EPA 608 Universal key terms

A number comparing a refrigerant's ability to destroy stratospheric ozone to CFC-11, which is set at 1.0. Higher values indicate greater ozone harm.

A number comparing a refrigerant's heat-trapping effect in the atmosphere to carbon dioxide over a chosen time period. Higher values mean a stronger contribution to climate change.

A refrigerant class containing chlorine, fluorine, and carbon that strongly depletes stratospheric ozone. CFCs are banned from production and use in most applications.

A refrigerant class containing hydrogen, fluorine, and carbon but no chlorine. HFCs do not deplete ozone but are potent greenhouse gases, such as R-134a and R-410A.

A refrigerant mixture whose components have different boiling points, producing a temperature glide during phase change. It must be charged as liquid to maintain the intended composition.

The difference between the bubble point and dew point temperatures of a zeotropic refrigerant blend at a given pressure. It affects charging and system performance.

The separation of components in a zeotropic blend when it leaks or boils, because components vaporize at different rates. This changes the remaining refrigerant's composition and performance.

Removing refrigerant from an appliance and storing it in an external container without intentionally processing it. Recovery is required before opening a system or disposing of equipment.

Cleaning recovered refrigerant by removing oil, moisture, and non-condensables so it can be reused, typically in the same appliance or another appliance owned by the same person.

Reprocessing used refrigerant to meet the purity specifications of new product, which requires an EPA-certified reclaimer. Reclaimed refrigerant can be sold and used in any appliance.

A refrigerant release small enough that EPA does not require recovery under the venting prohibition. It generally applies only to very small amounts released during service or repair.

Intentionally or knowingly venting refrigerant to the atmosphere, which is prohibited for ozone-depleting refrigerants and their substitutes. Proper recovery is required instead.

A refillable, DOT-approved cylinder used to hold recovered refrigerant. It must never be filled above 80% of capacity and must be labeled with the refrigerant type.

A safety requirement that recovery cylinders be filled to no more than 80% of their capacity by weight, leaving room for liquid expansion and preventing dangerous overpressure.

A vacuum level low enough, typically below 500 microns, to remove moisture and non-condensable gases from a refrigeration system before charging.

A unit of vacuum equal to one-thousandth of a millimeter of mercury. Micron gauges measure deep vacuum during evacuation to verify moisture and non-condensables are removed.

An evacuation method that alternately pulls a vacuum and breaks it with dry nitrogen, repeated three times, to remove moisture and non-condensables from a system.

Using dry nitrogen to sweep air and moisture from tubing or to displace oxygen during brazing, preventing oxidation inside the system.

Gases such as air or nitrogen that do not condense at normal system pressures and temperatures. They raise condensing pressure and must be removed by evacuation or purging.

Adding refrigerant to a system as a liquid, often into the liquid line or receiver. It is required for zeotropic blends to prevent fractionation.

Adding refrigerant to the low-pressure side as a vapor. It is slower than liquid charging and is used for single-component refrigerants to avoid liquid slugging the compressor.

A refrigerant safety classification for mildly flammable fluids under ASHRAE Standard 34. A2L refrigerants require special handling and leak detection because of flammability.

EPA's rule that prohibits knowingly venting ozone-depleting refrigerants and their substitutes during service, maintenance, repair, or disposal. Refrigerant must be recovered instead.

EPA's category for household refrigerators, freezers, room air conditioners, dehumidifiers, and similar units with small refrigerant charges, typically five pounds or less.

Recovery equipment that relies on the appliance's own compressor to move refrigerant into a recovery container. It is commonly used for small appliances and cannot recover all refrigerant.

Recovery equipment with its own compressor that does not depend on the appliance's compressor. It can recover refrigerant faster and to lower levels than system-dependent equipment.

The percentage of refrigerant removed from an appliance compared with the amount originally in it. EPA sets minimum recovery efficiency requirements that vary by appliance type and equipment.

EPA's equipment category for systems using refrigerants such as R-22, R-410A, and R-134a that operate at relatively high pressures. Type II certification covers these appliances.

A Type II appliance that uses a refrigerant operating at pressures higher than R-22, such as R-410A. It requires gauges, hoses, and recovery equipment rated for the higher pressure.

The difference between the actual temperature of refrigerant vapor and its saturation temperature at the same pressure. It is used to check charge in systems with a fixed orifice.

The difference between the saturation temperature of liquid refrigerant and its actual liquid temperature at the same pressure. It is used to check charge in systems with a thermostatic expansion valve.

The temperature at which a refrigerant changes between liquid and vapor at a given pressure. It is found on a pressure-temperature chart and is used to calculate superheat and subcooling.

A metering device that controls refrigerant flow into the evaporator to maintain a set superheat. Systems with a TXV are typically charged by measuring subcooling.

A metering device with a fixed opening that does not adjust to load changes. Systems using a fixed orifice are typically charged by measuring superheat.

A high-pressure HFC blend used in residential and commercial air conditioning. It requires POE oil and pressure-rated equipment because it operates at higher pressures than R-22.

EPA's category for systems that use low-pressure refrigerants such as R-11 or R-123, typically centrifugal chillers whose evaporators operate in a vacuum.

A machine that cools water or another fluid for building cooling. Large centrifugal chillers often use low-pressure refrigerants and require special recovery and purge procedures.

A device on low-pressure chillers that removes air and other non-condensable gases from the refrigerant. It helps maintain efficiency and prevents excessive condensing pressure.

A high-volume compressor used in large chillers that raises refrigerant pressure using a spinning impeller. It can operate with low-pressure refrigerants and may create a vacuum in the evaporator.

A low-pressure HCFC refrigerant used mainly in centrifugal chillers. It has a low ozone depletion potential but is being phased out.