Refrigerant cross contamination — system / recovery tank contamination scenarios and remedy

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Contamination paths — where and how mixing happens. Check: Main paths: ① Reusing the recovery hose between multiple systems without purging — residual gas in the hose carries into the next system. ② Adding a different gas to a recovery tank (R-410A added to an R-22 tank) — instant mix. ③ Using the manifold immediately on an R-410A system right after R-22 work — trace contamination from gauge residue. ④ Different gas left in a charging can (oil/refrigerant pumped back from a compressor in prior work). ⑤ Improper retrofit — adding only POE without recovering the mineral oil. ⑥ Residual oil inside the recovery machine (gas dissolves into recovery-machine oil → trace contamination in the next gas job). What to do: Prevention: ① Color-code hoses and manifolds by gas (R-22 yellow / R-410A pink / R-32 teal, etc.) — keep dedicated sets per color. ② Label recovery tanks 'Single Refrigerant' and verify with the identifier before and after use. ③ Cap both ends of the manifold when disconnecting from a system to seal in residual gas. ④ Run a 'self-purge' cycle on the recovery machine when switching refrigerants (per maker manual). ⑤ For retrofits, the mineral → POE procedure (2–3 oil swaps) is mandatory. ⑥ Tech tool box — separate compartments per refrigerant type for hose, manifold, and recovery tanks. When contamination is found — system vs recovery tank handling. Check: Identify with the identifier — ① System contamination — apply the interpretation from refrigerant-identify-kit. Single gas <90% = confirmed contamination. ② Recovery tank contamination — when the identifier shows multiple refrigerants or air ≥3%. ③ Manifold/hose contamination — trace level, only detected by the identifier on the next job. Handling direction: System contamination → recover the whole system + check compressor and filter-drier + recharge with fresh refrigerant. Recovery tank contamination → quarantine label ('CONTAMINATED') and outsource to a professional recovery service (never reuse). Manifold/hose → purge with N₂ blow or replace. What to do: Procedure: ① System contamination — a) recover everything to a tank labeled 'CONTAMINATED', b) replace compressor and filter-drier (run an acid test; if ≥0.05 mgKOH/g, run the burnout clean-up — see compressor-oil-acid), c) evacuate ≤500 micron + 30-min decay, d) charge from a fresh can, e) re-verify with identifier post-charge (single gas ≥98%). ② Recovery tank — a) label 'CONTAMINATED — Mixed Refrigerants', b) quarantine in storage, c) hand off to a certified professional recovery service quarterly or when full. ③ Manifold hoses — purge with ~5 bar N₂ from both ends for 1 min → re-verify. Discard hoses older than 5 years or with cuts/cracks. ④ Recovery machine maintenance — for frequent use, schedule maker-recommended cleaning and oil change every 6 months.

Refrigerant cross contamination — system / recovery tank contamination scenarios and remedy

Likely causes

Contamination paths — where and how mixing happens

When contamination is found — system vs recovery tank handling

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