Re: Reclaiming R-134a from system

Posted by T_Bone on May 16, 2004 at 12:47:17 from (4.240.132.195):

In Reply to: Reclaiming R-134a from system posted by Shane on May 15, 2004 at 16:36:46:

Hi Shane,

To answer your question, Yes you can vapor recover any refrigerant.

You will need to put the receiver in an "ice water bath" then apply heat to the condensor. This method will get you closer to the refrigerant boiling point, -40º.

From the refrigerant boiling point tempature you will see that you will leave some refrigerant behind in the system as a ice water bath is 32º.

As Bob pointed out slow down the vapor tranfer and is more important at the beginning than at the end as vapor pressure drops very fast towards the end of transfer.

Specific gravitity will stop all metal transfer in "saturated vapor" form transfers.

Air is not compressable "when" mixed with a refrigerant and they act as two seperate gases with-in a closed refrigeration system. Knowing this then brings up other considerations when recharging the system.

When the refrigertion system is opened to the atmoshere, then moister ladden air rushes into the system to replace the displacement of the refrigerant. The free moist air will overwhelm the refrigerant desiccant (dryer) and must be removed. Why?

Water mixed with oil creates a acid base. That acid will attack the refrigeration componets over time. Water comes from the moister in the air and the oil comes from adding refrigerant oil for the compressor as well as other system componets.

The recomended procedure for compressor replacement requires three system blow down charges before evacuation. Blow down charge = filling the system with a inert gas then discharging this gas in looped manor. The blow down charge removes moister, air, as well can be used for checking for system leaks (my preferred method). I do not like refrigerant leak detectors as it's very easy to miss small leaks. I NEVER use refrigerant dye for leak testing as the dye is known to plug expansion valves.

Either carbon dioxide or dry nitrogen can be used as the blow down charge. I use dry nitrogen as it's a stable gas, meaning once to tempature nitrogen pressure is very stable. As the nitrogen pressure remains stable, a gauge leak test can be preformed. Any small leak can quickly be detected. Another advantage is dry nitrogen absorbs moister shortening the evacuation time considerably.

After three blow down charges then it's time to evacuate the system with a vaccum pump. At 28.5hg, water starts to boil at 70ºF. At 29.925hg the system is mostly free of any mositer but needs to be held at 29.925hg for 1hr for a completely dry system with blow down charges being used. If no blow down charges are being used, then evacuation time is considerabley more.

It would be cost effective to have the system "properly" recharged after replacing system componets if you don't have the correct equipment.

T_Bone

Follow Ups:

Post a Followup Name: E-Mail: Subject: Re: Re: Reclaiming R-134a from system Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]