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Old 05-18-11, 10:04 PM   #11
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Quote:
Originally Posted by S-F View Post
FWIW I have the small kit from Home Depot. I got it for doing exhaust work on the car. For cutting. I would be very careful with oxygen and mapp since it cuts a steel exhaust pipe pretty easily. I imagine it would make pretty short work of a copper tube.
I saw some melting points of different metals, and you are right about steel vs. copper.

Melting temperatures of metals

But, cast iron is pretty close to copper..


Maybe a heating tip, instead of a cutting or welding tip will work for heating
copper enough to draw in a filler alloy..

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Old 05-21-11, 08:24 AM   #12
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Humm, CO2 is sometimes used as a shielding gas in wire-feed welders...

I'm very low on Nitrogen. What would happen if I used CO2 to flush out the air?
And trickled CO2 slowly while brazing??

Would it cause some horrible deposits to form inside the copper tube?

I have about 10 pounds of CO2 (Don't tell Al Gore)!
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Old 05-21-11, 11:08 AM   #13
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Hey Rich,
That nozzel is way to big...We are using #2 tips on our rigs for all our braizing...
What kind of system do you have ?..Is it a split system ?..Air handler in the closet or attic and condencing unit outside..Or a package unit ?...
I think what you are saying is, that You want to braize and fix the pinhole leak while having refrigerant still in system ? I posed the question to my teacher...Thats not a good idea if thats what your planning ?..Refrigerant is flamable..Im sure ya know...!and goes boom lol...Im not sure if Im understanding your plan ?..

If your adding nitrigen to the system I assume it doesnt have any refrigerant left ?..

We were discussing using nitigen when braizing..As the copper heats it creates and ash that will fall inside the pipe..So some techs actually crack the system and add a slow flow of nitrogen as they braize...
Most techs after fixing issues such as yours will.....add a dryer inline to collect moister.. then make sure system is sealed( no leaks) Vacuum down the system..Which intern removes moister..You should hold vac. for atleast 15 minutes..If pressure holds ?..Then charge the sytem to spec.
I hope that at this point your not rolling your eyes lol..I have read your post a couple times and still feel Im missing a detail or two lol...But ?..Im sure ya have a handle on things!! Lee
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Old 05-21-11, 06:05 PM   #14
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The R410A has all leaked out, months ago, before the outdoor unit was replaced.

Here's the system.
http://ecorenovator.org/forum/geothe...l-project.html

Thanks for the info on the number 2 tip. I've got no clue what that is, but I'll look it up.

I have not purchased a rig yet. After I get some filler metal,
I'll check out my old torch with MAPP gas to see what's possible.
Then, I'll look into getting a portable torch rig.

I've been talking to a buddy who told me not to buy tanks,
since I might be able to get them locally for less money (no shipping).

And he tells me the local Gas supply guys don't re-fill the tanks,
they swap them for loaner tanks, when you come in for a refill.

If you bring in your own tanks(to trade for full ones),
you have to present a bill-of-sale, because they don't want
to be charged with receiving stolen property.
(A lot of thefts in this area, it's near Boston)..
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Old 05-22-11, 10:19 AM   #15
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OK...So your going to vacumm the system when fix is complete.Thats a pretty neat system..I havent seen that before.
Yep..When ya take new tanks to get filled they swap them..If your not going to buy a complete rig..( Tanks and all) Check out Northerntool.com.They have setups for about $150.00. Again..speaking with my teach..He frowned upon buying rig and tanks seperate...I guess tanks can get pretty expensive..and when all said and done..Your paying about the same ?..Ya might be able to find tanks on ebay etc. But dunno about the regulators..I think thats where all the money is ?
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Old 05-22-11, 11:15 AM   #16
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Quote:
Originally Posted by Daox View Post
Does map gas alone not get hot enough to braze for HVAC?
Funny you should mention that.

A few years ago, this guy I knew (who I must emphasize IS NOT ME) got into home distilling. Now this means a lot of copper: a large-diameter, packed column for the vapor, and a smaller, jacketed one for the condensed goodies.

For strength, he thought "silver solder/brazing" was the way to go. Using *just one* H-D mapp canister was unworkable on Cu of over 1/2" I.D. What DID work was duct-taping TWO bottles together, such that the flames pointed at the same general location. This could heat copper up to 2" I.D. to brazing temp, and probably could work on much bigger pieces.
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Old 05-22-11, 04:11 PM   #17
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Default electro soldering/brazing...

Just when you thought it was safe to go outside...

I have a buddy that used a hand held spot welder to heat copper water pipe for soldering.

I never heard of anybody doing that before, but he said it worked great for him. Faster than gas.

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Old 05-22-11, 11:06 PM   #18
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At work, I have an American Beauty soldering rig.. It's a auto-transformer connected to the pinchers.


I use them to solder SMA connectors on .141" hardline coax cables.
The cables are good up to about 25 gHz..
I grip the base of the connector (sliver plated alloy) with the pincher probes.
When I step on the foot petal, the current turns the connector red hot
within a few seconds. A ring of solder, wrapped around the cable melts
and flows into the connector body, bonding it to the cable's shield.

It's the little brother of this one..
YouTube - ‪Resistance brazing 3/8 and 1/2" copper tubing, using American Beauty resistance soldering equipment.‬‏
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Old 05-22-11, 11:26 PM   #19
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I've got 8.8 oz of filler metal coming at the end of this week.
I hope it works ok on AC plumbing. I plan to try it with MAPP gas.
May not even melt.. It's an experiment.


Check out the sellers note on the auction page..

PLEASE READ CAREFULLY: UP FOR AUCTION IS 4.4 OUNCES (4 RODS 36 INCHES LONG) OF SILVER BRAZING ROD. THESE RODS ARE FROM THE 70'S AND ARE NOT STAMPED. I'VE HAD THEM SINCE THEN AND USED THEM MANY TIMES FOR SWEATING COPPER, ETC., FLOWS VERY NICELY. ON THE TATTERED BOX I WROTE MANY YEARS AGO WITH PEN: 15 ALLOY EH 144 1/8 X .05 X 36 IN. SINCE THEY'RE NOT STAMPED I AM LISTING THEM AT 5% SILVER AND NOT 15% CONTENT TO COVER MY BUTT IN THE EVENT OF NIT PICKING (NO OFFENSE INTENDED). IF YOUR JOB IS CRITICAL FOR 5% PLEASE DO NOT BID ON THESE RODS. THEY ARE 36 INCHES LONG. FOR SHIPPING PURPOSES I WILL BEND THEM TO FIT INTO A SMALLER BOX. YOU CAN ALWAYS BEND THEM BACK OR CUT THEM WHEN YOU GET THEM. FREE SHIPPING IN LOWER USA. I'M LISTING THESE 4 RODS AT A TIME BUT IF YOU WANT MORE JUST BID ON THE REST, FREE SHIPPING, MAKES NO DIFFERENCE. THESE RODS STILL HAVE SOME LUSTER BUT ARE NOT BRIGHT AND SHINY. KEY WORDS: SILVER SOLDER BRAZE BRAZING WELDING SWEATING
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Old 05-22-11, 11:34 PM   #20
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Quote:
Originally Posted by Xringer View Post
Humm, CO2 is sometimes used as a shielding gas in wire-feed welders...

I'm very low on Nitrogen. What would happen if I used CO2 to flush out the air?
And trickled CO2 slowly while brazing??

Would it cause some horrible deposits to form inside the copper tube?

I have about 10 pounds of CO2 (Don't tell Al Gore)!

I used Google and found a couple pages like this one..

co2 purge - HVAC-Talk: Heating, Air & Refrigeration Discussion

"CO2 is OK as a purge gas, as long as it is dry CO2".

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