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Pipe and Fittings for Compressor Air System

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  • Pipe and Fittings for Compressor Air System

    I am working on my shops air system this weekend. I am using Black Iron pipe for transportation to each machine or user point. I have a couple of those overhead pull down reels with 25' of hose that are going up.

    Over at HF they have those three female outlet manifolds which are handy to have.

    I have notice that lots of this have 1/8 NPT (misting unit), 1/4 NPT (air guns and most things I use) and then a couple of older (50s and 60s built) ait tools are 3/8 NPT. I have a 6Hp with 30 gallon tank compressor and aux. tank that is 100 gallons.

    Should I run all of this in 3/8 or 1/2 pipe? At each work area, there are four, have pressure regulators and run the compressor and air system at a higher pressure? And should I adapter all of the tools and what nots on the tool, keeping each air outlet the same?



  • #2
    For yor main pipe, run something big like inch and a quarter or inch and a half. For the drops you can use half inch and then an adapter to whatever tool you'll be using. Pitch the pipe run away from the compressor and at the end put in a drop almost to the floor with a ball valve attached. This is to drain the line. Drain it every time you use it. Put a drop where the run rises to the ceiling right after the filter also close to the floor. This is another drain.Water is death to air systems.

    Others swear by copper or PVC. I have seen black iron pipe systems 30 years old and never a leak. Much safer than the others as well.

    [This message has been edited by Rustybolt (edited 08-21-2004).]


    • #3
      I ran a 1" main, 1/2" drops, 1" hose to connect to the compressor.

      Also I ran my drops up first so they would not act as a drain. Some of drops terminates in a tee with the quick connects horz, and a drain valve vert. The drops on the center of the wall have the quick connect vertical with no drain. I did this for clearance issues if I place something in front such as a tool box.

      Here is a photo of the plumbing

      I guess I need to wire brush the threaded connection to remove the excess teflon tape. If you are using teflon tape, start one thread from the end. This will help prevent teflon tape from entering your system.

      [This message has been edited by JPR (edited 08-21-2004).]


      • #4
        Since you only have a 6 hp compressor your flow rate is low enough to allow you to use 1/4" pipe or even smaller and not suffer any significant losses due to piping if you keep the runs under about 100 ft. I use 1/2" or larger pipe just because it is more easily available. Larger pipe gives you some significant additional compressed air storage. Black iron (steel) pipe is the best way to go on compressed gas, cheaper in the long run and much safer than plastic pipe. Copper is more trouble to modify and more expensive, especially when you go to sizes larger than 1/2". Liquid pipe dope is a better way to go than teflon tape, especially when you are workng with stainless steel.


        • #5
          I only run large diameter black iron from the tank to each work station and then bust it down.Reason being on a 3/8 pipe a 100' run will loose 8cfm and 20psi from air friction alone,not to mention resistance from fittings.
          As said above I would run a main truck line of 1 or 1-1/4" and branch lines of 3/8 or 1/2.
          And of course slope all horizonal runs back to the tank 1/4" per foot so condensate drains back to the tank,otherwise you will have a "wet" system.
          I just need one more tool,just one!