Recovery cylinder fill limit and a mystery mixed cylinder
You are decommissioning three split systems in a retail unit: charges of 2.8 kg, 3.5 kg and 4.2 kg, a total of 10.5 kg of R-410A. Your recovery cylinder is marked water capacity 12.0 L, tare 9.0 kg, maximum working pressure 32 bar, and the plant room is at 26 C, where liquid R-410A has a density of about 1.05 kg/L. The previous contractor has also left behind a cylinder labelled 'R-410A / R-32 mixed, do not use' containing roughly 4 kg. The client asks you to 'stick that in the same cylinder and take it away with the rest'.
1. Calculate whether all 10.5 kg will fit in the recovery cylinder, and state how you would control the filling operation.
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Working
- The fill limit is 80% of water capacity: 0.80 x 12.0 L = 9.6 L of liquid.
- At 26 C, R-410A liquid density is about 1.05 kg/L, so the maximum net charge is 9.6 x 1.05 = about 10.1 kg.
- Recovered total is 10.5 kg, which exceeds that, and the margin only shrinks as the cylinder warms. Use a second cylinder; do not 'just get it in'.
Filling controls
- Fill by weight, not by feel or by time: gross weight must not exceed tare + permitted net fill; check the tare stamped on the cylinder, not the label.
- Non-return/valved recovery cylinder in date for pressure testing, correct connection, no over-pressurisation; monitor pressure and stop if it approaches the working pressure.
- Weigh each system's recovery separately so the records match the decommissioning, and allow for the gas still in the hoses and the recovery machine.
Judgement point
- An overfilled cylinder with liquid filling the ullage can go hydraulic and relieve or rupture on a warm van – this is the classic decommissioning accident.
2. How should you deal with the 'R-410A / R-32 mixed' cylinder, and why is mixing recovered refrigerants unacceptable?
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Handling the mixed cylinder
- Do not decant it into your R-410A cylinder. Keep it separate, verify the contents as far as you can, label it clearly with what is known, the approximate weight, the date and the source, and store it upright and secured.
- Consign it to a permitted waste contractor for destruction or specialist reclamation, with a waste transfer note; recovered refrigerant of unknown composition has no reuse route.
Why mixing is unacceptable
- It destroys any possibility of reclamation – a reclaim plant cannot economically separate an unknown blend, so the whole cylinder becomes waste.
- It creates a safety problem: the mixture's composition, pressure and flammability classification (R-32 is A2L, R-410A is A1) are unknown, so cylinder rating, storage and transport assumptions are no longer valid.
- Records become meaningless: you cannot state what gas was recovered from which system.
Judgement point
- Refusing the client's request costs a few minutes of explanation; agreeing contaminates 10.5 kg of recoverable gas and puts an unclassified mixture on the road.
3. What records must accompany the decommissioning, and can the recovered R-410A simply be charged back into a replacement system on the same site?
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Records
- For each system: refrigerant type, charge, quantity recovered, date, and the system it came from.
- The cylinder identity, tare weight, gross weight and net contents.
- Who did the recovery (certified individual and company) and where the gas went – reclamation, recycling on the same equipment, or destruction – supported by a waste transfer note or reclaim documentation.
- The operator's own F-gas records updated to show the equipment is decommissioned and the charge removed.
Can it be recharged?
- Not as a matter of course. Recovered refrigerant may only be put back into equipment if it has been reclaimed to the required specification and is documented as such, or, in limited circumstances, recycled and returned to the same equipment it came from by the same operator.
- Batch gas from three different systems, of unknown moisture, acid and oil content, is a candidate for reclamation or destruction, not for a new machine under warranty.
Judgement point
- Reusing 'free' gas can void a manufacturer's warranty and, if it is off-specification, take out a compressor – explain the cost of that to the client rather than quietly doing it.