Thinking of using PVC pipe for air?

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Harold_V
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Thinking of using PVC pipe for air?

Post by Harold_V » Fri Sep 19, 2008 9:26 pm

For those that are not well advised on the use of PVC pipe for air, or other compressed gasses, and have an interest in being enlightened, please follow this link.

http://www.chaski.org/homemachinist/vie ... p?p=126306

Harold

thomas harris
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Post by thomas harris » Mon Oct 06, 2008 4:33 pm

we have it all over the shop and I really was against adding on to it, but did it under protest. I did pull the residential pvc water pipe out, as it only has a rating slightly above 100 psi. At least scd. 40 is rated for close to 200 psi.

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Sam_E
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Post by Sam_E » Wed Nov 12, 2008 12:19 am

I live in the mid-west with high humilities in the summer. I like copper because it dissipates heat better which means less moisture in the air. For the plasma cutter I still use an air dryer.

CAengr
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Post by CAengr » Wed Nov 12, 2008 12:59 pm

There has alot of discussion on PVC for compressed gases, but one thing I have not seen discussed is PVC sensitivity to UV. Over the years PVC has been used for watering systems and the pipe underground seems to last; but the pipe going out of the ground is made very brittle by UV exposure. Even schedule 40 becomes brittle after long exposures to UV. Had some stored outside and after a few months I started to move it and some of the lengths fell off the pile and broke like glass. So use caution if you are working around PVC compressed gas lines.

There are better pipes to use for compressed gases PVC is dangerous!


CAengr

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Frank Ford
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Post by Frank Ford » Sun Dec 07, 2008 12:30 am

Been there, done that. PVC worked just fine, but tended to develop cracks and small leaks near stressed areas after only a couple of years. After reading about other failures, I replumbed with the simplest of all - rubber air hose. It goes anywhere easily, doesn't leak, and holds up well.
Cheers,

Frank Ford

sailingamerican

SCH 40 air lines.

Post by sailingamerican » Fri Dec 12, 2008 1:13 am

I have used SC 40 for 30 years in my grage shop. I have had several joints break but then again I had a pipe dropping down and I bumpted the pipe and broke the line. It is not safe but then I did not call the safty team to inspect. You can not run it in a comercial building anywhere. For the home it works great. I changed out to black pipe when I went too a 2 stage air compressor with 175 psi. I did not want to take a chance and have it blow apart. I have a dryer on the line but we do not have much humidity here. 12 - 15 percent for the most part.

As for the pvc in the sun. I live here in hot sunny California and I have a pipe rack on the back of the shop. The sun kills the pvc. When you use cutter it snaps and shatters. It breaks apart. It is no good for the sun. I wanted an air line on the back porch. I ran pvc pipe through the attic and that was 30 years ago. It is still in good shape. I have a hose real in a nice box under th eporch roof.

Be safe and don't use pvc pipe. The one in a million time it will blow just might hurt you. Not worth a few dollars.

thomas harris
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Post by thomas harris » Sun Dec 21, 2008 9:03 am

We had a lot of extra pipe behind the building. I was asked to add some lines onto the system as mentioned above. We had problems with leaks and it didn't register why. There were actual cracks in the pipes. I thought is was happening because my cutting techniques were poor. Now after reading the post on uv exposure I understand the reason. I was not to keen on using this material from the get-go.

Maddog55
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Introduction/my experience with PVC air pipe.

Post by Maddog55 » Wed Feb 04, 2009 10:03 am

A little bit about myself: My name is Matt, I live in Plano
Texas and I have a small shop where I do machine work on
Antique Kawasaki two-stroke triples as well as Harley Davidson
engines. I have a lathe, mill, TIG, Flowbench and some other
stuff like a cylinder boring machine.

(This is a hobby/side business, I'm a Telecom engineer for my
real job)

Nuff of that:

I can tell you first hand that PVC is NOT good for air line.

I had my shop plumbed for PVC a copuple years ago. it was
real nice, had the coily drops all around the machines and
everything. It was there for about 6 months without any trouble.

One night, I went out to the shop for a smoke, (wife won't let
me smoke in the house).

Anyway, I happened to be standing near the compressor where
the PVC line went up the wall and into the attic space.

While I was standing there, that line blew up into a thousand
little bits. It took the metal shielded cable that carried the
220V to the compressor with it. The explosion made a huge
spark when that (shielded) wire shorted out against the panel.

It knocked me to the ground and all the lights in the place were
out. I was lying there on the floor in total darkness. I thought I
was dead, I'm not kidding. I layed there for a minute and pinched
myself to see if I was still alive.

I escaped with only minor injuries (Thank God). I could have been
blinded or killed.

Bottom line: DONT USE PVC for AIR. Bad idea!
"Those that beat their Guns into plowshares, will
eventually plow for those that did not"

Thomas Jefferson

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Mid Day Machining
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PVC Pipe

Post by Mid Day Machining » Thu Aug 06, 2009 8:26 am

I use PVC pipe in my garage shop, and have for years. I use 1/2 inch because it will withstand more pressure than 3/4, then I regulate the pressure in to the pipe down to 40 PSI. You really don't need more than 40# PSI to blow off your machines. Any more than 40# PSI and you just blow chips everywhere you don't want them. I even regulate my spray mister down to about 6# PSI and that way it takes about a week to use a 1/2 gallon of spray coolant. I use a FogBuster spray mister, and they are wonderful.

nortly
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Location: Ontario

Post by nortly » Sat Feb 06, 2010 4:23 pm

PVC can't take the pressure pulsations normally found in a a compressed air system if you want quick and easy. look at what SMC has to offer. I have 0.75 Black Pipe in my shop it wasn't expensive. all one needs to do is rent the tools from the local rental place. I run my shop air at 140psi

tomjaksa
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Re: Thinking of using PVC pipe for air?

Post by tomjaksa » Sat Apr 01, 2017 12:19 am

The only way i use PVC for compressed air is as a sleeve to keep the rubber hoses nice and neat on the walls.
I deal with commercial salt chlorine generators. One customers main filter pump gave up. While they were waiting for a replacement they did not switch the chlorinator off. The pipes were 250mm (10 inch). Thr guys came to install the new pump........The last thing the guy remembered before waking up in hospital was switching the grinder on to remove a rusty bolt. The whole filter plant utterly disintegrated. Shards of about about 2 inch PVC pipe everywhere. One cast iron butterfly went through the steel door. How nobody lost their life i will not know. When PVC pipe is under pressure its an explosive device.

I understand it like this:
You can compress air
The energy from compressing it is being held by the pipe
You cannot compress liquid
Compressor technicians fill air tanks with water when they pressure test.

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BigDumbDinosaur
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PVC AIR PIPE IS A REALLY BAD IDEA!

Post by BigDumbDinosaur » Sat Apr 01, 2017 6:51 pm

I'm old-school and use schedule 40 black pipe, 3/4 inch for main runs and 1/2 inch for stubs. A PVC pipe explosion can be deadly, as was determined by the U.S. military many years ago. DON'T DO IT!
Sam_E wrote:I live in the mid-west with high humilities in the summer. I like copper because it dissipates heat better which means less moisture in the air. For the plasma cutter I still use an air dryer.
Copper works well as long as you use type K (not the more common type L sold in hardware stores and Homely Depot) and silver-solder the joints. Some municipalities will allow copper as a substitute for iron pipe. Incidentally, soft solder doesn't do well on runs in which pulsing occurs. Owing to the smoother internal profile of copper pipe when assembled you get less loss per foot or per elbow.

Long runs of copper can expand and contract quite a bit due to temperature fluctuations. An expansion loop or short piece of hose at periodic intervals takes care of this problem.
Last edited by BigDumbDinosaur on Sun Apr 02, 2017 12:54 am, edited 1 time in total.
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