Centrifugal pumps have what advantage(s) over reciprocating pumps?（）.

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• The pumps employed on board ship can be divided into two main categories ie（） pumps and centrifugal pumps.

  A . gear B . nonpositive displacement C . positive displacement D . rotary

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• Most pump manufacturers recommended that the discharge piping for centrifugal pumps be （）.

  A . one size larger than the pump discharge nozzle B . the same size as the pump discharge nozzle C . one size smaller than the pump discharge nozzle D . installed with a short radius elbow at the pum

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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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• 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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• Which of the following pumps belongs to centrifugal pump?（）

  A . Reciprocating pump B . Screw pump C . Diffuser pump D . Water-ring pum

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• 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 shaft B . a single stepped impeller mounted in a progressively staged casing C . a large radial clearance between the impeller and casing to prevent overheating due to D . an increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stage

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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 features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）

  A . Close radial clearance between impeller hub and casing B . Low rotational speed of impeller C . Removable end plate D . Replaceable impeller and casing wearing ring

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• The function of a centrifugal pump double volute casing is to （）.

  A . reduce radial thrust to the impeller B . double the liquid velocity through the pump when compared to a single volute C . reduce hydraulic end thrust D . provide the effect of multi-staging

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• Attempts are made to eliminate axial thrust in centrifugal pump by （）.

  A . providing the impeller with balancing holes B . the use of symmetrical impeller C . neither A nor B D . either A or B

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• When installed for bilge pumping or ballast duty, centrifugal pumps require a （） to remove air from the suction pipe.

  A . air chamber B . head lank C . primer D . prime mover

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• The basic function of the centrifugal pump impeller is to （）.

  A . directly increase the pressure of the liquid being pumped B . directly increase the velocity of the liquid being pumped C . convert the potential energy of the liquid to kinetic energy D . separate air from the liquid being pumped

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• What is a characteristic of all centrifugal cargo pumps? （）

  A . They are self-priming B . Decreasing the speed of rotation will decrease the discharge pressure C . Opening the discharge valve wider will increase the discharge pressure D . All of the above

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• Most pump manufacturers recommend that the suction piping dimension for centrifugal pumps be （）.

  A . one size smaller than the pump suction nozzle B . the same size as the pump suction nozzle C . one size larger than the pump suction nozzle D . installed with a short radius elbow at the pum

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• When starting a centrifugal pump, the discharge valve should be （）.

  A . closed B . opened fully C . cracked open D . partly ope

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• A centrifugal pump can’t supply water after startingYou should check （）.

  A . priming water B . power supply C . packing gland D . bearing lubricatio

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• Which of the listed statements is correct concerning the starting of centrifugal pumps?（）

  A . They should always be started with the discharge valve closed B . They should always be started with the discharge valve opened C . A priming pump is always required to flood the impeller suction D . They should always be started with the sealing line valves closed

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• On modern ships, centrifugal pump with a self-primer has replaced reciprocating pump as bilge pump because（）

  A . centrifugal pump is cheaper than reciprocating pump B . the size of centrifugal pump with same capacity is smaller than that of reciprocating pump C . centrifugal pump makes maintenance easier than reciprocating pump does D . all of the above

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• A centrifugal bilge pump requires priming （）.

  A . primarily to lubricate the shaft seals B . due to the inability of this type of pump to lift water to cover the suction (eye) of the impeller C . to initially unload the pump by having its head pressure equal to discharge pressure D . in order to overcome the potential energy of water in the discharge line

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• Which of the following statements is true concerning centrifugal pumps?（）

  A . They are particularly suited for pumping high viscosity fluids B . They are started with the discharge valve opened C . The flow of liquid is developed by imparting energy due to the rotation of an impeller D . They are always mounted in a horizontal positio

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• To operate a centrifugal fire pump at reduced capacity, you should （）.

  A . readjust the relief valve B . throttle the suction line C . throttle the discharge valve D . open the priming line

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• Which of the following statements is true concerning centrifugal pumps？

  A.They are particularly suited for pumping high viscosity fluids B.They are started with the discharge valve opened C.The flow of liquid is developed by imparting energy due to the rotation of an impeller D.They are always mounted in a horizontal position

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• Dynamic pumps are classified as centrifugal or axial. axial pumps operate on the principle of centrifugal force.（）

  是 否

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