WorksheetsSTAR EXAM 2
Total questions: 25
Worksheet time: 13mins
26. Before proceeding to make any braze connection in a refrigeration system all of the internal piping should be purged of atmosphere with
CO²
R-22
nitrogen
A or C
27. The liquid receiver is located between the?
compressor suction and the evaporator
compressor discharge and the condenser
condenser and the expansion device
expansion device and the evaporator
28. Which device is used in a refrigeration system to protect the compressor from liquid slugs?
suction accumulator
liquid receiver
TXV
none of the above
29.Which device is used to stop the flow of liquid or vapor in a refrigeration system?
suction accumulator
liquid receiver
TXV
solenoid valve
30. Why is it important to know the direction that a scroll compressor is rotating?
it will run smoother in one direction of rotation over the other
it will run quieter in one direction of rotation over the other
it will only pump refrigeration in one direction of rotation
rotation does not matter
An electric motor that has a voltage rating of 120 volts will have an upper and lower allowable voltage limit of
110 to 145 V
100 to 200 V
87.2 to 135 V
108 to 132 V
32. On a fully welded hermetic compressor the electrical start components are located
inside of the compressor shell
at the disconnect box for the compressor unit
at the thermostat
on the external of the compressor at the terminal box
33. On most hermetically sealed compressors
the motor and pumping mechanism are cooled by liquid refrigerant
the motor does not come into contact with any refrigerant
the motor and pumping mechanism are cooled by refrigerant vapor
the belt drive must be adjusted precisely
34. The difference between oil pump discharge pressure and crankcase pressure on a refrigeration compressor would be called
net oil pressure
gross oil pressure
differential oil pressure
net discharge pressure
35. The amount of space between the piston at top-dead-center and the bottom of the valve plate of the compressor would be defined as?
clearance volume
displacement
total volume
dead space
36. The flapper valve design is less efficient than the discus valve design because
the re-expanded refrigerant in the cylinder is much less
the spring tension is less
the cylinder has more clearance volume than the discus
it will allow liquid into the cylinder
37. Liquid refrigerant entering the compressor is potentially more damaging for this type of compressor over the others listed
screw
reciprocating
scroll
rotary
38. Discus, ring, and flapper valves are not used on
reciprocating compressors
screw compressors
scroll compressors
both b and c
39. The main function of a condenser in a refrigeration system is?
reject the heat that is absorbed in the evaporator
change the refrigerant from a liquid to a vapor
absorb heat from the product or space
pump the refrigerant around the system
40. The shell and tube condenser is a type of
low pressure condenser
air-cooled condenser
evaporative condenser
water cooled condenser
41. One of the main disadvantages of a water-cooled condenser is that mineral deposits can build up acting as a/an
restrictor
rust inhibitor
conductor
insulator
42. A flow regulating valve could be used on this type of condenser
shell and tube
air cooled
tube in tube
Both A and C
43. On a water cooled condenser the water leaving the condenser is normally ______ lower than the condensing temperature of the unit
40º F
35º F
25º F
10º F
44. On a standard efficiency air-cooled condenser the ambient air entering the condenser will be approximately ________ lower than the condensing temperature if the unit is under normal load and properly charged
10º F
30º F
55º F
100º F
45. A head pressure control system would be used on this type of application
unit located in a colder climate but only operating in summer
months
unit located in a warm climate operating all year
unit located in a warm climate but only operating in the summer
months
unit located in a colder climate operating all year
46. What type of expansion valve regulates its flow based from suction line superheat?
hand expansion
TXV
automatic
none of the above
47. Systems where the pressure drop across the evaporator is excessive would typically use a/an.
externally equalized TXV
internally equalized TXV
pressure limiting TXV
self equalizing TXV
48. On a system equipped with a TXV, when the load on an evaporator decreases.
the TXV decreases the flow of refrigerant
the TXV increases the flow of refrigerant
the TXV will maintain the flow of refrigerant
the TXV decreases the pressure across the evaporator
49. When referring to a power head on an expansion device the bulb is
on an automatic expansion value
attached to one end of a capillary tube
at the inlet of the expansion value
normally charged with a fluid similar to that of the system
refrigerant
50. By subtracting the low side evaporator outlet temperature from the low side saturation temperature the technician would be calculating?
compressor superheat
evaporator superheat
heat of compression
loss effect
