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Refrigerants and refrigerant oil

Refrigerants and refrigerant oil. The clean air act of 1990. The Environmental Protection Agency [EPA] enforces regulations set in place by the clean air act governing the repair and service of automotive air conditioning systems.

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Refrigerants and refrigerant oil

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  1. Refrigerants and refrigerant oil

  2. The clean air act of 1990 • The Environmental Protection Agency [EPA] enforces regulations set in place by the clean air act governing the repair and service of automotive air conditioning systems. • Fines and prison terms have been imposed on technicians who have violated EPA rules on vent refrigerants into the atmosphere. • The EPA monetarily rewards whistle blowers for information leading to prosecution of violators.

  3. Technician certification • EPA section 609 states: All persons repairing or servicing motor vehicle air-conditioning (MVAC) systems for consideration [being paid for it] must be properly trained and certified by a program authorized by EPA. • Refrigerant handlers certification is done through ASE, MACS [Mobile Air Conditioning Society] and other institution • Currently certification is required for the purchase of R-12 but not for R-134a

  4. Refrigerant properties • A good refrigerant needs to be: • Low boiling point – well below 0 deg. F at atmospheric pressure • High boiling point at pressures above 200 psi • Non toxic • Non flammable • Compatibility with refrigerant oil • Must be compatible with the rubber hoses and seals usedin the A/C system • Have little or no effect on the environment • Inexpensive

  5. Refrigerant properties • Ammonia is often used as a commercial refrigerant but cannot be used in automobiles due to it’s high toxicity. • The ammonia we see in household cleaners is extremely dilute – about 1% by volume. • Inhaling the fumes from concentrated ammonia can be fatal. • Propane is an excellent refrigerant, but imagine what would happen if you were in a front end collision in a car that used propane as a refrigerant.

  6. Chlorofluorocarbons - CFCs • Automotive air conditioning systems installed on cars built before 1990 used refrigerant compounds made from: • Chlorine • Fluorine • Carbon • Hydrogen • Chemicals containing these elements are known as CFCs • R-12 was used on most cars prior to 1993. • R-12 is dichlorodifluoromethane [CCL2F2] • R-12 was marketed by DuPont under the trade name ‘Freon’

  7. CFCs and the environment • In the 1980s it was determined that CFCs that were released into the atmosphere were destroying the ozone layer. • Ozone is a form of oxygen [O3] that is present in the upper stratosphere at 20 to 30 miles above the earth’s surface. • The ozone layer absorbs UV [ultra violet] radiation. • UV radiation in small doses causes sunburn and skin cancer. • If the ozone layer was to be totally destroyed all land base life on earth would be at risk.

  8. CFCs and the environment • Research in the 1980s revealed that it was the chlorine in CFCs that was damaging the ozone layer. • As a result of the Montreal protocol of 1990 CFCs were phased out and replaced by HFCs [Hydrogen-fluorine-carbon] . • The EPA at this time implemented rules requiring reclamation and recycling of refrigerants and began requiring the technicians who service auto A/C systems to be licensed in refrigerant recovery and handling.

  9. R-12 • R-12 was used on all automotive A/C systems on vehicles built prior to 1990. • The world wide production of R-12 has been banned but bootleg R-12 from Asia is still widely available. • Recycled R-12 is also widely available • Only licensed A/C technicians can purchase R-12 • R-12 is the best option for keeping the A/C system in an older car running. • R-12 boils at -21 deg F. • At 30 psi R-12 boils at 32 deg F.

  10. R-134a • R-134a replace R-12 in the early 1990s. • It contains no chlorine so it will not harm the ozone layer but it is also a greenhouse gas. • The SAE is currently evaluating possible replacements for RE-134a but the auto industry has not yet made a decision on what it will be. • R-134a boils at -26 deg F when exposed to atmospheric pressure. • At 27 psi R-134a will boil at 32 deg F.

  11. Retrofits • In the late 1990s the cost of R-12 skyrocketed to over $30 a pound. • Most vehicles built for R-12 were retrofitted to use R-134a or alternatives when their A/C systems needed service. • Retrofitting to R-134a involved changing the service fittings and adding POE refrigerant oil that was compatible with the new refrigerant. • A retrofit label that lists the type of refrigerant should have been installed at the time of retrofit.

  12. Blended refrigerant • Some refrigerants are a mix of two or more chemicals. • Since two chemicals have two different boiling points as refrigerant is lost slowly over time the chemical with the higher boiling point is lost at a faster rate. • Blends were commonly used in retrofits in the 1900s and early 2000s. • R-22 is a blend that was used in stationary A/C systems and sometimes found in some retrofit systems. It is not compatible with the rubber used in most automotive A/C systems and should never be used as an automotive refrigerant.

  13. Future refrigerants • Two refrigerants that are often mentioned as possible replacements for R-134a are: • R-152a • CO2 [Carbon Dioxide] • R-152a has all the properties of an excellent refrigerant except that it is toxic • The system would have to locate the evaporator outside the cabin to utilize R-152a • CO2 is an excellent refrigerant but needs to be compressed to very high pressures [over 700 psi]

  14. Refrigerant containers • Refrigerant is sold in 30 lbs. disposable tanks and 12 oz. cans. • Refrigerant tanks are color coded. • R-12 is white • R-134a is light blue • Refrigerant tanks for R-12 have a 7/16” x 20 conventional threaded fitting for hose attachment. • Refrigerant tanks for R-134a have a ½” x 16 Acme thread fitting for the hose connection.

  15. Refrigerant oil • The bearings and rings in the compressor and the expansion valve require a continuous supply of lubrication oil. • A few ounces of oil circulate with the refrigerant and keep all of the mechanical components well lubricated. • The oil must have a low viscosity to prevent it from turning into wax and blocking the orifice/expansion valve where temperatures will be around 32 deg. F.

  16. Mineral oil • R-12 systems used a mineral oil type lubricant. • Mineral cannot be used in R-134a systems • It will congeal at the bottom of the condenser and evaporator blocking the flow of refrigerant. • Normally light yellow color • Available in 500 or 525 viscosity • Slightly hygroscopic – like brake fluid it absorbs water

  17. PAG • Polyalkylene glycol • Synthetic oil chemically similar to antifreeze • Developed for R-134a systems • Light blue color • Available in 3 viscosities 46, 100 and 150 • Most late model cars that use Asian compress require PAG 46 • Older domestic compressors normally require PAG 150 • Highly hygroscopic – avoid skin contact

  18. Ester - POE • Polyol Ester [POE] is compatible with both R-12 and R-134a so it was used in most retrofits • Clear color – no tint • Slightly hygroscopic • Although it is marketed as a universal oil it should not be used in R-134a systems as PAG is a much better lubricant

  19. A/C system placard • By law new vehicle must have an A/C system placard under the hood that lists: • The type of refrigerant used • The volume of refrigerant needed to fully charge the system • Normally the type and amount of refrigerant oil is also displayed • The placard color for R-134a systems should be gold and yellow

  20. Refrigerant identification • When servicing new cars the type of refrigerant is stated on the A/C system placard under the hood. • When working on and older car the refrigerant listed on the placard may not be what was originally used when the car was built. • Refrigerant identifier machines are available that can chemically analyze the refrigerant currently in the system so that proper recovery can be done.

  21. Desiccants • Desiccants are chemicals that absorb moisture. • A porous bag of desiccant material is installed inside the accumulator or receiver drier to absorb any moisture that may find it’s way into the system. • Water in the system can freeze and block the orifice so that no cooling occurs. • Water also reacts with refrigerant to form acid that corrodes metal parts. • The receiver/drier or accumulator are normally replaced anytime a component is replaced in the system.

  22. UV leak detector dyes • The source of small A/C system leaks are normally detected by adding a dye to the refrigerant and inspecting the system using a UV light source. • The dye glows yellow/green when illuminated by UV light. • Dye can be introduce into the system with a small can of refrigerant mixed with dye, adding liquid dye concentrate to the refrigerant during a recharge or with a special syringe.

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