Often confused · Recover, recycle, reclaim
Mixed or unknown refrigerant: what the EPA 608 expects
Mixed refrigerant is two or more refrigerants that ended up together by accident, and the EPA 608 treats it as a recovery problem: the Core test topics say never to mix refrigerants (EPA test topics, checked October 7, 2026), because recycling can't separate one refrigerant from another and only reclaim to the AHRI 700 standard can return used refrigerant to the market.
Part of Recover, recycle, reclaim in the Study guide
Blend versus mix
A designed refrigerant blend compared with a mixed refrigerant
| Item | Blend | Mix |
|---|---|---|
| How it got that way | Formulated by the manufacturer to a fixed recipe | Two refrigerants met in one system, hose or cylinder |
| Has an R-number | Yes, e.g. R-407C, R-410A, R-454B | No; it matches no specification |
| PT behavior | Predictable from the blend's PT chart | Matches no chart, which is often how you find it |
| Back into an appliance | Yes, the same owner's equipment | Not until a reclaimer has dealt with it |
| Charging note | Zeotropic blends fractionate, so they are charged as liquid | Not charged at all |
Yellow edge: the two columns say different things on this row.
Fractionation and "don't mix refrigerants": EPA test topics, Core, checked October 7, 2026. Liquid charging of zeotropic blends is standard practice that follows from fractionation; the rule text doesn't state it.
Why recycling can't rescue a mix
Running a mixed cylinder through the recovery machine's filter-driers will not make it usable. Recycling cleans refrigerant for reuse by separating oil and passing it through filter-driers (40 CFR 82.152, eCFR as of October 5, 2026). That removes moisture, acid and particles. It does nothing to pull one refrigerant out of another, so a recycled mix is still a mix.
Reclaim is the step built for this. A reclaimer reprocesses refrigerant to the AHRI 700 purity standard and proves it by chemical analysis, and only reclaimed refrigerant may be sold to a new owner (40 CFR 82.154(d), eCFR as of October 5, 2026). The recover, recycle, reclaim topic sets the three definitions side by side.
The rule does give recovered refrigerant one shortcut: it may go back into the same appliance, or another appliance the same owner has, without recycling or reclaim (40 CFR 82.154(d) and 82.156(h), eCFR as of October 5, 2026). That allowance assumes you know what the refrigerant is, which a mix no longer lets you say.
Mixes rarely start in a cylinder. A previous contractor tops off an R-407C system with R-22 because both sat on the truck, and the system now holds a refrigerant with no name. Every pound recovered from it is mixed refrigerant, however careful the recovery. A blend is a recipe and a mix is an accident, and the exam rewards spotting which one a scenario describes.
Terms around mixed refrigerant
- Recover
- Remove refrigerant from a system and store it in an external container, without testing or processing it.
- Recycle
- Clean refrigerant for reuse in the same owner's equipment, using oil separation and filter-driers.
- Reclaim
- Reprocess refrigerant to AHRI 700 purity, verified by analysis, at a certified reclaimer.
- Fractionation
- A zeotropic blend's components boiling off or leaking at different rates, which shifts the blend away from its recipe.
Blend, mix or unknown
Work out first whether each scenario still has a nameable refrigerant; that decides where it can go.
0 right · 0 of 7 answered
What should a technician do when servicing a small appliance if the refrigerant type cannot be determined from the nameplate?
Why each option is right or wrong
Answer: B. Recover it into a separate cylinder designated for unknown refrigerants
- AWrong: venting is prohibited, and charging R-410A into an unknown system is unsafe.
- BCorrect: recover an unidentified refrigerant into its own cylinder so it can't contaminate a cylinder of known refrigerant.
- CWrong: guessing the refrigerant can contaminate an R-134a recovery tank if you are wrong.
- DWrong: a halide torch detects leaks of chlorinated refrigerants; it can't identify which refrigerant is present.
When the refrigerant type cannot be determined, the technician should recover it into a separate cylinder designated for unknown refrigerants to prevent contamination of known refrigerant supplies. Mixing different refrigerants can render them unusable and increase disposal costs.
A technician neglects to verify system labels and service data before servicing, accidentally mixing R-22 and R-410A in a recovery cylinder. Where does this mixture go?
Why each option is right or wrong
Answer: A. Send the cylinder to a reclaimer for destruction.
- ACorrect: a mixture like this can't be recycled or reclaimed normally, so it goes to a reclaimer and is usually destroyed, often for a fee.
- BWrong: venting is prohibited no matter how the refrigerant got mixed.
- CWrong: a technician can't separate refrigerant mixtures in the field; that takes a reclaimer's facility, if it can be done at all.
- DWrong: a recycling machine removes oil and moisture but can't separate one refrigerant from another.
Mixed refrigerants can't be separated on site or by a recycling machine. The cylinder goes to a reclaimer, which usually sends a mixture it can't process for destruction, for a fee. Checking labels before service avoids it.
A technician needs to recover refrigerant from a failed R-134a refrigerator immediately after servicing an R-410A system. Which action is required to prevent cross-contamination?
Why each option is right or wrong
Answer: A. Use a dedicated recovery cylinder for R-134a and purge the recovery machine
- ACorrect: use a cylinder dedicated to R-134a and clear the leftover R-410A from the recovery machine first so the two refrigerants never mix.
- BWrong: mixing refrigerants on purpose creates a mixture that usually can't be reclaimed, even if it is labeled.
- CWrong: venting leftover refrigerant from the recovery machine is still venting, which is prohibited.
- DWrong: flushing with nitrogen doesn't make an R-410A cylinder dedicated to R-134a, and the nitrogen itself becomes a contaminant.
Refrigerants must never be mixed. The technician must ensure the recovery cylinder is dedicated to R-134a and that the recovery machine is thoroughly purged beforehand.
While preparing to service a small appliance, a technician observes that the pressure-temperature readings deviate significantly from the refrigerant listed on the factory label. What is the most appropriate action?
Why each option is right or wrong
Answer: B. Verify the actual refrigerant type using a refrigerant identifier
- AWrong: adding the labeled refrigerant to a system that may hold something else creates a mixture.
- BCorrect: when PT readings don't match the label, confirm the actual refrigerant with an identifier before recovering or charging.
- CWrong: recovering into equipment set up for the labeled refrigerant risks contaminating its tank.
- DWrong: putting a possibly different refrigerant into the labeled refrigerant's cylinder contaminates the whole cylinder.
Substitutes have different pressure-temperature characteristics. The technician must positively verify the actual refrigerant type before recovering it to prevent dangerous and expensive cylinder cross-contamination.
A technician encounters a small appliance with heavily contaminated refrigerant due to a severe compressor burn-out. How should this refrigerant be handled?
Why each option is right or wrong
Answer: D. Recover it and send it to an EPA-certified reclaimer
- AWrong: venting is prohibited even when the refrigerant can't be recycled locally.
- BWrong: burning refrigerant with a torch creates toxic decomposition products (such as phosgene and acids) and isn't approved destruction.
- CWrong: filtering doesn't make venting the rest legal; all of it has to be recovered.
- DCorrect: recover the contaminated refrigerant and send it to a certified reclaimer to reprocess or arrange its destruction.
Contaminated refrigerant still has to be recovered; it can't be vented. Send it to an EPA-certified reclaimer to reprocess or arrange its destruction.
What happens to severely mixed refrigerant that reclaimers can't process?
Why each option is right or wrong
Answer: B. Transport to a destruction facility
- AWrong: mixing contaminated refrigerant into virgin refrigerant just contaminates more refrigerant.
- BCorrect: a mixture that can't be reclaimed is sent for destruction using an approved destruction technology, usually arranged through the reclaimer.
- CWrong: contamination never makes venting allowed.
- DWrong: a filter-drier removes moisture and acid, not other refrigerants.
Mixed refrigerant that can't be reclaimed is sent for destruction using an approved destruction technology, usually arranged through the reclaimer. Venting it is still prohibited, however contaminated it is.
What is the primary purpose of having separate recovery cylinders for different refrigerant types in small appliance service?
Why each option is right or wrong
Answer: B. To prevent cross-contamination between different refrigerants
- AWrong: separate cylinders don't make recovery faster; they keep refrigerants from mixing.
- BCorrect: keeping each refrigerant in its own cylinder prevents mixtures that can't be reused or reclaimed.
- CWrong: storage capacity isn't the reason; the reason is keeping each refrigerant pure.
- DWrong: recovery cylinders are all gray with a yellow top, so color coding isn't the reason to separate refrigerants.
Separate recovery cylinders prevent cross-contamination between different refrigerant types, which would make them unreclaimable and potentially damage equipment.
More practice across all four sections: Practice test · Timed mock