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Air-Conditioning Systems > Mechanical A/C Service Exam > Flashcards

Mechanical A/C Service Exam Flashcards

1
Q

According to the ASHRAE refrigerant safety classification standard which designations would be the safest?

A

A-1

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2
Q

When transporting cylinders containing used refrigerant, DOT requires that you?

A

Attach DOT classification tags

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3
Q

What refrigeration compound have the highest ozone depletion potential (ODP)?

A

CFC’s

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4
Q

Approved refrigerant recovery cylinders can be identified by which color code?

A

Yellow tops and grey bodies

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5
Q

Under EPA’s regulations, what standard must reclaimed refrigerant meet before it can be resold?

A

ARI 700

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6
Q

The sate of refrigerant entering the compressor of a refrigeration system is ____.

A

low pressure vapor

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7
Q

Refrigerant that is cleaned using oil separation and single or multiple passes through devices, such as replaceable core filter-driers, which reduce moisture, acidity, and particulate matter is ____.

A

recycling

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8
Q

What leak detection method is most effective for locating the general are of a small leak?

A

Electronic leak detector

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9
Q

A compound pressure gauge for the low side of a system measures pressure in ____?

A

PSIG and inches of mercury

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10
Q

When first inspecting a hermetic system known to be leaking you should look for?

A

traces of oil

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11
Q

When charging a system with nitrogen ____?

A

only charge with nitrogen vapor and use a regulator

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12
Q

Refrigerant entering the thermal expansion device of an R-22 heat pump is ____.

A

saturated or sub-cooled high pressure liquid

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13
Q

Replacement of ____ is a repair which would always be considered major under EPA’s regulations.

A

an evaporator and condenser

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14
Q

At high temperatures R-12 and R-22 can decompose to form ____.

A

hydrochloric and hydrofluoric acid and phosgene gas

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15
Q

According to ASHRAE standard 15 a sensor and alarm are required for type A-1 refrigerants to sense ____.

A

oxygen deprivation

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16
Q

A ____ is not a method presently used for checking the fill level in a recovery tank.

A

sight glass

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17
Q

DOT Regulation 49 CFR requires that the ____ be recorded on the shipping paper for a hazard class 2.2 nonflammable compressed gases?

A

number of cylinders of each gas

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18
Q

What is not a standard recommended safe work practice when recovering refrigerants.

A

wearing a respirator when working with refrigerants

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19
Q

System dependent recovery equipment connote be used when?

A

the charge of the system is over 15 pounds

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20
Q

Reclamation of a refrigerant means that it is ____.

A

processed so that it meets the standard for new refrigerant

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21
Q

The principle of evacuating a system using a vacuum pump is to lower the system pressure so any moisture can ____.

A

boil off or vaporize

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22
Q

Air in a refrigeration system mainly causes ___?

A

the system to work harder due to increase in condensing temperature
*over time it can also degrade the oil and cause acids to form

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23
Q

The most accurate way to measure a vacuum is with a ____.

A

micron gauge

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24
Q

What is the micron level to which a system should be evacuated down to?

A

500

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25
Q

When charging refrigerant by weight you can charge with?

A

both liquid and vapor refrigerant

26
Q

The sub-cooling charging method gives an indication of the amount of ____?

A

liquid refrigerant at the expansion device

27
Q

What is the process called when each of the refrigerant used in a blended refrigerant leak at a different rate if released into the atmosphere changing the proportions of the refrigerants used in the blend?

A

fractionation

28
Q

After a leak in a system using a zoetrope refrigerant is repaired and the system has been evacuated the system should be charged with ____?

A

new refrigerant

*its not possible to determine if the old refrigerant is the required blend

29
Q

When charging a system that uses a zoetrope refrigerant the system should be charged with _____.

A

liquid refrigerant

30
Q

When determining the type of burnout in a system with a hermetic compressor the fist thing to do is ____.

A

check the moisture and acid content of the system

31
Q

NEMA states three phase motors should operate successfully under running conditions at rated load when the voltage imbalance does not exceed ____.

A

1%

32
Q

A metering device is a refrigeration system control that ____.

A

converts high pressure high temperature liquid refrigerant to a low temperature low pressure mix of liquid and vapor refrigerant

33
Q

A significant difference between a DX evaporator and a flooded evaporator is ____.

A

in the DX evaporator the refrigerant is converted to vapor in the evaporator whereas it remains in liquid form in the flooded evaporator

34
Q

The correct location of a TXV sensing bulb is ____.

A

at the evaporator outlet

35
Q

What is the purpose of a crankcase heater?

A

to prevent liquid refrigerant from slugging the compressor

36
Q

What element in refrigerants causes ozone depletion?

A

chlorine

37
Q

The component directly following the evaporator of a refrigeration system is the ____.

A

accumulator

38
Q

When under a deep vacuum a hermetic refrigeration’s compressor ____.

A

motor winding could be damaged if energized

39
Q

When evacuating a system, the use of a large vacuum pump could ____.

A

cause trapped water to freeze

40
Q

The component of a refrigeration system which converts a high pressure vapor to a high pressure liquid is the ____.

A

condenser

41
Q

Horizontal piping runs used in refrigeration systems should ____.

A

pitch down in the direction of refrigerant flow

42
Q

A compressor with a piston that travels back and forth in a cylinder is a ____.

A

reciprocating

43
Q

Components most often found in the refrigeration system liquid line are ____.

A

receiver, sight glass/moisture indicator, filter drier

44
Q

Annealed copper tubing shall not be used in normal sizes larger than ____.

A

2”

45
Q

The exhaust from a refrigeration equipment room shall not be less then ____ from a property line or opening into a building.

A

20 feet

46
Q

Operating a three phase electrical motor at a phase imbalance above ____ will most likely damage the motor.

A

5%

47
Q

The purpose of flux used in soldering is ____.

A

keeps the metal clean once soil has been removed

48
Q

Why are expansion valves adjustable?

A

to adjust for different altitudes and to adjust for different sizes of liquid receivers

49
Q

An ampere measures the flow of ____.

A

electrical current

50
Q

When an air conditioning system is not in operation, the accumulator should have adequate liquid holding capacity of not less than ____ percent of the entire system capacity.

A

50

51
Q

Open flame that comes in direct contact with R-22 creates ____.

A

phosgene gas

52
Q

Effective July 1, 1992 section 608 of the ____ prohibits individuals from intentionally venting ozone-depleting substances used as refrigerants.

A

Refrigeration Recycling Rule

53
Q

Section 608 does not consider small releases of refrigerant resulting from the disconnection of hoses, however, effective November 15, 1993 recovery and recycling equipment must be equipped with ____>

A

low-loss fittings

54
Q

Technicians repairing small appliances such as household refrigerators, window air conditioners, or water coolers must recover ___% of the refrigerant when the compressor is not operational and ____% when the compressor is operational.

A

80/90

55
Q

Refrigerant recovered or recycled can be returned to the same system or ____ without restriction.

A

systems owned by the same person

56
Q

Refrigeration systems in commercial and industrial process refrigeration sectors are required to repair leaks within ____ days when the equipment leaks at a rate that would release ____ percent or more of the charge over a year.

A

30/35

57
Q

Refrigeration systems in all sectors except commercial and industrial process refrigeration sectors are required to repair leaks that would release ____ percent or more of the charge over a year within 30 days of discovery.

A

15

58
Q

To translate psig to psia when using a temperature-pressure chart, ____ must be added.

A

14.7

59
Q

Refrigeration oil must be heated up to ____ degrees F before removing it from a system to minimize refrigerant release.

A

130

60
Q

The EPA Type I Certification is for ____

A

servicing small appliances (household refrigerator, window air conditioners)

61
Q

The EPA Type II Certification is for ____

A

servicing and disposing of high or very high pressure appliances except small appliances and MVAC’s

62
Q

The EPA Type III Certification is for ____

A

servicing and disposing of low-pressure appliances

Air-Conditioning Systems (7 decks)

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