HVAC - CH 09 - Refrigerant and Oil Chemistry

1. What is a primary reason why many refrigerants manufactured a few decades ago are now banned? A. Their high cost of production B. Their negative effect on the natural environment C. Their tendency to cause system malfunctions D. Their incompatibility with modern oils

B. Their negative effect on the natural environment. The information indicates that refrigerants manufactured a few decades ago are now banned due to their negative environmental impact.

2. True or False: Contained within a system, refrigerants are considered pollutants.

False. While contained within a system, refrigerants are stable, are not pollutants, and produce no harmful effects.

3. What specific action is illegal according to regulations regarding refrigerants? A. Importing refrigerants without a license B. Willfully purging or venting certain refrigerants to the atmosphere C. Storing refrigerants in non-DOT-approved containers D. Using older refrigerant service equipment on newer systems

B. Willfully purging or venting certain refrigerants to the atmosphere. It is established by regulations that it is illegal to knowingly release certain refrigerants to the atmosphere.

4. When transferring refrigerant from one container to another, what personal protective equipment is specifically recommended? A. Safety glasses and a hard hat B. Gloves and goggles C. Ear protection and steel-toed boots D. A respirator and a full-body suit

B. Gloves and goggles. One of the safety guidelines advises wearing gloves and goggles any time refrigerant is transferred between containers.

5. What type of containers should refrigerants be transferred into? A. Any commercially available container B. Specially insulated containers C. Department of Transportation (DOT)-approved containers D. Containers with pressure relief valves only

C. Department of Transportation (DOT)-approved containers. The guidelines state to transfer refrigerants only into DOT-approved containers.

6. When retrofitting refrigerants and oils, what general advice is given? A. Use the most cost-effective alternatives B. Always follow retrofit guidelines C. Prioritize energy efficiency over compatibility D. Ensure all original components are retained

B. Always follow retrofit guidelines. A key piece of advice for retrofitting is to always follow the established guidelines.

7. Why should R-22 service equipment never be used on R-410A equipment? A. R-22 equipment is too old for R-410A systems. B. R-410A operates at higher pressures that R-22 equipment cannot handle. C. The refrigerants are chemically incompatible. D. R-22 service equipment will contaminate R-410A.

B. R-410A operates at higher pressures that R-22 equipment cannot handle. Service equipment for R-410A must be rated to handle its higher operating pressures.

8. For detecting R-123 refrigerant leaks, what specific devices are required according to ASHRAE Standard 15? A. Pressure gauges and thermometers B. Room sensors and alarms C. Halogen leak detectors D. Combustible gas monitors

B. Room sensors and alarms. ASHRAE Standard 15 requires the use of room sensors and alarms to detect R-123 refrigerant leaks.

9. Where should pressure relief devices on refrigeration systems be vented? A. To an indoor collection system B. To the outdoors C. Into a sealed recovery tank D. Directly into the atmosphere

B. To the outdoors. Pressure relief devices should be vented to the outdoors to prevent the buildup of excessive system pressures.

10. What does a high-pressure reading in a recovery tank indicate? A. The tank is nearly full of liquid refrigerant. B. The presence of air or other noncondensables in the tank. C. The recovery process is proceeding too slowly. D. The refrigerant is at its optimal temperature.

B. The presence of air or other noncondensables in the tank. A high-pressure reading in a recovery tank signals the presence of air or other noncondensables.

11. What percentage of the earth's total ozone does stratospheric ozone account for? A. Less than 10% B. Approximately 50% C. More than 90% D. Exactly 75%

C. More than 90%. Stratospheric ozone accounts for more than 90% of the earth’s total ozone.

12. What is the primary function of stratospheric ozone? A. To absorb infrared radiation B. To shelter the earth from UV-B radiation C. To regulate tropospheric weather patterns D. To produce standard oxygen molecules

B. To shelter the earth from UV-B radiation. Stratospheric ozone shelters the earth from UV-B radiation, which is essential for human health.

13. Which chemicals are rapidly depleting stratospheric ozone? A. Naturally occurring atmospheric gases B. Man-made chemicals containing nitrogen C. Man-made chemicals containing chlorine D. Hydrocarbons released from natural sources

C. Man-made chemicals containing chlorine. Stratospheric ozone is rapidly being depleted by man-made chemicals containing chlorine, including CFC and HCFC refrigerants.

14. What percentage of the total ozone is found in the troposphere? A. About 10% B. About 25% C. About 50% D. About 90%

A. About 10%. The troposphere holds only about 10% of the total ozone.

15. What is tropospheric ozone pollution popularly referred to as? A. Greenhouse effect B. Smog C. Acid rain D. Ozone hole

B. Smog. A popular term for tropospheric ozone pollution is smog.

16. How does sunlight create "bad ozone" in the troposphere? A. By reacting with water vapor B. By acting on chemicals present in the troposphere C. By directly breaking down oxygen molecules D. By reflecting off the earth's surface

B. By acting on chemicals present in the troposphere. Sunlight acting on chemicals in the troposphere creates bad ozone.

17. What is the chemical composition of an ozone molecule? A. Two oxygen atoms (O2) B. One oxygen atom (O) C. Three oxygen atoms (O3) D. Four oxygen atoms (O4)

C. Three oxygen atoms (O3). Ozone is a form of oxygen gas that is made up of three oxygen atoms.

18. How many miles above the earth is stratospheric ozone typically found? A. Within 7 miles B. Between 7 and 30 miles C. Between 30 and 300 miles D. Above 300 miles

B. Between 7 and 30 miles. Stratospheric ozone is found in a shell 7 to 30 miles above the earth.

19. True or False: The sun's ultraviolet radiation is powerful enough to break down the ozone molecule into a standard oxygen molecule and a free oxygen atom.

True. The sun’s ultraviolet radiation breaks down the ozone (O3) molecule into a standard oxygen (O2) molecule and a free oxygen (O) atom.

20. What natural process also produces ozone in the stratosphere? A. Volcanic eruptions B. Plant photosynthesis and bonding of oxygen molecules with free oxygen atoms C. Ocean currents D. Geological activity

B. Plant photosynthesis and bonding of oxygen molecules with free oxygen atoms. At the same time, more ozone is produced through plant photosynthesis and the bonding of standard oxygen (O2) molecules with free oxygen (O) atoms.

21. Once in the stratosphere, what specific atom is separated from a CFC or HCFC molecule by ultraviolet radiation? A. A fluorine atom (F) B. A hydrogen atom (H) C. A carbon atom (C) D. A chlorine atom (Cl)

D. A chlorine atom (Cl). Once in the stratosphere, ultraviolet radiation will separate a chlorine atom (Cl) from a CFC or HCFC molecule.

22. Approximately how many ozone molecules can one chlorine atom destroy? A. Up to 1,000 B. Up to 10,000 C. Up to 100,000 D. Up to 1,000,000

C. Up to 100,000. One chlorine atom (Cl) can destroy up to 100,000 ozone molecules.

23. Which international agreement uses the Ozone Depletion Potential (ODP) index for regulatory purposes? A. The Kyoto Protocol B. The Paris Agreement C. The United Nations Environment Programme (UNEP) Montreal Protocol D. The Copenhagen Accord

C. The United Nations Environment Programme (UNEP) Montreal Protocol. Under the United Nations Environment Programme (UNEP) Montreal Protocol, an index called the ozone depletion potential (ODP) has been used for regulatory purposes.

24. What health effect is specifically mentioned as a result of increased UV-B radiation reaching the earth? A. Increased respiratory illnesses B. Increased skin cancers and cataracts C. Increased incidence of heart disease D. Increased neurological disorders

B. Increased skin cancers and cataracts. The depleted ozone molecules in the stratosphere let more UV-B radiation reach the earth, causing an increase in skin cancers and cataracts in humans and animals.

25. Besides human health effects, what other biological impacts are attributed to increased UV-B radiation? A. Increase in marine life B. Strengthening of the human immune system C. Decrease in plant and marine life D. Increase in plant growth

C. Decrease in plant and marine life. Increased UV-B radiation can also lead to a decrease in plant and marine life.

26. What drives stratospheric winds, which in turn affect weather patterns on earth? A. The rotation of the earth B. Heat generated when stratospheric ozone intercepts ultraviolet light C. The interaction of high and low pressure systems D. Solar flares

B. Heat generated when stratospheric ozone intercepts ultraviolet light. When stratospheric ozone intercepts ultraviolet light, heat is generated, which is the force behind stratospheric winds affecting weather patterns.

27. What is the process called where the atmosphere's absorption of heat energy radiated from the earth's surface leads to warming? A. Atmospheric inversion B. The greenhouse effect C. Thermal equilibrium D. Solar intensification

B. The greenhouse effect. This warming process, caused by the atmosphere’s absorption of the heat energy radiated from the earth’s surface, is called the greenhouse effect, or global warming.

28. What gases are often referred to as greenhouse gases? A. Nitrogen and oxygen B. CFCs, HCFCs, HFCs, carbon dioxide, and water vapor C. Noble gases like argon and neon D. Pure hydrocarbons like methane and ethane

B. CFCs, HCFCs, HFCs, carbon dioxide, and water vapor. Naturally occurring gases and tropospheric pollutants like CFCs, HCFCs, and HFCs—as well as carbon dioxide, water vapor, and many other chemicals—are referred to as greenhouse gases.

29. What is the baseline Global Warming Potential (GWP) of carbon dioxide (CO2)? A. 0 B. 1 C. 10 D. 100

B. 1. Carbon dioxide (CO2) has a baseline GWP of 1.

30. By what percentage has the amount of carbon dioxide in the atmosphere increased in excess of its usual concentration? A. 10% B. 15% C. 25% D. 50%

C. 25%. Human needs have resulted in an increase in the amount of carbon dioxide in the atmosphere by 25% in excess of its usual concentration.

31. What is the primary cause of the increase in atmospheric carbon dioxide? A. Deforestation B. Volcanic activity C. Combustion of fossil fuels D. Industrial chemical processes

C. Combustion of fossil fuels. Most of this increase is due to the combustion of fossil fuels, a by-product of electricity generation required by the modern world.

32. What percentage of generated electricity is used to power refrigeration and air-conditioning equipment? A. 10% B. 25% C. 50% D. More than half

D. More than half. In fact, more than half of the electricity generated is used to power refrigeration and air-conditioning equipment.

33. How can refrigeration or air-conditioning systems with relatively small refrigerant charges greatly impact global warming, even if they never leak? A. By being improperly charged, leading to inefficiency and longer run times. B. By directly releasing small amounts of refrigerant into the atmosphere. C. By requiring frequent maintenance procedures. D. By interacting with other atmospheric pollutants.

A. By being improperly charged, leading to inefficiency and longer run times. Even refrigeration or air-conditioning systems with relatively small refrigerant charges that never leak may have a great impact on global warming if the equipment is improperly charged, leading to inefficiency and longer run times.

34. What term describes the warming impact that considers both direct and indirect global warming effects of refrigerants? A. Global Warming Potential (GWP) B. Ozone Depletion Potential (ODP) C. Total Equivalent Warming Impact (TEWI) D. Environmental Impact Factor (EIF)

C. Total Equivalent Warming Impact (TEWI). The total equivalent warming impact (TEWI) takes into consideration both the direct and indirect global warming effects of refrigerants.

35. What class of refrigerants will reduce TEWI when used in place of CFCs? A. HFOs and HCs B. HCFCs and HFCs C. CO2 and Ammonia D. All natural refrigerants

B. HCFCs and HFCs. Using HFC and HCFC refrigerants in the place of CFCs will also reduce the TEWI.

36. Which two molecules are most refrigerants made from? A. Propane and butane B. Methane and ethane C. Ammonia and carbon dioxide D. Nitrogen and oxygen

B. Methane and ethane. Most refrigerants are made from two molecules, methane and ethane.

37. What are methane and ethane referred to as due to containing only hydrogen and carbon? A. Halogenated hydrocarbons B. Chlorofluorocarbons C. Pure hydrocarbons D. Hydrofluorocarbons

C. Pure hydrocarbons. These two molecules contain hydrogen (H) and carbon (C) and are referred to as pure hydrocarbons (HCs).

38. Why were pure hydrocarbons not widely used as refrigerants after the 1930s? A. Their high cost B. Their flammability C. Their high toxicity D. Their low efficiency

B. Their flammability. Pure hydrocarbons were at one time considered good refrigerants, but because of their flammability they were not used after the 1930s to any large degree.

39. What is the chemical formula for ammonia? A. CH4 B. C2H6 C. NH3 D. H2O

C. NH3. Ammonia contains only nitrogen and hydrogen (NH3).

40. When are new molecules said to be "halogenated"? A. When hydrogen atoms are replaced with oxygen. B. When carbon atoms are linked by a double bond. C. When hydrogen atoms are removed from methane or ethane and replaced with halogens like chlorine or fluorine. D. When nitrogen atoms are introduced into the molecule.

C. When hydrogen atoms are removed from methane or ethane and replaced with halogens like chlorine or fluorine. Any time some of the hydrogen atoms are removed from either the methane or ethane molecule and replaced with halogens such as chlorine or fluorine, the new molecule is said to be halogenated.

41. What elements are contained in Chlorofluorocarbons (CFCs)? A. Hydrogen, chlorine, and carbon B. Chlorine, fluorine, and carbon C. Hydrogen, fluorine, and carbon D. Hydrogen and carbon

B. Chlorine, fluorine, and carbon. CFCs contain chlorine, fluorine, and carbon.

42. Why are CFCs considered the most damaging to stratospheric ozone? A. They react with oxygen in the lower atmosphere. B. Their molecules are not destroyed before they reach the stratosphere. C. They absorb too much UV-B radiation. D. They are highly flammable and cause explosions.

B. Their molecules are not destroyed before they reach the stratosphere. CFCs are considered the most damaging to stratospheric ozone because their molecules are not destroyed before they reach the stratosphere.

43. Since what date did it become illegal to intentionally vent CFC refrigerants into the atmosphere? A. January 1, 1990 B. July 1, 1992 C. November 15, 1995 D. January 1, 1996

B. July 1, 1992. It became illegal to intentionally vent CFC refrigerants into the atmosphere on July 1, 1992.

44. Which CFC refrigerant was commonly used for residential and light commercial refrigeration and centrifugal chillers? A. R-11 B. R-113 C. R-12 D. R-114

C. R-12. One important refrigerant is R-12, because it is commonly used for residential and light commercial refrigeration and for centrifugal chillers in some commercial buildings.

45. Which CFC refrigerant was used for centrifugal chillers in office buildings and as an industrial solvent? A. R-11 B. R-12 C. R-113 D. R-114

A. R-11. R-11 is used for many centrifugal chillers in office buildings and also as an industrial solvent to clean parts.

46. What elements are contained in Hydrochlorofluorocarbons (HCFCs)? A. Hydrogen and carbon B. Chlorine, fluorine, and carbon C. Hydrogen, chlorine, fluorine, and carbon D. Hydrogen, fluorine, and carbon

C. Hydrogen, chlorine, fluorine, and carbon. HCFCs contain hydrogen, chlorine, fluorine, and carbon.

47. Why do HCFCs have less potential for ozone depletion compared to CFCs? A. They contain less chlorine. B. They are less stable in the atmosphere and tend to break down before reacting with stratospheric ozone. C. They are heavier than air and do not reach the stratosphere. D. They have a shorter atmospheric lifespan.

B. They are less stable in the atmosphere and tend to break down before reacting with stratospheric ozone. Although these refrigerants have much less potential for ozone depletion because they tend to break down in the atmosphere, releasing the chlorine before it reaches and reacts with the ozone in the stratosphere.

48. What is the scheduled total phase-out year for the HCFC group of refrigerants? A. 2020 B. 2025 C. 2030 D. 2035

C. 2030. The HCFC group is scheduled for a total phase-out by the year 2030.

49. When did it become illegal to intentionally vent HCFC refrigerants into the atmosphere? A. January 1, 1996 B. July 1, 1992 C. November 15, 1995 D. January 1, 2010

B. July 1, 1992. As with CFCs, it became illegal to intentionally vent HCFC refrigerants into the atmosphere on July 1, 1992.

50. What is the earlier phaseout date for HCFC-22 (R-22) in new equipment? A. 2007 B. 2010 C. 2015 D. 2020

B. 2010. HCFC-22 (R-22) has an earlier phaseout date of 2010 for new equipment.

51. What does "total phaseout" mean regarding refrigerants? A. No new systems can use them, but existing stock can be used. B. No production and no importing of the refrigerants. C. They can only be used for essential applications. D. They must be destroyed immediately upon recovery.

B. No production and no importing of the refrigerants. Total phaseout means no production and no importing of the refrigerants.

52. What international agreement was modified in 2007 to accelerate the HCFC phaseout schedule? A. The Kyoto Protocol B. The Montreal Protocol C. The Clean Air Act D. The Copenhagen Accord

B. The Montreal Protocol. The Montreal Protocol was modified in 2007 and the HCFC phaseout schedule was accelerated.

53. What percentage reduction in HCFC production from the 1989 baseline was accelerated from 65% to 75% in 2007? A. 35% B. 50% C. 75% D. 90%

C. 75%. In 2007, reduction of HCFC production was accelerated from 65% to 75% from the baseline production year of 1989.

54. What elements are contained in Hydrofluorocarbons (HFCs)? A. Hydrogen and carbon B. Chlorine, fluorine, and carbon C. Hydrogen, fluorine, and carbon D. Hydrogen, chlorine, fluorine, and carbon

C. Hydrogen, fluorine, and carbon. The third group of refrigerants is the HFC group, which contains hydrogen, fluorine, and carbon atoms.

55. True or False: HFC molecules contain chlorine atoms and thus deplete the earth’s protective ozone layer.

False. HFC molecules contain no chlorine atoms and will not deplete the earth’s protective ozone layer.

56. Since what date did it become unlawful to intentionally vent HFC refrigerants into the atmosphere? A. July 1, 1992 B. January 1, 1996 C. November 15, 1995 D. January 1, 2010

C. November 15, 1995. On November 15, 1995, it became unlawful to intentionally vent HFC refrigerants into the atmosphere.

57. Why is retrofitting an R-12 system to R-134a complicated? A. R-134a is highly toxic. B. R-134a is not compatible with any oil left in an R-12 system or some R-12 system materials. C. R-134a operates at much higher pressures. D. R-134a has a significantly higher ozone depletion potential.

B. R-134a is not compatible with any oil left in an R-12 system or some R-12 system materials. The original plan to replace R-12 with R-134a is complicated because R-134a is not compatible with any oil left in an R-12 system and also not compatible with some of the materials used to construct R-12 systems.

58. What is required to ensure compatibility when retrofitting an R-12 system to operate with R-134a? A. Only a refrigerant charge adjustment. B. A complete oil change, checking system gaskets, and contacting the manufacturer for compressor material compatibility. C. Replacement of the entire system. D. A simple filter drier replacement.

B. A complete oil change, checking system gaskets, and contacting the manufacturer for compressor material compatibility. Retrofitting an R-12 system to R-134a requires a complete oil change, removal of residual oil, checking all system gaskets for compatibility, and contacting the manufacturer for compressor material compatibility.

59. What elements are contained in Hydrofluoro-olefin (HFO) refrigerants? A. Hydrogen and carbon B. Chlorine, fluorine, and carbon C. Hydrogen, fluorine, and carbon D. Hydrogen, chlorine, fluorine, and carbon

C. Hydrogen, fluorine, and carbon. Hydrofluoro-olefin (HFO) refrigerants are also composed of hydrogen, fluorine, and carbon atoms.

60. How are HFOs distinguished from HFCs chemically? A. HFOs contain chlorine, while HFCs do not. B. HFOs are derivatives of alkanes, while HFCs are derivatives of olefins. C. HFOs have carbon atoms linked by a double bond, while HFCs have single bonds. D. HFOs are entirely natural, while HFCs are man-made.

C. HFOs have carbon atoms linked by a double bond, while HFCs have single bonds. HFOs are distinguished from HFCs by being derivatives of olefins (which have carbon atoms linked by a double bond) rather than alkanes (which have single bonds between carbon atoms).

61. What are the Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) values for popular HFO refrigerants like HFO-1234yf and HFO-1234ze? A. High ODP, High GWP B. Low ODP, High GWP C. Zero ODP, Extremely low GWP D. Zero ODP, Medium GWP

C. Zero ODP, Extremely low GWP. Both HFO-1234yf and HFO-1234ze have a zero ODP with extremely low global warming potentials (GWPs).

62. What is the ASHRAE safety rating for HFO-1234yf and HFO-1234ze? A. A1 B. B1 C. A2L D. A3

C. A2L. The safety rating for refrigerants such as HFO-1234yf and HFO-1234ze, which are slightly flammable and have low toxicities, is A2L.

63. Which HFO refrigerant is a low GWP replacement for R-134a in mobile air-conditioning systems? A. HFO-1234ze B. HFO-1234yf C. R-32 D. R-123

B. HFO-1234yf. HFO-1234yf is a low GWP replacement for R-134a intended for use in mobile air-conditioning (MAC) systems in the automotive industry.

64. Which HFO refrigerant is intended to replace R-410A and offers a 75% reduction in GWP? A. HFO-1234yf B. HFO-1234ze C. R-32 D. R-125

B. HFO-1234ze. HFO-1234ze is intended to replace R-410A in residential and light commercial air-conditioning and heat pump applications while offering a 75% reduction in GWP.

65. What type of oil are HFOs miscible in? A. Mineral oil B. Alkylbenzene lubricants C. Polyol ester (POE) oils D. All traditional lubricants

C. Polyol ester (POE) oils. HFOs are miscible in polyol ester (POE) oils.

66. What ASHRAE safety group are Hydrocarbon (HC) refrigerants classified in? A. A1 B. A2L C. B1 D. A3

D. A3. HC refrigerants are classified by ASHRAE in the A3 safety group, meaning they are highly flammable.

67. What elements are contained in pure HC refrigerants? A. Hydrogen and carbon B. Hydrogen, chlorine, and carbon C. Hydrogen, fluorine, and carbon D. Hydrogen, chlorine, fluorine, and carbon

A. Hydrogen and carbon. Pure HC refrigerants have no chlorine or fluorine in their molecules as they contain only hydrogen and carbon.

68. What is the Ozone Depletion Potential (ODP) of HC refrigerants? A. Low B. Medium C. High D. Zero

D. Zero. Since HCs do not contain any chlorine, they have a zero ODP.

69. What GWP value do R-290 (propane) and R-600a (isobutane) have? A. 0 B. 3.0 C. 1430 D. 2088

B. 3.0. R-290 (propane) and R-600a (isobutane) both have a GWP of 3.0.

70. Which of the following is considered a "natural refrigerant"? A. CFC-12 B. HFC-134a C. Ammonia D. HCFC-22

C. Ammonia. The most efficient and environmentally safe refrigerants that exist in the world today are all natural refrigerants, which include hydrocarbons, ammonia, air, water, and carbon dioxide.

71. In the United States, under what program have some HC refrigerants been approved for use, and under what conditions? A. Clean Air Act, for all existing equipment. B. Montreal Protocol, as direct drop-in replacements. C. EPA’s Significant New Alternative Policy (SNAP) program, only in new equipment, in limited conditions, and with limited charge amounts. D. ASHRAE Standard 34, for retrofitting older systems without restriction.

C. EPA’s Significant New Alternative Policy (SNAP) program, only in new equipment, in limited conditions, and with limited charge amounts. In the United States, only some HC refrigerants have been approved by the EPA under its Significant New Alternative Policy (SNAP) program, for use only in new equipment, in limited conditions, and with limited refrigerant charge amounts because of their high flammability.

72. For what purpose have small percentages (less than 3%) of HC refrigerants been used in HCFC- and HFC-based refrigerant blends in the United States? A. To increase the blend's flammability. B. To reduce the blend's overall cost. C. To assist in oil return to the compressor. D. To enhance the blend's cooling capacity.

C. To assist in oil return to the compressor. For many years, small percentages of HC refrigerants have been used in many HCFC- and HFC-based refrigerant blends in the United States to assist in oil return to the compressor.

73. What is the maximum refrigerant charge allowed for R-290 (propane) in household refrigerators in the US under EPA SNAP approval? A. 2.0 ounces (57 grams) B. 3.5 ounces (100 grams) C. 5.3 ounces (150 grams) D. 10.0 ounces (283 grams)

C. 5.3 ounces (150 grams). R-290 (propane) can be used in household refrigerators, freezers, combination refrigerators and freezers, vending machines, and room air-conditioning units as long as the refrigerant charge does not exceed 5.3 ounces (150 grams).

74. True or False: Retrofitting equipment containing HC or other flammable refrigerants is allowed in the United States.

False. Retrofitting equipment containing HC refrigerants and other flammable refrigerants is not allowed in the United States.

75. What color must all refrigerant piping through which a refrigerator or freezer is serviced be, if it uses a flammable refrigerant? A. Blue B. Green C. Red D. Yellow

C. Red. All refrigerant piping through which the refrigerator or freezer is serviced must be colored red.

76. What is the specific Pantone Matching System (PMS) color for flammable refrigerant piping? A. PMS #100 B. PMS #185 C. PMS #200 D. PMS #255

B. PMS #185. This red must be Pantone Matching System (PMS) #185.

77. How far must the red piping extend from the compressor and on each side of the process tubes or service ports? A. At least 0.5 inches B. At least 1 inch or 2.54 centimeters C. At least 2 inches or 5.08 centimeters D. At least 3 inches or 7.62 centimeters

B. At least 1 inch or 2.54 centimeters. The red color must be present on the refrigerant process tubing and service ports or wherever a service technician may puncture the tubing for service purposes, extending at least 1 inch or 2.54 centimeters from the compressor and at least 1 inch on each side of the process tubes or service ports.

78. What should a service technician do if the cabinet and compressor/condensing unit data do not match when identifying the type of refrigerant? A. Proceed with service as usual, noting the discrepancy. B. Retrofit the system to a universally compatible refrigerant. C. Immediately stop work and notify appropriate authorities, as an unauthorized retrofit may have occurred. D. Replace the compressor without further investigation.

C. Immediately stop work and notify appropriate authorities, as an unauthorized retrofit may have occurred. If the data from both the cabinet and compressor or condensing unit do not match, an unauthorized retrofit may have been done, and an immediate stoppage of work should follow, with appropriate authorities notified.

79. What safety precaution should be taken before energizing a compressor when its terminal covers are off? A. Ensure the compressor has been running for at least 10 minutes. B. Verify the system is fully charged with refrigerant. C. Make sure the compressor’s terminal covers are in place. D. Spray the terminals with a non-conductive cleaner.

C. Make sure the compressor’s terminal covers are in place. One of the safety precautions to prevent terminal venting is to make sure the compressor’s terminal covers are in place before energizing the compressor.

80. What can occur if the compressor is energized while under a deep vacuum? A. Increased efficiency B. A short in the motor windings at the fusite terminals or a weak spot in the windings, potentially damaging the compressor. C. Improved oil circulation D. Lower operating temperatures

B. A short in the motor windings at the fusite terminals or a weak spot in the windings, potentially damaging the compressor. Energizing the compressor when under a deep vacuum can cause a short in the motor windings at the fusite terminals or at a weak spot in the windings, which may damage the compressor.

81. Why are refrigerants such as oil and refrigerant considered good electrical insulators? A. They have high thermal conductivity. B. They are excellent dielectrics. C. They are naturally occurring substances. D. They are non-flammable.

B. They are excellent dielectrics. Both oil and refrigerant are excellent dielectrics, meaning they are good electrical insulators.

82. What does LEL stand for in the context of flammable gas safety? A. Low Energy Level B. Lowest Explosion Limit C. Lower Exposure Limit D. Liquid Emission Limit

C. Lower Exposure Limit. The lower exposure limit (LEL) of a gas is the lowest concentration of the gas in air capable of producing a flash or fire in the presence of an ignition source.

83. What is the Lower Exposure Limit (LEL) concentration in air for propane (R-290)? A. 1.8% B. 2.1% C. 8.5% D. 9.5%

B. 2.1%. Propane (R-290) has an LEL of 2.1% concentration in air.

84. What is the Upper Exposure Limit (UEL) concentration in air for isobutane (R-600a)? A. 1.8% B. 2.1% C. 8.5% D. 9.5%

C. 8.5%. Isobutane (R-600a) has a UEL of 8.5% concentration in air.

85. Which of the following can cause an explosion when exposed to proper concentrations of HC gas and air? A. A vacuum pump switch B. A pressure switch C. A halide torch D. All of the above

D. All of the above. Sparks from a vacuum pump switch, pressure switch, contactors, electronic leak detector, halide torch, light switch, defrost timers, or thermostats can cause explosions when exposed to the proper concentrations of HC gas and air.

86. When should a combustible gas leak detector or monitor be used before a service procedure involving flammable refrigerants? A. After disconnecting power. B. After starting the service procedure. C. Before disconnecting power or unplugging anything. D. Only if a strong odor is detected.

C. Before disconnecting power or unplugging anything. Never disconnect power or unplug anything or begin a service procedure before checking for flammable refrigerants in the area with a combustible gas leak detector or monitor.

87. What three actions are essential for service technicians to take regarding combustible gases? A. Recover, Recycle, Reclaim B. Monitor, Ventilate, Eliminate C. Measure, Test, Report D. Install, Operate, Maintain

B. Monitor, Ventilate, Eliminate. Service technicians must: Monitor the area for combustible gasses. Ventilate the area to get rid of any combustible gasses. Eliminate any sources of ignition.

88. What type of leak detectors are specifically recommended for HC gases? A. Electronic leak detectors only B. Halide torches C. Non-ignitable types such as ultrasonic detectors, liquid solutions, or ultraviolet additives D. Bubble solution only

C. Non-ignitable types such as ultrasonic detectors, liquid solutions, or ultraviolet additives. Always use non-ignitable type leak detectors for HC gases such as ultrasonic detectors, liquid solutions, or ultraviolet additives.

89. What type of tools are recommended when working with flammable refrigerants? A. Steel tools B. Insulated tools C. Spark-proof tools, like brass tools D. Battery-powered tools

C. Spark-proof tools, like brass tools. Service technicians should use spark-proof tools, and many brass tools are spark-proof.

90. True or False: It is safe to use a torch to remove refrigerant components if the system is de-pressurized.

False. Never use a torch to remove refrigerant components; always use tubing cutters.

91. What is a specific requirement for transporting HC cylinders in a vehicle? A. They must be transported horizontally. B. The vehicle must be labeled to indicate it is carrying flammable gas. C. They must be transported empty. D. They must be transported only at night.

B. The vehicle must be labeled to indicate it is carrying flammable gas. The vehicle must be labeled to let the general public know it is carrying a flammable gas.

92. How must HC cylinders be transported in a vehicle? A. On their side B. In the upright position C. In a sealed trunk D. On their back

B. In the upright position. HC cylinders must be transported in the upright position.

93. What is a storage requirement for hydrocarbon cylinders? A. They can be stored near air intakes for ventilation. B. They must be stored away from any ignition source. C. They can be stored at any height as long as they are secured. D. Access to storage areas should be unrestricted.

B. They must be stored away from any ignition source. Store cylinders away from any ignition source.

94. What is the first step in the DuPont numbering system for refrigerants? A. The first digit from the right is the number of carbon atoms. B. The first digit from the right is the number of fluorine atoms. C. The first digit from the right is the number of hydrogen atoms. D. The first digit from the right is the number of chlorine atoms.

B. The first digit from the right is the number of fluorine atoms. The first digit from the right is the number of fluorine atoms.

95. In the DuPont numbering system, what does the second digit from the right represent? A. One less than the number of hydrogen atoms. B. The number of hydrogen atoms. C. One more than the number of hydrogen atoms. D. Twice the number of hydrogen atoms.

C. One more than the number of hydrogen atoms. The second digit from the right is one more than the number of hydrogen atoms.

96. In the DuPont numbering system, what does the third digit from the right represent? A. The number of carbon atoms. B. One less than the number of carbon atoms. C. One more than the number of carbon atoms. D. The number of carbon atoms minus one, with zero indicating one carbon atom.

D. The number of carbon atoms minus one, with zero indicating one carbon atom. The third digit from the right is one less than the number of carbon atoms, and if this number is zero, there is one carbon atom and the refrigerant is methane-based.

97. Given the chemical formula CHCl2CF3 for R-123, how many carbon atoms does it have based on the DuPont numbering system? A. 1 B. 2 C. 3 D. 4

B. 2. For R-123, the third number from the right is 1. According to the rule, this is one less than the number of carbon atoms, so there are 1 + 1 = 2 carbon atoms.

98. Given the chemical formula CCl2F2 for R-12, how many carbon atoms does it have based on the DuPont numbering system? A. 0 B. 1 C. 2 D. 3

B. 1. For R-12, the third number from the right is 0. This indicates one less than the number of carbon atoms, so 0 + 1 = 1 carbon atom, meaning it is methane-based.

99. What do the small letters like "a, b, c, d…" at the end of a refrigerant number (e.g., R-134a) represent? A. The level of toxicity. B. How symmetrical the molecular arrangement is, indicating isomers. C. The boiling point range. D. The specific manufacturer.

B. How symmetrical the molecular arrangement is, indicating isomers. The small letters “a, b, c, d, . . .” at the end of the numbering system represent how symmetrical the molecular arrangement is, indicating isomers of one another.

100. True or False: R-134 and R-134a are chemically identical refrigerants.

False. R-134a and R-134 are completely different refrigerants with completely different properties, despite having the same number of atoms of the same elements, differing only in arrangement (isomers).