Copper "Propress" Fittings for Shop Compressed Air

Hi Guys,

Doing compressed air installation at my new home shop. I've used sweated copper pipe in my work shops and I have been happy with it. But time consuming and invariably I always have a few slow leaks in the soldered joints.

The plumbers all seem to love the copper press fittings. Propress is a common brand name. Example:
7742 - Viega 7742 - 3/4" x 3/4" x 1/2" Propress Copper Tee

Basically there is an o-ring and then you use a specialized crimper to crimp the copper and squeeze the o-ring. The Milwaukee crimper is $2800. But it looks like for $200 there is a favorably reviewed hand crimper:
IWISS IWS-1632AF Plumbing Copper Pipe Crimper Press Tube Tools with 1/2" 3/4" 1" Jaws Suitable for Viega Copper Only, Pro-Press, Elkhart, Conex Pipe Fittings - - Amazon.com

From what I read, these fittings are rated for compressed air service. But I haven't found anyone who has done shop air plumbing with it.

Any thoughts?

Thanks,

-Jim

kb0thn said:

Hi Guys,

Doing compressed air installation at my new home shop. I've used sweated copper pipe in my work shops and I have been happy with it. But time consuming and invariably I always have a few slow leaks in the soldered joints.

The plumbers all seem to love the copper press fittings. Propress is a common brand name. Example:
7742 - Viega 7742 - 3/4" x 3/4" x 1/2" Propress Copper Tee

Basically there is an o-ring and then you use a specialized crimper to crimp the copper and squeeze the o-ring. The Milwaukee crimper is $2800. But it looks like for $200 there is a favorably reviewed hand crimper:
IWISS IWS-1632AF Plumbing Copper Pipe Crimper Press Tube Tools with 1/2" 3/4" 1" Jaws Suitable for Viega Copper Only, Pro-Press, Elkhart, Conex Pipe Fittings - - Amazon.com

From what I read, these fittings are rated for compressed air service. But I haven't found anyone who has done shop air plumbing with it.

Any thoughts?

Thanks,

-Jim

Click to expand...

I'd think it would be hard for an o-ring and a $200 crimper to beat a silver-soldered copper connection. These could be terrific for water (max. 60 psi or so, a fairly viscous fluid, and a wet joint) and not be happy after several years of 150 or so psi, thinner air, and vibration? Each silver soldered joint (a few percent silver is a bit better than tin-lead) is maybe a couple minutes of work. Seems that $200 for the crimper would buy a couple home shops worth of time to solder them up? Fittings are also a bit more expensive.

Could be the new fittings are terrific for air. But last time I was an early adopter for the latest and greatest (OK, decades ago and CPVC pipe and fittings) it took a few years to learn they were crap.

My own home shop has soldered copper running through two floors, inside and out service, with maybe 20 outlets. Not a leak after 15 years or so. I went with type L tubing (lighter than K, heavier than M) and it seemed about the right balance between durability and cost for a home shop.

Thought #1: The Propress system is expensive.

Thought #2: It is pretty easy to get a leak proof joint when soldering copper tube. Use the classic lead-tin solder that used to be normal for water and is easier to use than the lead free stuff they use for water now.

Larry

At a fire house we saw they used a PEX pipe system.

Simple roll it out and crimp the connections.



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I use black pipe and Teflon thread sealant to run the air in my shop. Makes it real simple to add fittings and valves since everything is already uses pipe thread. And you can use larger lines to get around the shop without sacrificing flow, then neck down for drops. All the fittings are cheap and easy to get.

I used Pex for a replacement on a leaking flexible air line (didn't really need to be flex) in my garage for a quick "field expedient" fix once. Still there after almost 10 years. Still doesn't leak, probably will last 50 more.

Tony Quiring said:

At a fire house we saw they used a PEX pipe system.

Click to expand...

Regular PEX is not rated for compressed gas of any kind. For compressed air, you need to go with PEX-AL-PEX, which is rigid. IIRC, it's only rated for 188 PSI max. Look for Parker Transair. Tubing and fittings are not cheap.

As for copper, the only "legal" pipe for compressed air is "K". Joints are to be brazed or welded.

But what the heck, there are still idiots out there running PVC.
JR

JRIowa said:

As for copper, the only "legal" pipe for compressed air is "K". Joints are to be brazed or welded.

Click to expand...

In the interest of doing it right: Where or what standard defines what is "legal" for compressed air service? I see various of the pressed copper manufacturers claiming their stuff is suitable for compressed air service.


At work I bought one of those Maxline HDPE / aluminum / HDPE compressed air kits. Was underwhelmed with it. Tubing couldn't get straight enough for my liking and the fittings were bulky. My air lines run on strut along side straight conduit and wireway. Putting in a roller coaster of air line didn't do it for me.

Thanks

We are seeing more use of the compression joints on copper. It is not because it is better in any way but because it saves labor. I'm not sure but in addition to the tools being expensive I think the fittings also cost more. For my own application I still and will sweat joints they will last longer than I will.

As far as the plastic systems go, at work we have been using some ABS air line now for about 20+ years. It is rated for compressed air. It was chosen for cleanliness since it is a pharmaceutical plant. We are starting to see some failures and are switching back to copper. Having 3" air lines fail is just a little too exciting.

kb0thn said:

In the interest of doing it right: Where or what standard defines what is "legal" for compressed air service?

Click to expand...

Since OSHA regs haven't been updated since they were written, any inspection now deffers to "Industry Standards". For machine tools etc, it's usually an ANSI standard. There is a book/website published by the copper tubing manufacturers. It has their standards for all copper tubing and pipe. Somewhere in it is the listing for K type with allowable working pressures and shock loads.

Even then, if an OSHA inspector goes through your place, he might not even notice the air lines.
JR

kb0thn said:

From what I read, these fittings are rated for compressed air service. But I haven't found anyone who has done shop air plumbing with it.

Any thoughts?

Click to expand...

The usual trade guys I see buying those are using them for water. And they are not big sellers.

For air these are the most secure:



Application engineers tell me that a pipe bursts before the joint fails.
All you need is a small wrench
Going from pipe to thread is a given.
Elbow, straight, different diameters, etc.
Brass, stainless.
Joints can be taken apart.

Mechanical joints or welded are all that's legal around here. If the fire melts the pipe "or O-ring", you have a potential of the fitting failing. Then the blast of air feeds the fire. I know soldered copper is not legal, but not sure of silver brazed.

Theres nothing wrong with decent threaded galvanised pipe in my experience, so long as you use a dryer at the tank - compressor before you flood the network. Can't believe at the cost of copper anyone would contemplate it for air service?

I have installed 3/4" through 3" propress air lines in copper and stainless. It is a nice system. They do hold well, I had a stainless 90 unbend to a 45 and it was barely leaking.

The copper is cheap when using 2" and less, over 2" is very expensive. Stainless is god expensive. Copper itself is an expensive option to begin with.

I have the Ingersoll Rand simple epl? pipe installed in my shop. That stuff is great. I got it from a customer who moved and gave me the old stuff. The fittings are completely reusable and it's all aluminum pipe. Another expensive option

The best thing using PP and the IR piping is adding in a drop anywhere is simple and fast. PP fittings are 1 and done, IR fittings are reusable forever.

Copper PP is using type L pipe only. PP is rated to 200 psi, tested to 600

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It's not hard to sweat a copper joint that won't leak.

As just a comment, it's been a while since I looked, but I think even the thin wall copper pipe has a burst strength over over 2000psi.

Here are some pressure ratings: http://www.alascop.com/pdf/cu/water_tubing_1.pdf

In a home shop, like the OP, I doubt anything over 1" would be needed - 3/4" more likely. Ordinary tin-lead solder doesn't give much of a safety margin for a two-stage compressor (175 psi), but it's adequate. Use a solder/braze with just a bit of silver in it and the joint is near as strong as the tubing.

Two of the reasons K type is required in industrial settings are, first, that larger tube sizes are often used and, second, that some degree of physical protection of the tubing against bumps and scrapes is desired. IMO, the thinnest stuff isn't worth the trouble of installing, but L type works fine in a well-designed home shop. My own shop has a about three hundred feet of mostly 3/4" tubing; some of it zig-zagged on a cool (below grade concrete) wall to cool the air down a bit. Not that expensive for 3/4 and 1/2" tubing; and it won't rust (no flakes to be filtered out of the air) and is easier than black pipe in the event of extending the system.

Bondo said:

I have installed 3/4" through 3" propress air lines in copper and stainless. It is a nice system. They do hold well, I had a stainless 90 unbend to a 45 and it was barely leaking.

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Awesome! This is just what I was hoping to hear.

Part of wanting to try the pressed copper fittings is just to keep up with what is going on. I'm a relatively young guy (33), so I can't get stuck in my ways too soon. I'm also building a house this year and will be doing the radiant plumbing myself. Building the pump / manifold / water heater myself saves about $2k versus buying a a factory made system. And I can put on the components I want versus some value engineered pre-built system.

GregSY said:

It's not hard to sweat a copper joint that won't leak.

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I've done probably 400 sweated 1/2 - 1" fittings in the last year. I think I had 4 or 5 that have leaked. Two were on a radiant heat system and were royal pains in the butt to fix. Depressurize and attempt to dry out the area around the fittings. Got it fixed, but melted the fiberglass behind the plumbing and now it looks ugly. The other two fittings were compressed air on the work shop system. To be fair to me, I think it might have been my father in law that soldered them. But same story. They are behind equipment and getting in there to fix the leak has been a challenge. On the fourth attempt and am about to give up and just cut out the section and do repair couplings on the side so I can get on with life.

adama said:

Can't believe at the cost of copper anyone would contemplate it for air service?

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It's about as cheap as I can imagine around here. 1/2" L copper is $8.41 per 10ft and 3/4" is $14.32 per 10ft. Black steel pipe is $10.89 for 1/2 and $13.69 for 3/4". That's made in Asian basically unthreadable garbage pipe. Good copper solder or press fittings are about the same price as Chinese black steel fittings. And even though I own a big Ridgid 500 pipe threader and dies, it still takes me longer to cut and thread steel pipe than it does copper.

Thanks,

-Jim

Closing the system and pressurizing with air (with a gauge in the system) for 24 hours before charging with water is SOP for plumbers around here. Heat shields are useful, too.