A.tightened up
B.sealed up
C.opened up
D.unscrewed
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A.use
B.release
C.protect
D.effect
A.paved
B.cleaned
C.welded
D.dismantled
A.water
B.oil
C.heat
D.steam
A.safety valve
B.blow down valve
C.scum valve
D.feed check valve
A.strainers
B.valves
C.elements
D.separators
最新試題
Which of the following statements is correct concerning heat transfer?（）
The output volume of a positive fixed displacement pump can be changed only by （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
Low compressor head pressure in a refrigeration system can be caused by（）.
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 thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）