A.Shortage of refrigerant oil
B.Slight shortage of refrigerant
C.Excessive condenser cooling water flow
D.Faulty expansion valve
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A.vary their speed according to temperature and load
B.start and come up to speed before air compression begins
C.change speed according to overload demands
D.reduce compressed air charge density
A.radiation
B.conduction
C.convection
D.condo-radiation
A.used in either the fully dosed or fully opened position
B.installed with the stem down
C.used for steam service only
D.used to throttle or regulate the flow of liquid
A.Radiation
B.Conduction
C.Natural convection
D.All of the above
A.A gate valve
B.A globe valve
C.Any check valve
D.Any needle valve
最新試題
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
Thermostatic expansion valves can be adjusted for （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
When the steering gear is in operation, you should （）.
A salinity indicator is used to determine the （）.
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A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
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