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
A positive displacement pump is that where the volume of the pump chamber is alternately increased to （） and then decreased to （）.
A
draw the liquid in；force the liquid out
B
force the liquid out；draw the liquid in
C
suction；draw
D
deliver；outlet
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
All of the following are attributes that can be specified when creating a logical volume EXCEPT:() A.Number of logical partitionsB.Disk where logical volume will resideC.Size of the logical volume control blockD.Position of the logical volume on the disk
The amount of fluid delivered by a positive displacement pump can be regulated by _____.A.throttling the pressure lineB.changing the speed of the driving rotorC.either A or BD.None of the above is tree
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
The free surface corrections depend upon the dimensions of the surface of the free liquids and the ______．A.volume of liquid in the tankB.displacement of the vesselC.location of the tank in the vesselD.height of the center of gravity of the vessel
The free surface effects of a partially full liquid tank decrease with increased ______．A.Density of the liquidB.Placement of the tank above the keelC.Displacement volume of the shipD.Size of the surface area in the tank
All of the following are attributes that can be specified when creating a logical volume EXCEPT:（）A、Number of logical partitionsB、Disk where logical volume will resideC、Size of the logical volume control blockD、Position of the logical volume on the disk
With a scalable volume group, where is the logical volume control information stored on the disk?（）A、In the ODMB、In the volume group descriptor areaC、In the first 512 bytes of the logical deviceD、In the first block of the user data within the LV
Where can a system administrator find information regarding configured physical volumes， volume groups， and logical volumes besides the Volume Group Descriptor Area （VGDA）？（）A、/etc/filesystemsB、/etc/environmentC、Object Data Manager （ODM）D、Logical Volume Control Block （LVCB）
单选题If you heard a ‘crackling’ noise in centrifugal pump, the most probable cause of the problem would be（）Ainsufficient speedBcavitationCexcess discharge pressureDexcessive net positive suction head B
单选题Which of the following hydraulic systems is not one of the three sub-division of the Hydraulic drive system?（）AConstant pressure systemBVariable pressure systemCVariable displacement systemDConstant volume system
单选题A screw pump belongs to （） according to its working principle.Areciprocating pumpsBpositive displacement pumpsCcentrifugal pumpsDcentripetal pumps
单选题Gear pumps are of positive displacement type pumps because they discharge a near constant amount of liquid （） pressure.Adepending onBin relative toCregardless ofDbecause of
单选题A variable displacement system of hydraulic drives consists of （）.Aa variable displacement axial piston pumpBa constant displacement axial piston pumpCa reciprocating piston pumpDa centrifugal pump
单选题Which of the listed pumps is NOT a positive displacement pump?（）ACentrifugalBReciprocatingCGearDRotary
单选题With a scalable volume group, where is the logical volume control information stored on the disk?（）AIn the ODMBIn the volume group descriptor areaCIn the first 512 bytes of the logical deviceDIn the first block of the user data within the LV
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Lube oil pumps taking suction from the sump of most small marine engines are usually （）.Aof the diaphragm typeBof the centrifugal typeCof the positive displacement typeDindependently driven by electric motors
单选题In a diesel engine, a positive displacement type blower is usually （）Agear drive by the engineBdriven by an exhaust gas turbineCdriven by a camshaftDdriven by separate motor
单选题The bore of a diesel engine cylinder describes the （）Aswept volume of the cylinderBinside diameter of the cylinderCpiston displacement in the cylinderDlength of the piston stroke
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The pressure of a liquid leaving the pump can be referred to as the （）.Atotal headBdischarge headCnet positive suction headDsuction head
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 vane pump belongs to （） according to its working principle.Areciprocating pumpBpositive displacement pumpCcentrifugal pumpDcentripetal pump
单选题The amount of fluid delivered by a positive displacement pump can be regulated by （）.Athrottling the pressure lineBchanging the speed of the driving rotorCeither A or BDNone of the above is tree