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
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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
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
A.insufficient lubrication
B.insufficient refrigerant
C.excess refrigerant
D.excessive opening of the expansion valve
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
A.Radiation
B.Conduction
C.Convection
D.Each of the above
A.Shortage of refrigerant oil
B.Slight shortage of refrigerant
C.Excessive condenser cooling water flow
D.Faulty expansion valve
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
最新试题
The control mode in which the final control element is moved from one of two flexed positions to the other is known as ().
One cause of high head pressure occurring in a refrigeration system can be ().
A salinity indicator is used to determine the ().
The rate of heat transfer from a hot region to a cold region is affected most by the ().
Which of the following statements is correct concerning heat transfer?()
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?()
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 ().
A salinity indicator is used to determine the ().
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?()
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its ().