Noise in a refrigeration compressor can be caused by （）.

单项选择题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

单项选择题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

单项选择题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

单项选择题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

单项选择题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