View Full Version : PVC Compressed Air lines
Five-10
04-14-2007, 03:29 PM
Anyone here using PVC pipe for their compressed air lines and if so how does it work? Copper is so expensive these days and steel always rusts inside.I just bought a building and will be moving in soon. It isn't plumbed for air. I have a 40hp screw compressor with a backup 30hp screw feeding 5 cnc machines.
No emphatically not!!!!! :eek: :eek: :eek: :eek:
Apart from causing heart attacks to any safety inspectors that come by it is far too dangerous.
When PVC fails under pressure it goes with a real bang and cracks propagate through the lengths of pipe very fast. You have a very good chance of filling your place with PVC shrapnel moving very fast.
There are no simple plastics that are safe for compressed gases. If you wanted to use a carbon fiber reinforced composite that might work..at many times the price of copper.
Use copper or galvanized. You should have a dryer on your compressor for CNC machines so with this there should be no water in the air to rust galvanized.
JEFFY
04-14-2007, 08:09 PM
DON'T EVER USE PVC FOR AIR LINES! Geof is right, pvc and air is like vineger and oil.
If you don't believe me go to any of the plastic fitting company's web sites(Nibco, Lasco, Spears, Mueller ect)they all say "DON'T USE ON COMPRESSED AIR/GASES" I worked in the plumbing industry for years and none of the manufactures approve of its use on any compressed gases.
If you want to see plastic fail, put a foot or two of pvc in your freezer for a couple of hours then drop it on the floor. It will shatter just like glass.
Please note, that this applies to hard plastic that is glue or threaded together.
If you really want plastic, look into flexiable plastic tubing(like the brake lines on semi-trucks) I myself use copper in my shop.
Please read the following link
http://www.spears.com/tech_updates/Tech-2-No.106_web.pdf
http://www.spears.com/prod_dimensions_spec/40-4-0206_0206.indd.pdf
http://www.lascofittings.com/supportcenter/CompressedAir.asp
Caprirs
04-14-2007, 08:55 PM
PVC is unsafe and illegal to use for air lines.
The key is as Geof stated, the explosive (not combustion, but rapid expansion) nature of compressed gases. PVC is rated to high pressure for liquids because liquids under pressure are not compressible. If you have a crack in a water line, you'll get a fountain which is annoying but not dangerous. The same crack in a PVC air line will cause the plastic to splinter and shatter because once vented, the compressed gas keeps trying to expand.
mactec54
04-15-2007, 03:08 AM
Five-10
There is a plastic pipe you can use it is Duraplus ABS Airline Pipe it is
OSHA aproved and you can get it from ( IPEX ) This is designed for compressed gases this will not shatter like PVC can
Five-10
There is a plastic pipe you can use it is Duraplus ABS Airline Pipe it is
OSHA aproved and you can get it from ( IPEX ) This is designed for compressed gases this will not shatter like PVC can
I stand corrected, Thank You.
I checked and found the Duraplus is rated at 185psi up to 73F and they also have a Duratec that is rated 160psi at 140F.
Now all I have to do is find a supplier and see how the price compares to copper or galvanized. It should certainly be easier to install.
The IPEX website does say it is a new product; I wonder how new.
tobyaxis
04-15-2007, 11:40 AM
Anyone here using PVC pipe for their compressed air lines and if so how does it work? Copper is so expensive these days and steel always rusts inside.I just bought a building and will be moving in soon. It isn't plumbed for air. I have a 40hp screw compressor with a backup 30hp screw feeding 5 cnc machines.
No Way!!!!!!!! I saw some JackA$$ do this in a shop and while a co-worker was next to one of the lines it exploded. He is deaf in one ear now. Not to mention the scars on his face and ear.
Never Ever Do This!!!!!!!!!! The Dangers are far too great to take the cheap way out.
That new product might work better but never use PVC.
I should make it clear; this is the only sentence I stand corrected on:
"There are no simple plastics that are safe for compressed gases."
tobyaxis
04-15-2007, 08:47 PM
I should make it clear; this is the only sentence I stand corrected on:
"There are no simple plastics that are safe for compressed gases."
Sorry my post was windy. Yours is simple and to the point.
BTW: your up too 3000 posts.:D
Sorry my post was windy. Yours is simple and to the point.
BTW: your up too 3000 posts.:D
And you say you are the windy one; you are an amateur when it comes to windy.:)
tobyaxis
04-15-2007, 09:04 PM
And you say you are the windy one; you are an amateur when it comes to windy.:)
Well, unfortunately I lack experience and age LOL.:D I won't ever catch up to you but some day be as windy as you are now LOL.:rolleyes: :p
Cheers!!!!!:cheers:
Five-10
04-16-2007, 08:55 AM
OK, I decided to go Copper. Max Machine cuts no corners machining so I'm not going to start cutting corners with my new building. By the way my Haas service tech is the one that mentioned pvc to me. He's was complaining about rust in my steel lines as he was replacing the leaky regulator on my new VF6SS.
... rust in my steel lines as he was replacing the leaky regulator on my new VF6SS.
Get a good dryer, it is worth it in the long run. When a solnoid faults because of water in the air you can lose the cost of the dryer very quickly.
Five-10
04-16-2007, 12:08 PM
I should have mentioned in my first post that I have an air dryer (325 SCFM) So I don't really get any water in my lines. This building I'm in now was a tractor trailer repair shop and The airlines were in place when I leased it. They didn't have an air dryer and the steel pipes are all rusted inside.
Oh so you blew rust particles into your machines without knowing it? That is a nasty lesson to learn; don't use existing airlines without a detailed inspection.
ger21
04-16-2007, 03:45 PM
The IPEX website does say it is a new product; I wonder how new.
We've had Duraplus air lines in our shop for 8-9 years or so. Haven't had any problems with it.
At maximum operating temperature for PVC (140ºF, 60ºC) the strength is derated to approximately 20% of the strength at 73ºF (23ºC). For CPVC the strength is reduced to 20% of the initial strength at 200ºF (93ºC). PVC is degraded by sunlight further weakening it.
For threaded fittings, derate to 50%
For cold regions, derate at least 50% depending upon temp. Ask any spud gun advocate why he doesn't shoot in the winter time.
This is far too great a hazard to save a few bucks. Keep in mind, copper is easy to install, modify, and later remove. And, it's reuse and/or scrap value increases with time. Think of it as a long term investment.
.... Ask any spud gun advocate why he doesn't shoot in the winter time....
Spud gun advocates should be using ABS pipe :)
ger21; I had never bumped into Duraplus and I never bothered searching for rigid plastic airlines because I never expected to find anything.
I agree wholeheartedly. You are obviously aware of the hazards. Good for you !
mecheng9
04-24-2007, 09:16 PM
Five-10,
It sounds like the copper is a good idea and a good air filter and drier.
regards,
Mecheng9
MDLang
04-25-2007, 01:16 AM
It seems we may be encountering some resistance to change and old prejudices against using certain materials.
Like ger21 our shop has all plastic lines and has been this way for 7 years. No problems.
Mike
ImanCarrot
04-25-2007, 07:58 AM
I use Aluminium "Transair tube Aliuminium 37X40" it's rated to a PMax of 13 Bar.
I second what Geof says about a dryer- I just cannot afford to have water vapour on my slideways... and change the filters regularly. The dryer should be inline after the resevoir (which didn't make sense to me, but that's what the company who service it said).
You also need to drain the resevoir tank every day (i get about a pint of water a day from mine).
Also, in the UK for insurance purposes, the system has to be inspected regularly for employer liability insurance purposes.
Also! don't be tempted to use cheap oil in your pump, it will separate and emulsify with water vapour.
It seems we may be encountering some resistance to change and old prejudices against using certain materials.
Like ger21 our shop has all plastic lines and has been this way for 7 years. No problems.
Mike
Mike. Old prejudices against using this PVC for compressed gasses are well founded. Perhaps reinforced by the constant warnings from ALL manufactures and safety agencies? My experience in the spud gun sport confirms the inherent hazards. I did my own controlled environment research (destructive testing) on PVC and confirmed the false sense of security fostered by relying on only the PSI rating printed on the pipe.
As has been noted numerous times, piping with threads need be derated by 50%. Fittings to be derated by 50%. Temps of 140F (near the receiver) require a derating of 80%. Yep, derated BY 80% ! ! ! Cold weather demands a derating of 50% (Charts available). Ultraviolet lite exposure for 2 years demands a derating of 25%. Duration loading induced stress, cyclical shock loads of pressure and/or physical vibration further exacerbates the risk of catastrophic failure.
I can not imagine taking a chance knowing so many industrial professionals, including insurance companies, have pursued this matter with due diligence. There are several other plastic products quite suitable for compressed gasses.
...As has been noted numerous times, piping with threads need be derated by 50%. Fittings to be derated by 50%. Temps of 140F (near the receiver) require a derating of 80%. Yep, derated BY 80% ! ! ! Cold weather demands a derating of 50% (Charts available). Ultraviolet lite exposure for 2 years demands a derating of 25%....
Let's see: 50 + 50 + 80+ 80+ 50 + 25 = derating 285% Crikey the PVC pipes are going to be sucking air in. Have we found a new type of compressor? :D
Reminds me of the story about the guy who put so many fuel saving attachments on his car he kept having to empty the gas tank he was saving so much.
Let's see: 50 + 50 + 80+ 80+ 50 + 25 = derating 285% Crikey the PVC pipes are going to be sucking air in. Have we found a new type of compressor? :D
Reminds me of the story about the guy who put so many fuel saving attachments on his car he kept having to empty the gas tank he was saving so much.
Geof. New type of compressor? Self powered? You may be on to something. Let's see, air rushing in, nowhere to go? Place a de Laval nozzle on one end, equip with wheels, and take it to Bonneville?
Geof. New type of compressor? Self powered? You may be on to something. Let's see, air rushing in, nowhere to go? Place a de Laval nozzle on one end, equip with wheels, and take it to Bonneville?
WE HAVE SOLVED THE PROBLEM OF GLOBAL WARMING. VEHICLES WHICH EMIT ONLY A RUSH OF AIR.
WE HAVE SOLVED THE PROBLEM OF GLOBAL WARMING. VEHICLES WHICH EMIT ONLY A RUSH OF AIR.
A diplomatic way of announcing to the entire world this idea blows?
A diplomatic way of announcing to the entire world this idea blows?
Yes, but it is cold air, or whatever the ambient temperature is I guess, so we are still better than politicians.
Yes, but it is cold air, or whatever the ambient temperature is I guess, so we are still better than politicians.
Way too much fun. However, I sincerely hope others reading this light hearted banter will not dismiss the real world hazards of using common PVC for shop compressed air lines.
Edit: Keep in mind the word often used is 'GRENADE' in describing a failure.
Way too much fun. However, I sincerely hope others reading this light hearted banter will not dismiss the real world hazards of using common PVC for shop compressed air lines.
Edit: Keep in mind the word often used is 'GRENADE' in describing a failure.
If, after reading this thread and others on this topic, someone insists on using PVC for a compressed air line they deserve to get their peanut brained head blown off. Pratical Darwinism I think it is called.
NC Cams
04-25-2007, 05:24 PM
I didn't know better and duplicated what a Master's degreed engineering friend had for air pipe in his basement, namely PVC. THe stuff was installed waist high and higher in my garage and has been there since 1989 or so, hot cold, you name it.
When I moved into my current shop, the previous tennant (the landlord's father) had plumbed his air lines God knows when with PCV as well. We've been here going on 6 years and not a single issue.
The shop is pretty much ambient and higher temp and the shop lines drop to no pressure at nights when we shut off the ball valve when we turn off the compressor (minor leaks would make the compressor run during the night so we turn it off).
Yet, asside from splitting one screw in fitting due to 1/2 turn too tight, we've had no issues whatsoever with PVC. Frankly, neither did the degreed engineer friend who plumbed both his former and his latest shop with the same plastic pipe.
I can say that there were two grades of pipe at Home Depot were we got our stuff from. When we bought it, we simply bought the stuff with the highest pressure rating, glued it together and have been fat dumb and happily using it ever since.
Clearly, God wathes out for drunks and little children. I quit drinking decades ago and although I will grow old, I refuse to grow up. Maybe that's why I've been as lucky as I've been with the plastic pipe I'm using....
....Clearly, God wathes out for drunks and little children. ...
And degreed engineers onviously. Which is fortunate..who else would waste the time.
I didn't know better and duplicated what a Master's degreed engineering friend had for air pipe in his basement, namely PVC. THe stuff was installed waist high and higher in my garage and has been there since 1989 or so, hot cold, you name it.
I'm confident, given enough time, we could garner myriad testimonials of those having challenged life's risks and survived. A few anecdotal recitations will not dissuade me from eliminating obvious hazards in my shop.
I wonder how much 'shop time' I would get following an 'incident' that buried shards of PVC into my wife's face? Or even allowing my children and grandchildren to be exposed because I though I was a tough guy. IMHO, The risk to others is far too great.
Forewarned is forearmed. OK, no more preaching.
tobyaxis
04-25-2007, 06:47 PM
I'm confident, given enough time, we could garner myriad testimonials of those having challenged life's risks and survived. A few anecdotal recitations will not dissuade me from eliminating obvious hazards in my shop.
I wonder how much 'shop time' I would get following an 'incident' that buried shards of PVC into my wife's face? Or even allowing my children and grandchildren to be exposed because I though I was a tough guy. IMHO, The risk to others is far too great.
Forewarned is forearmed. OK, no more preaching.
Preaching????????? In no way is this Preaching. It is called Common Sense and Safety Practices. This is a very good point.
Cheers!!!!!!:cheers:
ImanCarrot
04-30-2007, 12:29 PM
Pratical Darwinism I think it is called.
lol, which reminds me of my special theory of alcoholution and the fact that drinking makes you cleverer...
Alchohol kills brain cells, which many theorists fully accept. Now in any system with lots of brain cells, like a human, the stupider ones will die off soonest (according to Darwin) so drinking lots will leave all the cleverer ones.
Hence more alcohol= more intelligence :)
Sorry, it's nearly home time (ie nearly pub time).
eddie6675
05-06-2007, 07:51 AM
I'm glad I saw this thread.. I hav'nt been using pvc for air line per say, but I did make a pnumatic tool from one. Run about 15 psi through it. I cant't imagine that's too much but still. It does get warm at times and its got moving parts- better find a different pipe. Thanks fellas!
MDLang
05-06-2007, 04:59 PM
PJ,
Originally Posted by MDLang View Post
It seems we may be encountering some resistance to change and old prejudices against using certain materials.
Like ger21 our shop has all plastic lines and has been this way for 7 years. No problems.
Mike
Mike. Old prejudices against using this PVC for compressed gasses are well founded. Perhaps reinforced by the constant warnings from ALL manufactures and safety agencies? My experience in the spud gun sport confirms the inherent hazards. I did my own controlled environment research (destructive testing) on PVC and confirmed the false sense of security fostered by relying on only the PSI rating printed on the pipe.
I apologize for not being more specific with regards to the PLASTIC in use. I never said we use PVC.
I should have mentioned that we DO NOT use PVC plastic but use HDPE plastic for our compressed air lines
Polyethylene, More specifically PE100 (HDPE) is the APPROVED plastic for compressed air lines.
Check it out. Old prejudices indeed are usually well founded at some point but die hard because they become generalizations.
"PLASTIC for use in air lines is bad."
Not true, but like you said "PVC for use as airlines" is.
Mike
PJ,
I apologize for not being more specific with regards to the PLASTIC in use. I never said we use PVC.
I should have mentioned that we DO NOT use PVC plastic but use HDPE plastic for our compressed air lines
Polyethylene, More specifically PE100 (HDPE) is the APPROVED plastic for compressed air lines.
Check it out. Old prejudices indeed are usually well founded at some point but die hard because they become generalizations.
"PLASTIC for use in air lines is bad."
Not true, but like you said "PVC for use as airlines" is.
Mike
Mike, perhaps I was presumpeous in equating your use of 'plastic' to the use of 'PVC' in the thread. The above clarification resolves any question re the matter. I'm sure we are on the same side of the issue. Even to the notion that 'Old Wives Tales' do persist in this rapidly changing world which perpetuates old fears.
We're cool with this. Thanx for the update. Lloyd
wddanie
11-15-2007, 02:45 PM
Did you use the IPEX and how do you like it? I have to setup a compressor and copper looks way to expensive now and I am just starting the search for alternatives. I'd appreciate your advice.
Thanks,
Doug Danielson
mxtras
11-15-2007, 06:36 PM
Copper prices are dropping like Senator Craig in an airport restroom. You guys might want to keep your eyes on the price and pounce when it bottoms out.
Scott
307startup
11-16-2007, 01:02 AM
I too work in a shop that is plumbed almost entirely with Schedule 80 PVC pipe. It's climate controlled and we drain water nightly as well as shut off the compressors.
If that aluminum air pipe weren't so ridiculously priced that's what I'd go with at home. I guess I'll go with IPEX tubing, as I'm already familiar with the PEX water tubing...I plumbed a tankless water heater and stackable washer and dryer with it. I'm already planning to use it for my bath & kitchen remodel.
I guess what baffles me is...why is it okay to transport fluid with air in it, through PVC pipe? Explosive decompression is going to be a much bigger problem due to imcompressibility of fluids, than with just air. Also, when I worked in the landscaping business, we always used an industrial air compressor to blow out the underground sprinkler systems for winter. A lot of older sprinkler system used PVC plumbing rather than the flexible PE tubing commonly used now. The practice was sound, because a lot of water mains in municipal applications that were updated in the '70's-'90's used PVC. From the '90's-up, HDPE is used almost exclusively. It's not unusual to see clay piping, iron piping & PVC piping strung together due to repairs. The industrial air compressor could put out 90 PSI at idle and up to 210 psi at WOT. We almost never had to replace PVC sprinkler systems, unless the owner requested it. They weren't buried below the frost zone either, typically only 2-3' down, whereas another 3-4' lower would have kept the pipe at an average temp of 60-65*...at least around these parts.
My thought is that if you were that concerned with flying shards of PVC, you could just wrap it with the foam wraps used to cover exposed water pipe for winterizing. It's much easier to control debris when it's jacketed (like EOD does by placing body armor over and around unexploded ordinance) than it is to stop flying shrapnel.
Just my $.02...adjusted for inflation...is worth roughly $.0191 ;)
Rhodan
11-16-2007, 12:18 PM
I use sched 40 and sched 80 PVC all the time at work (swimming pools). We had a fibreglass filter fail once and I plumbed in a new one. To fit the new filter I had to remove a 5 foot section of 6" sched 80. I cut it and and put down one end then dropped the other from about 8 inches above the ground. Well, the entire pipe shattered like glass. Shocked the hell out of me!
Caprirs
11-16-2007, 09:27 PM
It isn't simply the pressure rating as a potential method of failure (e.g., bursting). There are other ways for an air line to fail.
Consider the possibility the air line gets impacted by a clumsy person wielding something reasonably hefty. For example, a guy is pushing a heavy cart and bumps the line. Or a forklift driver isn't paying close attention. When the PVC breaks, it will likely explode pieces and send them out at high speed. Crack propagation in the plastic can also be catastrophically rapid.
By comparision, a metal pipe might bend or get a breech resulting in a leak. But it would take a serious beating before breaking wide open. It can tear, but not shatter. It is a safer failure than the PVC.
From another point of view, compare an welding gas cylinder to a similar cylinder pressurized by a hydraulic pump. If I break the valve off the gas cylinder, I have a rocket. If I break the valve off the hydraulic cylinder, I need only a mop because the cylinder will not try to reach the moon.
1964455
03-04-2008, 02:22 AM
There's some stuff on the market called ChemAir, it's similar to pvc and goes together the same way, very flexible and wont shatter and designed specifically for compresed air. Cheaper than copper last time I looked. I can attest to the durability after running into some of it with a fork lift...woops.
brett11771
03-03-2009, 07:44 PM
I was putting in a air line into black pipe and the line broke i still have steel bits and parts in my wrist my boss is useing galvnise pipe how does this work. We run 8 cnc machines . the air cylinders will the galvniseing inside the pipe be bad for the machine.
Tony3
12-22-2010, 07:57 PM
I have used IPEX (DuraPlus) ABS air line for 15 years. It is connected to two 30HP rotary screw compressors. It has been fine, although we need to use a special compressor oil to avoid deterioration of the plastic air line. I am about to install another system in a second location and I am considering aluminum. Any comparisons?
yuanyelss
01-07-2011, 02:07 AM
I was presumpeous in equating your use of 'plastic' to the use of 'PVC' in the thread. The above clarification resolves any question re the matter. I'm sure we are on the same side of the issue. Even to the notion that 'Old Wives Tales' do persist in this rapidly changing world which perpetuates old fears.
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vidio1
01-07-2011, 09:51 AM
This is what I've used in my shop; Compressed Air Piping, Compressed Air Systems, Do It Yourself Air Tool System (http://www.rapidairproducts.com/)
I've used it for about 2 years now with no problems. It's economical to get started, expandable as needed, and a "drop" for a new outlet can be made in 5 minutes. I used 1/2" but I think it goes up to 1".
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