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Term 3 - Review Tests > Re-Fresher #1 > Flashcards

Re-Fresher #1 Flashcards

1
Q

Heat flows in what direction?

a) cold to warm
b) warm to cold
c) liquid to gas
d) all of the above

A

b

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2
Q

Most substances change their physical state by?

a) becoming invisible
b) becoming molecules
c) addition or removal of heat
d) addition of heat only

A

c

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3
Q

Cold or low temperatures

a) cause molecules to move rapidly
b) slow bacteria growth
c) cause increase bacteria growth
d) cause food to spoil

A

b

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4
Q

How many centimetres in one inch?

a) 25.4cm
b) 0.254cm
c) 2.54cm
d) 1.5cm

A

c)

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5
Q

What determines the temperature at which refrigerant will vaporize?

a) pressure
b) temperature
c) volume
d) enthalpy

A

a

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6
Q

which of the following shows the principle of convection?

a) movement of heat by fluid or air
b) heat waves from sun
c) heat travelling through a solid object from end to end
d) radiation from the sun

A

a

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7
Q

heat may be transferred from one body to another by

a) radiation
b) conduction
c) convection
d) all of the above

A

d

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8
Q

liquid can boil only __________ temperature

a) at its evaporation
b) below its evaporation
c) at or above is evaporation
d) at or below evaporation

A

a

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9
Q

a compound gauge is used to

a) show the highest and lowest temp
b) show press-temp
c) measure psig and vacuum
d) give accurate reading in usually range and approximate readings over wider range

A

c

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10
Q

What type of lubricant is recommended for r134a?

a) mineral oil
b) polyol ester based
c) both a and b
d) neither a or b

A

b

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11
Q

In the low side float system of refrigerant control, when does needle valve open?

a) this system has no needle valve
b) liquid line evaporator falls
c) when compressor reduces pressure in evaporator
d) evap pressure is low and temp is above normal

A

b

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12
Q

In the txvsystem of refrigerant control, when does needle valve open?

a) this system has no needle valve
b) liquid line evaporator falls
c) when compressor reduces pressure in evaporator
d) evap pressure is low and temp is above normal

A

d

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13
Q

A ______ system has two compressors with an intercooler between them

a) cascade refrigeration
b) compound refrigeration
c) modulating refrigerating
d) multiple evaporator

A

b

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14
Q

Which of the following is not a positive displacement compressor?

a) centrifugal
b) rotary
c) regiprcoating
d) scroll

A

a

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15
Q

A compressor service valve has how man openings?

a) one
b) two
c) three
d) four

A

c

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16
Q

The valves of a reciprocating compressor are opened by?

a) oil pressure
b) high pressure
c) temperature difference
d) pressure difference

A

d

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17
Q

What does a high side float do?

a) turns the motor on and off
b) controls temperature in cabinet
c) controls liquid level in receiver
d) both a and b

A

c

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18
Q

Which compressor requires a check valve in the discharge line?

a) reciprocating
b) rotary
c) scroll
d) screw

A

b

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19
Q

What is called a constant pressure-metering device?

a) AXV
b) TXV
c) capillary tube
d) piston

A

a

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20
Q

How many forces are required to operate a TEV?

a) one
b) two
c) three
d) four

A

c)

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21
Q

What is meant by superheat?

a) diff between sending bulb temp and air leaving evap
b) diff between sensing bulb temp and evap press
c) diff between evap temp and temp of freon leaving

A

c

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22
Q

What causes a liquid cross charged txv to open?

a) gravity
b) bi-metal strip bends when heated by a resistor
c) an electromagnet
d) vapour pressure

A

d

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23
Q

What forces a solenoid valve to open?

a) gravity
b) bi-metal strip bends when heated by a resistor
c) an electromagnet
d) vapour pressure

A

c

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24
Q

What type of valve is used in a reversible heat to switch from cooling to heating?

a) suction pressure valve
b) three check valves
c) three way solenoid valve
d) four way solenoid valve

A

d

25
Q

What may be the cause if a cap tube unit frosts down the suction line?

a) low freon
b) too much freon
c) wrong size tube
d) either a or b

A

b

26
Q

Which colour will the flame of a halide torch leak detector show in the presence of an HFC refrigerant?

a) blue
b) green
c) bright blue with white smoke
d) can not be used with HFC

A

d

27
Q

Which refrigerant is NOT heavier than air

a) propane
b) r22
c) ammonia
d) isobutane

A

c

28
Q

On a PH chart in what units is pressure measured?

a) psig
b) in Hg
c) psia
d) in Hg Vac

A

c

29
Q

Inside the curve of a PH chart indicates what function?

a) change of state of refrigerant
b) change of liquid to gas
c) change of gas to liquid
d) removal of heat

A

a

30
Q

Refrigerant cylinders are equipped with which relief device?

a) fusible plug
b) don’t need a relief
c) pressure relief
d) both a and c

A

d

31
Q

R123 serves as a replacement for R11 in which type of application?

a) scroll
b) centrifugal
c) screw
d) rotar

A

b

32
Q

What viscosity oil should be used in low temp applications?

a) 300ssu
b) 200ssu
c) 150ssu
d) it doesn’t matter

A

c

33
Q

What is the minimum dielectric strength of oil used in hermetic and semi-hermetic systems?

a) 35kv
b) 25kv
c) 2500v
d) 2.5mv

A

b

34
Q

Which line is the most critical when it comes to sizing a refrigeration system?

a) discharge
b) condensate
c) water line
d) suction line

A

d)

35
Q

Proper line sizing is used to ensure

a) close temperature control
b) proper oil return
c) good refrigerant velocity
d) both b and c

A

d

36
Q

Refrigerant piping of less than 7/8 must be supported every

a) 12ft
b) 10ft
c) 8ft
d) 6ft

A

d

37
Q

What is the purpose of a trap at the base of a suction riser?

a) add restriction to piping
b) slow oil to collect during running cycle
c) allow refrigerant to collect in off cycle
d) allow refrigerant to collect in run cycle

A

c

38
Q

Which refrigerant is least miscible with oil?

a) r12
b) r22
c) r507
d) ammonia

A

d

39
Q

Compression ratio is calculated by dividing

a) discharge by suction
b) absolute suction by absolute discharge
c) absolute discharge by absolute suction x100
d) absolute discharge by absolute suction

A

d

40
Q

Which is the most common method used to cool hermetic compressors?

a) refrigerant
b) oil
c) water
d) air

A

a

41
Q

What is superheat?

a) heat added to change state of freon
b) heat added to increase pressure or refrigerant in the suction line
c) total heat of refrigerant in vapour state
d) heat added to refrigerant after all liquid is gone

A

d

42
Q

Group B refrigerants are

a) harmful
b) toxic
c) lethal
d) all of the above

A

d

43
Q

An azeotropic blend does not change in composition when?

a) evaporates
b) condenses
c) both a and b
d) neither a or b

A

c

44
Q

Which accessory ensures only vaporized refrigerant goes to the compressor?

a) metering device
b) EPR
c) receiver
d) heat exchanger

A

d

45
Q

What must not be used when leak checking refrigeration system?

a) nitrogen
b) oxygen
c) refrigerant
d) carbon dioxide

A

b

46
Q

What type of condenser uses air and water as the condensing medium?

a) evaporative
b) finned tube
c) bare tube
d) all of the above

A

a

47
Q

What is the counter flow principle

a) refrigerant passes in the opposite direction of air
b) refrigerant passes in the opposite direction of water
c) condenser uses counter flow fan
d) refrigerant flows in same direction as water

A

b

48
Q

In a flooded evaporator where is the freon?

a) in the shell
b) in the lines
c) in the tubes

A

a

49
Q

When using a water tower, how many fpm are required for proper condensation?

a) 1.5gpm/ton
b) 1.5rpm/ton
c) 3.2gpm/ton
d) 3gpm/ton

A

d

50
Q

Vibration eliminators are not installed near the

a) compressor discharge
b) compressor suction
c) evaporator
d) condenser

A

c

51
Q

If an oil separator is not insulated it will

a) act as a refrigerant condenser and expel heat
b) not remove oil from hot vapour
c) not return oil to compressor
d) all of the above

A

a

52
Q

In a multiple evaporator installation, what type of motor control is most frequently used?

a) thermostatic
b) defrost motor control
c) pressure
d) either or c

A

d

53
Q

What is the most common accessory used in a refrigeration system?

a) sight glass
b) heat exchanger
c) filter/drier
d) vibration eliminator

A

c

54
Q

What causes cloudy ice cubes?

a) trapped air
b) moisture
c) rapid freezing
d) slow freezing

A

a

55
Q

What does the sight glass in the liquid line frequently indicate?

a) low charge
b) moisture in system
c) refrigerant flow
d) both a and b

A

d

56
Q

What is the purpose of a sight glass on a compressor?

a) check moisture content
b) check low side pressure
c) check oil level
d) a and b

A

c

57
Q

Suction line has a slight slope to

a) aid liquid return
b) aid oil return to compressor
c) prevent moisture from accumulating on the low side
d) prevent liquid condensation

A

b

58
Q

Horizontal suction lines should slope toward the compressor at approximately

a) 1/4” for every 10ft
b) 1/2” for every 10ft
c) 1/4” for every 5ft
d) both b and c

A

d)

Term 3 - Review Tests (9 decks)

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