ABS for Air

[alberto]

It is with great trepidation that I start this thread but here goes. No flaming, this is an honest question. We'll see how stupid it might be. Be nice. I've searched for this topic, but the search function ignores the term ABS in a search.

First the disclaimer: I AM NOT ASKING ABOUT PVC USE FOR COMPRESSED AIR.

My question is, has anyone used ABS for their compressed air system?

Why isn't ABS a safe alternative for an air system? ABS is much more ductile and not prone to shattering like (the other product), presumably eliminating the main problem with (the other product). I understand that most of it is not rated for air use and OSHA disclaims its use on grounds that only one or two ABS systems are rated for air use, but why wouldn't it be generally safe to use, even if not rated? I found the attached chart on the internet, which shows that the Izod Impact rating at 73 F of ABS is about 10 times higher than for (the other product).

 

[Crusty Nut]

Not flaming you, but why? Why not just use a bombproof (as in safe) product like copper, black pipe, or a legit rated safe for air non-metal product?
If you would expect or demand an employer to provide you with a safe work place, why would you not provide one for yourself?

 

[Stuart in MN]

If the manufacturer says it's not to be used with compressed air, that's good enough for me. There is, or was, one brand of ABS pipe specifically designed for compressed air. However, it wasn't something you'd find at the local big box store, and I've heard it's out of production anyway.

 

[Steevo]

ABS would appear to have the pressure ratings to accommodate air line usage . . . .
The lowest grade shows 175PSI rating for a 1" pipe ( for water pressure).

So . . . why doesn't anyone use it for air pressure?
Unlike "the other product", I have never even heard of anyone using ABS for pressurized service, other than for sprinkler systems, which are what, 40 psi?, maybe 75?

 

[djjsr]

Just curious, what size abs pipe are you proposing? I think the smallest I've ever seen is 1 1/2" for drain lines and a pipe that size will store some serious energy.

 

[alberto]

Not flaming you, but why? Why not just use a bombproof (as in safe) product like copper, black pipe, or a legit rated safe for air non-metal product?
If you would expect or demand an employer to provide you with a safe work place, why would you not provide one for yourself?

It's intellectual curiosity. I didn't say I was going to use the normal ABS nor did I say the normal ABS was safe. Mostly, I'm trying to understand the difference between the regular ABS and the ABS stuff they sell specifically for air use (for example http://www.nibco.com/assets/ChmairTech.pdf), beyond the sales pitch language about extensively modified formulation.

Just curious, what size abs pipe are you proposing? I think the smallest I've ever seen is 1 1/2" for drain lines and a pipe that size will store some serious energy.

Hmm, good point. Now that you mention it, I also have not seen it in the smaller dimensions, except for the stuff that is advertised for use for air, which comes as small as 20mm.

 

[alberto]

ABS would appear to have the pressure ratings to accommodate air line usage . . . .
The lowest grade shows 175PSI rating for a 1" pipe ( for water pressure).

So . . . why doesn't anyone use it for air pressure?
Unlike "the other product", I have never even heard of anyone using ABS for pressurized service, other than for sprinkler systems, which are what, 40 psi?, maybe 75?

What the chart doesn't show is that it gets lower by a fair amount above 73 degrees. There's a chart on the internet which lead me to conclude that above about 100 degrees, you want to stop using the system or lower the pressure a bit. Fortunately, I'm not usually working in > 100F temps. so not that big an issue for me. You'd just have to make sure the temp out of the compressor isn't high, which I would do with a cooler.

 

[Jack Olsen]

I don't have any info/opinion on ABS as an air line. However, if you want to search three-letter words, or want to do boolean type searches on this site, you can use Google. Just go to the basic Google search page and type in:

site:http://www.garagejournal.com abs "air line" (or anything else).

Here's the search, as an example. (Since the GJ site is turning part of that into a link.)

 

[alberto]

I don't have any info/opinion on ABS as an air line. However, if you want to search three-letter words, or want to do boolean type searches on this site, you can use Google. Just go to the basic Google search page and type in:

site:http://www.garagejournal.com abs "air line" (or anything else).

Here's the search, as an example. (Since the GJ site is turning part of that into a link.)

Thanks a million for posting this, you are the man !!

 

[rsanter]

The short answer is that you want to use something that is rated for use at the required pressures for what you are using (air)
Air and water pressure is not the same because of the compressibility of air.

Let me tell you by personal experience. I worked at a company that made PVC fittings among other things. We had a tested that we could put a piece of pipe into that had a fitting installed onto it for purposes of testing. Now even though I am an engineer I could never see in my head how pressure was not that same as pressure with the only difference being between water and air.
So I tested it......I installed a section of pipe that had a fitting glued into it, closed the chamber and followed the procedure to fill the pipe with water and purge the air out before beginning the test. So I did that and proceeded to allow the water pressure to build until the pipe and fitting actually began to swell up or 'grow' a little bit indicating that the material was beginning to yield so I stopped the test

So I did the test again with a new part but did not purge the air from the system as per spec. No this system can only pump water, not air so it was pumping water into the test section adding to the air already in there.
There were no signs or anything happening other than the needle on the pressure gauge rising. Then at a little more that the pipe rating the fitting and pipe exploded a lot like a grenade making a very loud boom. There was no warning or sign of impending failure, just a loud boom. Fortunately it was all contained in a chamber or it could have been a bad thing.
What I performed was the water hammer test. This is exactly what happens when a new system is charged up without the air being vented out. There are regular failures on pipe systems in houses, buildings and sprinkler due to water hammer.

So why don't they just make it thinker or alter the plastic material....bla bla bla
I don't know as I think the thicker material should have an acctable safety margin. But the industry has not decided to move forward with this so it is what it is

So why not use ABS....the glue joint....PVC can be solvent welded making a very strong joint. ABS cannot be solvent welded, just glued. Think the same glue you use on plastic models. The S in ABS is for styrene just like they make models out of

Bob

 

[Dustin Echoes]

I ran into a similar conundrum when I was building a "too big" potato cannon. You can get pressure rated abs, it's called solid core abs. normal drain pipe is cellular core, and NOT pressure rated. For those who care, the cannon will fire a standard beer bottle a little over a kilometer. Runs on ether (starting fluid).

 

[Norcal]

There is a air line piping system made of ABS, & I think the pipe is metric so you have to use proprietary fittings & not PVC, I do not know any pro or cons, but as long as it is made for compressed air & has some sort of 3rd party approval / testing there should be no issues, safety concerns as long it's installed per manufacturers instructions.

 

[RVDan]

We used 2" schedule 40 solid core ABS at the last place I worked. The only issue was at the end fittings, they would constantly crack where the we adapted the ABS down to pipe thread for the air couplers. The eventual solution was adapting to a flexible line in between the ABS and air coupler so nobody was pulling on the connection anymore.

It worked fine for about ten years, actually worked better than before because all that two inch pipe acted as an extra air tank.

Somebody changed it all in the last couple years to a flexible white plastic line of some sort and crimped connections. I'm not sure why, I think somebody heard about somebody who knew somebody who told somebody that it was illegal.

 

[NUTTSGT]

I ran into a similar conundrum when I was building a "too big" potato cannon. You can get pressure rated abs, it's called solid core abs. normal drain pipe is cellular core, and NOT pressure rated. For those who care, the cannon will fire a standard beer bottle a little over a kilometer. Runs on ether (starting fluid).

I believe that deseves a thread of it's own.

 

[Falcon67]

I need some flexible "jumpers" to hook my horizontal iron attic runs to the vertical runs poking through the ceiling, only because I'm not going to shell out for the tools to cut and thread pipe. I looked at the local ABS stuff and most of it is water pipe and maxes out at 100 psi. I did find some 1/2" ID reinforced flexible pipe that is rated to 225psi. I'd use it for little short jumpers in the attic, but not anything longer than 12~18". I still have to get a brand name and check the temperature rating for the stuff. I'd use PEX but by the time you pop for the tools, you're out some bucks.

ABS for air would probably be a lot like PEX for air. Have to watch the temp pressure degradation for sure. It probably fails like I'd expect PEX to fail - with a tear or rip and not so much explosions and shrapnel.

 

[Dustin Echoes]

I believe that deseves a thread of it's own.

I'll see what I can do about that.

 

[DekeT]

I ran into a similar conundrum when I was building a "too big" potato cannon. You can get pressure rated abs, it's called solid core abs. normal drain pipe is cellular core, and NOT pressure rated. For those who care, the cannon will fire a standard beer bottle a little over a kilometer. Runs on ether (starting fluid).

I want to hear more about this. With pics.

 

[DekeT]

I need some flexible "jumpers" to hook my horizontal iron attic runs to the vertical runs poking through the ceiling, only because I'm not going to shell out for the tools to cut and thread pipe.

Hydraulic hose is a good flexible connection for air lines.