I know Black Iron Pipe for Air but?............

[autoist]

I was in both an upholstery shop & a body shop that use PVC..I even asked one of the owners about it & he said he'd only had one leak & it didn't "shrapnel" - just hissed.

I know you shouldn't use it but lots of folks do without problems.

 

[rsanter]

based on testing I have done (while working at a plastics company) the PVC pipe will hold 150% or more of its rated pressure when used with liguid in the lines.
when filled with air or partly filled with air I have seen them explode between 1/4 and 1/2 of its rated (water) pressure.
I would not recomend you use pvc but I have seen many people do so without having trouble. that bieng said I would again recomend that you do not, but if you are going to then use my testing as a refrence at least.
I have thought about using the sch80 if I were to do it but I have never actually got myself to the point af being willing to take the chance. keep in ming that when it fails it may not be you that gets hurt. it may hit your car with the $2000 paint job, or worse how about hitting your kid or your wife......is it worth it?
I just had to run an air line between the two hose reels I mounted and again thought about using a piece of pvc, and again I didnt and I just went with a piece of air hose I had on hand.

bob

 

[AZAV8]

Then we have nate that should know better and he should be replacing that dangerous **** in his Dad's shop...

You CAN NOT use PVC/ABS for compressed air!
Even the manufacturers say NO!!!

What Torque1st said, in spades!!!

If you didn't see it, Lowe's has signs posted that PVC pipe is NOT suitable for compressed gas service. Neither is ABS. Both are thermoplastics which cannot withstand compressed gas pressure waves internally nor can they withstand external impact blows from hammers, tools, etc. They will shatter into sharp shards, i.e. shrapnel and cause serious injury.

I speak from experience. I am a mechanical engineer who has designed hundreds of garage, shop, industrial, piping systems. NEVER, NEVER, NEVER use plastic pipe for compressed gas systems!

Now for the practical differences between copper and black iron (steel) pipe. The steel pipe will corrode internally from the condensed moisture out of the compressed air. This will result in rust stains, flakes, etc. which will show up in your air, tools, paint, etc. Even if you use galvanized pipe you will still get corrosion (rust) because when you cut and thread the pipe you expose steel to the moisture in the compressed air.

Copper will not rust. Any of the three types of copper, K (green), L (blue) or M (red) is suitable for most home shop compressed air systems.

The copper will be easier to fabricate and support since you do not have to thread it.

When I design commercial or home compressed air systems I always specify copper pipe and fittings.

For a good resource on copper pipe and technical info; Google "Copper Developement Association and find their Copper Tube Handbook.

And to reiterate:
NEVER, NEVER, NEVER use CPVC, PVC and/or ABS plastic pipe for compressed gas piping systems!

Phil

 

[PPFAMike]

What an active thread. Let me help.

I am the Codes and Training person for the Plastic Pipe and Fittings Association (PPFA).

Most plastic pipe and fittings are not suitable for compressed air/gas use, because as so many have stated here, the failure mechanism is brittle rupture - ie. flying shards. There are a few special air rated products that are exceptions, but the manufacturers instructions and recommendations need to be followed exactly. They are very special products.

I think the ABS air/gas system from NIBCO was green in color and has been dropped from manufacture. IPEX may have some air/gas products available.

Another serious issue is that tramp oils and other materials from compressors can slowly stress crack the pipes over time from the inside. Failure may occur without sharp impact and the system would look just fine.

We do not even recommend that normal piping systems are tested with air even at low pressure, due to risk of injury or death if ther is a failure.

Another issue - static pressure does not care if it is generated from water or air. 100 psi is 100 psi. The difference between a water and air system is in the potential energy release of compress air/gas is much, much higher and violent.

I understand that there are PVC air systems in use in gas stations and garages around the country, some maybe in use for decades, but they are potentially all very hazardous.

www.ppfahome.org

 

[StingRay]

And there we have it. Sombody sticky this and put the debate to bed forever. Thank you Mike and Phil for making it crystal clear.

 

[bgott]

I guess that PVC is out for potato cannons, too, eh?

 

[sparky1562]

I guess that PVC is out for potato cannons, too, eh?

Yes. Start using copper for those things.

 

[Uncle Buck]

All this talk about blk iron, why not use galvanized pipe

The most important reason for not using galvanized pipe is that over time the coating chips off the pipe and travels downline and creates obstructions in the line.

 

[c39er]

The most important reason for not using galvanized pipe is that over time the coating chips off the pipe and travels downline and creates obstructions in the line.

Now I understand what those silvery metallic things are I keep coughing up in my glass of water.
Bob

 

[Torque1st]

The most important reason for not using galvanized pipe is that over time the coating chips off the pipe and travels downline and creates obstructions in the line.

The galvanizing chipping is probably much less of a problem than rust in black iron. Piping systems should be cleaned and flushed after installation anyway.

 

[Uncle Buck]

Now I understand what those silvery metallic things are I keep coughing up in my glass of water.
Bob

The galvanizing chipping is probably much less of a problem than rust in black iron. Piping systems should be cleaned and flushed after installation anyway.

The answer never made much sense to me to be honest, but I recall reading that somewhere one time.

 

[Torque1st]

Now I understand what those silvery metallic things are I keep coughing up in my glass of water.
Bob

-Fish scales...

Water pipes, copper or galvanized, are quickly covered with a layer of scale inside. Very few places use galvanized for water anymore except for repairs on an existing galvanized system.

 

[rustbucket49]

I just went down this road - I put in PVC and then the very next day I read a thread on here about NOT using PVC. I knew it in my head, but my heart convinced me to go cheap. After reading the thread here, I went back, scrapped out the PVC and put in copper. I'm glad I did because about a week later I had a major impact on the air line w/ a pick axe. It dented the copper, but would have easily ruptured the PVC. I agree that PVC for air line is a bad practice - particularly since it deteriorates (or can if exposed to some sunlight) with time and cycling. And copper is not that much more expensive than PVC now (and it can be cheaper than black pipe for equivalent lengths)....just my $0.02.

 

[ChrisE]

What Torque1st said, in spades!!!

Copper will not rust. Any of the three types of copper, K (green), L (blue) or M (red) is suitable for most home shop compressed air systems.

The copper will be easier to fabricate and support since you do not have to thread it.

Phil

Is this copper pipe available at Lowes or Home Depot or would I need to go to a more specialty plumbing supply?

What is the best pipe size to use for a residential two car garage? I'll probably run this all the way along the back wall and down the side wall, probably about 50' to 55'.

Thanks

 

[e-tek]

What Torque1st said, in spades!!!

Now for the practical differences between copper and black iron (steel) pipe. The steel pipe will corrode internally from the condensed moisture out of the compressed air. This will result in rust stains, flakes, etc. which will show up in your air, tools, paint, etc. Even if you use galvanized pipe you will still get corrosion (rust) because when you cut and thread the pipe you expose steel to the moisture in the compressed air.

Phil

Some great - though largely repetitive - information here.

I would, however, like to add what I know from direct experience. I have worked in 5 body shops and visited over a hundred as a paint rep and have seen black pipe used in all of them - without exception. While that was 15plus years ago, I would suspect most, if not all, are still using the same material. What I want to refute is that black pipe scale or rust will end up in your tools or paint. As long as the system has filters and/or oilers near the end points, I have never seen, nor heard of a situation where rust or scale atributed to any paint problems or tool malfunctions. I have seen situation where poor/inadequate/dirty filters have contributed to problems, but I would think that could occur in a copper-piped system as well.

Also - and this is a bit "nit-picky", I fail to see how cuttting threads would expose steel to moisture, when the threads are on the outside surface and both telfon tape and pipe dope would seal this off.

Though I can see some benefits of copper line, I remain in the Black Pipe camp. This is due to several reasons, including Black Pipe being a better heat conductor (due to its mass), ease of installation and adding to/changing configurations, as well as it's crush-proof properties.

 

[kerwinq]

What is the best size pipe to use for about a 50 foot run from the compressor to the main air hose that will be used?

 

[djd99]

My shops had 1/2" black pipe in it for 20 years now and have not had 1 issue with it, If one would ask I would recommend it. I probably have 80 to 90 foot of it ran.

 

[1320stang]

Okay, my PVC airpipe story...

My buddy is a drag car chassis builder. His first shop had a 120 gallon, lay down, two stage, 220v 3 phase compressor. I was installed just inside the roll up door about 4 feet to the right and had a metal braided hose to isolate vibration that ran from the end of the compressor to a 2" line mounted to the wall behind the compressor, then up towards the ceiling of his 40'x60' shop. The shop is your typical steel framed metal building with the plastic faced wide rolls of insulation. He and I are standing in the middle of the shop one day looking out the door talking when the 2" line that ran horizontially behind the compressor (there is about a foot of distance between the tank and the pipe) blew up.

A huge bang and a large cloud of pieces of yellow insulation about 10' in diameter started falling down from the air, and although neither of us saw it, we heard a secondary noise 60' across the shop just right after the initial bang over the noise of the compressor dumping all it's air while the motor kicked on to make up the lower pressure. He runs over to turn the breaker off and then we go to look for the source of the secondary noise. We found embeded in the insulation of the wall about 4' above the floor a piece of 2" pipe 6" or 7" long and about 1/4 of the circumference wide (it was a long diamond shape, sort of a double ended dagger). If you ran a string from where it came to where it stopped, we were standing about 4 feet off to one side of this line. This string would have also ran thru the tank, so either the piece traveled in an arc to get where it landed, or it bounced off the horizontal purlin that was about 8' above the floor and probably 6' above the pipe that blew.

There was nothing that fell on it, or hit it, the hose off one end of the tank, and the armored cable off the other end kept someone from sliding somthing behind the tank, so it wasn't hit. I don't know if that compressor ran at 175 psi like my upright or if it was higher, like 250-300# range. I do know I won't run it, nor will I work or even go into someone's shop that has it.

 

[SteveU]

What is the best size pipe to use for about a 50 foot run from the compressor to the main air hose that will be used?

I have approx 45' of 1" black pipe in an 'M' pattern before my filter regulator & air hose and have never had any water make it to the filter. One of the main reasons to have a hard line is to cool the air & condense the water out so that it doesn't ruin your air tools. Keep in mind that the larger the pipe the slower a given volume of air will move thru it & the more time it will have to shed it's water vapor. For a 50' run I personally would go 1" but would recommend that you go with at least 3/4" and then use a filter/regulator right before your air hose to filter out anything that would harm your tools.

 

[JOHNMAN]

Please, please lock this thread.

It's a dead horse and needs not be beaten yet again.

The general consensus here is that it is ill advised to use PVC for air piping.

I tend to agree.


In the end, you can do what you want. You will be responsible for your own actions.






Begin story:

Once upon a time we used PVC in our home garage shop. We never had a problem with it exploding. It was in place for over 10 years. When we moved, we decided that it would be best to remove it. While taking it down, it was so brittle that it could literally be broken by hand. Because of the age hardening of the PVC pipe, I will not use it for air. I wonder about it being used for drain piping and vent stacks (I'm sure it becomes brittle over time as well but since it isn't typically under pressure and sees little stress, I suppose it is ok).

End story time....

I will continue using copper for the majority of my air lines as I find it easier to work with and it's available at most hardware stores.

Please don't get into a discussion about OSHA or my ranting will escalate.




Rant on.......

If OSHA rules were always followed to the letter, nothing could be built or worked on. Our country would never be able to produce anything and new construction could not happen. While I agree that some of the safety mandates that OSHA nazis have come up with are potentially a benefit, most are absolute BS. They seem to try to create only rules.

Rules can never and will never take the place of the need for common sense and taking responsibility of one's own actions..

Rant over......






just my $0.02

 

[Torque1st]

What is the best size pipe to use for about a 50 foot run from the compressor to the main air hose that will be used?

Take a look at the pipe size chart and the info posted in a recent thread here:
http://www.garagejournal.com/forum/showpost.php?p=482886&postcount=18
http://www.garagejournal.com/forum/showpost.php?p=483694&postcount=26

 

[matt_i]

Just to add to what's already been stated...metal pipe is my choice over, say, PEX as the "cold metal" is an excellent aid to condensing out water.

The black iron is tried and tested in industry for going on probably 100 years. You have to thread, you have to clean it, ideally paint, it can develop irritating leaks, you have to muscle pipe wrenches which can quickly screw up finished drywall. I'm guessing most of us don't own Ridgid 535s or even manual pipe dies, due to the cost, sometimes multiple trips to a friendly hardware store can get this done for you, though.

Copper can leak but you can resolve the leaks quickly and with a sense of certainty. There is no corrosion potential. Obviously the heat from soldering can dramatically affect finished drywall but wet towels, fiberglass pads and some pre-planning can help to minimize the problems. The other advantage is if you have to make changes later, you simply cut and add. The cutting tool is on the order of $25-50 and a hacksaw could be substituted. Iron would requiring removal back to a joint, installing a union, or attempting to thread "in place".

One curiousity about me: I do not ever install solder-only ball valves. I will always install male NPT adapters on a copper pipe and buy ball valves which have female NPT threads. Reason: ZERO chance of ever burning the seat out of the valve at installation, repair, or modification.

Last tidbit is installing a piece of flex hose between the compressor and the hard lines. If installing a 1/2" system, a 1/2" hose might seem appropriate. However any barbed fitting is going to reduce down to 3/8" or so...right at the start of the system. I'd strongly consider a 3/4" flex hose for a 1/2" system.

I hate to even mention the initials PVC but one last consideration....supposing you were lucky enough that the shrapnel didn't kill anyone or open up a gaping hole in the building, if the compressor was left ON (IOW to pressure-switch control) it would then run 24x7, running up your electricity bill to incredible rates and/or burning up the compressor itself. Depending on how you enable the pressure switch or how remote your shop is...this small detail could become a large consideraton.

 

[JohnMcD348]

Use the search feature and you'll find several years of posts about this subject...

I did and I found many and read alot. That's why I was wondering about the black plastic pipe that was laid up in the same area as the black iron pipe. And like a single minded idiot, I was at Lowe's agian today but was on a mission to pick up a few things and get out quick and only after did I remember I had intended on going back over to the area the had the pipe to look at it and get a quick shot of them so all could see what I was talking about.

Maybe next time.....

 

[Torque1st]

I did and I found many and read alot. That's why I was wondering about the black plastic pipe that was laid up in the same area as the black iron pipe. And like a single minded idiot, I was at Lowe's agian today but was on a mission to pick up a few things and get out quick and only after did I remember I had intended on going back over to the area the had the pipe to look at it and get a quick shot of them so all could see what I was talking about.

Maybe next time.....

Black plastic pipe at the home box stores is ABS and is not allowed for compressed air either.

Go to any ABS or PVC pipe manufacturer's website and you will find a warning similar to this from a major manufacturer:

DO NOT USE CHARLOTTE PIPE PRODUCTS FOR COMPRESSED AIR OR GASES
Charlotte Pipe and Foundry Company products are not intended to be used for distribution or storage of compressed air or gases. Use of Charlotte Pipe products in inappropriate applications could result in product failure, serious injury or death.

 

[phrogs]

PVC= compressed air = dumb as dumb as holding a hand grenade with the pin pulled for an indefinite amount of time.

There is a major difference between fluid pressure and gas pressure usually three time of a difference.

I disagree you can still throw the grenade as long as the spoon is still on and you havent milked it your good

 

[JohnMcD348]

I'll say, after reading through all these posts, I am sorry I asked the question without researching the material I was asking for. Monday I will make a special trip back to actually get the information off the pipe I was asking about.

So far the last 3 pages and 65 posts have been nothing more than the same thing that has been stated in 100 or more threads already.

Again to the senior members here who read and post to this thread and the 100's like them, I am sorry for starting another one for the fray.

 

[GTRClive]

I'm a Engineer of 22 years and have never fitted any black iron pipe to any of the 50+ CNC Machines I have personally built. Yes BIP it's cheap ( although Galvanised is close to 4 times the price here in Calgary), and my last shop I used Gav Pipe, but I'm installing Plastic pipe this time. You have to move with the times, and after using Plastic push-in fittings with plastiic pipe now for over 20 years thought it was about time I used them at home...

Just MHO

http://www.plasticsmag.com/ta.asp?aid=4299

 

[Torque1st]

I'm a Engineer of 22 years and have never fitted any black iron pipe to any of the 50+ CNC Machines I have personally built. Yes BIP it's cheap ( although Galvanised is close to 4 times the price here in Calgary), and my last shop I used Gav Pipe, but I'm installing Plastic pipe this time. You have to move with the times, and after using Plastic push-in fittings with plastiic pipe now for over 20 years thought it was about time I used them at home...

Just MHO

http://www.plasticsmag.com/ta.asp?aid=4299

That stuff isn't PVC or ABS either. Plastic has it's uses in some places. I have specified a lot of plastic air lines with Imperial Eastman, Legris, Parker, and later copycat fittings for hundreds of automated machines and machine tools.

 

[Stinger]

Anybody tried this compressor plumbing kit? Thoughts?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=66747

 

[Torque1st]

Anybody tried this compressor plumbing kit? Thoughts?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=66747

Try using the search function. There have been numerous discussions of that product.

 

[DHS]

Someone once told me that osha allows pvc to be used for air lines but it has to be buried in the ground, does anyone know if this is true?

 

[Torque1st]

Someone once told me that osha allows pvc to be used for air lines but it has to be buried in the ground, does anyone know if this is true?

It is true. All risers must be of metal pipe tho. Burial will not help a lot. There is a well documented incident where the buried PVC line failed and blew a 3' crater in the ground. There are other types of plastic line that are better for burial. A search here will find them.

 

[Stinger]

Try using the search function. There have been numerous discussions of that product.

Not sure what I need to search for then...searched "harbor freight complete garage air kit" and "central pneumatic complete garage air kit" and not one thread had anything to do with it?

 

[aleccolin]

i have used 1/2" pvc for the last 23 years with ZERO issues in my home shop. i keep my compressor on 24/7 with the line pressure at 150 lbs. again ZERO issues. galv. or black iron pipe would be a pain in the *** to install. if you are afraid of using pvc then i suggest using copper. that is the best way to go & much faster / cleaner / better than threaded pipe.

Knuckle, you are on borrowed time. Take a weekend and change it out.

PVC is fine for air. It's just a fluid like water, except that since it's compressible you don't get the water-hammer effect that you do in wet applications. According to this site 1/2" ID Sch 40 PVC has an operating pressure of 358psi and a burst pressure of 1940 psi. What PVC isn't good at is resistance to mechanical damage, vibration, and as always it's only as good as its connections (and the person doing them!). It probably depends on what state you're in as to whether it's actually LEGAL, but as long as it isn't in a location where it can't be hit or close to the compressor or some other form of heat and vibration, it DOES work.

Personally, the biggest reason I don't like it for air lines is because it looks like garbage.

 

[Torque1st]

PVC is fine for air. It's just a fluid like water, except that since it's compressible you don't get the water-hammer effect that you do in wet applications. According to this site 1/2" ID Sch 40 PVC has an operating pressure of 358psi and a burst pressure of 1940 psi. What PVC isn't good at is resistance to mechanical damage, vibration, and as always it's only as good as its connections (and the person doing them!). It probably depends on what state you're in as to whether it's actually LEGAL, but as long as it isn't in a location where it can't be hit or close to the compressor or some other form of heat and vibration, it DOES work.

Personally, the biggest reason I don't like it for air lines is because it looks like garbage.

NO, you are way off base. PVC is rated for liquid pressure not compressed gas. Check any of the manufacturers websites. Compressed gas is way different than liquid under pressure. Read the rest of the posts here for an explanation. PVC is not legal for compressed gas anywhere that I know of.

As far as a search; do not use quotations and do not use as many terms. Use Google to search the site if necessary.

 

[DHS]

There is a huge difference in water and air. Occasionally at work I have to flush air out of water main out of fire hydrants and let me tell you when you hit big burst of air it feels like the hydrant is going to come apart, you can feel the ground shake. I personally would NOT use pvc for air lines and currently just use a flexible hose till i can afford black iron or copper.

 

[rburke65]

You should have asked while you were at lowes or get some info from the pipe and Google it.

 

[Costner]

I wouldn't use PVC for air in my shop, but I do know a guy who has a hybrid design in his shop. All of his lines are black iron, but up in the ceiling of the garage he has a six inch diameter PVC "tank" that stores additional air volume. This line is two sections of pipe so it has to be close to 20 feet long, and it is plumbed down into the compressor.

I guess the idea is that this PVC holds quite a bit of air and therefore his compressor volume is increased quite a bit. I suppose since it is in the ceiling there is no threat of impacts to the PVC and it rests upon a plywood subfloor along with a layer of drywall on the ceiling of the garage, so I guess I personally wouldn't worry about it.

He is an airline mechanic by trade and seems to know quite a bit about this type of thing, but considering all of his exposed lines are black iron rather than PVC I guess that tells me something. Personally if I were installing lines I would stick to copper - it just looks better than the alternatives.

 

[Rolling_Thunder]

I just added airlines to my garage along with Insulation and 15/32 plywood walls. I used scheduled 40 PVC behind the walls and used black pipe elbows and piping coming out of the walls and strapped down to a 2/4 stud coming out. So even if you were to smack it pretty good it would harm it!

 

[Costner]

So even if you were to smack it pretty good it would harm it!

I'm guessing this isn't what you meant to say, but the anti-PVC crowd will probably agree with you.