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Austin's Sheet Metal 4th Year > AC TQ Prep > Flashcards

AC TQ Prep Flashcards

1
Q

What should you do when filling refrigerant from zero to 100?

A

Make sure you turn it on when it’s 50% full.

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2
Q

What is latent heat (Hidden Heat)?

A

Latent heat is the amount of heat required to change the state of a substance without changing its temperature.

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3
Q

What is a micron?

A

A micron is a measurement equal to one-one millionth of a meter.

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4
Q

What is sensible heat?

A

Sensible heat is the heat required to produce a change in temperature of a substance but not change its state.

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5
Q

How can you detect sensible heat?

A

The intensity can be detected by a thermometer or by touch.

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6
Q

What is relative humidity?

A

Relative humidity is the amount of moisture in air compared to the amount of moisture the air would hold at the same temperature if it were saturated full of water.

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7
Q

What is critical temperature?

A

Critical temperature is the highest temperature at which a gas may be liquefied.

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8
Q

What is saturation temperature?

A

Saturation temperature is a condition of both pressure and temperature at which both liquid and vapor can exist in the same container simultaneously.

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9
Q

What is critical pressure?

A

Critical pressure of a liquid is the pressure at which a liquid will remain a liquid no matter how much heat is applied to it.

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10
Q

What color is the vacuum hose?

A

The vacuum hose is black.

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11
Q

What types of ACR copper tubing are available?

A

Type K (thick wall), Type L (thin wall), Type M (red).

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12
Q

What is R22?

A

R22 is a hydrochlorofluorocarbon (HCFC) with low chlorine content and low ozone depletion potential.

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13
Q

What are the basic components of an AC system?

A

Compressor, evaporator, condenser, liquid metering device, piping.

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14
Q

What is the atmospheric pressure at sea level?

A

14.7 lbs per square inch.

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15
Q

What does 1 BTU change?

A

1 BTU changes 1 pound of H2O 1°F

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16
Q

What reduces the capacity of an outdoor condenser?

A

Temperature.

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17
Q

What are the three types of condensers?

A

Water cooled, air cooled, and evaporative.

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18
Q

What is temperature a measure of?

A

Temperature is the measure of the intensity of heat of a substance and the measure of its molecular speed expressed in degrees.

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19
Q

What is subcooling?

A

Subcooling is defined as a liquid that has been cooled below the boiling (condensing) temperature at a specified pressure.

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20
Q

What is superheat?

A

Superheat is defined as a vapor heated to a temperature above its saturation point after a liquid has vaporized.

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21
Q

What are the three types of metering devices?

A

Capillary tube, thermostatic expansion valve, and orifice.

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22
Q

What are the three types of dehumidifiers?

A

Heat pump, chemical absorbent, ventilating humidifier.

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23
Q

How do dehumidifier heat pumps and air conditioning heat pumps work?

A

They work under the same principle.

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24
Q

What speeds up the evacuation process?

A

Removing the stem in the Schrader valve.

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25
Q

What amount of vacuum must be obtained to render the system free of refrigerant?

A

10” to 11” HG.

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26
Q

What method is used for checking the refrigerant charged on a system equipped with a TXV?

A

Check proper sub-cooling for TXV systems.

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27
Q

Which hoses are connected to each service valve?

A

Low side gauge (blue) to low side of system, high side (red) to high side of the system, middle is connected to inlet port or recovery unit.

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28
Q

What are the four main types of electronic leak detectors?

A

Ion source, thermistor, halogen, and ultrasonic.

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29
Q

What is the maximum capacity of any service or storage cylinder used for refrigerant?

A

80%, to allow for expansion.

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30
Q

What does blue represent in refrigerant hoses?

A

Blue = Suction Low Pressure vapor.

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31
Q

What does red represent in refrigerant hoses?

A

Red = High pressure liquid discharge.

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32
Q

Where should superheat temperature measurements be taken?

A

Within 3 feet of the compressor suction connection.

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33
Q

What do you need to record superheat?

A

You need the vapor line temperature (low side gauge) and the vapor line pressure (low side gauge).

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34
Q

What should measured superheat be within?

A

Measured superheat should be within 2°F +/- of the superheat found on the table.

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35
Q

What color is the compound gauge for the low side?

A

Blue.

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36
Q

What pressure should the system be tested at?

A

125 psi to 150 psi.

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37
Q

What side of the system is the evaporator considered to be on?

A

Low pressure side.

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38
Q

What is the standard flange depth and door thickness for access doors?

A

1” to 1½”.

39
Q

What determines the depth of a louver?

A

The depth of the louver is approximately 4”.

40
Q

What determines the gauge of a damper?

A

Louvre width determines the gauge of the damper.

41
Q

What is the gas supply pressure range?

A

5.5” wc - 13” wc, manifold pressure set to 3.5” wc.

42
Q

What is the color coding for manifold gauge sets?

A

Blue for low, red for high, yellow for center manifold gauge.

43
Q

What should you not do with gauge sets?

A

Do not use gauge set on different refrigerant without purging it first.

44
Q

What should you remember about gauge usage?

A

Gauge should never be subjected to move more than 75% of their full scale range on the gauge face.

45
Q

What should you use when servicing air conditioning?

A

Labels, service fittings, and a refrigerant identifier.

46
Q

What is the minimum test period for high and low pressure?

A

2 hours.

47
Q

What are the minimum air pressures for R410a?

A

Low - 236 psig, high - 444 psig.

48
Q

What temperature range does the high limit switch open?

A

Between 180°F and 200°F.

49
Q

Where is the high pressure switch located?

A

In tubing between the discharge side of the compressor and the condensing coil.

50
Q

What are the three cycles of an air forces heat pump?

A

Heating, cooling, defrost cycles.

51
Q

What is used for measuring revolutions per minute (RPM)?

A

Tachometer.

52
Q

What does a pilot tube measure?

A

Both static and total pressure.

53
Q

What does a velometer measure?

A

Velocities (FPM) directly in the grills.

54
Q

What does an anemometer measure?

A

Velocities in the grills; two types are thermal and rotating.

55
Q

How long should FHR 2003 records be kept?

A

At least 5 years.

56
Q

What does the national action plan recommend regarding CFCs?

A

Not filling autos with CFCs after Jan 1, 2000.

57
Q

Is it okay to refill a refrigeration system with refrigerant?

A

Yes, if the system passes a leak test; but refilling with CFC refrigerants is not permitted.

58
Q

What must refrigerant containers be?

A

Refillable and recyclable.

59
Q

Is refrigerant handling certification accepted across provinces?

A

No, it is not normally accepted in another province.

60
Q

Can anyone use a photocopied certificate?

A

No, no one can use a photocopied certificate.

61
Q

What must be attached to refrigeration equipment before disposal?

A

A notice stating the date, time, name, and certificate number for the removal of all refrigerant.

62
Q

Is refrigerant handling recertification compulsory in Alberta?

A

No, it is not compulsory.

63
Q

What is reusing a refrigerant?

A

To remove it from a system, store it in an approved container, then return it to the same system.

64
Q

What is recycling in refrigerant handling?

A

The removal of a refrigerant, cleaning in an onsite processor, and then returned to the original refrigeration system.

65
Q

What is reclaiming refrigerant?

A

To reprocess recovered refrigerant as necessary to meet approved virgin specifications.

66
Q

What is refrigeration oil considered after removal?

A

Hazardous waste.

67
Q

What regulations apply to hydrochlorofluorocarbon refrigerants (HCFC)?

A

Federal Halocarbon Regulation.

68
Q

What is the fastest way to remove refrigerant from a system?

A

Removing liquid then vapor refrigerant.

69
Q

How long should leak testing records be kept?

A

5 years.

70
Q

What should certified persons place on a system once they are sure it does not contain refrigerant?

A

A ‘no-refrigerant’ notice.

71
Q

What is the only gas added to a system for pressure testing?

A

Nitrogen.

72
Q

What does not cause ozone layer depletion?

A

Smog.

73
Q

What is R134a and R410a classified as?

A

HFCs, which do not damage the ozone layer.

74
Q

Why do HFCs not harm the ozone layer?

A

Because they do not contain chlorine.

75
Q

What can refrigerant releases affect?

A

Both the ozone layer and global warming.

76
Q

What is a global warming concern regarding refrigerants?

A

Venting of HFCs.

77
Q

What is prohibited regarding CFC sales?

A

Selling CFCs in containers smaller than 410 kilograms.

78
Q

What is prohibited regarding CFC containers?

A

Selling CFCs in containers containing 10 kg or less.

79
Q

What is prohibited regarding HCFCs?

A

Selling, manufacturing, or importing HCFCs in containers containing 2 kg or less.

80
Q

How often must refrigerants be tested?

A

Every 5 years.

81
Q

What will happen to HCFC refrigerants after Jan 1, 2020?

A

They will not be produced, imported, or exported in or from Canada.

82
Q

What type of containers can refrigerant be purchased in?

A

Containers that are refillable.

83
Q

What must certified persons know about commonly used refrigerants?

A

Which are CFCs, HCFCs, or HFCs.

84
Q

What do CFCs contain?

A

Chlorine, fluorine, and carbon; they are now banned.

85
Q

What do HCFC refrigerants contain?

A

Hydrogen, chlorine, fluorine, and carbon; they were legislated to be phased out on Jan. 1, 2020.

86
Q

What do HFCs contain?

A

Hydrogen, fluorine, and carbon; HFC systems use polyolester oil.

87
Q

What are halons and bromines used for?

A

In fire extinguishing and contribute significantly to the depletion of the ozone layer.

88
Q

When is a triple evacuation used?

A

If the system is deemed to be dirty or wet.

89
Q

What are two reasons for performing a deep evacuation?

A

To remove moisture and non-condensable gases.

90
Q

What should be checked before obtaining the proper charge?

A

The airflow across the evaporator coil to ensure the correct cubic feet per minute (CFM). 400 to 425 is recommended

91
Q

What is the recommended CFM per ton of cooling?

A

Between 400 CFM to 425 CFM.

92
Q

What should you ensure when returning cylinders?

A

That valves are closed, protective caps are in place, and any outlet cap or plugs have been replaced.

93
Q

What is recommended regarding residual pressure in cylinders?

A

A residual pressure of at least 25 pounds per square inch (psi) should remain in the cylinder.

Austin's Sheet Metal 4th Year (13 decks)

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