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RACM > REF UNITS 8 - 9 > Flashcards

REF UNITS 8 - 9 Flashcards

1
Q

(8.2) How do you check for a leak in an evaporator coil?

A

pressurize system with nitrogen (equalize high and low sides)

position leak detector probe at drain trap

2 positive tests confirm a leak

use spray foam to locate exact leak

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2
Q

(8.2) How do you check for a leak in a condenser coil?

A

pressurize system with nitrogen

cover unit with tarp

monitor for 10 minutes

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3
Q

(8.3) How do you check for temperature dependent leaks?

A

partially block condenser’s air intake (this raises system temperature)

(You can pressurize system with warm water)

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4
Q

(8.3) How do you check for combination-dependent leaks?

A

check for pressure, then vibration, then heat.

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5
Q

(8.3) How do you check for cumulative microleaks?

A

use a helium mass spectrometer

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6
Q

(8.4) How do you perform a standing pressure test?

A

pressurize

allow rest for 10 minutes

mark pressures on manifold

come back like the next day or an hour or something, depending on the size of the system.

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7
Q

(8.4) What element do halide leak detectors respond to?

A

chlorine

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8
Q

(8.7) define degassing

A

removing air and other non-condensable gasses from a system using a vacuum pump.

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9
Q

(8.7) define dehydration

A

removing moisture from a sealed system.

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10
Q

(8.7) define evacuation

A

the removal of any gases not characteristic to a system using a vacuum pump.

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11
Q

(8.7) how many microns are in 1 inch of mercury?

A

25,400 microns

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12
Q

(8.7) What is the range of a “deep vacuum”?

A

250 to 500 microns

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13
Q

(8.7) How do you perform a triple evacuation?

A
  1. pull vacuum of 1500 microns, then add a bit of nitrogen.
  2. repeat.
  3. pull to a deep vacuum, let sit for 10 to 15 minutes.
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14
Q

(9.2) What is the chemical composition of ozone?

A

O3

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15
Q

(9.2) Where is good ozone located?

A

the stratosphere (7 to 30 miles above the earth)

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16
Q

(9.2) What type of radiation does the sun protect us from?

A

ultra-violet radiation (UV-B)

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17
Q

(9.2) Where is bad ozone located?

A

the troposphere (ground to 7 miles above the earth)

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18
Q

(9.2) What element in refrigerants are ozone depleting?

A

chlorine

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19
Q

(9.2) What is tropospheric ozone also known as?

A

smog

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20
Q

(9.2) How many ozone molecules can 1 chlorine atom destroy?

A

up to 100,000

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21
Q

(9.3) Define GWP

A

(global warming potential) the scale that measures the global warming impact of a substance’s emissions.

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22
Q

(9.3) How is GWP measured?

A

as a ratio compared to the GWP of carbon dioxide

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23
Q

(9.3) What gas is the #1 contributor to global warming?

A

CO2

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24
Q

(9.3) Define TEWI

A

(total equivalent warming impact) the scale that measures the total impact of refrigerants on global warming.

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25
Q

(9.4) Why do CFC’s have the highest ODP?

A

because their molecules are not destroyed before reaching the stratosphere.

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26
Q

(9.5) Why is July 1st of 1992 an important date?

A

it became illegal to intentionally vent CFC and HCFC refrigerants.

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27
Q

(9.5) When were CFC’s phased out?

A

by the end of 1995.

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28
Q

(9.5) What is the GWP and ODP of CFC’s?

A

high GWP, high ODP.

29
Q

(?) What is mass equal to?

A

volume X density

30
Q

(9.5) What are some examples of CFC refrigerants?

A

any of the r-10s (like R-11, R-12).

31
Q

(9.6) What is the GWP and ODP of HCFC refrigerants?

A

medium GWP, medium ODP

32
Q

(9.6) When are HCFC’s scheduled to be phased out?

A

by 2030

33
Q

(9.6) what was the Montreal protocol?

A

An agreement signed in 1987 by the United States and other countries to control the release of ozone-depleting substances. specifically banning R-22.

34
Q

(9.something) How is ODP scaled?

A

from 0 to 1

35
Q

(9.7) What is the GWP and ODP of HFC refrigerants?

A

medium GWP, no ODP

36
Q

(9.7) Why is November 15 1995 an important date?

A

it became illegal to intentionally vent HFC refrigerants.

37
Q

(9.7) What are some examples of HFC refrigerants?

A

R-134A, R-410A

38
Q

(9.8) What refrigerants are known as the 4th generation of refrigerants and why?

A

HFOs, and because they are pretty cheap and not harmful to the environment.

39
Q

(9.8) What is an example of an HFO?

A

HFO-1234yf

40
Q

(9.8) What oils work well with HFO’s?

A

POE oil

41
Q

(9.8) What is the GWP and ODP of HFO refrigerants?

A

low GWP, no ODP

42
Q

(9.8) How flammable are HFOs?

A

slightly

43
Q

(9.9) How flammable are HC refrigerants?

A

very flammable

44
Q

(9.9) what are HC refrigerants also known as?

A

natural refrigerants

45
Q

(9.9) What areas are there warnings to technicians of an HC unit?

A

compressor or condenser, evaporator, exposed piping, exterior.

46
Q

(9.9) Define terminal venting

A

when one or more terminal pins blows out of its terminal, allowing a pressurized refrigerant and oil spray to escape into the atmosphere.

47
Q

(9.9) Define LEL

A

(lower exposure limit) the lowest concentration of the gas in air capable of producing a flash or fire in the presence of an ignition

48
Q

(9.9) Define UEL

A

(upper exposure limit) the highest concentration of a gas in air capable of producing a flash or fire in the presence of an ignition source

49
Q

(9.10) How are refrigerants numbered?

A
  1. # of fluorine atoms
  2. # of hydrogen atoms + 1
  3. # of carbon atoms -1
50
Q

(9.11) which refrigerant is listed first when displaying blend ratio?

A

the refrigerant with the lowest boiling point.

51
Q

(9.11) What is the max number of refrigerants in a blend?

A

5

52
Q

(9.11) Define azeotropic blend

A

works as a single refrigerant, no fractionation.

53
Q

(9.11) Define near-azeotropic blend

A

a blend that can fractionate.

54
Q

(9.11) Define zeotropic blend

A

a refrigerant blend that has a large temperature glide.

55
Q

(9.13) What are the 3 most used synthetic oils in the industry?

A

alkylbenzenes, glycols, esters

56
Q

(9.13) What refrigerants tend to work well with alkylbenzene oils?

A

HCFCs

57
Q

(9.13) What refrigerants tend to work well with ester-based oils?

A

HFCs

58
Q

(9.14) What did the United States Clean Air Act Amendments of 1990 accomplish?

A

regulated the use and disposal of CFCs and HCFCs

59
Q

(9.15) When did de minimus release come into effect?

A

July 1st, 1992

60
Q

(9.15) Define recycling

A

separating oil from refrigerant using filter driers, and returning it back to the system.

61
Q

(9.15) What machine do you need to recycle refrigerant?

A

a recycling machine

62
Q

(9.15) Define reclamation

A

sending the refrigerant to a reprocessing site

63
Q

(9.16) What is a type I certification tech able to work on?

A

small systems with 5 pounds or less of refrigerant in them.

64
Q

(9.16) What is a type II certification tech able to work on?

A

high pressure appliances

65
Q

(9.16) What is a type III certification tech able to work on?

A

low pressure appliances

66
Q

(9.16) What is a type IV certification tech able to work on?

A

all appliances

67
Q

(10.3) What is the liquid line service valve also known as?

A

the king valve

68
Q

(10.7) When do you calculate charging a system with subcooling?

A

when the system uses a TXV

69
Q

(10.7) When do you calculate charging a system with superheat?

A

when the system uses a fixed-bore metering device.

RACM (23 decks)

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