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In practice, the refrigerant flow after the evaporator is designed to ensure that the vapor leaving the evaporator is slightly （）.
A . saturated
B . super-cooled
C . wet
D . superheated
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As the refrigerant passes through the valve orifice, its pressure is reduced and part of the refrigerant turns into （）.
A . liquid
B . oily mixture
C . emulsion
D . vapor
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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 gla
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To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the （）
A . suction service valve as a vapor
B . suction service valve as a liquid
C . discharge service valve as a vapor
D . charging valve as a liquid
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Before charging a refrigeration unit, the refrigerant charging lines should be（）
A . flushed with clean refrigerant oil
B . purged with the refrigerant
C . washed with an ammonia and alcohol solution
D . grounded to compressor
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In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the（）.
A . compressor
B . condenser
C . receiver
D . evaporator
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Personnel working with refrigeration systems, and subject to the exposure of refrigerants should wear （）.
A . face shield
B . a respirator
C . rubber gloves
D . an all purpose gas mask
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Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）
A . Sub-cooled liquid
B . Sub-cooled vapor
C . Superheated vapor
D . Liquid
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Moisture in the refrigerant may （）.
A . freeze on the expansion valve seat and reduce the flow of liquid refrigerant
B . emulsify the oil in the condenser
C . freeze in the king valve
D . clog the oil tra
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A liquid sight flow indicator in a refrigeration system is examined and gas bubbles are noted in motion with the fluid flowThis means （）.
A . the system is fully charged
B . there is air leaking in from the condenser
C . ice crystals are forming in the refrigerant
D . the system contains less than a full charge of refrigerant
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In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.
A . compressor；condenser
B . condenser；evaporator
C . throttle valve；evaporator
D . evaporator；condenser
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The temperature of a refrigerant gas is the highest （）.
A . at the compressor discharge
B . at the compressor suction
C . in the expansion valve
D . in the receiver
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Which of the listed refrigeration system components keeps the refrigerant circulating through the system?（）
A . Expansion valve
B . Condenser
C . Evaporator
D . Compressor
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The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the （）.
A . condenser
B . vapor generator
C . accumulator
D . evaporator
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In which of the listed refrigeration system components does superheating of the refrigerant take place?（）
A . Expansion valve
B . Evaporator
C . Drier
D . Receiver
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In a compression refrigeration cycle, the temperature of the liquid refrigerant experiences its greatest decrease in the（）.
A . evaporator
B . compressor
C . expansion valve
D . condenser
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To add refrigerant to the high side of an air conditioning system, you should introduce the refrigerant through the （）.
A . discharge service valve as a vapor
B . suction service valve as a liquid
C . charging valve as a liquid
D . condenser purge valve as a vapor
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In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by （）.
A . increasing refrigerant pressure in the coil
B . increasing chilled water flow through the cooler
C . sub-cooling the refrigerant in the condenser
D . superheating the refrigerant in the compressor
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If a refrigeration compressor is running continuously without lowering temperature as normal in the refrigerator, the trouble may be （）.
A . excessive condenser cooling water
B . warm food in the refrigerator
C . a shortage of refrigerant
D . s shortage of compressor oil
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If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is （）.
A . too much refrigerant in the system
B . oil entrained in the refrigerant
C . less than a full charge of refrigerant in the system
D . ice crystals forming in the refrigerant
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When the temperature of the refrigerant flowing out from the condenser is below the condensing temperature, it is said to be （）.
A . dry
B . wet
C . super-cooled
D . superheated
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Refrigerant enters the condenser as a （）.
A . high pressure liquid
B . low pressure vapor
C . high pressure vapor
D . low pressure liquid
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The milk is ______ the refrigerator.
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Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause______.
A.carbon deposits on the compressor suction valves
B.the evaporator temperature to increase
C.rapid corrosion of the thermal expansion valve
D.no operating problems
