Test Topics

Environmental Impacts

• Destruction of ozone by chlorine
• Presence of chlorine in chlorofluorocarbonchlorofluorocarbonA compound consisting of chlorine, fluorine, and carbon. CFCs are very stable in the troposphere. They move to the stratosphere and are broken down by strong ultraviolet (UV) light, where they release chlorine atoms that then deplete the ozone layer. CFCs are commonly used as refrigerants, solvents, and foam blowing agents. The most common CFCs are CFC-11, CFC-12, CFC-113, CFC-114, and CFC-115. The ozone depletion potential (ODP) for each CFC is, respectively, 1, 1, 0.8, 1, and 0.6. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, global warming potentials (GWPs), and CAS numbers. CFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (CFC) and hydrochlorofluorocarbonhydrochlorofluorocarbonA compound consisting of hydrogen, chlorine, fluorine, and carbon. The HCFCs are one class of chemicals being used to replace the CFCs. They contain chlorine and thus deplete stratospheric ozone, but to a much lesser extent than CFCs. HCFCs have ozone depletion potentials (ODPs) ranging from 0.01 to 0.1. Production of HCFCs with the highest ODPs are being phased out first, followed by other HCFCs. A table of ozone-depleting substances (http://www.epa.gov/ozone/science/ods/classtwo.html) shows their ODPs, GWPs, and CAS numbers. HCFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (HCFC) refrigerants
• Identification of CFC, HCFC, and hydrofluorocarbonhydrofluorocarbonA compound consisting of hydrogen, fluorine, and carbon. The HFCs are a class of replacements for CFCs. Because they do not contain chlorine or bromine, they do not deplete the ozone layer. All HFCs have an ozone depletion potential of 0. Some HFCs have high GWPs. HFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (HFC) refrigerants (not chemical formulas, but idea that R-12 is a CFC, R-22 is an HCFC, R-134 is an HFC, etc.)
• Idea that CFCs have higher ozone-depletion potential (ODPODPA number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11. Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. The halons have ODPs ranging up to 10. Carbon tetrachloride has an ODP of 1.2, and methyl chloroform's ODP is 0.11. HFCs have zero ODP because they do not contain chlorine. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers.) than HCFCs, which in turn have higher ODP than HFCs
• Understanding of the atmospheric effects from the types of refrigerants
• Health and environmental effects of stratospheric ozone depletion
• Evidence of stratospheric ozone depletion and role of CFCs and HCFCs

Clean Air Act and Montreal Protocol

• CFC phaseout date
• R-22 phaseout date
• Venting prohibition at servicing
• Venting prohibition at disposal
• Venting prohibition on substitute refrigerants
• Maximum penalty under the Clean Air ActClean Air ActA law amended by Congress in 1990. Title VI of the CAA (http://www.epa.gov/ozone/title6/index.html) directs EPA to protect the ozone layer through several regulatory and voluntary programs. Sections within Title VI cover production of ozone-depleting substances (ODS), the recycling and handling of ODS, the evaluation of substitutes, and efforts to educate the public.
• Montreal ProtocolMontreal ProtocolThe international treaty governing the protection of stratospheric ozone. The Montreal Protocol on Substances That Deplete the Ozone Layer and its amendments control the phaseout of ODS production and use. Under the Montreal Protocol, several international organizations report on the science of ozone depletion, implement projects to help move away from ODS, and provide a forum for policy discussions. In addition, the Multilateral Fund provides resources to developing nations to promote the transition to ozone-safe technologies. The full text of the Montreal Protocol (http://ozone.unep.org/Publications/MP_Handbook/Section_1.1_The_Montreal_Protocol/) is available from the United Nations Environmental Programme (UNEP). (the international agreement to phase out production of ozone-depleting substances)

Section 608 Regulations

• Definition/identification of high and low-pressure refrigerants
• Definition of system-dependent versus self-contained recovery/recycling equipment
• Identification of equipment covered by the rule (all air-conditioning and refrigeration equipment containing CFCs or HCFCs except motor vehicle air conditioners)
• Need for third-party certification of recycling and recovery equipment
• Standard for reclaimed refrigerant [Air Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 700-2016]
• The sales restriction
• The Clean Air Act prohibition on venting

Substitute Refrigerants and oils

• Absence of "drop-in" replacements
• Incompatibility of substitute refrigerants with many lubricants used with CFC and HCFC refrigerants and incompatibility of CFC and HCFC refrigerants with many new lubricants (includes identification of lubricants for given refrigerants, such as esters with R-134; alkylbenzenes for HCFCs)
• Fractionation problem--tendency of different components of blends to leak at different rates

Refrigeration

• Refrigerant states (vapor versus liquid) and pressures at different points of refrigeration cycle; how/when cooling occurs
• Refrigeration gauges (color codes, ranges of different types, proper use)
• Leak Detection

Three R Definitions

• Recover
• Recycle
• Reclaim

Recovery Techniques

• Need to avoid mixing refrigerants
• Factors affecting speed of recovery (ambient temperature, size of recycling or recovery equipment, hose length and diameter, etc.)

Dehydration Evacuation

• Need to evacuate system to eliminate air and moisture at the end of service

Safety

• Risks of exposure to refrigerant (e.g., oxygen deprivation, cardiac effects, frost bite, long-term hazards)
• Personal protective equipment [gloves, goggles, self-contained breathing apparatus (SCBA)-in extreme cases, etc.]
• Reusable (or "recovery") cylinders versus disposable cylinders [ensure former Department of Transportation (DOT) approved, know former's yellow and gray color code, never refill latter]
• Risks of filling cylinders more than 80 percent full
• Use of nitrogen rather than oxygen or compressed air for leak detection
• Use of pressure regulator and relief valve with nitrogen

Shipping

• Labels required for refrigerant cylinders (refrigerant identification, DOT classification tag)

Recovery Requirements

• Definition of "small appliance"
• Evacuation requirements for small appliances with and without working compressors using recovery equipment manufactured before November 15, 1993
• Evacuation requirements for small appliances with and without working compressors using recovery equipment manufactured after November 15, 1993

Recovery Techniques

• Use of pressure and temperature to identify refrigerants and detect noncondensables
• Methods to recover refrigerant from small appliances with inoperative compressors using a system-dependent or "passive" recovery device (e.g., heat and sharply strike the compressor, use a vacuum pump with non-pressurized recovery container)
• Need to install both high and low side access valves when recovering refrigerant from small appliances with inoperative compressors
• Need to operate operative compressors when recovering refrigerant with a system-dependent ("passive") recovery device
• Should remove solderless access fittings at conclusion of service
• HydrofluorocarbonHydrofluorocarbonA compound consisting of hydrogen, fluorine, and carbon. The HFCs are a class of replacements for CFCs. Because they do not contain chlorine or bromine, they do not deplete the ozone layer. All HFCs have an ozone depletion potential of 0. Some HFCs have high GWPs. HFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (HFC)-134a (also called R-134a) as likely substitute for chlorofluorocarbonchlorofluorocarbonA compound consisting of chlorine, fluorine, and carbon. CFCs are very stable in the troposphere. They move to the stratosphere and are broken down by strong ultraviolet (UV) light, where they release chlorine atoms that then deplete the ozone layer. CFCs are commonly used as refrigerants, solvents, and foam blowing agents. The most common CFCs are CFC-11, CFC-12, CFC-113, CFC-114, and CFC-115. The ozone depletion potential (ODP) for each CFC is, respectively, 1, 1, 0.8, 1, and 0.6. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, global warming potentials (GWPs), and CAS numbers. CFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (CFC)-12 (also called R-12)

Safety

• Decomposition products of refrigerants at high temperatures

Leak Detection

• Signs of leakage in high-pressure systems (excessive superheat, traces of oil for hermetics)
• Need to leak test before charging or recharging equipment
• Order of preference for leak test gases [nitrogen alone best, but nitrogen with trace quantity of hydrochlorofluorocarbonhydrochlorofluorocarbonA compound consisting of hydrogen, chlorine, fluorine, and carbon. The HCFCs are one class of chemicals being used to replace the CFCs. They contain chlorine and thus deplete stratospheric ozone, but to a much lesser extent than CFCs. HCFCs have ozone depletion potentials (ODPs) ranging from 0.01 to 0.1. Production of HCFCs with the highest ODPs are being phased out first, followed by other HCFCs. A table of ozone-depleting substances (http://www.epa.gov/ozone/science/ods/classtwo.html) shows their ODPs, GWPs, and CAS numbers. HCFCs are numbered according to a standard scheme (http://www.epa.gov/ozone/geninfo/numbers.html). (HCFC)-22 (also called R-22) better than pure refrigerant]

Leak repair requirements

• Allowable leak rate for commercial and industrial process refrigeration
• Allowable leak rate for other appliances containing more than 50 pounds of refrigerant
• Leak repair recordkeeping
• Extensions to the timeframe to repair leaks that exceed the threshold leak rate

Recovery Techniques

• Recovering liquid at beginning of recovery process speeds up process
• Other methods for speeding recovery (chilling recovery vessel, heating appliance or vessel from which refrigerant is being recovered)
• Methods for reducing cross-contamination and emissions when recovery or recycling machine is used with a new refrigerant
• Need to wait a few minutes after reaching required recovery vacuum to see if system pressure rises (indicating that there is still liquid refrigerant in the system or in the oil)

Recovery Requirements

• Evacuation requirements for high-pressure appliances in each of the following situations:
  • Disposal
  • Major versus non-major repairs
  • Leaky versus non-leaky appliances
  • Appliance (or component) containing less versus more than 200 pounds
  • Recovery/recycling equipment built before versus after November 15, 1993
• Definition of "major" repairs
• Prohibition on using system-dependent recovery equipment on systems containing more than 15 pounds of refrigerant

Refrigeration

• How to identify refrigerant in appliances
• Pressure-temperature relationships of common high-pressure refrigerants [may use standard temperature-pressure chart--be aware of need to add 14.7 to translate pounds per square inch gauge (psig) to pounds per square inch absolute (psia)]
• Components of high-pressure appliances (receiver, evaporator, accumulator, etc.) and state of refrigerant (vapor versus liquid) in them
• The idea that hydrocarbons are not approved for retrofits

Safety

• Shouldn't energize hermetic compressors under vacuum
• Equipment room requirements under American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 15 (oxygen deprivation sensor with all refrigerants)

Leak Detection

• Order of preference of leak test pressurization methods for low-pressure systems
  1. Hot water method or built-in system heating/pressurization device such Prevac
  2. Nitrogen
• Signs of leakage into a low-pressure system (e.g., excessive purging)
• Maximum leak test pressure for low-pressure centrifugal chillers
• Leak inspection requirements for appliances that exceed the leak rate
• Reporting for chronically leaking appliances

Leak repair requirements

• Allowable annual leak rate for commercial and industrial process refrigeration
• Allowable annual leak rate for other appliances containing more than 50 pounds of refrigerant

Recovery Techniques

• Recovering liquid at beginning of recovery process speeds up process
• Need to recover vapor in addition to liquid
• Need to heat oil to 130°F before removing it to minimize refrigerant release
• Need to circulate or remove water from chiller during refrigerant evacuation to prevent freezing
• High-pressure cut-out level of recovery devices used with low-pressure appliances

Recharging Techniques

• Need to introduce vapor before liquid to prevent freezing of water in the tubes
• Need to charge centrifugals through evaporator charging valve

Recovery Requirements

• Evacuation requirements for low-pressure appliances in each of the following situations:
  • Disposal
  • Major versus non-major repairs
  • Leaky versus non-leaky appliances
  • Appliance (or component) containing less versus more than 200 pounds
  • Recovery/recycling equipment built before versus after November 15, 1993
• Definitions of "major" and "non-major" repairs
• Allowable methods for pressurizing a low-pressure system for a non-major repair (controlled hot water and system heating/pressurization device such as Prevac)
• Need to wait a few minutes after reaching required recovery vacuum to see if system pressure rises (indicating that there is still liquid refrigerant in the system or in the oil)

Refrigeration

• Purpose of purge unit in low-pressure systems
• Pressure-temperature relationships of low-pressure refrigerants

Safety

• Equipment room requirements under ASHRAE Standard 15 (oxygen deprivation sensor with all refrigerants)
• Under ASHRAE Standard 15, need to have equipment room refrigerant sensor for R-123