A.blue
B.green
C.orange
D.purple
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A.excessive condenser cooling water
B.warm food in the refrigerator
C.a shortage of refrigerant
D.s shortage of compressor oil
A.either all the way open or all the way closed
B.normally open
C.throttled depending on load
D.controlled by suction pressure
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
A.acid
B.alkali
C.salt
D.None of the above
A.proper combustion
B.water in the fuel
C.excess air
D.cold fuel oil
A.The safety valve escape piping should be disconnected from the valve body and a blank inserted
B.The boiler vent valves should be opened
C.All hand-hole/manhole covers should be tightened up as much as possible to preclude any leaks
D.All of the above
最新试题
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
A pressure drop through the refrigerant liquid line may cause （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
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 head pressure of a reciprocating refrigeration compressor is excessive, （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
The usual symptoms of cavitation in a centrifugal pump is （）.