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Discussion Starter · #1 · (Edited)
With the recent discussions about using PVC for air lines I contacted an engineer acquittance and asked for his input and he E mailed me this link. Looks like it actually may be illegal to use even in a private installation in some states and soon to be in others. Whether it is or not this is something that should be considered by someone thinking about or already using this very dangerous system. I think the problem here is that most people have no idea just how violent a PVC pipe rupture can be and how much damage it can do nor do most realize how easily it can happen.

www.osha.gov/dts/hib/hib_data/hib19880520.html

Just an added note to think about, he also pointed out that if you are involved in a PVC accident small deeply embedded and potentially life threatening shards will not show up on an x-ray!

Here are a couple of DOCUMENTED incidents.

PVC piping buried 3 feet underground at a Yakima manufacturing plant exploded, opening up a crater approximately 4 feet deep by 3 feet across.

Last year, a section of PVC pipe being used for compressed air exploded 27 feet above a warehouse floor. A fragment of the pipe flew 60 feet and embedded itself in a roll of paper. Fortunately, nobody was in the area at the time.
 

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Wow - these are extremely old bulleteins...but a search doesn't reveal anything newer than 1990 where OSHA states "...impact resistant acrylonitrile-butadiene-styrene (ABS) pipe, resists shatter-type failures under known sizing, pressure and environmental conditions"

The Use of Thermoplastic Pipe in Above Ground Locations: December 13, 1990

So what OSHA says (IMHO) if you use PVC for compressed gases it shouldn't be over 100psi, and buried, or encased in shatterproof covering.

But ABS piping can be used without the added protections for compressed gases...does anyone know more about ABS pipe?
 

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Discussion Starter · #4 ·
That's the surprising thing about this, this problem has been known for so long yet it is still done. There is no auguring that a PVC system will have the odds in it's favor however the possible consequences of a failure is too great to justify the cost difference between PVC and a safe system. It is just as dangerous today as it was 15 years ago just not as widely used today.
 

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oldred said:
That's the surprising thing about this, this problem has been known for so long yet it is still done. There is no auguring that a PVC system will have the odds in it's favor however the possible consequences of a failure is too great to justify the cost difference between PVC and a safe system. It is just as dangerous today as it was 15 years ago just not as widely used today.
Aw Crap ... really? :(

I was going to plumb my shop with Airmax brand (nylon?) tubing.
We used to sell this stuff at NAPA when I worked there, and it sounds like wonderful stuff. Light-weight, flexible, easy to wok with, and non-corroding. It's also more efficient than black pipe ... which is pretty porous, they say.

 

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ur best bet is using galvanized steel to plumb it using copper is more prone to leaks(im a plumber) pvc and anything flexabile i wouldnt trust someone can be lazy and pull and snap lines pvc i dont care what u use is prone to leaks the last 10 percent of every fitting is what holds it together if u want something easier to handle use type k thick wall copper and braze it using silver solder(not in rolls) there in sticks you either use a b tank or alot of map itll hold up to the psi and is less prone to leaks when done properly we use that for linesets in ac which regularly runs 150psi and has u can tell some are around for 25 years
 

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Discussion Starter · #7 · (Edited)
66, That really has nothing to do with PVC pipe and you are talking about true air products there designed for the purpose. While I think that stuff should be safe enough it would still seem to have the poor cooling properties of the PVC and IMO iron or copper would be a better choice for plumbing an entire shop. This would of course be open to debate as both types of systems have advantages and it would depend a lot on what the user wants and expects out of his system but safety should not be an issue and that is the biggest reason not to use PVC. I in no way mean to imply that I think iron or copper is the only safe thing to use, heck you can just use rubber air hose if you like as long as the working pressure rating is high enough and even though you may encounter some water there probably would be few other problems and it should work safely enough. Also it looks as if if it might be great for a dentists office but a tad small for a garage, I think it is designed more for trucks than truck shops.

Thanks for the link some folks may find that interesting and just what they are looking for however, while I am not saying that I think it is not a good product, I would recommend researching it and comparing the advantages/disadvantages before taking the plunge.
 

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oldred said:
66, That really has nothing to do with PVC pipe and you are talking about true air products there designed for the purpose. While I think that stuff should be safe enough it would still seem to have the poor cooling properties of the PVC and IMO iron or copper would be a better choice for plumbing an entire shop. This would of course be open to debate as both types of systems have advantages and it would depend a lot on what the user wants and expects out of his system but safety should not be an issue and that is the biggest reason not to use PVC. I in no way mean to imply that I think iron or copper is the only safe thing to use, heck you can just use rubber air hose if you like as long as the working pressure rating is high enough and even though you may encounter some water there probably would be few other problems and it should work safely enough. Also it looks as if if it might be great for a dentists office but a tad small for a garage, I think it is designed more for trucks than truck shops.

Thanks for the link some folks may find that interesting and just what they are looking for however, while I am not saying that I think it is not a good product, I would recommend researching it and comparing the advantages/disadvantages before taking the plunge.
OK.
Maybe I'll go and grab thier catalog or brochures ... not much info on Airmax's website.

Quality of products that we did sell seemed to be top-drawer. I'm talking about couplers and plugs, FRL's, regulators, etc. Built very well, and no leaks.

Thier claim to fame / catch-phrase was "pneumatic energy" ... and how their product avoided "wasting it" by leakage.

All of that nylon(?) pipe used "slip-fit" (I can't recall the term they used) fittings at all joints. You simply inserted the pipe into the fitting, and gave it a tug backwards to make sure that it was "captured". The harder you pull, the more it grips. To remove a component, you simply pushed a release collar inward, and pulled the pipe back out. You could even install a cap in the same manner.
 

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Discussion Starter · #9 ·
Leakage is not an issue on a properly done iron/copper system (hose reels, quick couplings and hoses is another matter). I can not imagine pipe leakage due to porosity being a problem unless you are using some kind of junk pipe and I don't think the pipe itself leaking is a problem at all. The fittings they have may very well be leak proof and easy to use to make a leak free assembly but with attention to detail fitting leakage is not a problem with iron/copper either. Durability is another question and I would think (just thinking here not stating as fact) that most any kind of plastic piping would require protection from outside damage from things like torch/welding sparks etc that would not faze a metal line. There are many things to consider and what works for one may not be the best choice for everyone so there very well may be a place for this system however I can see no place at all for a hazardous system of any kind, which this one is apparently not but PVC quite clearly is.
 

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I have been down this road several times and for me in an automotive shop I have found 1/2" black iron pipe to be the way to go as it passes code just fine with the inspectors and it is not all that hard to work with..One just needs a hand pipe threader and and a means of cutting it..I just use my chop saw..

Run it over head and put in a tee or two where you think you may be wanting to put another drop..I terminate my drops with a filter regulator so that covers the individual needs at a particular spot..Systems like this have been in service for many years with no known issues and sometimes doing things in the proven way is best..

Sam
 

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I've had PVC lines in my garage since '87. That said, I'd not do it over that way. In fact, I may be redoing my air system in the near future. PVC will work (and has worked well for me), but the older I get the more I think about the "danger factor" involved in doing things...

Russ
 

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Discussion Starter · #12 ·
Omt, Exactly, Logic like that is hard to argue with and while I suppose it is a good idea to at least look at new ideas I just fail to see why someone would want a fragile plastic air line instead of a good solid, safe and NEARLY INDESTRUCTIBLE metal piping system that will last a life time and then some. The cost savings with PVC over iron pipe is just not enough to justify the moisture problem not to even mention the dangers involved. Maybe there is some advantage to that AirMax system but I doubt it would take anywhere near the punishment that iron pipe would (or copper) and with iron or copper there is no question about either safety or performance. I know that some will argue that black iron pipe will rust and galvanized will flake off inside but in all the years I have worked on and with these types of pipe I have just not found this to be a problem. :confused: Unless a system is neglected to the point that it stands full of water all the time, in which case you will have problems no matter what you use, any small amount of rust that forms is going to be caught by the filter with other contaminates that will be there anyway. As far as the galvanized flaking, other than right after the first time it is used, I just cannot see a problem here and I really think it is overblown. Copper eliminates even these problems, if indeed problems they are, with the added benefit of better cooling but then cooling problems with the iron is rare anyway.

As the old saying goes "If it ain't broke don't fix it"
 

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Discussion Starter · #13 ·
S10, Twenty year old PVC is scary and I am really serious when I say that. If you think about the possible consequences of continuing to use that stuff and just how violent a failure can be it is scary. I am not trying to be a know-it-all here it is just that I have worked on air systems for a long time and I have seen the results of air explosions of different devices, some containing far less volume than a piping system. that old PVC could very well be a ticking time bomb and I would strongly urge you to replace it before it is too late.
 

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OldRed,
Thank you for the information. I will definitely be using either iron pipe or heavy copper for my air system.
Sometimes when people state facts in ways they do because they know the stories and have experience, other people take easy offense to that. :nono:
I have also ran across people that have been doing something a certain way, or using a certain product for so long. Then they find out the process or product isn't correct, or isn't safe, they get upset because it's what they are used to, and don't want to think of it being wrong this whole time.

Regardless of how people react, thanks for your information. Someone who has been around this stuff for so long obviously has a lot of information and experience to share.

Sorry, just felt I wanted to say something on the subject. Didn't mean to offend anyone or take over the thread. :boxing:

Rob
 

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Nhrafan26 said:
OldRed,
Thank you for the information. I will definitely be using either iron pipe or heavy copper for my air system.
Sometimes when people state facts in ways they do because they know the stories and have experience, other people take easy offense to that. :nono:
I have also ran across people that have been doing something a certain way, or using a certain product for so long. Then they find out the process or product isn't correct, or isn't safe, they get upset because it's what they are used to, and don't want to think of it being wrong this whole time.

Regardless of how people react, thanks for your information. Someone who has been around this stuff for so long obviously has a lot of information and experience to share.

Sorry, just felt I wanted to say something on the subject. Didn't mean to offend anyone or take over the thread. :boxing:

Rob
Rob, I've reread every post in this thread and don't see anybody being "offended" anywhere (certainly not me). I simply stated that I did mine with PVC, incidentally, way before this board existed (20 years ago!) and with no one's expertise to fall back on. As stated, I would not do it again this way even though I've never had an incident. Someday, I'll even get around to changing it out. :thumbup: These forums are a wonderful fount of information, but remember, us older guys grew up without them and did just fine.

Russ
 

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Rambo_The_Dog said:
Wow - these are extremely old bulleteins...but a search doesn't reveal anything newer than 1990 where OSHA states "...impact resistant acrylonitrile-butadiene-styrene (ABS) pipe, resists shatter-type failures under known sizing, pressure and environmental conditions"

The Use of Thermoplastic Pipe in Above Ground Locations: December 13, 1990

So what OSHA says (IMHO) if you use PVC for compressed gases it shouldn't be over 100psi, and buried, or encased in shatterproof covering.

But ABS piping can be used without the added protections for compressed gases...does anyone know more about ABS pipe?
So no one has used impact resistant acrylonitrile-butadiene-styrene (ABS) pipe in their shops? It would be nice to get some additional information on this material as it IS rated for compressed gas use.
 

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for what it's worth, i ran copper in my shop last year after discussing with my cousin (20+ years as a bodyman) and he told me once he was working in a shop and the limiting switch on the compressor went bad , he was working at a bench and the pvc line was at eye level , he just turned his back to the line to walk away from the bench and BOOM, the line exploded and he had shards of pvc in his back and a blood speckled shirt.... needless to say he advised against pvc so i ran copper (had to sweat 38 fittings..argh) but amazingly not one of em leaked ! so it really wasn't too bad.. i ran 3/4" copper
 

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Discussion Starter · #18 ·
I have no experience with ABS for compressed air but I understand it is far more flexible and the pressure rating is less heat sensitive so it should be safe from the shattering problem. If it is rated for the pressure it may very well be safe to use but I would still think it would make for a bad system due to cooling problems under high flow conditions, maybe? :confused:
When it comes right down to it just how much can one save on a 50' system and what would the trade-offs be? I would think that the few dollars saved would not be worth trading a time proven extremely durable system for a moisture prone and fragile plastic system but if it is safe and thats what someone wants it may work ok.

I did a quick search and came up with this, found it interesting :)

www.cbs.state.or.us/osha/interps/1989/im-89-06(rr).pdf
 

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59 wagon man said:
in my earlier days as a plumber in NJ we used abs on waste lines i have never seen it in anything smaller than 1-1/4" and the pressure on a waste line enen during testing purposes is only a few psi .
Low pressure on a sewage waste line is a GOOD thing.
If you ever had a high pressure rupture ... the crap would really fly. :D
 
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