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-   -   More DIY HVAC Progress (http://www.diychatroom.com/f17/more-diy-hvac-progress-113836/)

jerryk1234 08-12-2011 08:15 PM

More DIY HVAC Progress
 
Today Mr UPS delivered a copy of "Refrigeration & Air Conditioning Technology"( 6th edition ). Wow, that's a big book. Very practical.

A few days ago, a pound of "Sil-Fos 15" brazing wire arrived. Today, I finally found some time to play with it. It turns out that I already had a roll of 3/8" ACR tubing laying around in the garage ( long story ).

Lacking any connectors, I chopped off a couple of pieces of tubing ( waiting on a quality tubing cutter to come in the mail ). Cleaned them off, butted one to the other, and brazed them together. I have to say, it was a piece of cake. I set up my O/A torch for a nice little 1/4" neutral flame, heated the copper red hot, touched the brazing rod to it - and it just flowed. No fuss, no muss. A perfect-looking joint resulted. Visibly I would say "that ain't gonna leak". And it seems to be just as strong as the rest of the tubing. Need to get some unions to try out. Also need some real emery cloth - I used a metal cleaning buff on my Dremel.

- JerryK

yuri 08-12-2011 08:34 PM

If you can MIG and TIG weld you should have no problem as you don't have the SHAKES.:no:

Master of Cold 08-12-2011 09:03 PM

Out in the field I try to avoid getting the pipe red hot and glowing. On the 3/8 its almost impossible. When the copper gets red hot it reacts with the oxygen in the air and oxidizes the copper. The black flakes you see on the outside of the pipe are also on the inside. These flakes clog up sceeens, txv's and driers. By flowing nitrogen through the pipe you will avoid oxidation.

jerryk1234 08-13-2011 08:32 AM

Quote:

Originally Posted by Master of Cold (Post 705970)
Out in the field I try to avoid getting the pipe red hot and glowing.

*** So it doesn't HAVE to be red hot to flow the Sil-Fos? That's kind
of how it seemed, but I wasn't sure. Other data I've seen on the Web intimated that it needed to be red hot.


Quote:

Originally Posted by Master of Cold (Post 705970)
On the 3/8 its almost impossible.

*** Sounds like an excuse to buy a Meco torch :whistling2:

Quote:

Originally Posted by Master of Cold (Post 705970)

When the copper gets red hot it reacts with the oxygen in the air and oxidizes the copper. The black flakes you see on the outside of the pipe are also on the inside. These flakes clog up sceeens, txv's and driers. By flowing nitrogen through the pipe you will avoid oxidation.

*** Yes, I've seen very convincing You-tube videos showing this.

- JerryK

jerryk1234 08-15-2011 10:45 AM

Quote:

Originally Posted by Master of Cold (Post 705970)
Out in the field I try to avoid getting the pipe red hot and glowing.

*** Which rod do you use?

According to web references, copper glows at 1200F. ( http://wiki.answers.com/Q/What_tempe...become_red_hot ).

According to the Sil-Fos website, Sil-fos 15 melts at 1190F but does not
"flow" until 1475F. It seems to me that you need "flow" to get capillary
action - otherwise, sealing is mostly on the surface of the joint.

- JerryK

yuri 08-15-2011 11:16 AM

silfoss is a surface joint unlike silver solder which has to suck into the joint. you heat the joint until the silfoss flows and it is pretty hard to not get it red hot.

Master of Cold 08-15-2011 06:39 PM

There is getting the pipe to glow gently, and then there is the glowing orange, it still glows when you pull the torch away.


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