Refrigerants


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Selected Refrigerant Data



 BP Degrees Formula Color Toxicity Flammability Comment
R11 75F CCl3F Orange A=Not Toxic 1=Not Flammable -
R12 -21.6F CCl2F2 White A=Not Toxic 1=Not Flammable TXV has yellow top
R22 -41F CHClF2 Lt. Green A=Not Toxic 1=Not Flammable -
R134A -15F CF3CH2F Lt. Sky Blue A=Not Toxic 1=Not Flammable -
R410A -61F Blend Rose A=Not Toxic 1=Not Flammable AZ-20
R717 -28.2F NH3 Silver B=Toxic 2=Flammable Ammomia
R718 212F H2O Clear A=Not Toxic 1=Not Flammable Water


Classes of Refrigerants


Toxicity Flammability

The 3 R's of HVAC

  1. Recover - Remove refrigerant without filtering and store in an approved EPA container
  2. Recycle - Remove refrigerant, filter for nositure, oil and debris, then store in an approved EPA container
  3. Reclaim - Remove refrigerant, send to processing facility, where it is chemically tested and reprocessed in accordance with ARI-700


Phosgene

Definitions


  1. Alkyl Benzene Oil - A synthetic refrigeration oil commonly known as Zerol.
  2. Alternative Refrigerant - any of a number of refrigerants or refrigerant mixtures designed to replace the current CFC or HCFC refrigerants.
  3. Azeotrope - A mixture made up of two or more refrigerants with similar boiling points that act as a single fluid. The components of azeotropic mixtures will not separate under normal operating conditions and can be charged as a vapor or liquid.
  4. CFC Refrigerant - CFC refers to the chemical composition of the refrigerant. ChloroFluoroCarbon indicates that the refrigerant is comprised of Chlorine, Fluorine, and Carbon. Common CFC refrigerants are R11, 12,13,113,114, and 115.
  5. Drop-In Replacement - An alternative refrigerant that can be installed directly into an existing system with minor equipment changes. Most interim alternatives fall into this category.
  6. Ester Oil - A general term that applies to a family of synthetic refrigeration oils based on the chemistry of polyol esters. Ester oils are generally regarded as the oil to use with most of the alternative refrigerants. Ester oils are generally compatible with existing mineral oils, and system components. Ester oils are slightly hygroscopic and should be in non-porous containers.
  7. Forane - Atochem trade name for alternative refrigerants.
  8. Global Warming Potential - Global warming occurs when solar energy penetrates the atmosphere and the resultant infrared energy from the earth's surface is absorbed by certain gases and not allowed to leave. This process is commonly known as the greenhouse effect. Refrigerants are normally rated on a scale from 1 to 10.
  9. HCFC Refrigerant - HCFC refers to the chemical composition of the refrigerant. HydroChloro-Fluoro-Carbon indicates that the refrigerant is comprised of Hydrogen, Chlorine, Fluorine, and Carbon. Common HCFC refrigerants are R22.
  10. HFC Refrigerant - HFC refers to the chemical composition of the refrigerant. HydroFluoroCarbon indicates that the refrigerant is comprised of Hydrogen, Fluorine, and Carbon. Common HFC refrigerants are R134a.
  11. High Pressure Refrigerants (HP) - A term used for some alternative refrigerants designed to operate in the low temperature (-35° F to 0° F) range.
  12. Hygroscopic - A tendency for refrigeration oils to absorb moisture from the atmosphere.
  13. Interim Replacements (SHORT TERM) - Any of a number of refrigerants intended to serve as an intermediate solution during the transition from CFC to HFC refrigerants. Most interim replacements contain HCFC refrigerants like R22.
  14. Klea - I.C.I. Company trade name for alternative refrigerants.
  15. Long Term Replacements - Alternative refrigerants that are considered to have no adverse affect on the stratospheric ozone layer. Most long term replacements are HFC compounds.
  16. Medium Pressure Refrigerant (MP) - A term used for some alternative refrigerants designed to operate in the medium temperature (0° F to 4° F) range.
  17. Mineral Oil - Refrigeration oil currently in use but is not compatible with most of the alternative refrigerants. Refrigerant conversions often require. a procedure for the removal of existing mineral oil because of the incompatibility with alternative refrigerants.
  18. Near Azeotrope - A mixture made up of two or more refrigerants with different boiling points that, when in a totally liquid or vapor state, act as one component. However, when changing from vapor to liquid or liquid to vapor, the individual refrigerants -evaporate or condense at different temperatures. Near-azeotropic mixtures have a temperature glide (see below) of less than 10° F and should be charged in the liquid state to assure proper mixture (non-azeotropic) composition.
  19. Ozone Depletion Potential (ODP) - This is a relative indication of the effect of the chlorine in CFC's on breaking down the ozone layer. It is measured on a scale from 0 to 1 with 0 being non-depleting and 1 being the highest depleting.
  20. P.A.G. Oil - A general term that applies to a family of synthetic oils based on the chemistry of Polyalkyline Glycols. The primary application of P.A.G. oils will be for automotive air conditioning.
  21. Refrigerant - is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a gas to a liquid. Traditionally, fluorocarbons, especially chlorofluorocarbons were used as refrigerants, but they are being phased out because of their ozone depletion effects. Other common refrigerants used in various applications are ammonia, sulfur dioxide, and non-halogenated hydrocarbons such as methane.
  22. Suva - DuPont Company trade name for alternative refrigerants, replaces the Freon trade name.
  23. Temperature Glide - the temperature difference that occurs between the vapor state and liquid state during evaporation or condensation at constant pressure, i.e. the temperature in the evaporator and condenser is not constant. Temperature glide occurs in near-azeotropic and zeotropic mixtures.
  24. Zeotrope - A mixture made up of two or more refrigerants with different boiling points. Zeotropic mixtures are similar to near-azeotropic mixtures with the exception of having a temperature glide greater than 10° F. Zeotropic mixtures should be charged in the liquid state.

Refrigerant Cylinders
Link For Refrigerant DataSheets

Physical Properties


The ideal refrigerant:
  1. has good thermodynamic properties:

    • a boiling point somewhat below the target temperature
    • a high heat of vaporization
    • a moderate density in liquid form
    • a relatively high density in gaseous form
    • a high critical temperature
  2. is chemically unreactive
  3. is safe
Since boiling point and gas density are affected by pressure, refrigerants may be made more suitable for a particular application by choice of operating pressure. These properties are ideally met by the chlorofluorocarbons. Corrosion properties are a matter of materials compatibility with the compressor, piping, evaporator, and condenser. Safety considerations include toxicity and flammability.

History


Until concerns about depletion of the ozone layer arose in the 1980s, the most widely used refrigerants were the halomethanes R-12 and R-22, with R-12 being more common in automotive air conditioning and small refrigerators, and R-22 being used for residential and light commercial air conditioning, refrigerators, and freezers. Some very early systems used R-11 because its relatively high boiling point allows low-pressure systems to be constructed, reducing the mechanical strength required for components. New production of R-12 ceased in the United States in 1995, and R-22 is to be phased out by 2020. R-134a and certain blends are now replacing chlorinated compounds. One popular 50/50 blend of R-32 and R-125 now being increasingly substituted for R-22 is R-410A, often marketed under the trade name Puron. Another popular blend of R-32, R-125, and R-134a with a higher critical temperature, and lower GWP than R-410A is R-407C. While the R-22 and other ozone depleting refrigerants are being phased out, they still have value and can be sold but not manufactured.

Following the ban on chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), substances used as substitute refrigerants such as fluorocarbons (FCs) and hydrofluorocarbons (HFCs) have also come under criticism. They are currently subject to prohibition discussions on account of their harmful effect on the climate. In 1997, FCs and HFCs were included in the Kyoto Protocol to the Framework Convention on Climate Change. In 2006, the EU adopted a Regulation on fluorinated greenhouse gases, which makes stipulations regarding the use of FCs and HFCs with the intention of reducing their emissions. The provisions do not affect climate-neutral natural refrigerants.

Early mechanical refrigeration systems employed sulfur dioxide gas or anhydrous ammonia, with small home refrigerators primarily using sulfur dioxide gas. Being toxic, sulfur dioxide rapidly disappeared from the market with the introduction of CFCs. Ammonia (R717) has been used in industrial refrigeration plants for more than 130 years and is deemed to be environment-friendly, economical, and energy-efficient. The natural refrigerant carbon dioxide (R744) has a similarly long tradition in refrigeration technology.

Occasionally, one may encounter older machines which used other transitional refrigerants such as methyl formate, chloromethane, or dichloromethane (called carrene in the trade). Perhaps the most common of these to still retain a charge are the methyl formate Monitor Top refrigerators produced by General Electric.

Use of highly purified propane as a refrigerant is gaining favor, especially in systems designed for R-22. Moreover, propane is non-toxic. An odorant, such as ethyl mercaptan, can be added in trace amounts to alert persons of system leaks.

Uses


Natural refrigerants such as ammonia, carbon dioxide and non-halogenated hydrocarbons preserve the ozone layer and have no (ammonia) or only a low (carbon dioxide, hydrocarbons) global warming potential. They are used in air-conditioning systems for buildings, in sport and leisure facilities, in the chemical/pharmaceutical industry, in the automotive industry and above all in the food industry (production, storage, retailing). New applications are opening up for natural refrigerants for example in vehicle air-conditioning.

Emissions from automotive air-conditioning are a growing concern because of their impact on climate change. From 2011 on, the European Union will phase out refrigerants with a global warming potential (GWP) of more than 150 in automotive air conditioning (GWP = 100 year warming potential of one kilogram of a gas relative to one kilogram of CO2). This will ban potent greenhouse gases such as the refrigerant HFC-134a—which has a GWP of 1410—to promote safe and energy-efficient refrigerants. One of the most promising alternatives is the natural refrigerant CO2 (R-744). Carbon dioxide is non-flammable, non-ozone depleting, has a global warming potential of 1, but is toxic and potentially lethal in concentrations above 5% by volume. R-744 can be used as a working fluid in climate control systems for cars, residential air conditioning, hot water pumps, commercial refrigeration, and vending machines. R12 is compatible with mineral oil, while R134a is compatible with synthetic oil. GM has announced that it will start using HFO-1234yf in all of its brands by 2013. Hydrofluoro olefin (HFO)-1234yf, which is considered to have the highest potential for replacing R-134a. This new refrigerant has a GWP rating of 4 and is not a blend. Dimethyl ether (DME) is also gaining popularity as a refrigerant.

Some refrigerants, such as tetrafluoroethane, are seeing rising use as recreational drugs, leading to an extremely dangerous phenomenon known as inhalant abuse.

Disposal


As of July 1, 1992 it is illegal to release refrigerants into the atmosphere (intentional or accidental) because they can cause severe damage to the ozone layer. When CFCs are removed they should be recycled to clean out any contaminants and return it to a usable condition. Refrigerants should never be mixed together. Some CFCs must be managed as hazardous waste even if recycled, and special precautions are required for their transport, depending on the legislation of the country's government.

Refrigerants by class

Refrigerants may be divided into three classes according to their manner of absorption or extraction of heat from the substances to be refrigerated:

  • Class 1: This class includes refrigerants that cool by phase change (typically boiling), using the refrigerant's latent heat.
  • Class 2: These refrigerants cool by temperature change or 'sensible heat', the quantity of heat being the specific heat capacity x the temperature change. They are air, calcium chloride brine, sodium chloride brine, alcohol, and similar nonfreezing solutions. The purpose of Class 2 refrigerants is to receive a reduction of temperature from Class 1 refrigerants and convey this lower temperature to the area to be air-conditioned.
  • Class 3: This group consists of solutions that contain absorbed vapors of liquefiable agents or refrigerating media. These solutions function by nature of their ability to carry liquefiable vapors, which produce a cooling effect by the absorption of their heat of solution. They can also be classified into many categories.
Main article: List of refrigerants

The R-# numbering system was developed by DuPont and systematically identifies the molecular structure of refrigerants made with a single halogenated hydrocarbon. The meaning of the codes is as follows:

  • Adding 90 to the number gives three digits which stands for the number of carbon, hydrogen and fluorine atoms, respectively.
  • Remaining bonds not accounted for are occupied by chlorine atoms.
  • A suffix of a lower-case letter a, b, or c indicates increasingly unsymmetrical isomers.
  • As a special case, the R-400 series is made up of zeotropic blends (those where the boiling point of constituent compounds differs enough to lead to changes in relative concentration because of fractional distillation) and the R-500 series is made up of so-called azeotropic blends. The rightmost digit is assigned arbitrarily by ASHRAE, an industry organization.

For example, R-134a has 4 fluorine atoms, 2 hydrogen atoms, 2 carbon atoms, with an empirical formula of tetrafluoroethane. The "a" suffix indicates that the isomer is unbalanced by one atom, giving 1,1,1,2-Tetrafluoroethane. R-134 (without the "a" suffix) would have a molecular structure of 1,1,2,2-Tetrafluoroethane—a compound not especially effective as a refrigerant.

The same numbers are used with an R- prefix for generic refrigerants, with a "Propellant" prefix (e.g., "Propellant 12") for the same chemical used as a propellant for an aerosol spray, and with trade names for the compounds, such as "Freon 12". Recently, a practice of using HFC- hydrofluorocarbons, CFC- for chlorofluorocarbons, and HCFC- for hydrochlorofluorocarbons has arisen, because of the regulatory differences among these groups.

Blends

  • R-401A is an HCFC azeotropic blend of R-32, R-152a, and R-124. It is designed as a replacement for R-12.
  • R-404A is a "nearly azeotropic" blend of 52% R-143a, 44% R-125, and 4% R-134a. It is designed as a replacement of R-22 and R-502 CFC. Its boiling point at normal pressure is -46.5 °C, its liquid density is 0.485 g/cm.
  • R-406A is a zeotropic blend of 55% R-22, 4% R-600a, and 41%.
  • R-407A is a HFC zeotropic blend of 20% R-32, 40% R-125, and 40% R-134a.
  • R-407C is a zeotropic hydrofluorocarbon blend of R-32, R-125, and R-134a. The R-32 serves to provide the heat capacity, R-125 decreases flammability, R-134a reduces pressure.
  • R-408A is a zeotropic HCFC blend of R-22, R-125, and R-143a. It is a substitute for R-502. Its boiling point is -44.4 °C.
  • R-409A is a zeotropic HCFC blend of R-22, R-124, and R-142b. Its boiling point is -35.3 °C. Its critical temperatiure is 109.4 °C.
  • R-410A is a near-azeotropic blend of R-32 and R-125. The US Environmental Protection Agency recognizes it as an acceptable substitute for R-22 in household and light commercial air conditioning systems. It appears to have gained widespread market acceptance under several trade names.
  • R-500 is an azeotropic blend of 73.8% R-12 and 26.2% of R-152a.
  • R-502 is an azeotropic blend of R-22 and R-115.

Air as a Refrigerant

Air cycle is not a new technology. At the turn of the century air cycle or 'cold air machines' were available from companies such as J & E Hall... These were used on board ships and by food producers and retailers to provide cooling for their food stores.


Air has been used for residential, automobile, and turbine-powered aircraft air-conditioning and/or cooling. The reason why air is not more widely used as a general-purpose refrigerant is the misperception that the use of air is too inefficient to be practical.

Yet, with suitable compression and expansion technology, air can be a practical (albeit not the most efficient) refrigerant, free of the possibility of environmental contamination or damage, and almost completely harmless to plants and animals.