单项选择题Thermal energy in transition is also referred to as ().

A.heat
B.power
C.horsepower
D.foot-pound


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1.单项选择题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

2.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

3.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

4.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

5.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

6.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

7.单项选择题In the refrigeration system, a shortage of refrigerant is indicated by ().

A.the compressor short cycling on high pressure cut out switch
B.high suction pressure
C.high head pressure
D.bubbles in the sight glass

8.单项选择题Which of the following conditions must exist for heat to flow from one object to another?()

A.The two objects must be in physical contact
B.The two objects must be the same size
C.There must be an existing temperature differential
D.There must be an existing weight differential

9.单项选择题A warmer than normal compressor suction line might be caused by ().

A.insufficient lubrication
B.insufficient refrigerant
C.excess refrigerant
D.excessive opening of the expansion valve

10.单项选择题The unloading system on an air compressor will ().

A.increase compressor discharge pressure on demand
B.increase compressor operating speed as necessary
C.allow the motor to turn the compressor opposed only by friction
D.reduce the compressor frictional load when starting