单项选择题Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?()

A.The density of the air entering the compressor
B.The temperature of the air entering the compressor
C.The designed rotating speed of the compressor
D.A leaking head gasket


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2.单项选择题A cracked diaphragm in a thermostatic expansion valve will cause the valve to ().

A.return to a neutral position
B.flood the evaporator
C.open
D.close

3.单项选择题If an air compressor is used to supply air primarily to the combustion control system and other pneumatic controllers, the entire system is known as the ().

A.control air system
B.forced draft air system
C.supply air system
D.ships service air system

5.单项选择题If an air compressor is used to supply compressed air to outlets throughout the engine room and on deck of a vessel, the system is known as the ().

A.combustion control air system
B.supply air system
C.ships service air system
D.low pressure deck air system

6.单项选择题The sensible heat of air is dependent upon the ().

A.dry bulb temperature
B.wet bulb temperature
C.saturation temperature
D.water vapor superheat

7.单项选择题Which of the devices listed, when used on an electro-hydraulic steering gear, keeps the movement of the redder closely in step with the steering wheel?()

A.The follow-up gear
B.The rudder angle indicator
C.The synchronous electric transmitter
D.A rudder angle limit switch

8.单项选择题Propeller pitch speed minus ship speed divided by the propeller pitch speed is termed ().

A.apparent slip
B.tree slip
C.pitch
D.propulsive efficiency

9.单项选择题A multistage centrifugal pump can be BEST described as having ().

A.two or more impellers housed together in one casing and mounted on a single shaft
B.a single stepped impeller mounted in a progressively staged casing
C.a large radial clearance between the impeller and casing to prevent overheating due to
D.an increase in the discharge velocity of the liquid with a corresponding decrease in pressure through the stages

10.单项选择题If a refrigeration system compressor crankcase is sweating, you should ().

A.add refrigerant to the system
B.adjust the thermal expansion valve to the proper setting
C.adjust the float valve to the proper holding pressure
D.open the hand expansion valve