A.low water level
B.low oil pressure
C.excessively high fuel pressure
D.an improper air/fuel ratio
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A.Reciprocating pump
B.Screw pump
C.Diffuser pump
D.Water-ring pump
A.discharge is continuous
B.it has no internal valves
C.upon accidental closing of discharge valve, excessive pressure will not build up
D.all of the above are true
A.between the suction and discharge
B.below the liquid supply
C.above the liquid supply
D.any of the above
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （）
(1) reciprocating
(2) vane
(3) gear
A.（1）only
B.（1）and（2）
C.（1），（2）and（3）
D.（2）and（3）
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）
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
最新试题
The usual symptoms of cavitation in a centrifugal pump is （）.
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Low compressor head pressure in a refrigeration system can be caused by（）.
The output volume of a positive fixed displacement pump can be changed only by （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
A grease gun is generally used to lubricate a （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.