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R32 in its pure form is classified as A2. Why are HFO refrigerants less flammable than hydrocarbon refrigerants? What must be done before disposing of any appliance containing a CFC, HCFC, of HFC refrigerant? b. A non-ozone depleting substance used in a refrigerator or freezer.C. Many CFC, HCFC, and HFC refrigerants originate from these two base molecules of ethane and methane. This includes all hydrocarbon refrigerants. Methane gas has a LFL of 4.4%. Request a replacement from their certifying organization. How does the global warming potential of R-410A compare to that of carbon dioxide? So, since these formulas are patented DuPont & HoneyWell pretty much have a monopoly on the market. b. R-134a and R-410A a. b. R-134a d. Performing any activity that violates the refrigerant circuit. Describe how the heartbeat affects blood flow. d. None. They must be recovered before opening or disposing of appliances. a. AB lubricants Initial issues first: It is illegal to implement a flammable refrigerant to recharge an automotive air conditioning system. HFO refrigerants are composed of hydrogen, fluorine and carbon atoms but contain at least one double bond between the carbon atoms. HFO-1234ze is easier to manufacture than HFO-1234yf and less costly, which makes it attractive for large chillers that require high quantities of refrigerant. When a refrigerant is listed as unacceptable, its use is illegal. C. They are prohibited for use in the u.s.D. As more cities and states mandate lower building emissions or full electrification, learn how heat pump technology can help you contribute to decarbonization goals. Even though everyone has just switched over to R-410A in 2010 it looks like its days are already numbered. Which gas is used as the baseline measurement for global warming potential? Please click here to continue without javascript.. Technology Can Help Solve the HVAC Labor Issue, Moving Forward with R-290 Natural Refrigerant, Decarbonization with Heat Pump Technology, BNI Mechanical/Electrical Square Foot Costbook, 2023 Edition. Olefins have carbon atoms linked by a double bond where alkanes have single bonds between carbon atoms. Some refrigerant blends that incorporate HC refrigerants in small percentages for oil return purposes include R-402A, -402B, -403A, -406A, and -438A. Acceptable, subject to use conditions, for new vehicles only (June 6, 2012, 77 FR 33315), Operates at 5 to 10 times higher pressure than other MVAC systems, Under development by several foreign automobile manufacturers, Exempt from the Section 608 venting prohibition, meaning it is legal to knowingly release this refrigerant to the environment; however, CO. Engineering strategies and/or mitigation devices shall be incorporated such that in the event of refrigerant leaks the resulting CO2 concentrations do not exceed the STEL of 30,000 ppm averaged over 15 minutes in the passenger free space and the ceiling limit of 40,000 ppm in the passenger breathing zone. HFO refrigerants fall under the 'slightly flammable' category (A2L). The miscibility of HFOs with POE lubricants is comparable to that of R-134a. What characteristics of HFC refrigerants make them damaging to the environment? Find the rate at which the water level decreases initially, assuming it is very slow compared to the speed at which water comes out of the slit. How do the global warming potential of isobutane (R-600a), and R-441A compare to the GWP's of HFC-134a, R-404A, and R-410A? Which word applies to the process that returns refrigerant to new product specifications and that requires chemical analysis? Chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) have which of the following in common? Common applications include commercial refrigerators and bottle coolers, split air conditioning units, and domestic refrigerators and freezers. Refrigerants emitted in the course of normal operation of an appliance.D. Because of their lower GWP values, these refrigerants have a much shorter life cycle in the atmosphere. Prevent venting to the atmosphere. Under EPA's regulations, what standard must reclaimed refrigerant meet before it can be resold? HFOs are distinguished from HFCs by being derivatives of olefins rather than alkanes (paraffins). HFOs do exist that have A1 (nonflammable) safety ratings; however, further research and testing needs to be done with these refrigerants. a. recovery and reclaimed gas How do refrigerant blends leak from a system? b. R-134ad. On July 23, 1983, Air Canada Flight 143 was being readied Now in Russian Federation and other countries large-scale oil terminals (volume of one tank exceeds 100 000 m 3, total volume of tanks exceeds 300 000 m 3) are designed and constructed.Therefore fire safety of such objects becomes a very important task, solution of which is hardly possible without detail fire risk assessment.This study is aimed to a solution of this problem. Which refrigerant can be purchased by someone who is NOT a section 608 certified technician? Which of the following refrigerants is very high pressure and generally does NOT need to be recovered? Acceptable, subject to use conditions, for new vehicles only (June 12, 2008, 73 FR 33304), Moderately flammable (ASHRAE A2), but can be used safely, May be pursued by automobile manufacturers in the future, Engineering strategies and/or devices shall be incorporated into the system such that foreseeable leaks into the passenger compartment do not result in R-152a concentrations of 3.7% v/v or above in any part of the free space1 inside the passenger compartment for more than 15 seconds when the car ignition is on, Manufacturers must adhere to all the safety requirements listed in the SAE Standard J639, including unique fittings and a flammable refrigerant warning label as well as SAE Standard J2773, Refrigerant Guidelines for Safety and Risk Analysis for Use in Mobile Air Conditioning Systems.. The capital letter L refers to lower flammability. Proposed listing of HFO-1234yf as acceptable, subject to use conditions, for MVAC systems in newly manufactured nonroad vehicles 1. HFO refrigerants are actually unsaturated HFC refrigerants and are widely recognized as the next generation of refrigerants because of their environmental friendliness, cost-effectiveness, and great energy efficiencies. What leak detection method is considered to be the most efficient for locating the general area of a small leak? Since 1994, the most common refrigerant used in MVAC systems has been hydrofluorocarbon (HFC)-134a. Share sensitive information only on official, secure websites. It is hoped that this paper will initiate a dialog among stakeholders, and increase the likelihood that the more widespread use of flammable refrigerants does not result in a decline in safety. They can have very high global warming potentials. There is no difference between refrigerant grade hydrocarbon refrigerant and propane for grills. Please click here to see any active alerts. Although the refrigerant is classified as slightly flammable by ASHRAE, several years of testing by the Society of Automotive Engineers (SAE) proved that HFO-1234yf could not be ignited under conditions normally experienced by a vehicle. Vehicles may only be retrofitted with alternatives approved under SNAP for use as retrofits. The system may be leaking.D. c. HCFCs c. They are stored under pressure, causing them to jet upward when released. d. The purchaser is or employs a Section 608 certified technician. c. 100,000,000 molecules Hydrofluoroolefins (HFOs) The last round of changes took place Manufacturers have addressed the safety issues around using A2L refrigerants in air conditioning However, it is likely that in some air conditioner somewhere, at some point in time, refrigerant will be They are less flammable than hydrocarbon refrigerants, but most are still mildly flammable Why are some Recover the mixture into a separate recovery tank. They have also been adopted as blowing agents, i.e. They are no different than HFCs.B. What would the period of the pendulum in Problem 60 be if the pendulum were on the moon, where the acceleration due to gravity is one-sixth that on Earth? b. Solstice N40 Even though it protects us when it is in the stratosphere, ozone at ground level can be harmful to breathe and is a prime ingredient in smog. Suppose you have an unknown clear substance immersed in water, and you wish to identify it by finding its index of refraction. c. Samples of air taken from the stratosphere over erupting volcanoes show that volcanoes contribute a small quantity of chlorine to the stratosphere compared to CFCs and HCFCs. . Ozone is "good up high, bad nearby." In the new real-life test scenario, the refrigerant is dynamically dispersed at high pressure near to hot components of the test vehicles exhaust system. Manufacturers must conduct Failure Mode and Effect Analysis (FMEA) as provided in SAE J1739 (adopted 2009). An international treaty that addresses ozone-depleting substances and their alternatives. Medical Information Search d. R-1234yf. Aspects on the development of HFO and HFO/HFC refrigerants. They have ozone depleting potentials, and have low global warming potentials. Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs), have which of the following in common? What synthetic lubricant is presently used with ternary blends containing HCFCs? Most of the chlorine from volcano's don't make it to the stratosphere. Refrigerants in the A3 safety group are highly flammable. Chemical reactions predict there should be HCFCs in the upper atmosphere. a. Methane R-1234yf is still rated as an A2L refrigerant from ASHRAE. They are no different than HFCs. Why are some hydrofluoroolefin (HFO) refrigerants classified as A. The distributor is selling section 608 certified refrigerant. In addition to fines and being required to appear in court, what penalty can be imposed on service technicians who violate Clean Air Act provisions? in kilograms because Canada had recently switched to the metric system; Previous: Why Are These Strawberries On My Nipples. xcos2(x2)dx\int x \cos ^ { 2 } \left( x ^ { 2 } \right) d xxcos2(x2)dx. Why are some of the hydrofluoroolefins classified as A2L? Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), and Hydrofluorocarbons (HFCs) have what in common. It's a strange heating spiral - in a warming world, we need more refrigeration to cool ourselves and our food, but the use of these cooling systems accelerates climate change, which in turn leads. The purchaser is or employs a Section 608 certified technician. Which refrigerant depletes the ozone layer, a. R-717 Like the ozone-depleting substances they replace, most HFCs are potent greenhouse gases with very high global warming potentials (GWPs). c. Mineral oils D. With the system isolated and the vacuum pump turned off. New A2L listings for AC applications. If the atmosphere has less than 4.4% methane, combustion cannot occur even if a source of ignition is present. As a consequence, the refrigeration sector is moving towards refrigerants with a low Global Warming Potential (GWP 100) in accordance with the limit fixed by these regulations (150).In this regard, the old refrigerant R152a attracts renewed interest due to its low GWP (138) and its . a. What characteristics of CFCs and HCFCs make them more likely to reach the stratosphere than most other compounds containing chlorine? There has been some concern from various companies that the HFO refrigerants have a much higher flammability rate than its HFC predecessors. They are less flammable than hydrocarbon refrigerants, but most are still mildly flammable. highly fluorinated toxic chemicals. There has been talk about bringing back Carbon Dioxide refrigerants but at this point no one really knows what the future holds. b. Non-ozone depleting and have low global warming potentials. c. fossilization. c. foreign manufacturers b. R-123 Accidental releases associated with timely repair of an appliance.B. Use of the ozone-depleting refrigerant, chlorofluorocarbon (CFC)-12, in new motor vehicle air conditioning (MVAC) systems ended in the mid-1990s in the United States. They are less flammable than hydrocarbon refrigerants, but most are still mildly flammable.C. Official websites use .gov b. Hydrogen, Chlorine, Ferrite, & Carbon What is the Montreal Protocol? Brief 2 green Cooling. These refrigerants are created by nature, not a chemical company, and are often referred to as natural refrigerants. Why are HFO refrigerants less flammable than hydrocarbon refrigerants? Which of the following is a HFC refrigerant? How should refrigerant blends be charged? Secure .gov websites use HTTPS Remove all remaining refrigerant, render the cylinder useless, and recycle the metal. . The use of CO2 in MVAC systems must adhere to the standard conditions identified in SAE Standard J639 (EPA 2012b). What are the characteristics of hyrofluoroolefins (HFOs)? Also, oil changes may be needed with R-32. b. solvent conversion a. The system is ready to be charged.B. R32 is not a new refrigerant. Brainscape helps you realize your greatest personal and professional ambitions through strong habits and hyper-efficient studying. High discharge temperatures can affect system performance and durability in hot climates. For connections with refrigerant containers for use in professional servicing, use fittings must be consistent with SAE J2844 (revised October 2011). The GreenChill Program Most common refrigerant used in MVAC systems since the 1990s, Potent greenhouse gas with a global warming potential that is 1,430 times that of CO. Use of HFC-134a in MVAC systems accounts for an estimated 24% of total global HFC consumption. A breakdown of their new refrigerants are shown below. c. Measurement of HCFCs in air samples from the stratosphere. They do not dissolve in water or easily break down in the atmosphere. a. R-600a and R-441A For an appliance that uses a CFC, HCFC,or HFC refrigerant, which of the following violates the prohibitionon venting?A. The world switches away from the harmful HFCs and over the HFOs and then DuPont/HoneyWell get to charge a arm and a leg and nobody can say a damn thing because everybody needs it. In Lack's study, the effect of weather on the size of the finchs beak is an example of Under the Section 608 "safe disposal requirements", who is responsible for ensuring that CFC, HCFC, and HFC refrigerant has been removed from household refrigerators before they are dispose of? Acceptable, subject to use conditions, for new passenger cars and light-duty trucks only (March 29, 2011, 76 FR 17488; March 26, 2012, 77 FR 17344), Mildly flammable (ASHRAE A2L), but can be used safely, Models using HFO-1234yf include: Cadillac XTS, Chevrolet Spark EV, BMW i3 and i8, Chrysler 200, Chrysler 300, Dodge Challenger, Dodge Charger, Dodge Dart, Dodge Durango, Jeep Cherokee, Jeep Wrangler, Ram 1500, Fiat 500 and 500L, Alfa Romeo 4C, Honda Fit EV, Tesla Model S, Range Rover, and Range Rover Sport. I say for now because weve been through this before. Given int[] list = {1, 2, -1}, can you invoke sort(list) using the sort method in Listing 19.4? They must be recovered before opening or disposing of appliances. They have ozone depleting potentials, and have low global warming potentials. From which of the following does the ozone layer protect the earth? The R-12 and R-22 CFCs contained high amounts of Chlorine and it was found that Chlorine damaged the O-Zone. a. industrial melanism. Interested in participating in our Sponsored Content section? Browse over 1 million classes created by top students, professors, publishers, and experts. An international treaty that addresses ozone-depleting substances and their alternatives.B. Which ashrae classification means Matching search results: Many CFC, HCFC, and HFC refrigerants originate from these two base molecules of ethane and methane. As a non-flammable, energy-efficient replacement for R-134a, Solstice N15 can be used immediately by chiller and heat pump manufacturers, where safety standards and buildings codes limit the use of A2L and A3 refrigerants. A B. The flight crew knew they needed to A test for ozone concentration, A. Ozone depletion in the stratosphere is what type of problem? In which component of a system does the refrigerant change from a high-pressure vapor to a high-pressure liquid? Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), and Hydrofluorocarbons (HFCs) have what in common. That is why that refrigerant is rated as a B2L from ASHRAE. All Rights Reserved BNP Media. d. R-290 and R-404A, What is one of the most serious results of damage to the stratospheric ozone layer? A key consideration for widespread acceptance of HFO refrigerants is the development of standards and codes for safe use of these mildly flammable A2L refrigerants. Ultimately, only natural refrigerants will be approved for new installations. c. The purchaser owns certified recovery and/or recycling equipment. Which of the following refrigerants contain chlorine? Which of the following refrigerants is an HFO? b. HFCs What is unique about an azeotropic refrigerant mixture? Two popular HFO refrigerants are HFO-1234yf and HFO-1234ze (See table 1 here). For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine (e.g. What is the state of refrigerant entering the compressor of a refrigeration system? Additionally, HFOs are either A1 or A2L refrigerants, meaning they are either non-flammable or mildly flammable. How about $90 for your 410A? HFO refrigerants are categorised as having zero ODP (Ozone Depletion Potential) and low GWP (Global Warming Potential) and so offer a more environmentally friendly alternative to CFCs, HCFCs and HFCs. The ambient temperature Maybe this real By closing this message or continuing to use our site, you agree to the use of cookies. How do the global warming potentials of isobutane (R-600a), propane (R-290), and R-441A compare to the GWPs of HFC-134a, R404A, and R-410A? MVAC refrigerants are listed as either acceptable subject to use conditions or unacceptable. Are you used to paying around $100 for your 134a cylinders? John Tomczyk is HVACR professor emeritus, Ferris State University, Big Rapids, Michigan, and coauthor of Refrigeration & Air Conditioning Technology, published by Cengage Learning. They are less flammable than hydrocarbon refrigerants, but most are still mildly flammable.C. David Boswell Reid was a pioneer of post occupancy evaluations, allowing MPs to feed back on their comfort levels during the development of the Palace of Westminster's Victorian ventilation system The ability of a substance to destroy ozone in the stratosphere. What temperature does this indicate? measure the onboard fuel only in liters, which they reported as 7682L7682 \mathrm{~L}7682L. Thus, to determine how much fuel was on board and how much additional fuel was needed, the flight crew asked the ground crew for the conversion factor from liters to kilograms of fuel. If you are in the EU youve already been dealing with them for years and if you are in the states get ready! could become flammable with air in case of a leakage and the following chart gives a graphical positioning of R-1234ze(E) versus other refrigerants in the 'chance of flame occurring' ranking: R-1234ze(E) needs 10 times more concentration and 250,000 times more energy than hydrocarbons to become flammable, only above 30C. They contain Fluorine. d. They are attracted to Ultraviolet radiation. Thus, Edition 7.0 of this standard should facilitate the use of A3 refrigerants with respect to Edition 6.0. Servicing of existing vehicles using HFC-134a with HFC-134a will not be impacted and will continue to be allowed. An example of a CFC refrigerant is: Which type of lubricants are HFO refrigerants miscible in? They have toxicity characteristics. What is the state of refrigerant entering the compressor of a refrigeration system? Which type of refrigerant has the highest ozone depletion potential (ODP)? B. Well, its just a little bit different with the new HFOs. Fluorine makes HFO refrigerants less flammable than hydrocarbon refrigerants, which are highly flammable. They have toxicity characteristics. Which type of refrigerant typically has the lowest global warming potential? B. Substitutes for R404A/R507A and R410A. d. The purchaser is or employs a Section 608 certified technician. the use of hydrocarbons as refrigerants. Non-ozone depleting and have low globalwarming potentials. In your answer, be sure to: identify two factors that could influence the nutrients that can pass from the mother to the fetus, identify the group of hormones that alter cell membrane receptors and explain how this alteration can affect cell function, state the role of the uterus in the development of the fetus and the placenta. Release of mixtures of nitrogen and refrigerant that result from adding nitrogen to a fully charged appliance to leak check the appliance. a. What are the characteristics of hydrofluoroolefins (HFOs)? Visit our updated, This website requires certain cookies to work and uses other cookies to help you have the best experience. They can have very high global warming potentials. Servicing existing R-22 systems.C. What type of synthetic oils are commonly used in new HFC systems and for retrofitting HCFC equipment to HFC refrigerants? How many liters did they ask to be added? Benefits of using this refrigerant: With a GWP of 292, Solstice N15 is 80% lower than R-134a and 50% lower than R-124. Release of de minimis quantities in the course of making good faith attempts to recapture andrecycle or safely dispose of refrigerant.B. You have to leak-check a unit which has a lost complete charge. d. They have ozone depleting potentials and have low global warming potentials. Uses for these three HC refrigerants include new stand-alone retail refrigerators. Self-contained breathing apparatus (SCBA) or leave the area is required. Historically almost all refrigerants were flammable. Policy. After the phase-out of a refrigerant, where will supplies of that refrigerant for equipment servicing come from? Any substitute for a Class I or Class II substance used in a chiller.D. Join The NEWS on Facebook, Twitter, and LinkedIn today! Refrigerant cylinders should be all of the following EXCEPT: a. be free of rust and damage Refrigerants classified as HFO currently on the market comprise: R1234yf, R1234ze and R1234zd. d. They contain carbon. . H2 Mod 4 03205-13 Leak Detection, Evacuation,, Zoning, Ductless, and variable refrigerant fl, Adv Adm - Part 2: Objects and Applications. . An international treaty that addresses ozone-depleting substances and their alternatives. d. The length of time a refrigerant stays in the atmosphere. HFO refrigerants are in the category A2L, which means they are considered to be low toxicity and a rated as being slightly flammable. Because of HFOs slight flammability, extensive studies have been conducted for its safety in automobiles, centrifugal chillers, and other stationary applications. Refrigerants emitted in a catastrophic failure of an appliance.D. What evidence demonstrates that chlorine in the stratosphere is primarily from man-made chemicals rather than from natural sources such as volcanoes? SNAP lists substitutes as acceptable, acceptable subject to use conditions or unacceptable. At uneven rates due to different vapor pressures. To contrast 'chemical' fluorocarbon refrigerants with so-called 'natural' refrigerants is at best disingenuous, and arguably dishonest. d. Ammonia. c. R-410A An ozone-depleting substance used in a household or commercial air conditioner.B. What does a Section 608 certification allow a technician to do? What is the state of refrigerant entering the compressor of a refrigeration system? HFOs are not soluble in mineral-oil or alkylbenzene lubricants. A disposable cylinder should be reduced to what pressure before scrapping? For an appliance that uses a CFC, HCFC, or HFC refrigerant, which of the following violates the prohibition on venting? b. Rewiring an external electrical circuit. d. R-502. c. The Approved ASHRAE List(AAL) What evidence demonstrates that chlorine in the stratosphere is primarily from man-made chemicals rather than from natural sources such as volcanos? a. HFC refrigerants contain which of the following? R134a alternatives. Copyright 2023. How do the global warming potentials of isobutane (R-600a), propane (R-290), and R-441 compare to the GWPs of HFC 134a, R404a, and R-410A? It has significant advantages over R-32, which has medium GWP, an A2 refrigerant safety rating, and high discharge temperatures. c. R-22 Well, R-134a was banned in the European Union a few years ago and now it is being pushed for voluntary phase out in the United States. The refrigerants are flammable for two big reasons: flashpoint and the vapor pressure of the fluid. c. Replacing a component. They are less flammable 4.The Professor's Lesson on HFO, HC Refrigerants - ACHR News Author: www.achrnews.com Post date: 12 yesterday Rating: 5 (1222 reviews) Highest rating: 4 Low rated: 1 Summary: 5. b. c. They contain fluorine. c. Samples or air taken from the stratosphere over erupting volcanos show that volcanos contribute a small quantity of chlorine to the stratosphere compared to CFCs and HCFCs b. Radon d. Energy Star. b. Rewiring an external electrical circuit. a. Non-ozone depleting and have a low global warming potentials. R32 is a major component of other refrigerants, making up 50% of the R410A blend and 23% of the R407C blend. Beginning in 2025, chillers will have to use a refrigerant with a GWP less than 750. Other applications include vending machines, fridges, beverage dispensers, air dryers, and carbon dioxide cascade systems in commercial refrigeration. HFO-1234yf is a low-GWP replacement for R-134a intended for use in mobile air conditioning (MAC) systems in the automotive industry. They are "synthetic chemicals," not "natural.". HFO-1234ze is intended to replace R-410A in residential and light commercial air conditioning and heat pump applications while offering a 75 percent reduction in GWP. They are prohibited for use in the u.s.D. Purchase or handle controlled refrigerants. B. R32 is a higher pressure gas compared to other refrigerants such as R22 and R410A and it requires a higher pressure 6.2MPa cylinder. Which element in a CFC or HCFC molecule causes ozone depletion? HFO-1234ze also offers excellent energy efficiency, is cost-effective, and can be used in existing equipment design with minimal changes. Phasing out the use of chlorofluorcarbons and hydrochloroflurocarbons. You can view their press release on the Honeywell website. Use of Flammable Refrigerants in the U.S. a. R-134a Depletion of this layer by ozone-depleting substances will lead to higher UVB levels (a band of ultraviolet radiation), which in turn will cause increased skin cancers and cataracts and potential damage to some marine organisms, plants, and plastics. Nuclear radiation from the Van Allen belt. b. Gamma radiation form the sun. a. R-410A Charging any new system designed for R-407C.D. It is important for both consumers and technicians to be aware of these alternative refrigerants, their properties, and proper servicing procedures. Retrofitting equipment containing HC refrigerants is not allowed in the U.S. Only authorized HC refrigerants on the compressor and systems nameplate may be used in each specific piece of equipment. A lock (LockA locked padlock) or https:// means youve safely connected to the .gov website. They contain chlorine which damages the ozone layer. Which of the following refrigerants is an HFO? HFO refrigerants contain at least one double bond (C=C), which is different from the traditional saturated halohydrocarbon refrigerants such as the chlorofluorocarbons (CFCs), hydrochlorofluorocarbon (HCFCs), and hydrofluorocarbons . Secondly, the majority of all the patents on HFOs, including 1234YF, are held by two companies DuPont and HoneyWell. Which of the following gases is used as the baseline measurement for global warming potential? HFCs were the alternative to the O-Zone damaged CFCs of the 20th century. d. All refrigerant lubricants. They cause excessive pressure drop and increased recovery time. Which refrigerant does not contain chlorine? For additional information, visit Choosing and Using a Retrofit Refrigerants for a CFC-12 Motor Vehicle Air Conditioner. Under SNAP, all flammable refrigerants, except HFC-152a and HFO-1234yf, are listed as unacceptable for use in new and retrofit MVAC systems. You must have JavaScript enabled to enjoy a limited number of articles over the next 30 days. Non-ozone depleting, and have high global warming potentials.B.