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Thread: PVC for Compressed Air Line

  1. #31
    Quote Originally Posted by Jim Becker
    "Just say no to PVC" for this application. It's not rated for compressed air. Yes, some people have used it successfully, but it's not the right product for the job. Copper is easy and inexpensive.

    As to the flexible hose, I use the Flexeel hose that Chris mentions and have a review of it on my web site.
    I don't know where you live but where I am copper is definitely not inexpensive. My plumbing contractor suggested black pipe. He said he has used it for many customers like gas stations and the like. Just remember to add drains at both ends of the run. I do agree to avoid PVC.

  2. #32
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
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    65,675
    Rick, in the scope of "how much pipe", most folks shop air systems are not going to use a lot of copper. And unlike black pipe, you don't have to choose between working with fixed lengths or investing in/renting a cutting/threading machine. That, in my mind, can make copper easier to install...and learning how to sweat copper isn't a horrible thing for any homeowner to do since over time, there will be opportunities to repair the stuff in the domestic water supply in a large percentage of homes. (Saves big bucks if you don't need to call the plumber...)

    That said, I agree that black pipe is an appropriate material for this application and folks should consider it, comparing both cost and installation aspects for their particular shop. It would have been a pain to use in my shop, for example, but it was really easy to thread 3/4" and 1/2" copper into the places I needed it to go.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #33
    Jim (Becker),

    You make a good point about copper. I have plumbed a couple of photographic darkrooms with copper and I find it easy to work with. On the other hand, my Home Depot will thread black pipe for free, even if you don't buy it from them and I assume others will too. I would buy it from them anyway since it is less expensive from them than the other suppliers, again, in my area. My new shop will take 40-60 feet of pipe so the cost would be significant for me.

  4. #34
    I Plumbed my garage for Black pipe, and the HF threading kit I bought was really quite reasonable.

    Kind of a toss up I guess whether you like playing with fire (copper) or Threads.

    I liked the threads. No, that's not right, I like both, but from what I had read, the black piped seemed to provide more thermal mass to help cool the air and pull the moisture out. Since I was planning on using mine to paint a car, it seemd to make sense to use the black pipe as a dehumidifer. Just make sure you run the slope so it goes back to the tank.

    It's easy to cut black pipe with a pipe cutter and really, the threads aren't that hard to cut either. Just have some cutting fluid, and a pipe vise, and it goes really quickly.

  5. #35
    Quote Originally Posted by Joe Mayo
    Repeat after me ....
    I will never, ever, ever use PVC for compressed air.
    I will never, ever, ever use PVC for compressed air.
    I will never, ever, ever use PVC for compressed air.

    If the integrity of the PVC is compromised, it doesn't just break. It explodes, sending lots of shrapnel all over the place.

    Now that we got that out of the way … Black pipe or Type "L" copper tubing works well for compressed air. There was an article in FWW's Tool & Shop issue a couple of years ago describing how to run the pipe. They used 3/4 inch for the main line and 1/2 inch for the drops. Put a Tee fitting at each drop with a regulator on one side of the tee and a drip leg with a valve on the other side. When you connect your drops to the main line, go up towards the ceiling and solder 2 elbows together, doing a 180 to come back down. This will, in theory, keep the air drier. Finally pitch your main line back towards the compressor so that any water in the system drains back to the tank. Hook it up like you did the drops by using a tee with a drip leg and a valve. Don't forget to put a shutoff valve at the compressor. Then you won't have to discharge your system to drain the water from the drip legs. To reduce any vibration from the compressor to the lines, use a short piece of rubber hose connecting the shut-off valve on the compressor to the tee fitting at the beginning of the main line.

    Good Luck,
    -Joe
    You said pitch lines towards compressor- This means every air use will bring back moisture that is draining towards compressor. Have lowest point and drain at fartherest point from compressor

  6. #36
    Greg,

    I installed schedule 40 PVC in my shop 10 years ago with 15 different drop downs, my compressor stays at 125 lbs all day 7 days a week, no problems. Just make sure you clean, primer & glue good and most of all let it dry completely before applying pressure.

    Good Luck
    Guy

  7. #37
    Join Date
    Feb 2005
    Location
    Easthampton, MA
    Posts
    986
    http://www.osha.gov/pls/oshaweb/owad...ONS&p_id=20202
    "Since PVC material does not possess shatter resistant property, and since it is very clear from the industry's recognized practice that PVC pipes are prohibited for above ground transportation of compressed air and gases (unless the pipelines are encased in shatter resistant material), any such use by the employers, where employees may be exposed to hazards, will be in violation of Section 5(a)(1) of the OSH Act. Therefore, employers who are found to violate the above described conditions or manufacturer's recommendations, during an OSHA inspection, shall be issued a 5(a)(1) citation." quote from OSHA

    It's been my experience that many home shops eventually become real businesses so it's best to really know what's legal and best for insurance purposes. I've spent many years going in places and undoing usafe and just bad set-ups. You'd be amaized how many shops just run airlines any old way with no regard to standard procedures which minimize moisture issues. All good compressor companies have guidelines on how best to run airlines but I have seen few that read such info until they ran miles of airlines and experienced al kinds of water issues which could have been prevented early on.

  8. #38
    Quote Originally Posted by Rick Lizek
    All good compressor companies have guidelines on how best to run airlines but I have seen few that read such info until they ran miles of airlines and experienced al kinds of water issues which could have been prevented early on.
    this fits me to a "t" ! after a few ruined paint jobs and having to replace some cleco motors i started listening to what the folks whos business is compressed air had to say. it really doesn`t cost to do things right the first time, in fact it`ll probably save you a chunk of change in the long run..02 tod
    TO WHOM IT MAY CONCERN; I ACCEPT FULL LEGAL RESPONSIBILITY FOR MY POSTS ON THIS FORUM, ALL POSTS ARE MADE IN GOOD FAITH CONTAINING FACTUAL INFORMATION AS I KNOW IT.

  9. #39
    Join Date
    Apr 2006
    Location
    Mpls, Minn
    Posts
    2,882
    Be nice if all would put the Town/state in where the Join date is on the posted page, I have both pipe threading equipt and soldering/braizing/welding tools and would be happy to help thoose who needed either the equiptment or tech help to install pipe/copper.

    Unfornately I sold my power vise years ago, but threading pipe manually just takes a bit more time and isn't all that hard.

    Whether PVC is rated for it or not, I know of three people who had it come apart on the, me being one, and when it does there's the chance of pieces flying off and striking someone...
    You always wear protective eyewear in the shop? How about that daughter/son/wife that comes out to say hi?

    If I was going to go back to painting bikes/cars, I'd be more concerned with the water/particle filters I used than if copper or black pipe controled moisture better, drip tee's/traps at the end of each run will probably do more than the material you use.
    I think I used 2 water traps and 2 filters on the line I used for painting, and those I got at a commercial supply house.

    Nothing is worse than to be in the last stages of painting and have the gun spit out a chunk of water, especially when doing metalflake...

    I like black pipe also as I can hang stuff off it...

    Al ......light stuff btw...

  10. #40
    Join Date
    Dec 2003
    Location
    SF Bay Area, CA
    Posts
    15,332
    Quote Originally Posted by Rick Levine
    ...my Home Depot will thread black pipe for free, even if you don't buy it from them and I assume others will too.
    Seems that my two local HDs have a permanently broken pipe threader....
    Wood: a fickle medium....

    Did you know SMC is user supported? Please help.

  11. #41

    PVC, Copper, Black Iron pipe for air line

    Mention PVC for air lines and it WILL get a rise out of every partisan :-)

    On some other forum, I remember this discussion and a point that was made was the possible problem in case of a fire. Obviously the PVC and other plastic piping would soften, burst and blow compressed air possibly on the fire! Someone pointed ot that the soldered joints in copper would do that too although at somewhat higher temperature. That being said, I suppose threaded black iron (steel) pipe is safer from that catastophic scenario.

    Now where did I put that pipe threader ...

    -- Teri
    Quote Originally Posted by Al Willits
    Be nice if all would put the Town/state in where the Join date is on the posted page, I have both pipe threading equipt and soldering/braizing/welding tools and would be happy to help thoose who needed either the equiptment or tech help to install pipe/copper.

    Unfornately I sold my power vise years ago, but threading pipe manually just takes a bit more time and isn't all that hard.

    Whether PVC is rated for it or not, I know of three people who had it come apart on the, me being one, and when it does there's the chance of pieces flying off and striking someone...
    You always wear protective eyewear in the shop? How about that daughter/son/wife that comes out to say hi?

    If I was going to go back to painting bikes/cars, I'd be more concerned with the water/particle filters I used than if copper or black pipe controled moisture better, drip tee's/traps at the end of each run will probably do more than the material you use.
    I think I used 2 water traps and 2 filters on the line I used for painting, and those I got at a commercial supply house.

    Nothing is worse than to be in the last stages of painting and have the gun spit out a chunk of water, especially when doing metalflake...

    I like black pipe also as I can hang stuff off it...

    Al ......light stuff btw...

  12. #42
    Quote Originally Posted by Chris Padilla
    Seems that my two local HDs have a permanently broken pipe threader....
    That's odd, my HD also has a broken pipe threader. The automatic oiler has quit. I hope this isn't a trend. I did find another hardware store that will cut and thread for a small fee. I only have a few to make so it isn't an issue. I won't be ready to install the pipe for a month or so so it all may be moot.

  13. #43
    Quote Originally Posted by Jeffrey Makiel
    Threaded black pipe can be difficult to get leak tight at air pressures of 125 to 175 psi. This may not be important, but can be a nuisance because it will bleed down the air compressor's tank between uses unless it's valved off near the tank. Black pipe is best suited for low pressure applications like natural gas and low pressure steam (less than 15 psi).

    cheers, Jeff
    According to my plumbing contractor, as I have said in an earlier post, he has used black pipe for many compressor installations. He does use both teflon tape and teflon based pipe dope to insure a tight seal though.

  14. #44
    Join Date
    Dec 2005
    Location
    Robins, IA
    Posts
    171
    Quote Originally Posted by Chris Padilla
    Could PEX handle the pressure? This is the new "copper" plumbers are running in new houses.
    Chris, I looked into this and yes, PEX can handle the pressure. However, PEX rapidly deteriorates in sunlight and becomes brittle. So, unless your shop is in a cave, probably not the best solution.

    Matt

  15. #45
    After reading the section on choosing pipe for a compressed air system in Sandor Nagyszalanczy's book "Setting Up Shop" (he's a former editor of Fine Woodworking and American Woodworker) I have decided to use galvanized pipe instead. The cost is irrelevant compared to the time it would take, at least for me, to replace any sections if there was corrosion due to moisture. My compressor will be located in the utility room which is separated by a wall from the shop. The pipe will run through the wall into the shop and feed various locations in the shop. Check out his book, he makes some pretty good points.

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