air lines Plastic VS Metal

Re: air lines Plastic VS Metal

DB

>I would go with metal. When the plastic is under pressure and gets hit then it could shatter. You may have to use metal for insurance purposes, or OSHA regs. Check with Your insurance and OSHA first. There are some plastics that are rated for compressed air, not sure which ones.

Since it is for a school I would go with metal just to make sure that it is safe.

Re: air lines Plastic VS Metal

arw01

>Copper is the defacto, but has become very expensive. For liability issues in a school, I'd run galvanized 1/2" or 3/8" pipe. Switch to flexible rubber line when I dropped off the pipe.

No reason you could not just run rubber air line either except of code/osha possibly.

Alan

Re: air lines Plastic VS Metal

Marym

>I believe you will be better off with metal, for two reasons. First, safety, and secondly, the metal will help the air to condense, which will help you get the water out of the air and your tools.

Re: air lines Plastic VS Metal

mike from American Sycamore

>thanks for the great advise......I had a feeling that I should go with metal but knowing plastic is so much easier to cut and use...I want my system to look professional and certainly do not want any trouble ..I will go with metal.

Mike

Re: air lines Plastic VS Metal

Donald Pierson

>Mike,

I worked for a number of years in factory automation and most systems included compressed air. Metal is a lot better than the plastic with copper being the top of the line. The plastic ages and becomes brittle and subject to failure. Include some fittings at low points in the system for draining the water out. For a cheap quick and dirty "home" system the plastic will work for a while just do a good job on gluing the joints, I have seen a few bad joints fail, they were noisy and dangerous.

Check out...http://transair-usa.com/transair_produ

Clint Searl, at the base of Haycock Mtn

>

Re: air lines Plastic VS Metal

Barry Irby

>First I would check with OSHA and your insurance company and perhaps the Local Building Official. I might do all that under an assumed name to get the information without "triggering" them into starting a file on your situation.

Personally I think metal would be far better. My cousin ran an outdoor shower in PEX and a year later the pipes fell apart when she moved it SLIGHTLY to paint. Makes me wonder what happens to other plastic in the presence of sunlight. It may be UV inhibited, but how long are you planning to use this pipe?

I used a propane heater in my shop to knock the chill off before switching to an electric one to maintain the temp. The heater got shifted under my coiled air hose. After about a minute, POW! The curly hose burst. I could hold my hand above the heater and it was hot, but not so hot I could not keep my hand there. So, some of the plastic if temperature sensitive.

I know that you were not going to use either of these plastics and that this is not scientific by any stretch, but I think it indicates metal is better.

Another thought is that if any of the "hard" plastics were to burst either from age, UV, or from someone whacking it, there might be "shrapnel" that could put an eye out, as your mother used to say.

Re: air lines Plastic VS Metal

David Sparks

>I knew a guy who ran a pvc air line. It shattered and sent shards of plastic through both sides of a sheetrock wall. Luckily he wasn't in the shop when the line burst.

Plastic = Air Bomb!!!

Dave Anderson, SoCal - From Home

>I was surfing for PVC manufacturer websites last week and was actually surprised to read on one of them their strong admonition to NOT use PVC for compressed air.

If a manufacturer says don't use it, who are we to argue?!!!

Work Safely!

OSHA says NO to pvc on air lines *LINK*

Tim Greif - West of Chicago

>See the link below. Scroll down to the bureau chief's response to Mr. Cannova regarding comopressed air and pvc.


OSHA position

PEX

Kirk D.

>PEX will work but you need to rent or buy the expander to add copper fittings. Have several hundred feet in use with no leaks and it installs much faster.

Re: air lines Plastic VS Metal

Larry Clinton At Frankfort (Central)., Indiana

>Donald, my experience with plastic has been completely different from your. I worked as a Manufacturing Engineer for Emerson for 39 years - retired last year. I used a lot of plastic lines on automated machines. If fact plastic or rubber lines are the only way to connect to movable Pick and place grippers and other movable air cylinders. I had some plastic on equipment that operated 24 hrs / day 6 days / week for several years (>5) without failure. The bulk of the few failures we had could be attributed to 1. abrasive wear through due to the line being improperly installed and rubbing against a steel object during cycling. or 2. improper seating into the barbed fitting during installation. (these were normally found within a very short time after installation). The last automated assembly line we installed (over $20 million) about 5 years ago had well over 1000 ft. of various size (1/8" to 1/2") plastic line installed in over 100 individual sites. All valve manifolds and FRL's were piped in plastic. This automated assembly line ran 24/7 at a rate exceeding 140,000 cycles a week. The failure rate for the plastic tubing was less than 1 / month. Our main 6" line (loop) was steel - as the plant was built in the 1960's. We never had a dangerous failure of any plastic IE: shards or explosive rupture. Almost all valve manifolds on all equipment in the plant installed in the last 10 years were piped in "push-in" fittings and plastic tubing. We ran 3 125 Hp compressors and maintained between 100 and 125 psi throughout the plant. The plant is air conditioned and well heated so possibly that is the contributing factor to the differences we experienced.

One of the problems

Gary Camp - Bend, Oregon

>Larry were you using PVC in your plant, or a plastic rated for compressed gases? One of the issues is stored enegry. 120 psi of water has very little store energy, non-compressablity of water blah blah blah. Compressed gases on the other had have lots of stored energy. Many volumes of air need to be comressed to reach 120 psi.

I have hot water boilers where I work that are rated 50 psi for water but only 10 for steam. I had to ask the boiler inspector why. He only needed to say "Stored energy, water won't compress" It was kinda one of those "Duh" moments for me.

glc

Re: air lines Plastic VS Metal

Charles Self

>You can buy iron pipe at Lowe's, HD or similar places already threaded in a great variety of lengths, with every possible connector available and ready to screw on.

This is the spot where the big box stores shines.

Use either 1" or 3/4" for main lines, 3/4" or 1/2" for feeder lines (size of feeder depending on size of main lines). Place drains at EVERY drop.

Forget copper for the foreseeable future. The price is already too high even for house wiring.

Re: One of the problems

Larry Clinton At Frankfort (Central)., Indiana

>The plant I worked at was a stickler for safety. We had a in plant Safety director and a Corporate Safety person for our division. No product of any type was used that was not rated for the usage. We used the type of flex line rated for Air. The Pneumatic type line that is flexible. I can't remember the type of plastic - Polyurethane maybe? But the line is semi-rigid, comes in various colors - blue red etc. (I believe it is coded by color/size. The rating for pressure is quite high but de-rates quickly with rise in temperature. The fittings (as I remember) all had brass NPT thread for attachment to valves, pipe fittings etc. The remainder of the fitting is a hard plastic with a quick release spring loaded ring which releases barbs which hold the pipe in the fitting ("O" ring seals in the fittings). All the fittings and tubing work quite well as I stated.

Re: No pex

Rick L

>Pex cannot be exposed to sunlight without deteriorating. I've tlaked to the techs at Pex and they won'b back air lines as an application. There's a product called chemaire that is rated for air. Black pipe or L and K copper is the old standard for air. Drops should go up then drp back down for proper drainage. The main lines are pitched back to the tank for collecting water to drain. Having the drops go up keept water from accumulating in the drops. Kaeser Compressor has a new smart air line I just saw advertised recently. There's an aluminum air line with quick disconnects also available but it's pricey. There's plenty of documented advice on how to properly run air lines instead of going with what sounds good.

YES PEX !

Kirk D.

>Pex will work just fine. I must admit I forgot to add about keeping it out of the sun. In my application I ran it underground between buildings. When I came into a building I went to type L copper. Pex will be fine for air lines and it was much cheaper than any other product. They have had Pex under constant pressure for over 20 years without leaks. Also realize many houses have Pex plumbing. How could these have qualified for homeowners insurance if there was going to a problem with it. The sunlight issue I believe is more of a direct light issue. Otherwise how could plumbers use Pex in basements where there are windows and still pass state inspection.

Careful…

Rod Peterson -- Ormond Beach

>> Pex will be fine for air lines…

I don't want to be antagonistic, but in fairness to all, is this your personal opinion or is it based on empirical data? And if it is your personal opinion, what data do you have to back it up. I know, I know—this is the internet and everyone's an expert, but it's irresponsible to make a bold assertion on a topic of some importance without reliable and verifiable data behind it.

> …and it was much cheaper than any other product.

Almost assuredly true, but I will point out that this is the very same arguement used many times over the years for PVC, which has the unfortunate property of being entirely unsuitable for the particular purpose and can be downright dangerous.

> They have had Pex under constant pressure for over 20 years without leaks.

Similar to the PVC arguments, but as Gary Camp relates below, “stored energy” is the feature that turns the whole suitability  question of PVC for compressed gas on its ear.

> Also realize many houses have Pex plumbing. How could these have qualified for homeowners insurance if there was going to a problem with it.

Same as above. Suitability for water does not equal suitability for compressed gas.

> The sunlight issue I believe is more of a direct light issue.

That may or may not be the case, but as shown here and elsewhere in the thread, it may not even be the issue as to whether or not PEX is suitable. And, as I asked above, is there some scientific basis for your assertion?

> Otherwise how could plumbers use Pex in basements where there are windows and still pass state inspection.

Again, very much the same arguement as for PVC, which has been shown to be errantly applied.

I just want to strongly caution that taking a material suitable for one set of conditions and projecting a suitability of its use for another is a dangerous game without some serious engineering and testing to back it up. Personal opinion isn't remotely good enough a threshhold for serious consideration.

Rod

Re: Careful�

Kirk D.

>Don't forget Pex is not PVC. Also your compressor could explode when you least expect. Good judgement is advisable no matter what you do.

Kirk D.

PEX IS THE BEST

Kirk D.

>

Re: YES PEX !

DB

>I was just at the Uponor (formerly Wirsbo), one of the manufacturers of Pex. They list only three uses for Pex.

#1 Water distribution

#2 Radiant Heating

#3 Fire protection

I did leave them a note asking about the use of Pex for compressed air installions. Waiting for a reply, most likely not before Monday. I will post any answer that I get.

Re: Code violation perhaps...

Rick L

>The people I've talked to at PEX say it's not rated for air. So for Joe homeowner who puts it in his shop it might not but a big deal but the long term ramifications could be more significant. A lot of home based businesses become real businesses over time. What if they carried the Pex airlines into some factory application and there was a problem. Often insurance companies can void all kinds of claims if things aren't up to code. For instance we were discussing pellet stoves recently. Suppose you had a fire and installed a stove yourself without a permit,and you had a fire, the isurance company could deny your claim, even if it was of electrical origin. Look at all the folks who are fighting the insurance companies on wind versus flood damage from Katrina. You need documentaion from the manufacturer to use things properly.