A.either all the way open or all the way closed
B.normally open
C.throttled depending on load
D.controlled by suction pressure
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When a hydraulic vane pump is working, which of the following is in contact with the vanes?（）
(1) the rotor
(2) the internal surface of the housing
(3) the external surface of the housing
A.(1) only
B.(2) only
C.(1) and (2)
D.(1), (2) and (3)
A.Control of evaporation
B.A separate means to prevent feed-water contamination
C.Power circulating pump
D.Super-heater
A.check and regulate the water level
B.close the air cock once fires are lit
C.blowdown the gage glass
D.crack the steam stop to assure protective steam flow
A.furnace to be re-purged
B.electric charge to buildup in the igniter
C.fuel pump to restart
D.drum level to stabilize
A.The blow down valve
B.The scum valve
C.The air release cock
D.Scot-blower
最新試題
The major source of chemical contaminants in hydraulic fluid is （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
A pressure drop through the refrigerant liquid line may cause （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
A salinity indicator is used to determine the （）.
A salinity indicator is used to determine the （）.