Quite risky i think personally ....
Hes talking about isolating the charge and keeping minumum pressure on the side with the leak. Its a good way to change out bad switches or fix valve cores or do minor brazing repairs.
Am I understanding this correctly? Doing brazing repairs with refrigerant in the system?
Here's the problem I have encounter with any positive pressure in the system. It's trying to get out of your weld through a small pin hole :gah: Do you know what I'm talking about ? Now if you could continue to vent through another port that might work.
For example on an evaporator repair:
Close the liquid valve
push in the contactor to pump the system down to 2 PSI
crack open your low side gauge valve to let the residual pressure vent.
braze up the leak, close your gauge valves, set your service valves back to the normal position, start up the system.
Although this is probably not considered "deminimus release" I feel that it falls within the spirit of the law to minimize refrigerant release. On a big system, pulling a vacuum on the whole thing releases alot more refrigerant than venting 2 PSI from a 1/4 hose for 10 minutes.
I don't think the government cares about the spirit of the law. Intentionally venting is intentionally venting. I also disagree with your supposition that if the system was recovered to the EPA regulations that you would vent more refrigerant to the atmosphere when evacuating.Quote:
Originally Posted by craig1
One thing I haven't heard mentioned is the effect of brazing kind of heat does to the chemical composition of the refrigerant. This just my opinion...brazing on a system with refrigerant in it doesn't conform to any standard of best practices.
Given the choice between hoping I don't get caught for venting refrigerant, hoping I can braze under a positive pressure, hoping the pressure doesn't run out and non condensables are introduced to the system, and hoping the acid created in the system by overheating refrigerant is small enough that the system filter/driers can handle it.....I'll recover the gas and hook up a vacuum pump when the leak is fixed - every time.
just changed out a hi/lo pressure switch on a semi-hermetic compressor using this tactic. get everything ready for the switch, then crack system open. plug release port with finger, then quickly switch out fittings.
very little refrigerant lost with zero contamination getting into system because positive pressure was never lost. much less refrigerant lost vs pumping down system.
an empty 30lb tank of R-22 vapor... contains about 12oz of recoverable refrigerant.
Got eh done. Ball valves were at the roof mounted condensing unit. Suction & liquid line, thank you to whoever did the install. Had everything on the roof ready to go. Reclaimed the refrigerant. Used a drill bit I have to cut the tube sheet, it cuts on its side. Makes a clean cut out. Brazed some silfos in the hole. New drier. Nitrogen to pressurize and make sure it holds. Vacuum pump. Used reclaim to get refrigerant back in quickly. 3 hours.
Ball valves not service valves ?
1/4 turn ball valves.