05-27-11, 03:04 PM | #31 |
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MAPP gas would be fine for 1/2" copper and borderline for 3/4" copper. I have generally use acetylene for up to 1" copper and silver soldered the joints.
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05-27-11, 03:10 PM | #32 |
Lex Parsimoniae
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The mailman delivered my 15% (or 5%?) silver filler metal. See details at: http://ecorenovator.org/forum/tools/...html#post13673
I'll see if my torch w/ MAPP & new filler-metal rods will work on 1/2" copper this weekend, (I hope) and post the results. Last edited by Xringer; 05-27-11 at 04:18 PM.. |
05-27-11, 04:12 PM | #33 |
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HVAC, because of the incessant vibration and the relentless deep temperature-cycling really needs to be done with some kind of brazing rod. The trade seems to prefer 15% silver brazing rod. I'm doing ok with 5%, though the flow is maybe not so pretty.
HVAC is really a much more punishing environment than plumbing. Ironically, many of the HVAC guys I know talk about "soldering it up", but if questioned, will admit to brazing. -AC_Hacker
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05-27-11, 04:16 PM | #34 | ||
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Quote:
I found this dialog on a HVAC blog... thought you might find it interesting. Quote:
-AC_Hacker
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05-27-11, 06:39 PM | #35 |
Lex Parsimoniae
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Humm, "Addition of cadmium yields Ag-Cu-Zn-Cd alloys with improved fluidity and wetting and lower melting point; however cadmium is toxic. Addition of tin can play mostly the same role."
I'll bet tin is cheaper too. In any event, it's too much trouble to remove all the smoke/CO/gas detectors from the basement, so I'll be doing lighting the torch out in the (detached) garage.. Thanks for the warning about unlabeled filler.. Hope there isn't any radioactive isotopes in there! |
05-31-11, 11:53 PM | #36 |
Lex Parsimoniae
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Well, I tried to braze a cap on some 1/2" copper and it took forever to get the pipe
hot enough to accept some of the filler rod. I got it flowing on the top of the pipe at one point, but could not get it to flow inside on the sides or bottom of the pipe/cap. As a second test, I was going to place a wet cloth around the pipe, a few inches from the cap. After seeing the plain MAPP wasn't hacking it, I skipped the wet test. I think this is a job for a real torch. |
06-01-11, 01:16 AM | #37 | |
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OK, so you tried the propane torch... Were you able to get to a robust cherry red? If not, you might need a 'turbo torch'. There really is such a thing, it swirls the gas/air mix inside the torch for a better mix. I don't know that it would be worth your while to go and buy one just to see ($35 to $75). Maybe you have a friend that could loan you one so you could see if it helped. Here's the MAPP torch I use. Got it from a big-box place for about $40. I thought I was getting robbed, but it has made a big difference for me. I've used it for all my brazing, even brazing copper tube to a brazed-plate heat exchanger that has a completely water-soaked rag on the port I was brazing to. I'd say that the next step up after that is oxy acetylene, which really pours out heat. ...there may be an air/acetylene torch... check around. The Silfos doesn't need flux, but the parts still need to be clean. Did you wire brush or sand the surfaces you were brazing? -AC_Hacker
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06-01-11, 12:17 PM | #38 |
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Since the EPA drove the price of aceylene thru the roof due to the acetone in the tank($65 last time I filled my 100cuft bottle, ), I use propane-oxygen, same tips and regulators, have even done straight copper welds (12AWG as filler rod) but not on hvac. Oxy propane works well with silphos 15%.
You can usually score an oxy-acet rig (regulators, torch, hoses) off ebay for under $60 total, any propane tank works, and you only need a small oxy bottle (another $50 or so, have gotten some off CL for $20)) |
06-01-11, 12:48 PM | #39 | |
Lex Parsimoniae
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Inside the tip, it has vanes in a swirl configuration, so it might already be a type of 'turbo torch'. At first, I had the gas too low and it didn't work at all. So, I cranked up the flow and got better heating. But it was very hard to keep it hot enough to have flow for more than a second or two. Move the flame around to the other side, even a little and the flow 1/4" away was gone. Turned solid. Didn't get any cherry red at all. But, I had the garage door open and there may have been too much outdoor light to see the glow. Maybe I should try again and just keep the heat going for an extra 5 minutes or until it goes cherry?? I did clean the connections beforehand, but perhaps I didn't do a good enough job.?. My cleaner (unlike this one) is getting a bit old.. |
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06-01-11, 01:02 PM | #40 | |
Lex Parsimoniae
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I really like the idea of using Propane and oxygen. I can get 20 pounds of BBQ propane for about $15 around here. What do you mean " any propane tank works"? Are you referring to 'any' welding equipment propane tanks? I was thinking that maybe a regular portable rig tank like this one, #0384-0936 could be re-filled from a BBQ tank using an adapter? Then all I would need filled at a welding supplier is the O2.?. |
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