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
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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
A.a flash generator
B.a flash evaporator
C.a vacuum boiling evaporator
D.a boiler
最新試題
One cause of high head pressure occurring in a refrigeration system can be （）.
Which of the following statements is correct concerning heat transfer?（）
The major source of chemical contaminants in hydraulic fluid is （）.
Which of the listed pumps is NOT a positive displacement pump?（）
A grease gun is generally used to lubricate a （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
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?（）
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.