Re: Re: Re: Re: Re: 1066 Update

Posted by T_Bone on January 15, 2001 at 07:58:28 from (207.254.52.138):

In Reply to: Re: Re: Re: Re: 1066 Update posted by Lee K. on January 15, 2001 at 01:32:22:

Hi Lee, The reason you can't use R-12 hoses and compressors is the seal material for R-12 is not compatiable with R-134A and will leak straight thru. It's the R-134A oil and refrigerant mix that attacks the seals & hoses.

Although the "dye" sounds like a good idea in pratical therory and has been around for many years, and it has been proven to sink to a low elbow and stay out of refrigerant solution and will only show up as a leak when the system is almost completely empty. The only correct way to check for leaks is to pull a vacuum for 1hr or until 29.950hg is achived for 1hr, then charge the system with dry nitrogen to 150psi, with no pressure loss for 15 minutes. Nitrogen does not expand volume with pressure loss like refrigerant will and makes it a peferct stable pressure test gas. Carbon dixoide is the only other stable gas that can be used but doesn't have the moisture retention property of nitrogen gas.

Depending on the quanity of H2O in a system, 30 mintues is no way long enough to rid a typical refrigerant system of mositure at 29.925hg and higher once that system has been opened to standard ambient air (70F @ 50%rh). At 29.925hg water begins to boil at 70F, thus turning into a vapor to be evacuated. On any open refrigerant system the proper method of recharge, is to pull a vacuum to 25.0hg or better, charge with nitrogen, blow down, pull another vacuum to 29.925hg, charge with 150psi nitrogen and pressure test, blow down, pull the final vacuum of 29.950hg for one hour, then charge with refrigerant. Another benifit of dry Nitrogen is it's ability to absorb moisture. The reason of why it's so critical to make sure all moisture is out of a system, is that the refrigerant oil and water creates a very strong acid attacking all metal componets. If one were to install a electronic vacuum gauge, it would confirm the above infromation and is a standard compressor Manufactures recomendation.

At standard condensing temperature of any refrigerant, condensensing pressure is only effected by ambient temperature and not by the ambient humidity of standard air, in an "air" over condensor system.

Any Refrigerant system will continue to cool in an over charged state unless high pressure controls have been added to the system and the system will continue to operate until compressor lock-up occures. Efficency of the system will diminish in a over charge state.

The above info was meant to be helpful and not to criticize as I have spent the past 30yrs in refrigeration service, design and instruction.

T_Bone

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