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Old 02-25-2007, 02:49 PM
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Default Brazing material for refrigerant lines

Out of sheer boredom and the nasty weather I have been practicing brazing some 1/4" and 3/8" copper tubing. Does anyone know what refrigeration techs would normally use to braze / solder refrigerant lines together. I have been using sil-phos since everything is copper and it seems to do the job however, it just does not seem to flow like solder, and leaves what I would call an ugly joint (a little lumpy looking). Well maybe the stuff I am using is not Sil-phos, I was just outside for a minute and looked at the container. It says Harris Stay-Silv 15. Maybe it is old or something. I got the one pound tube at a rummage sale for $2.25. I tried some Safety-Silv 45 and it appeared to flow good in most areas, but there were some gaps which makes me think you need a pretty tight fit for this to work properly. I have been using my Smith Little Torch with the largest tip. I can get the largest tubing cherry red almost to the point of melting if I don't back off a little. I am set up with Oxygen and propane. If anyone knows what I should be using please let me know........thanks,

Pat.
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Old 02-25-2007, 04:06 PM
hench861 hench861 is offline
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Default solder

we use a product called dynaflux its good for mapp/propane ,and it works on copper and steel lines
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Last edited by hench861; 03-18-2007 at 07:40 PM.
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Old 02-25-2007, 04:52 PM
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My son and I use Sil-Fos. Works for us. Can usually be had from an AC/Heating supply house. Link: http://www.silfos.com/
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Old 02-27-2007, 05:25 AM
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Tips, flame settings etc have a little to do with the process. Check on the www to see what the manf's are offering and see how close you can come with what you have and what the local's offer.

The age of some flux will have an effect on quality as well. Preping the tube and fittings has it's share as well.

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Old 03-07-2007, 05:07 PM
wtom24 wtom24 is offline
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For copper to copper use 15% silver/phosphorous without flux-the phos provides the cleaning only if you start out clean. Be especially careful to have a neutral flame so the base metal is not contaminated. A lot of people try to use air-acetylene [Turbotorch] which always has an oxidizing flame and this will corrode the base metal during the process. The copper needs to be almost cherry red for proper flow. For copper to brass or steel use 45% silver solder with flux. The joint must be perfectly clean and coated with flux before heat is applied. Sil-Phos will foam if used with either brass or steel and the resultant joint will be porous. The supply houses sell 10%,5%, and no% sil-phos, but it's not worth the hassle because the lower silver content will not flow in the field. In a manufacturing setting you can get by with the cheaper stuff because the conditions are carefully controlled.
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Old 03-17-2007, 12:08 AM
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Pat , The Harris Stay Silv 15 is what I use at work all the time when pulling tees in copper mains , and is what all the refrigeration techs use also . Never had any trouble with using a turbo torch A/A when brazing joints . Heat is the important part , you need to heat it up till it starts to glow cherry red and add the rod keep the heat up and work your silver solder around the joint . I am a certified Medical Gas Brazer so I have experience with it . Dan
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Old 03-18-2007, 07:36 PM
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I'll cast my vote for the 15% stuff also !

It's what all my HVAC buddies use.......and remember, this IS brazing, not soldering.......so make sure to keep that heat up there !
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Old 03-18-2007, 07:59 PM
stseely stseely is offline
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I used to work for a airconditioning manufacturer (AAON) and also as a plumber where we ran medical gas piping, we always used 5% sil-fos, the higher the silver content the more expensive it is. For brass to brass or coper to bras we used the same only with flux. And anytime you join to steel or stainless use 45% silver solder with flux.

I would use a neutral flame and add the filler just before the copper gets red, if you are joining brass it will hardly turn red before it just melts. When silver soldering the joint needs to be very clean, I even use alcahol to clean the fittings if I have it available. Its also very important to not apply the heat directly to the flux, If you get the flux too hot it will become inactive. I also put flux on the silversolder. Their is also low and high temp silversolder I have always used the high temp which melts around 1100F.

Also don't forget your supposed to run a nitrogen purge while your brazing refrigerant lines.
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Last edited by stseely; 03-18-2007 at 10:38 PM.
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