EPA 608 key terms

The part of the Clean Air Act that regulates refrigerant handling and requires certification for technicians who service, repair, or dispose of appliances containing regulated refrigerants.

A number comparing how strongly a substance destroys stratospheric ozone relative to CFC-11, which is set at 1.0. Higher values mean greater ozone damage.

A number comparing how much heat a greenhouse gas traps over a chosen period relative to carbon dioxide, which is set at 1. Higher values mean greater warming impact.

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

Cleaning recovered refrigerant for reuse by removing oil, moisture, and other contaminants, usually with a filter-drier. Recycling does not restore refrigerant to new-product purity standards.

Reprocessing refrigerant to new-product purity specifications, verified by chemical analysis. Reclaimed refrigerant must meet AHRI Standard 700 before it can be resold or used in another owner's equipment.

Removing air, moisture, and non-condensables from a system with a vacuum pump until a deep vacuum is reached, typically measured in microns. Proper evacuation prevents acid formation and ice blockage.

A unit of length equal to one-millionth of a meter, used to measure deep vacuum. A vacuum of 500 microns or lower generally indicates adequate dehydration.

A device that removes air and moisture from a refrigeration system to create a deep vacuum. Its oil must be changed regularly and the pump should be isolated with valves after shutdown.

A tool with gauges and valves used to measure system pressures and to connect service equipment such as vacuum pumps, recovery units, and charging cylinders to an appliance.

Gases such as air or nitrogen that do not condense at normal system operating pressures, raising head pressure and reducing efficiency. They are removed by evacuation or purging.

A fluid used in a refrigeration cycle that absorbs heat by evaporating at low pressure and releases heat by condensing at high pressure. Each refrigerant has its own pressure-temperature relationship.

A refrigerant made of chlorine, fluorine, and carbon, such as R-11 or R-12. CFCs have the highest ozone depletion potential and their production is banned.

A refrigerant containing hydrogen, chlorine, fluorine, and carbon, such as R-22. HCFCs deplete ozone less than CFCs but are being phased out.

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

Any appliance that is fully manufactured, charged, and hermetically sealed at the factory and contains five pounds or less of refrigerant, such as household refrigerators, freezers, and window air conditioners.

A compressor or system enclosed in a welded shell with no accessible shaft seal, so refrigerant cannot escape through a rotating seal. This design is common in small appliances.

A short, sealed copper tube used at the factory to charge a hermetically sealed appliance. Technicians install access valves on it to recover refrigerant or service the sealed system.

A service port installed on a sealed system or process tube that allows connection of gauges and recovery equipment without permanently opening the refrigerant circuit. It contains a spring-loaded core.

Recovery equipment that relies on the appliance's own compressor or on the pressure inside the appliance to move refrigerant into a recovery container. It cannot pull a deep vacuum by itself.

A recovery method that uses only the appliance's internal pressure and gravity, with no mechanical pump, to transfer refrigerant into a container. It is often used for small appliances with a working compressor.

A refillable cylinder used to store recovered refrigerant. It must be DOT-approved, clearly labeled, never filled over 80 percent of its capacity, and have its valve protected.

A safety rule requiring that a recovery cylinder be filled to no more than 80 percent of its volume with liquid refrigerant, leaving room for thermal expansion and preventing hydrostatic rupture.

Releasing refrigerant into the atmosphere. Venting is prohibited for most refrigerants and for appliances above certain charge sizes, so technicians must recover refrigerant instead.

The process of finding refrigerant leaks using electronic detectors, ultrasonic devices, soap bubbles, or fluorescent dyes. Regular leak checks are required for appliances above a charge threshold.

Using dry nitrogen to displace air and moisture from tubing during brazing, preventing oxidation inside the system. Nitrogen must not be used to pressure-test a system beyond its rating.

The number of degrees a vapor refrigerant is above its saturation temperature at a given pressure. Measuring superheat helps verify proper charge and expansion valve operation.

The number of degrees a liquid refrigerant is below its saturation temperature at a given pressure. Measuring subcooling helps verify proper charge in systems with a thermostatic expansion valve.

A refrigeration appliance that uses a refrigerant with a boiling point above minus 50 degrees Fahrenheit at atmospheric pressure, such as R-22 or R-410A. It operates with positive pressure throughout.

A refrigeration appliance that operates with a saturated vapor pressure at or below 10 psig at normal operating temperatures, typically using R-11 or R-123 in centrifugal chillers.

A large cooling machine that uses a rotating impeller to compress low-pressure refrigerant vapor, commonly found in large buildings. Many use R-123 and operate below atmospheric pressure.

A device on low-pressure chillers that removes air and other non-condensables that leak into a system operating under vacuum. Efficient purging reduces refrigerant loss and energy waste.

A one-time pressure relief device on low-pressure chillers that bursts at a set pressure to protect the vessel. It must be replaced after activation and checked for leaks.

A graduated container used to measure and add liquid refrigerant to a system by weight. It must be equipped with a valve and never filled completely.

A table showing the saturation pressure of a refrigerant at various temperatures. Technicians use it to determine charge, diagnose problems, and convert gauge readings.

The condition in which a refrigerant is at its boiling or condensing point for a given pressure, with both liquid and vapor present. At saturation, temperature and pressure are directly related.