MOTOR VEHICLE AIR-CONDITIONING REFRIGERANT ALTERNATIVES
|
|
||||||||||||
| Overview: |
Alternative refrigerants for motor vehicle air conditioning systems have been identified to replace Chlorofluorocarbon-12 (CFC-12). CFC-12 was widely used in vehicle air conditioning systems for several decades, however it is an ozone-depleting substance and production was banned in December 1995. Ultimately, the CFC-12 production ban will force the conversion of all vehicle air conditioning systems from CFC-12 to an alternative refrigerant. In the interim, CFC-12 continues to be recycled to ensure that existing CFC-12 is used rather than being released into the atmosphere. EPA has proposed standards for the equipment that recovers and recycles CFC-12, as well as for alternative refrigerants. EPA’s Significant New Alternative Policy (SNAP) program was established in 1994 to review alternative refrigerants developed to replace ozone-depleting substances. Under authority of the Clean Air Act, EPA has determined that several refrigerants are acceptable for use as CFC-12 replacements in motor vehicles. The final rule implements provisions set forth in Section 609 of the Clean Air Act that require that automotive service technicians to recycle substitutes for ozone-depleting refrigerants that are used in the servicing of motor vehicle air conditioners (MVACs). This rule, the full text of which was published in the Federal Register on December 30, 1997at 62 FR 68025, also clarifies how the Act applies to some MVAC service practices. Under EPA’s SNAP rule, new refrigerants must be used in accordance with specific conditions including: 1) using unique fittings to prevent the accidental mixing of different refrigerants; 2) application of a detailed label giving specific information about the alternative; 3) removal of the original CFC-12 prior to charging the system with a new refrigerant; and 4) the installation of barrier hoses when applicable. The SNAP program does not determine whether the alternative will provide adequate performance or if it will be compatible with the air conditioning system components. There are several alternative refrigerants that have been reviewed by the SNAP program. Automakers have selected HFC-134a as the preferred alternative in new vehicles due to its performance and availability. HFC-134a has been tested and performance data is available. The other alternative refrigerants, which are blends, have not been widely tested. SNAP has reviewed a number of blends and deemed them acceptable; subject to fittings, labeling and that the alternative refrigerants are not used to "top off" existing refrigerant in a system. The alternative refrigerants include:
Currently, there are no substitutes that perform identically to CFC-12 or that can be blended with CFC-12. According to EPA, there are no "drop in" substitutes. In July of 1998, EPA proposed a new rule that would only allow certified technicians to purchase HFC-134a. This new rule would eliminate substitution mixing, which can severely damage equipment. Both OZ-12 (Hydrocarbon Blend A) and HC-12a (Hydrocarbon Blend B) were determined to be unacceptable substitute refrigerants because they lacked adequate risk assessment information that characterizes flammability risk. R-176 was determined to be unacceptable because it contained CFC-12. R-405A was deemed unacceptable because it contained a perfluorocarbon that exhibits extremely high global warming potential and a very long lifetime. Selection of an alternative may be based on a number of factors including: the type of vehicle, condition of the components, mileage, warranty, and even the climate in which the vehicle is operated. Conversion often requires air conditioning system flushing because refrigerant blends do not appear to be compatible with lubricants found in CFC-12 systems. Flushing can usually be accomplished after removing and recovering the existing refrigerant by simply draining the existing mineral oil, either from an oil drain plug or by removing the compressor, and draining from the suction line. In most automotive systems, 90 to 95 percent of the lubricant can be removed from the system in this manner. Equipment using HFC-134a requires synthetic oils such as polyalkylene glycol or polyol ester lubricating oils. HCFCs have ozone-depleting potential, and both HCFCs and HFCs are greenhouse gases that have global warming potential. EPA strongly recommends the containment and reclamation of these substitutes through closed-loop recovery systems to achieve the conservation of these refrigerants. The “no venting” regulation of the Clean Air Act Amendments, 58 FR 92, Section 608(c)(2), page 28,664 requires users to recover HFCs and other alternative (to CFCs) refrigerants when servicing equipment, effective 15 November 1995. Any motor vehicle air-conditioning system converted to an alternative, by law, must be evacuated and have its CFC-12 removed, recovered, and reused for servicing a vehicle not being converted. |
|||||||||||||||||||||||||||
| Compliance Benefit: |
Elimination of CFC-12 may help facilities meet the requirements under 40 CFR 82, Subpart D and Executive Order 12843 requiring federal agencies to maximize the use of safe alternatives to class I (i.e., CFC-12) and class II ozone depleting substances, to the maximum extent practicable. It should be noted that some of the alternatives for CFC-12 are HCFCs which are also ODSs. In addition, the substitution of CFC-12 at the facility decreases the possibility that the facility will meet reporting thresholds for CFC-12 under 40 CFR 355, 370 and EO 12856. Chemicals used as substitutions should be reviewed for SARA reporting issues. The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.
|
|||||||||||||||||||||||||||
| Materials Compatibility: |
HFC-134a and refrigerant blends do not appear to be compatible with the type of mineral oil lubricants found in existing CFC-12 refrigerant systems. For conversions, manufacturers typically recommend triple-flushing the lubricant from the system before charging with HFC-134a. Some blends may tolerate a higher proportion of mineral oil, since they contain two, or more, HCFCs, so triple flushing may not be necessary for some blend conversions.
|
|||||||||||||||||||||||||||
| Safety and Health: |
The SNAP-approved refrigerants for motor vehicle applications have been developed to minimize safety and health concerns. They are non-flammable under all expected working conditions and have low toxicity. Personal protective equipment is not mandatory, but when working with refrigerants, use of safety glasses or chemical splash goggles is always recommended. For more information on the safety and health aspects of these refrigerants, consult your local Industrial Health specialist, your local health and safety personnel, and the product MSDS prior to any refrigerant conversion.
|
|||||||||||||||||||||||||||
| Benefits: |
|
|||||||||||||||||||||||||||
| Disadvantages: |
|
|||||||||||||||||||||||||||
| Economic Analysis: |
Service technicians should consider several tradeoffs when selecting the new refrigerant. Consideration must be given to the condition of the vehicle’s air conditioning components, climate, quantity and type of testing of the HCFC blends, and cost of the refrigerant. Conversions of motor vehicle air conditioning systems now using CFC-12 to HFC-134a may be expensive if a complete conversion is required including replacement of the dryer, hoses, seals, refrigerant, and lubricant, and also flushing of the old lubricant. Although HFC-134a costs approximately $2.00 to $3.00 per pound, the cost of a complete HFC-134a conversion for a typical automobile CFC-12 system is estimated between $350 and $800. Some personnel claim that HCFC blends have less head pressure and require fewer component changes and some blends provide better performance than HFC-134a. As a result, the cost to retrofit using HCFC blends may cost as little as $100 to $200 depending on the vehicle. The HCFC blends cost $8.00 to $10.00 per pound. However, service technicians may want to consider other factors when deciding between HFC-134a and HCFC blends. These factors include:
The following economic analysis compares the costs associated with using CFC-12 versus HFC-134a. The analysis is based on information provided by a vehicle service shop in the southeastern U.S.: Assumptions:
Annual Operating Cost Comparison for CFC-12 and HFC-134a
Economic Analysis Summary
Capital Cost for Diversion Equipment/Process: N/A Payback Period for Investment in Equipment/Process: N/A Click Here to view an Active Spreadsheet for this Economic Analysis and Enter Your Own Values. |
|||||||||||||||||||||||||||
| Approving Authority: |
Approval is controlled locally and should be implemented only after engineering approval has been granted. Major claimant approval is not required.
|
|||||||||||||||||||||||||||
| NSN/MSDS: |
*There are multiple MSDSs for most NSNs. The MSDS (if shown above) is only meant to serve as an example.
|
|||||||||||||||||||||||||||
| Points of Contact: |
Air Force:
|
|||||||||||||||||||||||||||
| Vendors: |
Honeywell Elf Atochem N.A.,
Inc., Research and Applications Laboratory Intermagnetics General Refrigerant Gases People’s Welding
|
|||||||||||||||||||||||||||
| Sources: |
Mr. Michael Schleider, Robins Air Force Base, January
1999. |