Two Cylinders and an R-22 Cold Room
A technician is asked to look at a walk-in cold room at a small supermarket. The condensing unit nameplate reads R-22, charge 4.8 kg. The store has kept two cylinders from a previous contractor: one grey cylinder with a hand-written tag reading 'R-22 - RECLAIMED 2013' and a valve with a left-hand thread; and one rusted cylinder with no label at all. The owner says the second cylinder 'should be R-22 as well, they always bought them together'. At 21 degrees Celsius the unlabelled cylinder shows a standing pressure of about 9 bar on the technician's gauge set, which the owner says 'proves it is R-22'. The system is short of charge, the suction line is not sweating, and the owner wants it topped up and left alone before a bank holiday weekend.
1. What can and cannot be concluded from the 9 bar standing pressure? What would you actually do to identify the contents?
Read the worked answer
What the pressure tells you Standing pressure only tells you the saturation pressure at the cylinder's temperature. At 21 degrees Celsius the approximate values are:
- R-22: about 9 bar
- R-407C: about 9.3 bar
- R-134a: about 5.7 bar
- R-410A: about 14.4 bar
So 9 bar is consistent with R-22, but it is also consistent with R-407C, and a zeotropic blend can give a drifting reading as the cylinder sits. It rules out the R-134a and R-410A families and nothing more. Add gauge error, whether the gauge is reading gauge or absolute pressure, and the fact that cylinders are routinely decanted into each other, and the pressure is weak evidence.
What to do
- Check the valve type, cylinder markings, tare weight and any test date.
- Use a calibrated refrigerant identifier and record the result. Identifiers are not infallible on contaminated or blended gas, so treat an odd result as a red flag, not a clearance.
- Check purchase and service records for the site.
- If it cannot be positively identified, treat it as unknown refrigerant: label it 'CONTENTS UNKNOWN - DO NOT USE', store it upright and capped in a ventilated area, and send it for analysis or to a permitted waste operator.
2. Even if the reclaimed R-22 is genuine and in date, may it be used to top up this system? Explain the legal position.
Read the worked answer
No. R-22 is an HCFC, controlled separately from the HFC rules.
- Virgin HCFC has been prohibited for use in servicing since 1 January 2010.
- The use of recycled or reclaimed HCFC for maintenance or servicing of refrigeration and air-conditioning equipment has been prohibited since 1 January 2015. The narrow derogation that allowed an undertaking to reuse HCFC it had itself recovered expired on 1 January 2020.
A tag reading 'reclaimed 2013' does not make the gas usable today; if anything it confirms the material is well past the point where it could lawfully be charged into a system.
So what are the options?
- Recover the remaining R-22 from the unit using HCFC-compatible recovery equipment and send it for destruction.
- Repair the leak and either retrofit the system to a suitable HFC or HFO blend, or replace the unit. A retrofit is not a drop-in: R-22 systems use mineral oil, most HFC blends need POE, so the oil, the expansion device and often the line sizes need attention, and the charge must be recorded as a new refrigerant with its own GWP.
- Explain to the owner in writing why a top-up is not available, before the bank holiday rather than after.
3. What must happen to the unlabelled cylinder?
Read the worked answer
- Do not use it, and do not vent it to 'find out what it is'. Both are offences and the second is also a safety risk if the contents are flammable or at high pressure.
- Make it safe: confirm the valve is closed and the valve cap fitted, keep it upright, move it out of the walk-in and away from the food, store it in a ventilated, bunded area away from ignition sources and heat.
- Label it clearly as contents unknown, with the date and who applied the label.
- Check the cylinder itself: badly rusted cylinders may be structurally compromised and should be removed as a priority; check the last hydrostatic test date if legible.
- Dispose properly: either have the contents identified by a competent laboratory/refrigerant analyser, or consign the whole cylinder to a permitted hazardous-waste contractor, completing the waste transfer documentation.
- Record and notify: note in the site file that the cylinder was found unlabelled, and confirm your actions to the owner in writing so responsibility does not default back to you later.