Refrigerant Recovery Machines and Cylinders: Legal, Safe, and Effective Recovery Operations

1) Purpose of Recovery and Required Equipment

Refrigerant recovery is a controlled transfer process: you remove refrigerant from a system and store it in an approved cylinder so it can be reclaimed, recycled, or disposed of according to regulations. The goal is to prevent venting, protect people and equipment, and keep refrigerant streams identifiable (pure vs mixed vs contaminated).

Core equipment for effective, compliant recovery

• Recovery machine rated for the refrigerant and pressure class you will encounter.
• Approved recovery cylinder(s) with the correct DOT/TC rating and service pressure for the refrigerant.
• Refrigerant scale (digital preferred) to control fill by weight and prevent overfilling.
• Recovery-rated hoses (low permeation, with shutoff/ball valves) and appropriate fittings/adapters.
• In-line filter/drier (often a replaceable core or disposable filter) to protect the recovery machine from debris, acids, and moisture.
• Optional but strongly recommended: sight glass (liquid indication), temperature clamp for cylinder temperature, spare gaskets, and a dedicated oil drain container for oil-lubricated machines.

Think of recovery as a logistics task: correct container, correct routing, correct measurement, and controlled heat/pressure management.

2) Selecting Recovery Equipment

Refrigerant compatibility and pressure class

Always verify the machine is approved for the refrigerant type and pressure category. High-pressure refrigerants (including many HFC/HFO blends) require machines and cylinders rated for higher working pressures. Using an under-rated machine can cause nuisance shutdowns, slow recovery, or unsafe operating pressures.

Oil-less vs oil-lubricated recovery machines

• Oil-less machines reduce cross-contamination risk and simplify maintenance, but may be more sensitive to liquid slugging and may have different performance characteristics.
• Oil-lubricated machines can be robust and fast, but require oil management. Oil can become contaminated and must be changed per manufacturer guidance. Oil carryover can also affect performance if not maintained.

Push-pull capability (liquid transfer mode)

Push-pull is a method to move large quantities of liquid refrigerant quickly by using the recovery machine to create a pressure differential between the system and the cylinder. It is not appropriate for every job (see procedures section). Choose a machine that supports push-pull if you routinely work on systems with large charges and accessible liquid.

Speed vs portability

• Higher capacity machines reduce labor time, especially on large systems, but are heavier and may draw more power.
• Portable units are easier for residential/light commercial work and rooftop access, but may be slower on large charges.

Practical selection questions

• What refrigerants do you actually see (including blends and high-pressure types)?
• Do you need push-pull for large liquid charges?
• Will you be carrying the machine up ladders/rooftops?
• Do you have reliable power (and correct extension cord sizing) where you work?
• Do you need a machine that tolerates higher ambient temperatures or has strong high-head protection?

3) Cylinder Selection and Handling

DOT/TC ratings and service pressure

Use only cylinders approved for refrigerant recovery and rated for the refrigerant pressure class. The cylinder’s stamped markings and label indicate its service pressure and compliance. Never use disposable cylinders for recovery unless specifically permitted and rated for that purpose in your jurisdiction and by the cylinder manufacturer.

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Tare weight (TW) and why it matters

The tare weight is the empty cylinder weight. Recovery is controlled by net refrigerant weight, not by “feel” or pressure alone. You will use TW plus allowable fill to determine the maximum gross weight.

Fill limits (avoid overfilling)

Recovery cylinders are typically limited to 80% fill by volume to allow for liquid expansion with temperature rise. Because you usually control fill by weight, follow the cylinder’s guidance for maximum net fill. If you do not have the manufacturer’s chart available, use the cylinder’s labeled capacity and your company’s approved procedure to calculate the maximum allowable net weight for that refrigerant.

Key practice: keep the cylinder on a scale during recovery and stop before reaching the maximum allowable fill weight. Do not “top off” a cylinder because it seems to be taking refrigerant slowly—slow flow is often a pressure/temperature issue, not an empty-space issue.

Color/labeling and identification

Cylinder color is not a reliable identifier by itself. Use durable labels and tags that clearly state:

• Refrigerant type (or “mixed/unknown” if applicable)
• Source equipment ID/location (optional but helpful)
• Date
• Technician initials
• Condition notes (burnout, suspected moisture/acid, etc.)

Dedicated vs mixed refrigerants

• Dedicated cylinders (one refrigerant type per cylinder) preserve value and simplify reclaim/reuse decisions.
• Mixed refrigerant cylinders should be used only when the refrigerant is unknown or already mixed/contaminated. Mixed refrigerant is harder and more expensive to process and may be treated as waste depending on local rules and reclaim policies.

Handling essentials

• Transport cylinders upright and secured.
• Keep valve caps installed when not connected.
• Protect cylinders from heat sources and direct sunlight.
• Do not use cylinders with damaged valves, missing safety devices, severe rust, or out-of-date inspection where applicable.

4) Step-by-Step Recovery Procedures

The exact hose routing varies by machine model, but the control principles are consistent: protect the machine with filtration, control flow direction, manage pressure/temperature, and control cylinder fill by weight.

Before you start: job planning

• Identify the refrigerant (nameplate, records, or approved identifier if required by your process).
• Estimate charge size to select cylinder capacity and decide whether liquid recovery/push-pull is appropriate.
• Confirm cylinder is empty enough (by weight) to accept the expected amount within fill limits.
• Install an in-line filter on the inlet side of the recovery machine (and additional filtration if the system is contaminated).

Vapor recovery (common for small charges or final cleanup)

Use vapor recovery when: the system has mostly vapor, you are finishing after liquid removal, or push-pull is not appropriate.

1. Place the recovery cylinder on the scale and record starting weight.
2. Connect the recovery machine so it pulls vapor from the system and discharges to the cylinder vapor port (follow machine labeling for IN/OUT).
3. Purge air from hoses using the machine’s purge function or approved method to minimize non-condensables entering the cylinder.
4. Start the machine and monitor: cylinder weight, system pressure, and machine operating conditions.
5. Control cylinder temperature if head pressure rises (see Section 5).
6. Stop at the required endpoint per regulations/company policy and equipment type, and verify the system does not rebound above the threshold after a short stabilization period.
7. Close valves, perform machine purge (to clear refrigerant from the machine into the cylinder), then shut down.

Liquid recovery (direct liquid removal)

Use liquid recovery when: you can access liquid refrigerant safely and want faster removal than vapor-only recovery.

1. Confirm the recovery machine is rated for liquid handling and follow manufacturer instructions to prevent slugging.
2. Use a throttling method if required (for example, a metering device or partially opened valve) to avoid sending a solid column of liquid that can overwhelm the compressor.
3. Route liquid from the system to the machine inlet and discharge to the cylinder liquid port if the cylinder has one (or as directed by your cylinder/machine guidance).
4. Monitor scale continuously and stop well before maximum fill weight.
5. Transition to vapor recovery to remove remaining vapor and reach the required endpoint.

Push-pull recovery (high-speed liquid transfer—when appropriate)

Use push-pull when: the system contains a large amount of liquid refrigerant, has a clear liquid source, and the system configuration supports continuous liquid flow (typically larger receivers or systems with accessible liquid lines). Do not use push-pull on small systems, systems without a solid liquid reservoir, or when you cannot maintain stable liquid flow—vapor ingestion can stall the process and increase head pressure.

1. Set the cylinder on the scale and confirm adequate empty capacity.
2. Connect push-pull hoses per your machine’s diagram: the machine moves vapor from the cylinder to the system (pushing), while liquid flows from the system back to the cylinder (pulling) through the liquid line.
3. Start and confirm liquid movement (temperature change on lines, sight glass if used, and steady weight increase on the scale).
4. Watch for loss of liquid flow (weight gain slows, line temperatures equalize). When liquid transfer stops, switch to vapor recovery to finish.
5. Prevent overfilling: stop recovery before the maximum allowable cylinder weight is reached, even if the system still contains refrigerant—use a second cylinder if needed.

How to avoid overfilling (practical control method)

• Keep the cylinder on the scale for the entire operation.
• Know your maximum allowable fill weight before starting.
• Slow down near the end: as you approach the limit, recovery can surge if conditions change (e.g., cylinder cools or system warms).
• If you need more capacity, stop and switch to an empty approved cylinder—do not “make it fit.”

5) Managing Non-Condensables and High Head Pressure

Why head pressure rises during recovery

High head pressure usually comes from one or more of these conditions:

• Warm recovery cylinder (higher saturation pressure).
• Poor heat rejection at the recovery machine (blocked airflow, high ambient temperature).
• Non-condensables (air) in the cylinder or introduced through hoses/connections.
• Restricted flow (clogged filter, kinked hose, partially closed valve).

Control actions (in order of practicality)

• Cool the cylinder: place it in a cool water bath (if allowed by your procedures), use a wet towel and airflow, or move it out of sun/heat. Cooling lowers cylinder pressure and improves recovery speed.
• Improve machine airflow: keep the condenser clean, ensure clearance around the machine, and avoid recirculating hot air in tight spaces.
• Throttle flow if needed: if liquid slugging or rapid pressure rise occurs, reduce inlet flow to keep the machine stable.
• Check for restrictions: replace saturated filters, straighten hoses, fully open valves.
• Minimize non-condensables: purge hoses per machine instructions and avoid opening the recovery circuit to atmosphere.

Important: Do not attempt to “solve” high head pressure by defeating safety controls or bypassing pressure switches. If the machine trips on high pressure, treat it as a condition to correct, not an inconvenience.

6) Common Mistakes and How to Prevent Them

Recovering into the wrong cylinder

• Risk: mixing refrigerants, creating an unknown stream, increased disposal/reclaim cost, and potential safety issues if pressure ratings don’t match.
• Prevention: label cylinders clearly, verify refrigerant type before connecting, and use dedicated cylinders whenever possible.

Exceeding fill limits

• Risk: hydrostatic expansion can cause extreme pressure rise as temperature increases, potentially triggering relief devices or worse.
• Prevention: scale control from start to finish; calculate/verify maximum allowable fill weight; stop early and switch cylinders.

Using contaminated or permeated hoses

• Risk: introducing moisture, acids, debris, or wrong refrigerant into the recovery stream; damaging the recovery machine.
• Prevention: use recovery-dedicated hoses, cap ends when stored, and replace hoses that are oil-soaked, cracked, or suspected contaminated.

Skipping filters

• Risk: debris and acid damage to the recovery machine, reduced performance, and cross-contamination between jobs.
• Prevention: install an in-line filter on the inlet; use higher-capacity filtration for burnout/contaminated systems; change filters when pressure drop increases or per policy.

Running the machine into a vacuum improperly

• Risk: overheating, poor lubrication (for some designs), pulling air into the system through leaks, and misleading “completion” if the system rebounds.
• Prevention: follow the machine manufacturer’s guidance for end-of-recovery operation, stabilization/rebound checks, and purge steps. Treat deep vacuum operation as a controlled phase, not a race.

Recovery Setup and Shutdown Checklists

Setup checklist (before starting the machine)

• Confirm refrigerant type and pressure class.
• Select the correct recovery machine for the refrigerant.
• Select an approved cylinder with correct DOT/TC rating and adequate empty capacity.
• Inspect cylinder condition; verify valve operation and protective cap availability.
• Place cylinder on scale; record tare and starting gross weight.
• Calculate/verify maximum allowable fill weight; set a stop point.
• Install in-line filter on machine inlet (and additional filtration if needed).
• Use recovery-rated hoses; inspect gaskets; ensure valves are functional.
• Plan for head pressure control (shade, airflow, cylinder cooling method).
• Verify machine purge procedure and that discharge is routed correctly to the cylinder.

Shutdown checklist (after reaching endpoint)

• Close system valves and cylinder valves in the correct order to prevent backflow.
• Use the recovery machine’s purge function to clear refrigerant from the machine into the cylinder.
• Stop the machine and allow pressures to stabilize as required; verify no significant rebound.
• Record final cylinder weight; confirm it is below the maximum allowable fill weight.
• Cap/plug hose ends to prevent moisture ingress and cross-contamination.
• Label the cylinder immediately (refrigerant type, status, date, source info).
• Store cylinder upright, secured, and away from heat sources.
• Inspect filter condition and document if replacement is needed before the next job.

Safety Note: Refrigerant Decomposition from Open Flames and Hot Surfaces

Refrigerants exposed to open flames, brazing torches, glowing heating elements, or very hot surfaces can decompose into highly toxic and corrosive byproducts. This risk increases when refrigerant is present in the work area or trapped in components being heated. Keep recovery and isolation steps coordinated with any hot work: recover refrigerant first, verify isolation, ventilate the area, and keep torches/heat sources away from any potential refrigerant release path. If a sharp, irritating odor or respiratory irritation occurs during hot work, stop immediately, move to fresh air, and follow your site’s emergency procedures.