單項選擇題Noise in a refrigeration compressor can be caused by （）.

A.worn bearings and piston pins
B.slugging due to flooding back
C.too much oil in circulation
D.All of the above


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1.單項選擇題The air charge leaving an intercooler, or after-cooler of an air compressor can be expected to be （）.

A.superheated
B.super-cooled
C.at or below the dew point
D.All of the above

2.單項選擇題Before starting a reciprocating, steam-driven pump that has been idle for a period of time, you should （）.

A.open the steam line mot valve
B.drain the steam cylinder
C.close the steam cylinder drains
D.open the liquid cylinder drains

3.單項選擇題When air becomes trapped in the hydraulic fluid of a steering system, the （）.

A.rudder will respond sluggishly
B.hydraulic rams will over-speed
C.sight glass will show bubbles
D.ram relief valves will lift

4.單項選擇題If a refrigeration system were short of refrigerant, the condition would result in （）.

A.continuous running of the compressor
B.high suction pressure
C.high discharge pressure
D.short cycling of the compressor on the water failure switch

5.單項選擇題Condensate must be drained from the intercooler and after-coolers of an air compressor because （）.

A.the cooling effect of the condensate reduces the compressors efficiency
B.a danger of explosion exists whenever water is present in a compressor
C.water causes erratic operation of pneumatic components
D.the volumetric capacity of the first stage is reduced if water remains