Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? ()
(1) reciprocating
(2) rotary
(3) centrifugal
A.(1)only
B.(1)and(2)
C.(1),(2)and(3)
D.(2)and(3)
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A.increased;decreased
B.decreased;increased
C.decreased;decreased
D.increased;increased
A.kg
B.MPa
C.mH20
D.None of the above
Which of the following are components of a mechanical seal? ()
(1) stationary ring
(2) rotational ring
(3) packing
(4)spring
A.(1), (2) and (3)
B.(1), (2) and (4)
C.(2), (3) and (4)
D.None of the above
A.variable stroke pumps
B.multistage pumps
C.positive displacement pumps
D.triple-ported pumps
A.mixed-flow pump
B.axial-flow pump
C.centrifugal pump
D.displacement pump
最新試題
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?()
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will ().
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by ().
The rate of heat transfer from a hot region to a cold region is affected most by the ().
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of ().
A salinity indicator is used to determine the ().
An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will ().
One cause of high head pressure occurring in a refrigeration system can be ().
A salinity indicator is used to determine the ().