The Problem with CFC’s
By: Joubert Arthur
Since chlorofluorocarbons (CFCs) were developed in the 1930s, they have been widely used as air conditioner (A/C) and refrigerator coolants, aerosol can propellants, electronic parts cleaners, and foam blowing agents. CFC-12 (also called Freon or R-12) has been the coolant most frequently used in automobile A/C systems and accounted for 20 percent of all U.S. CFC consumption in 1992. CFCs have been useful in many applications because they are non flammable, non toxic and extremely stable in the environment.
Unfortunately, as stable CFC molecules rise into the stratosphere they are split by the sun's ultraviolet radiation. As chlorine molecules react with and split ozone molecules, they deplete the ozone layer, which is situated 10 to 30 miles above the Earth's surface. The ozone layer protects biological life from the sun's harmful ultraviolet radiation, which can cause skin cancer and eye cataracts and suppress the body's immune system. CFCs have also been identified as greenhouse gases, i.e. contributors to global warming.
The threat of CFCs to the ozone layer was considered so serious that an international treaty, the 1987 Montreal Protocol, was developed to phase out production and use of CFCs and most other ozone damaging chemicals by the year 2000. To date, 150 nations representing over 95 percent of the world's CFC consumption have signed this treaty.
The majority of automobiles manufactured prior to 1994 use Freon in their A/C systems. Since that time, several non-CFC refrigerants such as hydrofluorocarbons (HFCs) have been developed; and many more are in the development process. Since 1995, the most common substitute for CFCs in automobile A/C systems is HFC-134a (or R-134a). Unlike CFCs, HFCs contain no chlorine and do not harm the ozone layer; however, they are considered greenhouse gases.
Hydro chlorofluorocarbons (HCFCs) are also used as CFC-12 substitutes in A/C systems. HCFCs do contain chlorine but their ozone depletion capability is significantly less than CFCs. However, under the Montreal Protocol, HCFC production is scheduled to be banned by the year 2030.
In response to the global environmental problems caused by CFCs, HCFCs, and HFCs, the U.S. Environmental Protection Agency (EPA) has implemented comprehensive regulations governing their use.
Pollution Prevention Tips
General Operating Procedures
All Montreal Protocol participant countries ceased Freon production by January 1996. As supplies of stockpiled and recycled Freon decrease, the cost is increasing markedly. Proper collection and efficient recycling are not only incentives to prevent losses of Freon to the atmosphere, these pollution prevention measures also will also ensure rapid payback on recycling equipment.
The following practices should be adopted at all A/C service facilities:
Leaks: Detect refrigerant leaks with a simple visual inspection of the hoses, connections, and condenser. Visible oil leaks usually indicate a leak in the system. A leaking A/C system can also be detected by draining the refrigerant from the system and then monitoring its ability to hold a vacuum: pressure loss indicates a leak. Electronic sniffers can also be used for leak detection. Fluorescent leak detection systems are available but many compressor manufacturers advise against their use due to the abrasive nature of the dye particles. Use of flame detection systems is strongly discouraged as lethal phosgene gas (mustard gas), can be produced when CFC-12 comes in contact with an open flame. Also, avoid using leak detection products containing Freon.
Maintenance and Repair: Evacuate all refrigerant prior to A/C maintenance or repair. Make it a policy to encourage customers to have leaking A/C systems repaired rather than topped off with refrigerant. However, leak repair is not required under federal law.
Manifold Hoses: To prevent leakage, manifold hoses must have shut off valves within 12 inches of the ends of each line.
Cross Contamination: Avoid cross contamination of refrigerants. Cross contamination often occurs when the A/C system has been partially charged with a refrigerant other than the type designated on the system information label. A cross-contaminated A/C system will suffer reduced performance, damage from chemical breakdown, and lubrication problems. Additionally, a cross-contaminated system connected to recovery/ recycling equipment can foul components such as filters and dryers, which will have to be replaced. The cross-contaminated refrigerant can also be passed from contaminated recovery/recycling equipment to systems in other automobiles. Be wary of complex automobile A/C service histories and makeshift or damaged fittings which may indicate cross contamination. Another consideration is that since all cross-contaminated refrigerant must be sent to a refrigerant recycling facility for separation and purification, operating costs will increase.
Retrofitting : When an older A/C system is retrofitted, it is critical to evacuate the old refrigerant to avoid cross contamination for the reasons discussed above. HFCs (such as R-134a) or blends using HFCs are not compatible with mineral oil lubricants found in CFC-12 refrigerant systems. As existing A/C systems age and CFC-12 supplies become scarce and more expensive, the demand for conversion or retrofit to non-CFC refrigerants will increase. The entire conversion process involves replacing the dryer, hoses, seals, refrigerant, and lubricant as well as flushing of the old lubricant. EPA estimates the retrofitting process should cost between $100 and $800 depending on the make and model of the car. A basic retrofit involving a change to a non-CFC refrigerant is estimated to cost approximately $200.
For conversion to R-134a, some manufacturers recommend that the existing lubricant be triple-flushed from the system before it is charged with the new coolant. Flushing can usually be accomplished after the existing mineral oil is recovered and removed through an oil drain plug or from the suction line after the compressor is removed. Typically 90 to 95 percent of the lubricant is removed by this method. For best results, check with the vehicle manufacturer for specific retrofit guidelines and the availability of retrofit kits. Conditions for CFC replacements generally require specific labeling and unique fittings for different refrigerant types to prevent cross-contamination. Also, for refrigerants containing HCFC-22, barrier hoses are required between the system components.
Recharging: When recharging, do not use small (12-ounce) disposable containers of refrigerant but instead buy bulk containers, e.g., 30-pound containers. Since the cans cannot be reused and are not equipped with a shut off valve, any unused refrigerant remaining in the can will be lost to the atmosphere. Also, bulk purchases are less expensive.
Approved Containers: To avoid leakage of stored refrigerants, use only DOT- or UL-approved containers. Refrigerants should never be collected, salvaged, or stored in unapproved containers.
Labeling: To avoid cross-contamination, label containers to indicate the type of refrigerant stored. Segregate any contaminated refrigerant and store it for purification in a specifically labeled container.
Alternative Refrigerants
EPA's Significant New Alternatives Policy (SNAP) evaluates new alternate refrigerants for their ozone-depleting, global warming, flammability, and toxicity characteristics. When considering an alternate refrigerant, users should make sure it is both authorized under EPA environmental regulations and acceptable to the manufacturer of the vehicle. Some refrigerants, banned by EPA, are still on the market. In July 1996, the Independent Garage Owners of North Carolina reported HC-12a was being marketed as an alternative automotive refrigerant to some of its members. The refrigerant HC-12a is banned by EPA because it has a high flammability and creates an explosion risk when used in or around cars. Furthermore, a car containing an unauthorized refrigerant can contaminate the entire air conditioning recovery/recycling system in a garage. There are also legal penalties for using unauthorized refrigerant. Any garage or private citizen using unauthorized air conditioning refrigerant is subject to fines of up to $25,000 and imprisonment. EPA's list of authorized (legal) and unauthorized (illegal) CFC refrigerant alternatives can be obtained from the SOPH.
At this time, five alternate refrigerants have been approved for use by EPA. For a list of these refrigerants and conditions of use, call the EPA SOPH and request the fact sheet, "Choosing and Using Alternative Refrigerants for Motor Vehicle Air Conditioning."
Regulations Pertaining to HFC Usage
It is illegal to vent HFCs to the atmosphere. These chemicals must be collected during servicing.
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