REFRIGERATION AND AIR CONDITIONING
1.Short cycling of a refrigeration compressor refers to _____________.
A.frequently grounding out
B.frequently starting and stopping
C.running too fast
D.running too slow
2.The heat gained per pound of refrigerant in the evaporator is known as the _____________.
A.latent heat of vaporization
B.sensible heat
C.refrigerating effect
D.specific heat of vaporization
3.When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called _____________.
A.flooding back
B.superheating
C.overflowing
D.recycling
4.Which of the refrigerants listed is considered safe and ideal for most marine applications?
A.R-21
B.Ammonia
C.R-12
D.Sulfur dioxide
5.The heat removed from the refrigerant in the condenser of a refrigeration plant is the _____________.
A.latent heat of expansion
B.sensible heat of condensation
C.heat of compression
D.all of the above
6.The FIRST thing to do to ensure that a refrigeration unit will not start while undergoing repairs, is to ____________.
A.secure and tag the electrical circuit
B.place a crow bar in the flywheel of the unit
C.inform all persons in the area not to start the unit
D.make a log book entry
7.In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the _____________.
A.compressor
B.condenser
C.receiver
D.evaporator
8.Personnel working with refrigeration systems, and subject to the exposure of refgerants should wear ________________.
A.face shield
B.a respirator
C.rubber gloves
D.an all purpose gas mask
9.The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of _____________.
A.fusion
B.vaporization
C.condensation
D.sublimation
10.The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by _________.
A.passing it through the expansion valve
B.condensing refrigerant in the system condenser
C.passing the gaseous refrigerant through the heat interchanger on the suction side of the compressor
D.maintaining a high pressure on the system’s receiver
11.The amount of moisture in a given sample of air, when compared with the amount of moisture the air could hold if totally saturated at the existing temperature of the sample, is called ____________.
A.absolute humidity
B.specific humidity
C.effective humidity
D.relative humidity
12.When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be ____________.
A.dehydrated
B.purged
C.plugged
D.evacuated
13.People familiar with ammonia refrigeration systems become accustomed to its odor and may forget that the vapors _____________.
A.in a low concentration can cause death
B.will dissolve in perspiration and cause caustic burns
C.will burn or explode
D.all of the above
14.When subjected to high heat from a open flame, or an electric heating element, which of the listed refrigerants will break down and produce phosgene gas?
A.CO2
B.Methyl chloride
C.R-22
D.Sulphur dioxide
15.A refrigeration system contaminated with moisture can be affected by _____________.
A.acid formation
B.sludge formation
C.ice in the expansion valve
C.allowed to mix with compressor oil
16.Some chloronated flourocarbon refrigerants may decompose into a toxic irritating gas if it is ____________.
A.stored at temperatures below 60 degrees Fahrenheit
B.charged into a system having copper fittings
D.all of the above
D.exposed to an open flame or hot surface
17.In a direct expansion type cargo refrigeration system, a box is normally changed from chill to freeze by adjusting the _____________.
A.hand expansion valve
B.compressor suction valve
C.solenoid bypass
D.back pressure regulating valve
18.If the suction line between the evaporator and compressor is frosting up, the cause may be due to the thermal expansion valve _____________.
A.thermal bulb coming loose from the suction line
B.needle valve is stuck closed
C.thermal bulb is in a cold air stream
D.all of the above
