CFCs were widely used in older systems due to their stability and favourable thermodynamic properties, but their high ODP led to a global phase-out.

• Typical examples: R-11 and R-12, once common in chillers and refrigeration systems.
• High ODP — contribute significantly to ozone layer depletion.
• Banned from new equipment and heavily controlled for servicing legacy systems.

HCFCs were introduced as transitional replacements for CFCs because they have lower ODP. However, they still damage the ozone layer and are being phased out.

• R-22 (HCFC-22) was widely used in comfort cooling and refrigeration.
• Lower but non-zero ODP and moderate GWP.
• Production and import are being phased out under international agreements and Canadian regulations.

HFCs contain hydrogen, fluorine, and carbon but no chlorine, so they have zero ODP. They became common replacements for many CFC and HCFC applications.

• Examples: R-134a, R-404A, and R-410A.
• Zero ODP, but many have high GWP — leading to current efforts to phase down high-GWP options.
• Widely used in commercial refrigeration, residential and commercial air conditioning, and automotive systems.

HFOs are unsaturated fluorinated refrigerants designed with very low GWP and zero ODP, often used alone or in blends.

• Examples: R-1234yf and R-1234ze, as well as blends combining HFOs with HFCs.
• Many HFOs are classified as mildly flammable (A2L), requiring revised safety practices and updated codes.
• Increasingly used where regulatory pressure demands low-GWP alternatives.

Hydrocarbons such as propane and isobutane are natural refrigerants with very low GWP and zero ODP.

• Common designations: R-290 (propane) and R-600a (isobutane).
• Highly flammable (Class 3) — subject to strict charge limits and installation requirements.
• Used in small commercial and household appliances and, in some jurisdictions, larger systems with proper safety measures.

Brine solutions are typically salt-water mixtures designed to remain liquid at low temperatures.

• Common salts: calcium chloride or sodium chloride.
• Used in low-temperature secondary loops such as ice rinks and some industrial processes.
• Can be corrosive — requiring compatible piping materials and corrosion inhibitors.

Glycol solutions are widely used as secondary coolants in hydronic and refrigeration systems.

• Types: ethylene glycol and propylene glycol mixed with water in various concentrations.
• Provide freeze protection — used in chilled water, process cooling, and commercial refrigeration loops.
• Care must be taken to prevent environmental contamination from leaks and to maintain proper inhibitor levels.

Water and other engineered secondary solutions are also used as intermediate heat-transfer media.

• Water (R-718) is a natural refrigerant/secondary fluid used in many chilled-water systems for comfort cooling.
• Other engineered secondary fluids combine low freezing point, low viscosity, and corrosion inhibitors for specialized applications.
• System design must ensure adequate flow, expansion volume, and corrosion control.

Absorption recovery uses the principle that some liquids or media can absorb refrigerant vapour.

• An absorbent medium captures refrigerant vapour drawn from the system.
• The absorbed refrigerant is later processed or recovered in a controlled facility.
• Must follow approved environmental and safety guidelines; less common than mechanical units in typical field work.

Liquid recovery removes refrigerant while it is still in liquid state — typically the fastest way to remove large quantities when conditions permit.

• Recovery cylinder placed on a scale and connected to the liquid line or receiver outlet.
• Liquid flows or is pumped into the cylinder by gravity, pressure difference, or a recovery unit designed for liquid.
• Cylinders must not exceed ~80% liquid fill at the specified temperature — monitor mass on the scale at all times.
• Hoses must be rated for liquid refrigerant; flow must be controlled to avoid hydraulic shock.

Migration uses the natural tendency of refrigerant to move toward colder areas in the system. By cooling one part and warming another, refrigerant is induced to collect in a specific component for easier removal.

• A cold condition (ice bath, cooling jacket, or cold ambient) is applied to a receiver, condenser, or high point in the system.
• Warmer conditions elsewhere cause refrigerant to preferentially condense in the cooled component.
• Once most refrigerant has migrated, a recovery unit connects to that component for efficient removal.
• Helpful when isolating refrigerant away from components being serviced, such as evaporators or compressors.

The push-pull method is designed for rapid recovery of large liquid charges from systems equipped with receivers or large condensers.

• The recovery unit is connected so that vapour "pushes" liquid from the system into the cylinder.
• Vapour drawn from the recovery cylinder is discharged into the top of the system's receiver or condenser, increasing pressure on the liquid.
• The increased pressure forces liquid from the bottom of the receiver into the recovery cylinder through a liquid line.
• Continues until most liquid is transferred; final vapour recovery is then completed using standard vapour techniques.
• Most effective on systems with a large liquid volume and a clear liquid reservoir such as a receiver tank.

Vapour recovery removes refrigerant in its vapour state. Often used once the bulk of liquid has been removed, or on small systems where liquid lines are not easily accessed.

• The recovery unit draws vapour from the top of the system or receiver through the service manifold.
• As vapour is removed, system pressure drops, causing remaining liquid to boil off and be recovered as vapour.
• Monitor system pressure to achieve the required final recovery level as mandated by regulations.
• Avoid liquid slugging of the recovery unit — slow flow or reconfigure lines if liquid is suspected.

Core removal tools allow technicians to remove Schrader valve cores under pressure, creating a larger flow path and reducing restriction during recovery or evacuation.

• Attached to the service port and seals it while the internal mechanism removes the core.
• With the core removed, full-size hose connections can be used for higher flow rates.
• After work is complete, the core is reinstalled using the tool without venting refrigerant.

Refrigerant cylinders are specifically designed and rated containers for storing and transporting refrigerant. Using the correct type and following capacity limits are legal and safety requirements.

• Recovery cylinders are usually grey or another standardized colour with a yellow band — clearly labeled with the refrigerant type.
• Disposable cylinders (factory-charged) must never be refilled and must be disposed of according to regulations when empty.
• Refillable cylinders must be hydrostatically tested and inspected at regulated intervals and must not be used beyond their test date or if damaged.

Filter driers in recovery and recycling setups remove moisture, acids, and particulates from recovered refrigerant or from the system itself.

• Installed in the refrigerant flow path to protect the recovery unit and improve refrigerant quality.
• Must be replaced regularly — especially after compressor burnouts or on contaminated systems.

Gauge manifolds provide controlled access to system pressures and connection points for recovery, evacuation, and charging.

• Include high- and low-side gauges, hand valves, and hose connections.
• Used to monitor suction and discharge pressures and to connect to recovery units, vacuum pumps, and charging cylinders.
• Must be rated for the refrigerant and maximum working pressure of the system — especially for high-pressure refrigerants like R-410A and R-744.

Service hoses connect manifolds, recovery units, cylinders, and system service ports.

• Must be pressure-rated for the refrigerant in use and in good condition with intact gaskets and seals.
• Low-loss fittings or self-sealing couplers are commonly used to minimize refrigerant loss.
• Keep hoses clean and capped when not in use to prevent moisture and debris entry.

Recovery units are mechanical devices that compress and transfer refrigerant from a system into a recovery cylinder.

• Handle vapour, liquid, or both — depending on design; some have specific procedures for different recovery modes.
• Must be compatible with the refrigerant being recovered and maintained according to manufacturer schedules.
• Monitor operating conditions carefully — overheating, liquid slugging, or contaminated refrigerant can damage recovery units.

Service valves and access fittings provide connection points for manifolds, recovery equipment, and vacuum pumps.

• May be factory-installed (on condensing units or compressors) or field-installed as part of the system piping.
• Must be checked for leaks and capped to reduce the risk of accidental refrigerant loss and contamination.