|Joined: ||Fri Feb 27th, 2009|
|Location: ||California USA|
|This method is approved by the EPA under specific conditions that you can find on the EPA refrigeration site. It is generally used with functional compressors that are capable of drawing some minimal vacuum levels. The EPA is mainly concerned about preventing "unnecessary" (basically anything more than de minimus) purging of refrigerant to the environment. Gone are the days when you just opened a petcock at one end of the compressor and filled refrigerant from the other side. So even if you use those plastic gas bags, you've still got to either recycle the refrigerant back into the same machine you just worked on, or you've got to take it to a reclaimer/recycler.
Real problems arise with contaminated systems: mixed refrigerants, H2O in the system, or the dreaded "burn out." For dead compressors, there's a lightweight and nifty hand pump (Spooter) that was (and I think still is) EPA approved. It may be strong enough to clear contamination and moisture from some systems, but to really dry and clean some systems you'll need a deep vacuum pump.