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What size air lines do you use in your shop?

Discussion in 'The Hokey Ass Message Board' started by willishotrods, Oct 19, 2013.

  1. Joe King
    Joined: Oct 8, 2004
    Posts: 993

    Joe King

  2. dvs28
    Joined: Jul 30, 2006
    Posts: 61

    from pacific nw

    Walt, what do you know about cool.

    Posted using the Full Custom H.A.M.B. App!
  3. BornBuick
    Joined: Jan 2, 2010
    Posts: 258


    Well let's look at the physics for a moment regarding what a "manifold" system is suppose to do in the first place. Compressed air is hot air. Hot air is moist air. Fast air flow reduces the ability of the manifold system to do one of it's most important jobs. The radiant conduction of heat thereby allowing the air to cool and become less heavy with moisture.

    With that said the manifold system needs to be made of sufficient diameter size, length (run) and of the best material for "radiating" heat away from the manifold material not just transferring of the heat along it's axis. Steel then radiates heat in a superior fashion away from it's run axis than that of copper which on the other hand is an excellent transfer conductor of heat. The air stream flow then needs to be slowed down so this radiation of heat away from the air is to be made possible. So one can see that a plastic system may be a functional system but certainly not an optimal system at least for what a compressor manifold system is designed to do in the first place and anti corrosion is not one of the key aspects for cooling moisture laden hot compressed air.

    So with the slowing of the air and it's resulting cooling, the content of moisture is also removed from the air stream flow. Slow air speed is critical throughout your system.

    Then that means anything that reduces the air flow at any point, then once again increases the rate via a psi increase and speeds up the air makes it prone to moisture pickup from the moist laden walls of your manifold system and this is best accomplished when there is a sufficient surface area that will facilitate the hot moist area giving it a place to cool or walled surface on which to condense onto trapping the moisture while allowing the air to move on. Reduced air flow also limits the throughput of a system so the larger the I.D. diameter the better.

    I use a 1-inch I.D. steel piping and 3/4 I.D. inch drops. Full flow connectors and nipples and as few full flow couplers as possible at that. In other words one should not connect a 1/4 inch feed to a 3/8 inch coupler just so you can conveniently power up a 3/8 inch nippled tool that requires a true 3/8 inch I.D. flow rate. But you would do that if you wanted to slow the flow rate to a tool that requires only a true 1/4 inch I.D. flow rate.
    Last edited: Oct 20, 2013
  4. bolthead
    Joined: Nov 15, 2010
    Posts: 93


    I like copper. Have taken apart a few iron systems with rust inside. If your running a blast box it will need larger lines and couplers, I used to fix and use a bunch of these glass beading boxes and restricted lines to the box was a problem with most users. Same thing with HVLP spray guns too.
  5. spiders web
    Joined: Jan 16, 2011
    Posts: 387

    spiders web

    I used 3/4 black pipe. Ran to the ceiling then around the shop. on each drop I put the hose nipple 24" above the bottom of the run and has a drain on each drop. I have very little if any problems. I drain the lines at the start of the day and works great!!!!!!!!
  6. Because he was not a a knowledgeable man that night. He made a mistake because he was human.
  7. turdytoo
    Joined: May 14, 2007
    Posts: 1,568


    I use PVC but an ex-inlaw in the PVC business warned me against it even to the point of offering to give me the black pipe to replace it.
  8. Fedman
    Joined: Dec 17, 2005
    Posts: 1,163


    I thought the big negative to using PVC was in the event of a fire, fire melts line, and then it feeds the fire.
  9. BornBuick
    Joined: Jan 2, 2010
    Posts: 258


    Rust is not really a problem for air flow given it is surface rust and IF your system is properly sized and configured. Air does not pick up rust as it could not transfer it effectively. Water cannot transfer rust as a soluble only as a particle solute. Any filter system even a roll of toilet paper or a old pair of underwear stretched over the end of your air hose with a rubber band would stop all rust being carried as it is carried as solute particles and not as a melted soluble one with the water itself.

    That is why filters are installed at the end of the service access runs. Moisture laden air then in terms of physics however, is the real concern nut if your manifold system has rust on the surface. Every ferrous metal compressor tank has rust on it's surface 1-day after it is put into service unless it is epoxy coated on the inside and even then there is a good chance the weld seams over time will flash rust if porous.

    So with all of the above explained why should someone want to use a plastic manifold system to do a job that by it's compositional nature is not suited for the task other than it is easier to glue connectors together rather than have to pull out the monkey wrenches and the vise on the shop table to put things together not to mention all that elbow and wrist movement which is better saved for couch activities with the T.V. remote. :)
  10. Hotrodmyk
    Joined: Jan 7, 2011
    Posts: 2,307

    1. Northwest HAMBers

    3/4 and 1/2 black iron here
  11. Idaho/Dave
    Joined: Jul 22, 2007
    Posts: 625

    from Idaho

    Pex Plumbing, water line, try it you'll like it
  12. great stuff...but EXPENSIVE
  13. cryobug
    Joined: Jun 6, 2005
    Posts: 362


    I used schedule 40 pvc in my tire store when we first opened and replaced it with steel quickly after it started exploding after a few months of use. Felling very blessed nobody was hit by plastic shrapnel I took it out and never looked back.
  14. LZ
    Joined: Sep 9, 2007
    Posts: 618


    Its like anything else in life. I know people who smoke quite a lot and are older with no issues except the smokers cough. I have known people who lived healthy lifestyles and had horrible health issues, death at a young age.
    What people get away with sometimes does not make it OK for you.
    Have seen PVC in peoples shops. But one shop in particular they had a mix of things. Well one day a wonder bar slid over and clipped the edge of the PVC. It was not pretty and lucky someone did not get shrapnel.
    My new shop is getting black iron. No worries.:) It is really nice to have the Compressor electrical shut off easy to get to and a master air valve to shut off on outbound air to system. Had a friend years back who came in his shop one morning only to find some smoke and a terrible burnt oil smell. A rubber hose split open on a drop. The Compressor had been running for quite some time and was getting ready to seize:eek: . Not sure why the thermal overload did not shut it down?? He says he always cut off the electric but that one night he did not.
    Anyway my 2 cents.
    good luck bud
    Last edited: Oct 20, 2013
  15. You guys using PVC pipe should stay off our sister site, the Garage Journal... You'd be verbally gang banged about as quick as if you showed up here towing a Jeep with your Mustang... :eek: LoL To answer the question though I use 1/2" black iron pipe in my 30x40 shop and have drops with quick connectors every 10' I hate having 25' of hose getting in the way laying all over the floor. Here's a couple pics from before I filled the new shop with stuff so you can see the layout.

    Attached Files:

  16. bobadame
    Joined: Jan 20, 2009
    Posts: 174


    I used 3/4 " black iron pipe for the long main runs and 1/2" iron and copper for the short runs.
  17. LZ
    Joined: Sep 9, 2007
    Posts: 618


    Hey nice set up you have.
    take care
  18. 3/4 copper off the main line. Main line was here already and is 2" iron pipe straight up out of the compressor across the ceiling 80' or so.

    Problem with compressed air is its hot and wet.
    It needs to cool in order to drop the moisture out of it.
    Gravity will take care of the moisture once it cools as long as you plan for it.
    Long enough run to allow air to cool, pitched pipe so the moisture runs down hill, take off for drops off the "top of the pipe", dirt legs and drains at the ends.
    Joined: Jul 20, 2006
    Posts: 2,422


    When I first plumbede my garage for air, I used schedule 40 PCV pipe. Five or so years later, I had a pipe explode, sent shards of PCV pipe allover. Fortulatly, I was outside when it happened. I used 1/2 copper pipe and sweated fittings on the pipe. I have 3 water drains, and the pipe is sloped towards the drains to help get the water out. I used the copper pipe to try and keep out rust from he steel pipe out of air tools and paint guns. Other than the cost of the pipe, I am happy with copper for my air use.
  20. whtbaron
    Joined: Sep 12, 2012
    Posts: 579

    from manitoba

    Shop is still under construction but the air lines will be 3/4 iron with drops that are longer than the outlet and a drain at each drop. I also plan on putting filters and quick disconnects at each outlet so rust will never be an issue and the long drops help separate the moisture. One restriction not mentioned here is the air fittings. I've acquired a gazillion of those cheapy restrictive fittings over the years that I will now have to replace with quality high flow ones. Would have been much cheaper to bite the bullet from day one and buy quality high flow fittings. You can run 2" lines from your compressor, but your HLVP gun is only going to get what can move through the fitting at the gun and flexible hose outlets.
  21. bobbytnm
    Joined: Dec 16, 2008
    Posts: 1,670


    I think the biggest problem with yusing PVC is that when PVC fails it turns into schrapnel tossing sharp little plastic daggers everywhere. Yes, I know, people have used without any issues for years and years. I'm not saying its a horrible thing and for the most part if its protected from damage and secured from vibration or being pulled etc then it shouldn't be a problem. But if its in an area prone to being struck by anything then I'd be nervous.

    But....there is still a cheap source of airlines at your local hardware store. ABS pipe. When ABS fails it just splits and cracks without turing to schrapnel.

  22. ems customer service
    Joined: Nov 15, 2006
    Posts: 2,634

    ems customer service

    not all abs is the same , there is a abs that is air rated but it is a specialty product. probally not available at the local hardware store.
  23. caton462
    Joined: Jul 17, 2013
    Posts: 176


    Air dryer should be far enough down the line for the air leaving the compressor to cool to do a good job.
  24. BornBuick
    Joined: Jan 2, 2010
    Posts: 258


    Yeah but why as I explained earlier, should anyone want to use a PVC or any plastics for that matter, manifold system other than to simply transfer a tubed network of water laden air from their hot compressor to their cold over condensed over loaded filter system?

    IMO HVLP are texture guns that should be relegated to primer use only. Use a compliant gun with more psi kick to properly atomize the paint.
  25. oldsjoe
    Joined: May 2, 2011
    Posts: 2,607


    I researched this topic till my eyes bled before I decided what material I would use in my shop. After talking to pipe fitters and plumbers and plastic product engineers I went with
    1 1/4 schedule 80 pvc with the proper CLEANER PRIMER and GLUE. It was explained to me that the majority of failures to pvc air lines was improper use of too low of a schedule and or glueing techniques and the pvc getting brittle over time from being exposed to the elements ie SUN HEAT COLD or vibration from not securing the pipe to the wall properly. My pvc is run at ceiling height and the drops are approx every ten feet with at least a 24"drop with drain below the connection. I turn off the compressor whenever I am through with it and turn off the air supply at the ball valve where it enters the shop. My compressor is located in another building with the electric and air feed lines run under ground. The under ground feed is steel reinforced rubber to a 3/4" black iron pipe. I virtually have zero water in my lines I just drained the compressor last week for probably the first time in a year and only dampened the bottom of my catch pail. I used the large size feed lines to act as a mini reservoir of sorts. Everything to this point has worked flawlessly. I am in no means a commercial shop my compressor doesn't run continuously for hours at a time. But I will say the air in this shop is far cleaner and less wet than when I had 3/4" black iron pipe in my old shop. But again that's just one mans opinion.
  26. According to the instructions that came with my dryer it should be installed as close to the compressor as possible. HRP
  27. oldsjoe
    Joined: May 2, 2011
    Posts: 2,607


    Joined: Jun 3, 2005
    Posts: 10,258


    Big difference in a home garage vs a commercial shop where the compressor runs on n off all day, all year. Now that that's out of the way and we figured out what's best, let's talk about the HVLP guns. HIGH VOLUME LOW PRESSURE. The best result isn't from the fitting size or material or the finger you scratch your ass with. How well the entry air is regulated, plus the discipline required at the trigger, will give a nice consistent flow of material. The VOLUME noted is not necessarily the AIR VOLUME, more like the volume of material that's transferred from the cup to the surface. It's done with LESS AIR VOLUME WITHIN THE GUN to reduce the airborne paint we're used to seeing from syphon or simple top feed spray guns. When you buy a spray gun the spec you want to know is TRANSFER EFFICIENCY. What percentage of material ends up airborne. Monster difference from the Harbor Fright HVLP top cup junk for $80.00 vs a $500.00 Iwata 400. I did a lacquer job in 08 with the Iwata. Remember when it took 15-20 coats of lacquer? I applied even more material in only 9, and I'm pretty sure I could have gone 7 or 8. Flash time was also much longer than in the days of old.

    Carry on...
  29. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,624

    Atwater Mike

    I had PVC sch 80 for awhile, at first...3/4" across the ceiling and 1/2" dropdowns every 10 feet. (this was in my garage, with a 3/4" line running out the side and down the fence to the back...)

    Since then, I am replacing it with 1.5" galvanized, (the capacity of the large pipe and its lengthy run is akin to having another storage tank; the drop downs are 3/4" galvanized.)

    The 1.5" galv runs 100 feet from the garage compressor to my new shop in back, which will be plumbed with the 1.5" as well.

    Compressor is 7.5 H.P., 80 gallon tank.

    Please consider replacing PVC with copper or steel. Mine didn't explode, but I have a beautiful wife that works with me, and I never throw hand grenades at her...or PVC, either.
  30. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,219


    I'm not so sure this Chinese steel pipe is better than plastic.

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