In （） pumps a closed discharge valve will cause bursting discharge pressure.

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• The purpose of the wearing rings used in a centrifugal pump is to （）.

  A . prevent an internal explosion in the pump when it is overheated B . enable a visual inspection of the pump while it is running C . insure a proper alignment of the pump coupling to the driver D . accommodate for friction between the impeller and the easing

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• Which of the following types of hydraulic pumps would be used in a steering system?（）

  A . Lobe B . Screw C . Radial piston D . Volute

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• It is possible to mount a double suction centrifugal pump impeller with the vanes facing in the wrong directionThis would cause the pump （）.

  A . head capacity to improve B . discharge to be reversed C . efficiency to decrease D . slippage to decrease

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• The oil was pumped up in the settle tank such a height that it （）.

  A . spilled B . overflowed C . sprayed D . injected

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• The usual symptoms of cavitation in a centrifugal pump is （）.

  A . noise and vibration B . an increase in discharge pressure C . an increase in suction pressure D . lifting of the relief valve

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• Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.

  A . cavitation B . electrolysis C . abrasion D . corrosio

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• After installing a new hydraulic pump in a system, what special attention should be given to the hydraulic system?（）

  A . The relief valves in the system should be readjusted B . The filters and strainers should be checked frequently C . All system pressure should be readjusted D . The system should be drained and renewed with a fluid of different operating characteristic

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• The pressure head of a pump is given in the unit of （）.

  A . kg B . MPa C . meter fluid column D . None of the above is true

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• 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) screw

  A . （1）and（2） B . （1），（2）and（3） C . （1）and（3） D . （2）and（3）

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• A double suction centrifugal pump impeller has been installed in the reverse direction, and will （）.

  A . have a greater head capacity B . operate with increased impeller efficiency C . discharge through the suction side of the pump casing D . require more power to run the shaft

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• What is a function of the wearing rings used in most centrifugal pumps?（）

  A . Absorb erosion of high velocity discharge stream B . Seal pump shaft against entry of air C . Isolate the discharge side from the suction side D . Dampen the turbulent discharge flow

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• 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 up

  A . （1），（2） B . （2），（3） C . （1），（2），（3） D . （2）only

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• Because of the close tolerances used in diesel engine fuel oil pumps, a worn plunger requires（）

  A . grinding the spare plunger to the barrel B . replacing the plunger and the barrel C . highly polishing both the plunger and barrel D . replacing plunger only

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• Maintaining the close tolerances in diesel fuel pumps and injectors requires the use of（）.

  A . fuel/water separators B . day tanks C . injector test stand D . fuel filter

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• In a radial piston pump, reversal and control of fluid flow are accomplished by moving the （）.

  A、central valve B、radial plunger C、floating ring D、cylinder body

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• Operating a rotary pump at speeds in excess of design requirements could cause（）.

  A . decreased clearances between rotating parts B . decreased slippage to the suction side of the pump C . air binding in the discharge ports D . erosion and excessive wear

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• A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.

  A . the four-way control valve failing to shift B . the bleeder valve sticking in the open position C . cold hydraulic fluid D . a clogged air vent falter on the oil reservoir

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• Movement of the pump control rack in a fuel injection system using individual plunger-type pumps （）

  A . changes the position of the fuel inlet ports B . changes the length of the pump stroke C . varies the quantity of fuel delivered D . varies the compression of the delivery valve spring

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• In a vacuum boiling evaporator, the fresh water generated is pumped out by （）.

  A . a brine pump B . an air ejector C . a feed water pump D . a condensate pum

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• Increasing the speed of a centrifugal pump will result in an increase in its capacity in its capacityAnother means of increasing the capacity pump is to increase the（）

  A . diameter of the discharge piping, with all other factors remaining the same B . diameter of the suction piping, with all other factors remaining the same C . width of the impeller only D . diameter of the impeller

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• The pressure head of a water pump is given in the unit of （）.

  A . kg B . MPa C . mH20 D . None of the above

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• The static suction lift of a pump is the difference in elevation between the （）.

  A . centerline of the pump and the level of the liquid in the suction well when the source of liquid is below the pump B . centerline of the pump and the suction liquid level when the source of liquid is above the pump C . centerline of the pump and the level of the discharge liquid D . liquid levels of the suction and discharge

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• In reading a weather map，closely spaced pressure gradient lines would indicate（）.

  A . high winds B . high overcast clouds C . calm or light winds D . fog or steady rai

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• The metal powder is compacted by placing in a closed（)cavity under pressure in powder

  A．A.plastic B．B.metal C．C.wood D．D.sand

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