Seized Compressor: The 0 psig Exception and Hot-Work Safety
A 1996 process chiller with a 190 lb R-22 charge has a seized compressor that will not turn. The machine room is indoors, and the unit must be opened for a compressor replacement and a braze repair on the discharge line. A nitrogen cylinder with a regulator and a 200 psig relief is available. A second technician suggests using compressed air to blow out the lines and a halide torch to check the joints after brazing, and says the remaining charge can just be released because the compressor is dead and the unit is small.
1. What recovery level is required here, and how does the seized compressor change the analysis?
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Normal requirement would be 10 in Hg. The unit is post-November 15, 1993 (1996) and its charge is 200 lb or less (190 lb), which places it in the 10 in Hg tier. (Over 200 lb post-1993 is 15 in Hg; pre-1993 equipment is 4 in Hg.)
The seized compressor changes it: when the appliance's compressor is not operational and the system cannot be brought to the standard level, the requirement drops to 0 psig - recover to atmospheric and stop. This exists because a dead compressor cannot help move refrigerant, and the machine may not hold a vacuum anyway.
Judgment points:
- 0 psig means 0 psig and holding, not "open the valve and walk away." Recovery equipment and a scale are still used, and the amount recovered is still recorded.
- Releasing the charge because the compressor is dead is venting and is prohibited. The seized compressor excuses the vacuum level, not the recovery.
- Do not attempt to pull a deep vacuum on a shell whose compressor is seized and whose oil may be loaded with refrigerant; the oil will outgas for a long time and the vacuum will not hold.
2. Evaluate the two suggestions: using compressed air to blow out the lines, and using a halide torch on the brazed joints.
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Compressed air: no, under any circumstances.
- Air carries moisture into a system that was just evacuated - directly undoing the evacuation work.
- Air plus residual refrigerant and oil can form flammable mixtures and acids inside the piping, particularly when heated.
- If the system still contains refrigerant, compressed air is an oxidizer/fuel combination under pressure.
Use dry nitrogen for blowing out lines and for pressure testing.
Halide torch: legal but the wrong tool here. In an indoor machine room the flame is both a fire hazard and a decomposition risk - a halide torch drawn across leaking R-22 produces phosgene-type breakdown products, and the detector is unreliable in the presence of drafts or residual refrigerant. Use an electronic leak detector rated for HCFCs (or nitrogen pressure with bubble solution or ultrasonic) instead.
Nitrogen test safety is the other half of the answer: use a regulator, never full cylinder pressure, set a relief below the low-side test limit, isolate the high side, and never use oxygen or a refrigerant cylinder as a pressure source.
3. The second technician says the unit is small and dead, so the remaining refrigerant can be released. Address this, including what records the job must produce.
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The release is prohibited. Venting has been illegal since 1990 under the Clean Air Act, and there is no "dead compressor" or "small system" exemption - 190 lb is not a de minimis quantity in any reading of the rule. The de minimis exceptions are narrow (small releases inherent in good-faith recovery, connecting/disconnecting hoses), not "dump the charge."
Records and compliance for this job:
- Amount recovered, recorded on the service ticket, with the recovery cylinder labeled.
- The leak/repair record and the evacuation level actually achieved, including the basis for stopping at 0 psig (compressor not operational).
- Retain service records 3 years - the appliance is well over the 5 lb threshold, so the paperwork obligation runs the entire life of the job.
- Certification: everyone recovering, evacuating, or charging must hold the appropriate Section 608 certification; the technician here is Type II work.
- Final disposal: if the chiller is scrapped rather than repaired, the appliance must be evacuated before disposal and the final processor must receive confirmation that the refrigerant was recovered.
Framing for the customer: the release saves minutes and costs the contractor the certification and the fine; recovery and reclamation of 190 lb of R-22 is also worth real money given current pricing.