementCcentrifugalDcentripetal
单选题
A （） pump is that where the volume of the pump chamber is alternately increased to draw the liquid in and then decreased to force the liquid out.
A
injector
B
positive displacement
C
centrifugal
D
centripetal
参考解析
解析：
暂无解析
相关考题：
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
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
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
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
The amount of fuel delivered by a helical plunger fuel injection pump is controlled by ______.A.varying the pump discharge pressureB.varying the pump return pressureC.rotation of the pump plungerD.rotation of the pump barrel
单选题A positive displacement pump is that where the volume of the pump chamber is alternately increased to （） and then decreased to （）.Adraw the liquid in；force the liquid outBforce the liquid out；draw the liquid inCsuction；drawDdeliver；outlet
单选题The primary function of a fuel delivery check valve assembly is to（）Adeliver proper fuel quantity to the injection nozzleBprovide rapid fuel injection cutoffCcontrol fuel quantity entering the pump bodyDcontrol fuel pressure delivered to the combustion chamber
单选题Cargo pump relief valves are piped to the（）.Acargo pump pressure gaugesBcrossover lines interconnecting two pumpsCsuction side of pumpsDatmosphere through pump vents
单选题Before liquid can flow into a pump, the air in the suction line must be （） sufficiently to cause the liquid to flow into the suction chamber.AfilledBevacuatedCcompressedDcharged
单选题The static suction lift of a pump is the difference in elevation between the （）.Acenterline of the pump and the level of the liquid in the suction well when the source of liquid is below the pumpBcenterline of the pump and the suction liquid level when the source of liquid is above the pumpCcenterline of the pump and the level of the discharge liquidDliquid levels of the suction and discharge
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Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to（）Afacilitate bi-directional operationBprovide the greatest pump efficiencyCprevent pump clogging from marine growthDprevent cavitation at the pump outlet
单选题The pump has a constant stroke and the amount of fuel delivered is regulated by rotating （） which has a specially arranged helical groove cut into it.Athe pump cylinderBthe pump camCthe pump plungerDthe pump miler
单选题A positive displacement pump is that where the volume of the pump chamber is alternately （） to draw the liquid in and then （） to force the liquid out.Aincreased；decreasedBdecreased；increasedCdecreased；decreasedDincreased；increased
单选题If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be （）.Acontaminated fluidBpitted thrust ringsCworn pintle bearingsDobstructed suctions passage
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An increase in rotor clearances in a rotary pump will （）.Aincrease discharge pressureBdecrease pump capacityCdecrease pump cavitationDdecrease reaction ring clearance
单选题The output volume of a positive fixed displacement pump can be changed only by （）.Achanging the angle of the tilting plateBchanging the speed of the pumpCmoving the slide block and rotorDmoving the shaft trunnion block
单选题Through a （） pump, the liquid is transferred from the suction to the discharge by the mechanical variation of the volume of a chamber or chambers.Apositive displacementBejectorCcentrifugalDair compressor
单选题If the pump for a hydraulic anchor windlass is over heating, the cause may be （）.Aincreased pump speedBexcessive pump discharge pressureCtoo low of a tilting box angleDlow pump speed
单选题Each fire pump on a ship must have a pressure gauge located at（）.Athe pump dischargeBthe manifold connectionCeach fire station dischargeDthe pump station
单选题On modern ships, centrifugal pump with a self-primer has replaced reciprocating pump as bilge pump because（）Acentrifugal pump is cheaper than reciprocating pumpBthe size of centrifugal pump with same capacity is smaller than that of reciprocating pumpCcentrifugal pump makes maintenance easier than reciprocating pump doesDall of the above
单选题The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）Avarying the pump discharge pressureBvarying the pump return pressureCrotation of the pump plungerDrotation of the pump barrel