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
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Which of the following statements is correct concerning heat transfer?（）
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
A salinity indicator is used to determine the （）.
The major source of chemical contaminants in hydraulic fluid is （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.