The Stovebolt Site Forums The Shop Area The Tool Chest PVC air manifold lines

Recently mentioned that I used PVC pipe to move the air supply between my shops. Several mentioned that it was a "verbotten". Just wondered if anybody else was using the thick walled PVC and if they had any problems. I liked the 1" stuff because it acted like a volume chamber to keep my air tools working out at the end of the line. Maybe I'm all wet...don't want to be sitting on an IED! Would appreciate your comments.

Dave

I have used PCV air supply lines for years without any problems.It is marked with a Max PSI,so stay within that and you will be fine.I like the fact that it is real easy to change or add to your system.Now the yellow plastic "coil hose", I don't trust that at all !!

Fla54Chevy3100,

I read that thread as well and was interested as I have a shop plumbed with PVC (I installed it).

The burst pressure of the pipe is adequate and the glued joints are strong..it's easy to assemble and looks slick. I think the biggest concern is with the 'fragility' of the pipe if it took a direct hit from a flying ball pien hammer or part shooting out of a press.

I have read that any oil from the compressor that carries over into the air line in a vapor form will eventually degrade the pipe and make it brittle.

I will continue to use my system and won't worry too much. A ounce of common sense will usually prevent any catastrophe. Take a piece of PVC pipe and try to mash it, break it, shatter it...it's real tough.

I have seen soldered copper pipe systems and they look cool, have great heat transfer abilities and meet most codes. The current price of copper would make such a system pretty expensive though.

Everyone has a beastly story about the PVC exploding and killing 15 innocent children and a few dogs and cats. Don't let these people into your shop and all will be well.

Stuart

There must be something to the oil vapor theory, as I worked in a 20+ y/o shop plumbed w/PVC air lines & the lines were always popping & breaking. No one was ever killed but it was a PITA. Fatigue from the vibration may also be a factor. I know other PVC systems not as old that are holding fine. I used black iron pipe on mine. Brian

Here is some OSHA reading on the subject.

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

i like the idea of keeping the innocent children and ani-mules out. my dogs like to nock things over sometimes and it's hard for them to run the air tools with their paws.

Thanks for the responses. Good information! I'm not planning on tearing out my system as it has served me well for the past several years.

However, I will take some precautions. Have decided to set up a special "ball pien hammer-throwing area" outside of the shop.

As you mentioned, a little common sense can go a long way in reducing the chances for a catastrophic event. When you think about it, it's amazing that growing up without car safety seats, bike helmets, the USDA, EPA, OSHA and the government monitoring our every move, that any of us have survived. Ain't progress wonderful?

Dave

I was wondering how old that pvc was when it exploded. Does the pvc have the potential to explode at any time? or is there a time frame? just curious.

Anything under pressure has the potential to explode. As far as PVC is concerned, many factors would be involved in when it would decide to blow. How often you use your air system, what kind of temps your plumbing will experience, was it glued correctly, are there any nicks or defects in the pipe, age, pressures, chemicals degrading the pipe, vibration effects, etc. Don't know if anyone has done any experiments to see what explosion time frame might be.

As always, common sense should prevail.

You can bet that tucked away in some dusty corner up in DC, is a research group...a director @ $125K, a project mgr @ $110K, an OSHA laisson officer @ $95K, at least 3 Ind. techs @ $95,$90,and $85K respectively, a certified EMT @ $65K, a Network mgr.@ $75K, a mid-level HR @ $85K, a PR @ $95K, an office mgr @ $75K, with 3 sects @ $55k, 3 Industry folks on fellowships @ $95K each + housing + travel, and a janitor @ $40K to clean up the mess, if by chance it does explode. (Did I leave out anybody?)

Now picture these folks all sitting around the room, with coffee, donuts and small talk watching this 6' section of PVC pipe under 101 lbs. of pressure, waiting for it to explode.

$1.3 million to protect us from ourselves!!!!

I sure will sleep better tonight knowing that our government is looking out for me!!!! God, I love America!!!!

Dave

Didn't need any government workers to write the warning in this manufacturer's brochure:
Technical & Installation Data for PVC & CPVC Pipe and Fittings

"PVC AND CPVC PIPING PRODUCTS ARE NOT RECOMMENDED FOR SYSTEMS WHICH TRANSPORT OR STORE COMPRESSED AIR OR GASES. DO NOT TEST PVC OR CPVC PIPING SYSTEMS WITH COMPRESSED AIR OR GASES. ALWAYS BLEED ALL ENTRAPPED AIR FROM THE SYSTEM PRIOR TO TESTING."

This document is a little old .

However, these people reported no short-term problems below 100psi.

Fla54Chevy3100,
I have worked in government research, and I am offended that you think such a test could be completed for a measly 1.3 million dollars.

My apologies....I like to think small!!!

Dave

For a little more money I will stick with the black iron pipe.I ran air lines thru my truck shop and wood shop with black iron pipe.Seems to me its a lot safer than PVC.

I ran black iron ,my thought is now its done and done for ever. The other great part is if laidout right you get NO water at the tool ,just in your drops. ... My thought is would you hang from a plane on a rope rated for 200# if you were 195# ??

I am very glad that this topic was discussed. About a month ago, I had an oportunity to check out a Stock Car shop that had PVC installed as air lines. The shop had been set up this way a few years back, and so far, no problems have surfaced.

For my new shop, I originally wanted to use copper, that now seems like it would be quite costly. PVC was sounding like a good option for awhile, but that was only because of its low cost. This spring, I am going to evaluate my exact needs, then crunch some numbers. Sounds like my choices will be either steel pipe, or copper tubing.

It is important that we not jepardize safety only to save a couple bucks.

Thanks for everyones input on this.

John

OK , now ya all making me look , AND I JUST DID..I have my shop plumbed all around the ceilin with 1 1/2 PVC with 3/4 drops all over. my shop is heated as i live in Pa.
now here is my ? ..
the pipe reads it is rated for 600psi at 73 degrees ..?
I am putting 120psi in my system so I guess I should not be looking for a MASS EXPLOSION ?..

I know abought OSHA's rulin on copper & as #1 and black iron #2 for gases ....I have 4inch copper as the main line an all drops are not less than 3/4 copper all through the plant I work in as a Supervisor .
so what is the difference if i am putting 200psi of water in that PVC line rated for 600psi or an inert gas ?....
pressure is pressure ???
I feel it is just a myth .
just my 2 penny's

this is an update , to let folks know:
From my compressor to the water seperator and regulator I have a flex line and from that to the main line i have flex line , so vibration is not a factor.

Tim Bloom,

You are right..pressure is pressure! I too have a system plumbed with PVC, and I don't live in fear when in the shop.

From a purely technical standpoint, the manufacturer of the PVC doesn't recommend it for compressed air service so that should be the bottom line.

I don't think the plastic is 'inert'..its chemistry can be gradually changed through contact with oil and oil vapor. This will sometimes make it brittle, and although it will still hold 600 psi, a sharp blow will fracture it and cause it to fail.

When a pressure vessel is hydro-tested, it is filled with water and pumped up to the required pressure. If it fails, there is no explosion because the water, being incompressible doesn't have a bunch of stored energy behind it.

If you took the same vessel and pumped it full of air, when it failed it would blow its top, and maybe yours too.

I'm betting the pressure rating of the PVC pipe is for a liquid and not a gas.

I will use my PVC system and won't worry about it, but technically, it should be iron pipe or maybe copper pipe...something that won't fail when blasted with the flying chiesl or hammer.

So the statement that 'pressure is pressure' is only partially true when it comes to exploding things.

Stuart

Thanks Stuart, for explaining that. If mine were already done in PVC, I probably wouldn't be in any hurry to change it out either.

John

I know everybody reccomends black iron pipe, but what does black iron do with water and air , it rusts. So I used galvanized for mine. I found galvanized at a real building supply store for less than half the price of copper.

I am using black pipe as we also use it in some hydraulic line systems that use pressures upwards of 3300 PSI. If it can stand this I know it can stand 175PSI. Peace of mind in my shop were my grandchild sometimes visits me are worth everything. Just my 2 cents.

Harold, I had worried about rust also, but w/a trap/dryer @ the compressor the water elsewhere in the lines is negligible. The plumber at the local lumber shed recommended the black over the galvanized pipe, but I cannot remember why. Brian

When my company was leasing a shop, we installed PVC air lines. These lines lasted about a year and a half. We started having small leaks pop up here and there, and then we started having pipes explode without any contact from a flying object. PVC can degrade from the oil mist that air compressors give off and from heat. The PVC was run overhead, so it saw temps over 100 degrees often during the summer months.

Originally, we had the same thoughts as many of you guys about PVC being able to hold up to the pressure, but now we use nothing but black iron pipe for air lines. The PVC did not just break, it exploded. Shards of PVC went everwhere. Luckily there were no injuries.

Please be safe and instead of cheap.

How about PEX? There are compressed-air rated fittings for it and the tubing certainly is less expensive than black iron. It won't shatter when it fails, it just leaks.

I have work with lots of PVC, however, just in the transporting of liquids. Generally, I think PVC is very brittle.

Attention should be given to the glues used to bond the pipe and any threaded connections used. These are the weak areas.

The smallest strain on a PVC connection or impact, shatters the pipe or at the threaded joint.

If PVC was fantastic for air systems, all industries would use it because it is cheap to install, maintain or replace.

PEX is a wonderful system requiring special crimping tools and associated fittings...and as 4ontheFloor states..it just leaks.

If you can afford it.. go stainless steel or galvanized.

Safety first in any shop... don't go for cheap!

Greg

I think most of us are not talking about a lot of pipe here so spend just a few dollars more and be happy. My nephew did his with the PVC ran above the ceiling on top of the walls with drops. I ran mine with Galvanized and now I think he wish he had. Nephew used it because it was easy and quick to put together but with a little planning galvanized is a snap to. I used 10ft sticks around the wall with a quick connect at the end of every drop. It went quick and I really like it.

I know TIP reccomends black iron. Their reason for not using galvanized is that a flake of galvanizing can come off. I've been in the chemical industry since 1964, visited or worked in more than 2 dozen plants (I lost count long ago)and of all those that used threaded pipe for plant air & instrument air I can't remember seeing anything but galvanized. I've also never seen a case of galvanizing flaking off inside the pipe in air service.

Here is the TIP metal piping diagram. It suggests metal piping for its strenth and cooling/condensing characteristics. They do suggest black pipe but it is interesting to read the postings about galvanized.

This spring, I intend to set up a 50' run of pipe with 3 riser take-offs (and condensation drains). The TIP plans will be very helpful. My quandry is now black pipe vs galvanized pipe (I'm now leaning towards galvanized, after reading the postings above).

I would not recommend galvanized pipe systems if you are near a saltwater environment. Corrosion big time.

If that is not an issue for you, go for it!

Harold41... I agree with you.

I just purchased a lowes 60 gal. 135psi high flow compressor. My question now is about what size pipe to use. I plan on using copper. The compressor has 1/2 inch npt, so do I run 1/2 inch pipe through out my garage. Where do I install the filter at in the system. all the filters that I have seen at lowes or home depot are 3/8 inch npt filters. I want to do this right the 1st time & not have to worry about. thanks for any thoughts or opinions. James

James B,

Good purchase. Although the discharge pipe size is only 1/2", I think if you plumbed the long runs with 3/4, or even 1" if you could afford it (copper$$), these would act as 'mini-reservoirs', and make the system a little more industrial.

The drops off this main line could be in 1/2". Filters, or traps are usually located near the point of use, and I think I would use ones no smaller than the 1/2" drop diameter. Your working rubber lines will be 3/8", but the filter is rated in the CFM it will pass, so you want to keep the number high.

There are some nice layout diagrams around that show how to slope the main lines, and loop the drops to minimize water problems. Keeping the air cool and free of moisture is JOB #1, and this can be influenced with the initial planning of the system. I think Eastwood has a typical layout, but they should be all over the web. Good luck.

Stuart

On mine, I scored a big(3/4" NPT) dryer/trap from a service station supply house. I mounted it right on the compressor, then as Stuart has suggested I used 3/4" lines w/1/2" drops, use a tee arrangement w/a drain at bottom. Very little moisture ever in the lines, even in the summer w/80% humidity. But on the line I painted with usually I installed a small dryer(I just put 2 nipples on it, was portable)like what you describe just for added ins. I use my air impact a lot(sometimes on a long hose) & really don't need the volume/pressure reduction some dryers cause & the tiny amuont of moisture is not an issue.

Maybe I am over anaylizing this, I tried to look for a layout on line & I did'nt really find one. I just want something simple.

James B,

Simple is fine. The basics will still apply and are very simple. Put as much piping onto your garage as you want..I put my main stuff in the attic and made nice drops down the walls in various places.

It can be as simple as you want and any size you want. I have enclosed one of the layouts I found.

Look around your shop and decide where you want quick connects (drops) for hoses and tools..one one each wall, and one by the overhead door so you can drag a hose outside??

Locate your compressor out of the way and near some source of power. Buy the pipe of choice and connect the FROM to the TO!

Look at the link and chew on this fun project some more!

http://www.sharpe1.com/sharpe/sharpe.nsf/Page/Air+Piping+Layout

Stuart

Thanks for the help guys. James

Now that's a cool setup! Never thought about the risers above the main feed lines. May just have to look into upgrading my PVC system. So far, I've had no problems, but I've learned over the years that if I push my luck, I usually come out on the short end of the stick!!! Thanks for all your input!!!

Dave

OK THE GOOD THE BAD THE UGLY ,, PVC ?..brittle ..YES...degradaition from chemicals maybe.
Cast Iron ...tough but will over time definately rust from the inside out .."seen it happen" and fail.
Galvanized , will definately corrode and and fail in time ....I HATE GALVANIZED ....so I am Bias.
If you are building or redoing your shop air supply .....I an most will agree ...I know this is expensive ...but bye OSHA regs and all that is right in the world ..for safety and long term use ...COPPER is the choice ..for any air supply system ...so make your choice ?..for me i dont worry bought the PVC in my shop but then again i didnt have to spend 10 times more for what copper would cost ...so it is each his own on this subject.
NOUGH SAID

my pvc. is rated at 480 psi. works good the black iron might be good but would cost to much for me and to hard to repair i would worry about the black pipe in the salt air here