Brazing with silver solder

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anyone do any copper pipe silver solder brazing? Any tips for heat prep etc.. Have done a ton of plumbing brazing but the pressures this will be under (300 or so on a compressor at the store) i need to be sure of a good fit and seal. Thxs for your time, paul
Reply:For copper to copper joints, most of the refrigeration people I know use an alloy with copper, phosphorus and silver, often called Sil-Phos and made by a number of manufacturers. It comes in various grades and is self-fluxing on copper, but needs a flux with brass. One brand, Sil-Fos, has this site with a selection guide and alloy data:http://www.silfos.com/htmdocs/produc...ion_guide.html
Reply:I think sil-phos is a brand name.  I've used the same stuff from weldcote.  Make the copper shiny just like you would with regular plumbing solder.  You'll need O/A to get the temperature you need.  I usually use a welding tip (uhh.. 00 or 000 size I'll have to look in the shop tonight, but that's for 1/4 line).  You could probably get away with a cutting attachment if you're careful not to bump the lever.  It seems to me the silver braze is easier to use than most plumbing solder.  Getting it too hot doesn't seem to be as much of a problem (until you blow a hole in the copper!)The silver-phos-copper stuff doesn't need flux if the silver is 15% or less (might fudge a little more).  High silver content needs flux and is expensive.  I've never used the high silver content, but I think it's more prone to cracking under vibration.Edit: Are you using brass fittings?  You might skip those and use the copper sweat-to-thread fittings.Last edited by AndyA; 01-25-2010 at 09:54 AM.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:thxs guy this helps out a ton
Reply:Silphos 15 is fairly standard for refrigeration and air conditioning refrigerant lines.  It's self fluxing on copper and wets much easier than tin solders used for copper house plumbing.  The surfaces to be brazed need to be well cleaned and shiny, usually with emery cloth or wire brush.  Make sure the fittings are the right ones and fit properly.  (Don't use the wrong size fittings and rely on the silphos to fill in large gaps.)  I try to get some of the silphos to wick into the joint.  Don't overheat the fittings, particularly if using an acetylene torch as the copper can melt.  If the fitting is connected to and close to anything heat sensitive, wrap some wet towels around the copper line between the area being brazed and the equipment.  (Valves with rubber/plastic parts and compressors full of oil don't like to be heated!)This is a decent demo of silphos brazing though the results aren't the prettiest:[ame="http://www.youtube.com/watch?v=9YPOD9zHn7Q"]http://www.youtube.com/watch?v=9YPOD9zHn7Q[/ame]Last edited by Zac; 01-25-2010 at 04:15 PM.Electronics Engineer (embedded controls)Miller 200DX w/ Coolmate 3Thermal Dynamics 82 plasma cutterGrizzly G0678 8x30 millPM1440BV 14x40 latheHF 6x12 surface grinder
Reply:thxs fella's, had to replace a condensor which was leaking and a compressor which was locking up. Went really easy and simpler then water sweating really because of no flux and the sil-phos seems to hunt out the heat i guess. Nice to have the net to figure stuff out. Be safe, paul
Reply:Originally Posted by ZacSilphos 15 is fairly standard for refrigeration and air conditioning refrigerant lines.  It's self fluxing on copper and wets much easier than tin solders used for copper house plumbing.  The surfaces to be brazed need to be well cleaned and shiny, usually with emery cloth or wire brush.  Make sure the fittings are the right ones and fit properly.  (Don't use the wrong size fittings and rely on the silphos to fill in large gaps.)  I try to get some of the silphos to wick into the joint.  Don't overheat the fittings, particularly if using an acetylene torch as the copper can melt.  If the fitting is connected to and close to anything heat sensitive, wrap some wet towels around the copper line between the area being brazed and the equipment.  (Valves with rubber/plastic parts and compressors full of oil don't like to be heated!)This is a decent demo of silphos brazing though the results aren't the prettiest:
Reply:Originally Posted by PookieThis guy is obviously a self-appointed expert at sweating copper.  I have sweated a million miles of copper pipe and there was one glaring flaw with his work.  The way I learned, you always keep the flame 180* from the solder.  Heating on one side, soldering on the other.  That could be the very reason his work looked like pigeons had been there.