Refrigerants




Refrigerants are fluids used in the commercial HVAC field to transfer heat from one source to another. For example, in a water cooled chiller, refrigerant is used to remove heat from chilled water and transfer heat to condenser water. Or in a typical residential split air conditioner system, refrigerant is used to remove heat from the indoor air and transfer that heat to the outdoors through the use of a condenser.

The main requirement for a fluid to be classified as a refrigerant is the ability to transfer heat. Refrigerants must also be safe in order to be used for commercial and residential air conditioning purposes. Refrigerants are classified by the following information: (1) Flammability, (2) Toxicity, (3) Global Warming Potential (GWP), (4) Ozone Depleting Potential (ODP) and (5) Operating Pressure. The flammability and toxicity classifications are shown in ASHRAE 15. Be familiar with ASHRAE 15

Refrigerants can be split into four different types, (1) Hydrocarbons, (2) Chlorofluorocarbons, (3) Hydroclurofluorocarbons and (4) Hydrofluorocarbons.

Summary of Refrigerants for the Mechanical PE Exam

Ozone Depleting Potential [ODP]: The ODP is an index developed to identify how damaging a substance is to the ozone. The reference point from which all substances are compared is CFC-11. CFC-11 is assumed to have an ODP of 1, more damaging chemicals have a higher ODP and less damaging chemicals have a lower ODP. A summary of chemicals and their ODP is shown in the table below. Refrigerants with chlorine have a higher ODP. It is estimated that each chlorine atom destroys 100,000 ozone molecules.

Summary of ODP of Refrigerants for the Mechanical PE Exam

Global Warming Potential [GWP]: The GWP is an index developed to identify the potential for a substance to prevent infrared radiation from leaving the earth's atmosphere. The reference point, from which all substances are compared, is carbon dioxide. CO2 is assumed to have a GWP of 1, chemicals with a higher potential to contribute to global warming have a higher GWP and those with a lower potential have a lower GWP. A summary of chemicals and their GWP is shown in the table below.

Summary of GWP of Refrigerants for the Mechanical PE Exam



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