Joining copper for air lines

[roofster]

I'm starting a Franzinator project and wondering if most use solder or braze when creating copper air systems. I'll post pics as I go.

 

[6768rogues]

I use solder for air and braze refrigerant lines.

 

[mrobins297aaa]

stay brite #8

 

[LS6 Tommy]

I haven't seen a Franzinator on a compressor in years. Most of my pneumatic systems in my buildings use refrigerated dehydrators these days. They also cost a lot more than anyone wants to spend for a home compressor. Back in the "old days" the basic rule of thumb for HVAC systems was to braze if the joint would be exposed to heat or vibration, solder if not. These days they want to braze or at least silver solder all the joints with the higher operating pressures of the new refrigerants.
I think you'd be safe soldering with the pressures & temps an air system develops unless it's going to be close enough to the pump to experience a lot of vibration.


Tommy

 

[machine_punk]

If you solder the copper lines, you must make sure you decouple the compressor from the pipe. Put something in the system to keep the vibration away from the copper pipe...get a 6ft hydraulic hose made with NPT ends and use that to go from the compressor to the piping system. Your local hydraulic shop (pretty much every town has one) can put just about any end on a hydraulic hose of whatever length you need.

If you braze, you don't need to decouple the system (but it's a good idea anyway).

Kev

 

[Highlux]

silver solder. the pricey stuff.

 

[roofster]

I plan to decouple it from the compressor and looking at air hoses now. Should I consider hose barbs for 150-175 psi or should I go with something more robust? Also, should one end be a swivel fitting?

 

[koditten]

The hydraulic hose that was meantioned is the best way to go from your compressor to your Cu pipe system.

Dont worry about swivel ends, just get the hyd. hose with male pipe threads on both ends. Install a union on whatever side of the hose you think looks best.

 

[Angelfire]

Brazing is the best way to go but that being said, if you decide to solder, just be sure to pick a higher melting temp. solder. 95/5 Tin/Antimony is generally considered to be more than up to the task of compressed air (pipe would be rated at 625psi at 150F). Whereas a lower temp solder such as 50/50 Lead/Tin would only be rated at 150psi at the same temp.

 

[soapii]

Should I consider hose barbs for 150-175 psi or should I go with something more robust?

Hose barbs are more than capable of handling those pressures.

I have NPT hose barbs at my compressor and drops to break the system with rubber air line.

--Joe

 

[BD1]

You could use PROPRESS. Awesome for air and clean. Not cheap. Some supply houses will rent tool when you buy the fittings. We did many commercial installation using Propress.

 

[oldmerc]

Solder .

 

[scotstern]

What about Shark Bite? Just curious.....

 

[Charles (in GA)]

Copper Tube Handbook, by the Copper Development Assn.

This will give you all the strength specs on tubing types, jointing methods and strengths of joints, etc. If you are working with copper, you need this.

Charles

 

[shooting4life]

I used solder on my copper air lines. I used a stainless flexible hose that are used for hot water heaters as the whip. I have not had an issue with vibration or leakage.

If you are worried about a fire melting the solder, just remember the rubber hose will melt sooner than the fittings letting all the compressed air out into the fire.

 

[wanderer]

I would stay away from anything that uses an O ring to seal because it's not intended to handle oil from the compressor. That includes shark bite fittings.

That said, anything mentioned will probably work. I would solder myself.

 

[jwith68]

Solder is more than adequate for any pressures seen in up to a typical 2 stage compressor-supplied air system, ~175 psi. Brazing and silver solder hold great, but they're overkill, and may cause more problems than they solve. Unless you plan to nitrogen purge every joint, you will get significant amounts of flux residue and copper oxide on the inside of the joint that will then come off little by little and into the rest of the system. The higher melting point of the brazing rod/silver solder (~1150°F) causes this, while the sub-500°F melting point of solder does not.

If you feel like you really want greater joint strength than solder, look at Harris Sta-Brite 8, as mentioned earlier by mrrobins297aaa. It's used regularly with no issues on AC & refrigeration systems using high pressure refrigerants, even R410A, yet requires only regular sweating temps.

 

[roofster]

Somewhere I recall reading that a guy said to braze copper for air lines. I had read some things at the site Charles suggested and braze seemed like overkill, so I posted to see what most do, and solder seems perfectly adequate. Thanks all.

 

[Angelfire]

The point is to use the proper solder. A cooler melting solder will mean failure at lower temperatures/pressures.

The Handbook Charles posted has all the gory details.

 

[Charles (in GA)]

If you feel like you really want greater joint strength than solder, look at Harris Sta-Brite 8, as mentioned earlier by mrrobins297aaa. It's used regularly with no issues on AC & refrigeration systems using high pressure refrigerants, even R410A, yet requires only regular sweating temps.

Interesting and good to know.

Specs and info HERE

Charles

 

[Boomer343]

I use Stay Brite 8 to join copper to tool steel in a high frequency application tool running 10000 OPM and have yet to have a joint failure on the 40 units I've built so far.

You may choke on the price but it is worth the cost. Use their matching flux and directions and you won't ever have to worry.

 

[hayhauler71]

I soldered mine 8 years ago with no problems and used a 3/4 lead in hose for vibration

 

[bigpokie]

Pfffft. Just pro press it all. Saves sooooo much time ! Lol

 

[mrobins297aaa]

Solder is more than adequate for any pressures seen in up to a typical 2 stage compressor-supplied air system, ~175 psi. Brazing and silver solder hold great, but they're overkill, and may cause more problems than they solve. Unless you plan to nitrogen purge every joint, you will get significant amounts of flux residue and copper oxide on the inside of the joint that will then come off little by little and into the rest of the system. The higher melting point of the brazing rod/silver solder (~1150°F) causes this, while the sub-500°F melting point of solder does not.

If you feel like you really want greater joint strength than solder, look at Harris Sta-Brite 8, as mentioned earlier by mrrobins297aaa. It's used regularly with no issues on AC & refrigeration systems using high pressure refrigerants, even R410A, yet requires only regular sweating temps.

its great stuff, leaves a nice clean joint on the inside, a little pricey but it solders up with a propane torch.
in the 80's and 90's we did a ton ac systems with it and never had a problem with a joint coming apart.........only thing is you can't fill with it, like if you need to connect a 1/2" pipe to a 3/4" and you don't have a fitting, then you need to braze.

 

[OccupantRJ]

silver solder. the pricey stuff.

Yeah, the silver solder we use at work is $20 a troy ounce, 1/32" diameter, only $1,000 for a 50 Oz coil.

 

[mrobins297aaa]

about $65 on ebay...........stay brite #8

http://www.ebay.com/itm/Harris-Prod...ultDomain_0&hash=item3cd6f203a3#ht_1111wt_625

 

[Mr onetwo]

Definitely don't need to braze.If you do decide to braze, you should use nitrogen to purge the oxygen from the inside of the piping system.Otherwise, you will have flakes throughout your system.Check out this company for air compressor rated flex connectors...http://www.ebay.com/itm/Flexible-Me...011?pt=LH_DefaultDomain_0&hash=item2c6533bec3 I have purchased a lot of stuff from them...very good company!Also, Silvabrite 100 solder is rated for more pressure than the copper tube itself @ 300 degrees F and is much much cheaper than silver bearing solders.Make sure you use "L" copper tubing.Use proper techniques and be sparing with the flux and you will have no problems at all!I would recommend Harris Stay-Clean flux...very clean joints.

 

[Doradoguy]

After installing several thousand feet of copper for air systems, it's safe to say solder is does the job. Nitrogen purge won't help much unless you plan on installing proper filtration and dyers. I'm required to use silver soldier in medical applications, along with purging with nitrogen but it has nothing to do with strength. I have used shark bite in a pinch but don't like the fact it swivels. Most of my recent work is done in 2 inch black pipe. Flex line is a good idea for final connecting.

 

[lightn95]

question.... in the spring im going to move my compressor into my shed (about 50') from my garage.what would you guys recommend for the air lines underground. im not going to use black pipe. i cannt have any rust in the lines ! i was thinking 1" copper pitched down at the garage. and a ball valve to bleed out any condensation before it goes up into the garage. what do you guys think??

 

[Ross/Kzoo]

question.... in the spring im going to move my compressor into my shed (about 50') from my garage.what would you guys recommend for the air lines underground. im not going to use black pipe. i cannt have any rust in the lines ! i was thinking 1" copper pitched down at the garage. and a ball valve to bleed out any condensation before it goes up into the garage. what do you guys think??

And what are going to do about cathodic protection? I think that you're going to have some deterioration of the copper in contact with the ground.

 

[Mr onetwo]

question.... in the spring im going to move my compressor into my shed (about 50') from my garage.what would you guys recommend for the air lines underground. im not going to use black pipe. i cannt have any rust in the lines ! i was thinking 1" copper pitched down at the garage. and a ball valve to bleed out any condensation before it goes up into the garage. what do you guys think??

Perhaps you could use 1" CTS (copper tube size) poly water pipe.It will take the pressure and will last forever underground.You must get rid of as much water as possible before it goes underground and all the heat out of the air that you can with an aftercooler or ref. dryer.