Recovery Machine Changeover Between Refrigerants

Purpose

Cross-contamination does not usually happen in the cylinder. It happens in the machine, between two jobs, in the residual that stays behind in the compressor oil, the internal condenser, the filter drier and the hoses after the last recovery. The cylinder log then records a clean, dedicated fill, and the mixed refrigerant it actually received is invisible until a reclaimer rejects the lot.

The stakes went up when A2L equipment arrived, for two reasons that pull in opposite directions. A shop that once needed one recovery machine now needs a machine listed for flammable refrigerants as well, so the temptation to run one machine across both families is real. And a mixture of an A1 and an A2L refrigerant is no longer just unreclaimable, it is a cylinder whose contents have no safety classification anybody can act on, since the class belongs to a known composition and this one is not known.

Scope

Covers changing a recovery machine from one refrigerant to another: the decision whether to change over at all, the machine self-purge, evacuation, drier and oil service, hose and manifold handling, verification with a refrigerant identifier, and the machine log.

Does not cover cylinder selection, fill limits, dedication or the recovery job itself, which the refrigerant recovery and cylinder management SOP owns. Does not cover machine listing for flammable refrigerants, which the A2L service readiness SOP owns. Does not cover reclaimer acceptance or purity certification, which the reclaimed refrigerant SOP owns.

Roles and responsibilities

Procedure

1. Decide whether to change over at all, because dedication beats changeover every time. Read the machine's tag and log for the last refrigerant it handled, then ask whether another machine in the shop is already dedicated to the one you need. Acceptance: a tag naming the last refrigerant with a date, and a written decision to either use a dedicated machine or perform a changeover. Wrong looks like an untagged machine nobody can account for; stop rule is that a machine whose last refrigerant is unknown gets the full changeover regardless of what anyone remembers. Hazard at this step: none, a decision made at the rack, but the machine you are handling may still hold refrigerant under pressure, so read its own gauges before moving it.

2. Run the machine's self-purge into a cylinder dedicated to the outgoing refrigerant. Follow the manufacturer's purge or self-clearing cycle exactly, with the cylinder correct for what is coming out rather than for what is going in next. Acceptance: the purge cycle completed as the manual describes, with the outgoing refrigerant weight added to that cylinder's log. Wrong looks like purging into whatever cylinder is nearest, which converts a good cylinder into mixed waste and defeats the whole exercise; stop rule is that no purge starts until the correct dedicated cylinder is on the scale. Hazard at this step: the machine and its hoses hold liquid, so gauntlet gloves and sealed eye protection, stand out of line with each fitting, and where the outgoing refrigerant is an A2L the purge runs in a ventilated space clear of ignition sources.

3. Evacuate the machine to the level and hold time its manufacturer specifies for a changeover. Pull the machine down through its own service connections per the manual, not to a level you carry over from evacuating systems. Acceptance: the vacuum level and hold time the manufacturer states for changeover, both recorded. Wrong looks like a short pull judged by the gauge settling; stop rule is that a machine which will not hold the manufacturer's level has an internal leak or a saturated component and goes out of service rather than back on a truck. Hazard at this step: the vacuum pump exhausts whatever came out of the machine along with oil mist, so it runs with its exhaust routed outdoors or is itself listed for flammable refrigerants.

4. Replace the filter drier, and change the oil where the manufacturer calls for it. The drier holds the residual the evacuation cannot reach, so a changeover that reuses it has moved the contamination rather than removed it. Acceptance: a new drier of the manufacturer's specified part fitted, oil changed where the manual requires it for a refrigerant family change, and the old drier disposed of rather than set on the bench. Wrong looks like a drier changed on a calendar rather than at the changeover; stop rule is no correct drier in stock, no changeover, and the machine stays tagged to its old refrigerant. Hazard at this step: the removed drier holds refrigerant and oil under residual pressure, so it is cracked slowly with the port pointed away and disposed of per the waste stream your shop uses for used driers.

5. Change or dedicate the hoses, core tools and manifold along with the machine. Hose and manifold internal volume carries residual just as the machine does, so a changed-over machine on the old hoses is still a mixed set. Acceptance: hoses either replaced, or dedicated by colour or tag to one refrigerant and confirmed to be the set that belongs with this machine, plus core removal tools accounted for the same way. Wrong looks like the machine getting the full treatment while the hose bundle in the bottom of the tote is reused; stop rule is that hoses of unknown history are replaced rather than reasoned about. Hazard at this step: a hose disconnected under residual pressure whips and sprays liquid, so depressurize through the machine before breaking any connection and keep the fitting pointed away from your face.

6. Verify with a refrigerant identifier before the machine goes back to work. Charge the machine with a small quantity of the incoming refrigerant per the manual, run it through the machine, and sample it with a refrigerant identifier. Acceptance: the identifier reporting a pass for the target refrigerant against its own stated criteria, with the printout or reading retained. Wrong looks like verification by reasoning, meaning the drier was changed and the vacuum was held so it must be clean; stop rule is that a fail sends you back to step 2 for a second cycle, and a second fail takes the machine out of service for the manufacturer to look at. Hazard at this step: this puts a live refrigerant sample in the shop, so it is drawn in a ventilated area, and where the incoming refrigerant is an A2L there is no ignition source at the bench.

7. Re-tag the machine and log the changeover before it leaves the bench. Write the new refrigerant, the date, who did the work, the drier part number, the vacuum level held, and the identifier result on the machine tag and in the shop log. Acceptance: a tag whose refrigerant matches the identifier result, and a log entry that a reclaimer or an inspector could follow. Wrong looks like a tag updated with a marker and no log entry, which leaves the shop unable to say when the machine changed; stop rule is that an untagged machine does not go back on the rack. Hazard at this step: none, paperwork at the bench, and it is the step that makes step 1 work for the next person.

The record this produces

One running log per machine, keyed to the machine serial rather than to the truck it rides on.

Each entry: date, outgoing refrigerant, incoming refrigerant, purge cylinder serial and weight added, vacuum level and hold time reached, drier part number fitted, whether oil was changed, hose disposition, identifier result with the printout attached, and the tech who signed it. The machine tag carries the short version, meaning current refrigerant and date, so a tech at the rack does not need the log to make the step 1 decision.

The log has two readers beyond the shop. A reclaimer investigating a rejected lot will ask which machine filled that cylinder and what it handled before, and a shop that can answer keeps the relationship. The service manager reads changeover frequency, because a machine changing over repeatedly is a fleet-sizing decision wearing the costume of a bench task.

Worked pass: A2L-listed machine returning from an R-410A recovery

The shop runs three machines: two older units dedicated to R-410A and one newer machine listed for flammable refrigerants. On a busy Friday the listed machine was used to recover R-410A because it was the only one on the truck that day. It now has to go back to R-454B work.

Step 1: machine tag read R-410A with Friday's date, so a changeover was required rather than optional. Neither dedicated A1 machine could take the R-454B work, since neither is listed for flammable refrigerants, so switching machines was not an option and the changeover was the only path.

Step 2: self-purge cycle run per the manual into the shop's R-410A recovery cylinder, which gained 1 lb 2 oz, logged against that cylinder. Step 3: machine evacuated to the manufacturer's changeover level and held for the stated time, recorded. Step 4: new drier of the specified part number fitted, oil changed, since this manual calls for an oil change on a refrigerant family change rather than only on a like-for-like swap. Step 5: the hose set that had been on the machine during the R-410A recovery was retired to the A1 tote and a dedicated A2L hose set with the left-hand-thread adapter was fitted.

Step 6 FAILED on the first run. A small quantity of R-454B was cycled through the machine and sampled, and the identifier reported a fail, with R-410A present above its stated criteria. Under this step's stop rule that sends the work back to step 2 rather than forward, so a second purge, a second evacuation to the manufacturer's level and hold, and a second drier were run. The second identifier run reported a pass for R-454B and the printout was stapled to the log entry.

The first cycle had missed because the internal condenser and the oil charge hold more residual than the drier does, and one pass moves the bulk without clearing it. The identifier is the only thing in this procedure that can tell those two states apart, which is why step 6 exists and why reasoning from the drier change is named as the failure mode.

Bench time for the full changeover with the repeat came to about 3.5 hours across the day, against roughly 1.5 hours for a clean single-pass changeover. The shop logged three changeovers on that machine in the quarter, so about 5.5 hours of bench time in total, and the service manager used that number to justify a second listed machine rather than to argue for a faster procedure. That is the honest read: the procedure is not the cost, the fleet is.

References

• The recovery machine manufacturer's service manual for the self-purge cycle, changeover vacuum level and hold time, filter drier part number and oil change requirement, which is the governing document for steps 2 through 4
• AHRI Standard 700 for the refrigerant purity specification an identifier result is judged against, in the edition your reclaimer works to
• UL 1963, in the edition the machine was listed to, for recovery equipment including its flammable-refrigerant provisions
• 40 CFR Part 82 Subpart F for the venting prohibition that applies to every purge and hose breakdown in this procedure
• See related: Refrigerant Recovery and Cylinder Management, A2L Service Readiness and Tool Inventory, and Reclaimed Refrigerant Acceptance and Documentation