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Tuesday, June 30, 2009

As Freon Substitutes in Vehicle Air-conditioning Systems

Flammable hydrocarbon mixtures are being marketed and sold as CFC-12 substitutes for vehicles. They may be present in the air-conditioning systems of some vehicles. These mixtures pose a new fire hazard to workers in repair garages. The flammable mixtures may also pose a fire hazard to passengers of vehicles if a substantial amount of the mixture leaks into the passenger compartment.

Chlorofluorocarbon (CFC) refrigerants continue to be phased out and replaced with substitutes that are considered more "environmentally friendly." CFC-12 or R-12 (also known as "Freon-12") was widely used in automobile and truck air-conditioning systems for more than 30 years. As of January 1, 1996, under the federal Ozone-Depleting Substances Regulations, the use, sale, import, or export of CFC-12 was prohibited in Canada unless the substance was imported or manufactured prior to that date. There are some exceptions for recovered, recycled, reclaimed and used CFC-12. Vehicles manufactured after January 1, 1996 must not have air-conditioning systems intended to contain CFC-12.

The Danger

Hydrocarbon mixtures that are being marketed as CFC-12 substitutes may contain propane, butane and/or other highly flammable gases.

There is a danger that these gases may leak from vehicle air-conditioning systems and accumulate to levels that could burn or explode if a source of ignition is present. Mechanics working on a vehicle's engine compartment may be at risk of burns and other injuries. Mechanics may not expect such a hazard because, traditionally, only non-flammable CFC refrigerants were used.

Existing vehicle systems have not been designed to contain flammable hydrocarbon refrigerants. These mixtures may degrade hoses or gaskets that have been designed for CFCs or fluorocarbons, making the air-conditioning system more likely to leak.

Many repair procedures involve the use of open flame or the production of sparks. For example, certain detection systems used to check air-conditioning systems use a flame as the means to detect leaks. Other sources of ignition may include starters, alternators and faulty spark plugs.

Leaked hydrocarbon refrigerants may enter the passenger compartment of a vehicle. There may be sufficient amounts of flammable hydrocarbon gases in these air-conditioning systems to produce explosive air concentrations within the passenger compartment. An open flame or a lit cigarette may be able to ignite such a mixture.

The Canadian Vehicle Manufacturers' Association (CVMA) and the Association of International Automobile Manufacturers of Canada (AIAMC) do not support or encourage the use of hydrocarbon blends as refrigerants in vehicle air-conditioning systems due to safety concerns; however, these products are not banned from use in Canada.

Employer OH&S Responsibilities

There are safer alternatives to flammable hydrocarbon refrigerants in vehicle air-conditioning systems. The potential health and safety risks of alternatives should be evaluated when choosing a substitute for CFC-12.

The product R-134a (1,1,1, 2-tetrafluoroethane, a hydrofluorocarbon or HFC) is non-flammable and has been widely used as a replacement for CFC-12 in new vehicles. It is also being used to replace CFC-12 in existing vehicles, after retrofitting.

Mechanics and other workers in vehicle repair shops may be expected to work on vehicles that contain a flammable hydrocarbon mixture in the air-conditioning system. Because the atmosphere of their work area may become potentially explosive if the refrigerant leaks from the air-conditioning system, the employer must develop and implement safe work and emergency procedures that include the following.

  • Ensure workers are informed of the potential hazards and are trained in the work and emergency procedures.
  • Check for a label on the engine compartment for a flammability warning for mechanics. Some, but not all, vehicles with hydrocarbon refrigerants will have this warning.
  • Ensure the work area is well ventilated.
  • Check for leaks of flammable hydrocarbon mixtures from air-conditioning systems before doing engine repairs that use or could generate an ignition source (sparks, an open flame). For example, a properly calibrated electronic hydrocarbon leak detector (provided that it does not rely on the use of a high heat or ignition source), soap bubbles or fluorescent dyes detectable by a black light can be used to detect such leaks. The accumulation of flammable gases can be monitored using a properly calibrated explosion meter.
  • The strong smell of an odourant contained in some refrigerants may provide warning of a leak of a flammable hydrocarbon, but this cannot be relied upon, as many mixtures are odourless.
  • Ensure potential sources of ignition are eliminated or controlled where a leak or accumulation of flammable gases is suspected or detected. This includes distant sources of ignition as the gases are heavier than air and can travel along the ground.
  • Ensure workers do not smoke while doing repairs on a vehicle unless they have confirmed that the system is not leaking or that the system does not contain a flammable hydrocarbon mixture.
  • Provide fire-fighting and other emergency response equipment and supplies.
  • Ensure Environment Canada's Environmental Code of Practice for Elimination of Fluorocarbon Emissions from Refrigeration and Air Conditioning Systems is followed if a flammable mixture must be used (i.e. where the use of a non-flammable substitute is not reasonably practicable).

This Code of Practice recommends that vehicle operators consider the following points before using flammable hydrocarbons and other blends as replacement refrigerants.

  • Confirm the compatibility of the product with hoses and gaskets prior to retrofitting. Manufacturers should be contacted for a written confirmation of the product's compatibility and safety.
  • Remove all refrigerant present in the air-conditioning system if a different type of refrigerant is being added. Refrigerants mixed in a system may not work and could damage the system.
  • Adjust the quantity of refrigerant being added to the air-conditioning system. The density of the hydrocarbon blend may be different, affecting proper operation of the system.
  • Verify that the refrigerant comes with an American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) number and identify if it is flammable (Check the label or Material Safety Data Sheet (MSDS)). Affix a label with this information on the engine compartment of the vehicle as a warning to service mechanics.
  • Check with the vehicle manufacturer or supplier of the air-conditioning system about the refrigerant's safety, compatibility and performance.
  • Recovery and recycling equipment and fittings should be suitable for the specific refrigerant being recovered. Recovery equipment fittings should be different than those used for R-12 or R-134a.

Check the product's hazard information on its MSDS and label. Ensure that safety precautions are followed.

For more information, contact the Canadian Vehicle Manufacturers' Association at (416) 364-9333, the Association of International Automobile Manufacturers of Canada at (416) 595-8251, ext. 33 or the Occupational Health and Safety Division.

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