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
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