The volute of centrifugal pump also acts as a diffuser converting （）into pressure head.

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

A . Gasoline B . Water C . Lubricating oil D . sulphur compound

A . change in the impeller diameter B . square of the impeller radius C . cube of the impeller diameter D . impeller efficiency for large changes in its size

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

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

A . Impurities B . Lube oil C . Gasoline D . Diesel fuel

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

A . packing gland B . mechanical seals C . lantern rings D . wearing ring

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

A . reciprocating B . hydraulic C . turbine D . vane

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

A . The pump delivers full capacity when started, but gradually slackens off toan abnormally low flow B . The pump packing gland overheats after short operating periods C . The motor over-current protective device continually shuts the pump down D . Pounding noises can be heard at the pump suction chest

A . Oil is discharged from the impeller through the outlet B . Gravity causes the oil to flow toward the discharge C . The self-priming feature of the centrifugal pump enables it to draw its own suction as it starts D . The discharge capacity varies directly with the speed of the impeller

A . Impeller B . Electric motor C . Volute D . Eye

A . backwards B . forwards C . upward D . downward

A . high TBN value B . low oil floc point C . low oil demulsibility D . low oil neutralization number

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

A . throttling the pressure line B . changing the speed of the rotor C . either A or B D . None of the above is tree

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

A、clockwise, due to the bowl rotating clockwise B、clockwise, due to the bowl rotating counterclockwise; C、counterclockwise, due to the bowl rotating clockwise D、counterclockwise, due to the bowl rotating counterclockwise

A . by opening the separator manually B . by separating the lower part from the upper part automatically C . by separating the upper part from the lower part automatically D . continuously

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

是 否