A.kg
B.MPa
C.mH20
D.None of the above
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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
A.on top cover
B.on sides of bowl
C.in drain line on the discs
D.on the discs
A.oil
B.sea water
C.refrigerant
D.fresh water
最新試題
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
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The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
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When the steering gear is in operation, you should （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
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If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.