DIY Air Manifold

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I got tired of unplug/plug the air hose for the different uses. I checked for air manifolds, but nothing was to my liking and if, it was too expensive. I used 4" black pipe pieces and 3/8" T's. I connected the 1/4" air coupler with a 3/8" to 1/4" connector. First I wanted to use copper, but I wasn't sure how to best connect the pipe to the wall. I have read the discussion about possible rust using black pipe, but my air is very dry so this wasn't a problem for me.The right most coupler is for the plasma cutter. I can switch off the air flow and discharge the hose with the smaller valve.The left side coupler is connected to a low-CFM valve. The manifold is pressured with about 100 PSI preset at the compressor and can be relieved using the left most valve (below the pressure gauge).The frame is screwed with four screws to the studs:Frame without the manifold:What would be a project without a mishap. In all the excitment, I added the tray to the lower side of the frame first
Reply:Nice project!  Neat and organized.  It would look entirely out of character in my shop. I would suggest you change out the end elbows for tees and install a 6"  "dirt leg" in those locations as it is an ideal location to collect water if any should condense.  Install the ball valve or petcocks on the bottom of the "dirt leg" for drainage and system bleed down.Black iron is the preferred material for air systems.  PVC is dangerous when it splits, the appropriate copper is expensive and hard to work with (silver soldered joints etc.) and galvanized flakes off and screws up stuff.   I have been running black iron in this shop for 30 years and have zero trouble with rust contamination.RogerOld, Tired, and GRUMPYSalesman will call, Batteries not included, Assembly is required, and FREE ADVICE IS WORTH EXACTLY WHAT YOU PAY FOR IT!Dial Arc 250HFThunderbolt 225 AC/DCAssorted A/O torches
Reply:The manifolds I've seen done up are usually made with thru drilled round or square stock, then they cross drill and tap them to 1/4" NPT. Works great if you have someone with access to a decent sized lathe and long bits..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by Rog02Nice project!  Neat and organized.  It would look entirely out of character in my shop. I would suggest you change out the end elbows for tees and install a 6"  "dirt leg" in those locations as it is an ideal location to collect water if any should condense.  Install the ball valve or petcocks on the bottom of the "dirt leg" for drainage and system bleed down.Black iron is the preferred material for air systems.  PVC is dangerous when it splits, the appropriate copper is expensive and hard to work with (silver soldered joints etc.) and galvanized flakes off and screws up stuff.   I have been running black iron in this shop for 30 years and have zero trouble with rust contamination.
Reply:Originally Posted by DSWThe manifolds I've seen done up are usually made with thru drilled round or square stock, then they cross drill and tap them to 1/4" NPT. Works great if you have someone with access to a decent sized lathe and long bits.
Reply:Looks good. How did you attach the manifold to the rack?I break things for a living...
Reply:Originally Posted by smokin_dodgeLooks good. How did you attach the manifold to the rack?
Reply:A very clean good looking set up. I was just thinking today about what a mess I have running from the air compressor. Glad you posted the manifold...Richey
Reply:I probably would have clamped it on.  A pipe is still a really small pressure vessel, in a sense.  Although, 3/8 schedule 40 has a pretty decent wall thickness to ID ratio, so it'll probably be alright.  You could always hydro test it to 1.5 times the working pressure.
Reply:Thanks richey dbotos, I wasn't sure if it was best practice at all to weld a black pipe, but it seemed so practical. Yes, a clamp would be probably the best.
Reply:Better black pipe, than galvanized.  I'm no pipe-welding expert, but if I had to make recommendations on welding a longitudinal tab on like that, I would say you'd want the toes of the beads nice and tangential to the OD of the pipe with no undercutting (like a good bead of caulk) and then wrap the beads around the ends of the tab so there's not a sudden discontinuity.  If you really wanted to get nitty-gritty, you could do some kind of controlled post-heat and cool down and maybe even some peening...Last edited by dbotos; 06-07-2013 at 12:33 PM.
Reply:Originally Posted by dbotosI probably would have clamped it on.  A pipe is still a really small pressure vessel, in a sense.  Although, 3/8 schedule 40 has a pretty decent wall thickness to ID ratio, so it'll probably be alright.  You could always hydro test it to 1.5 times the working pressure.
Reply:Not really.  3/8 schedule 40 is 0.091" wall and 0.493" ID.  Working pressure is almost 1800 psi and burst is over 10,000.
Reply:Wouldn't think twice about welding that pipe. Good practical solution.Millermatic 200Hobart Handler 120Victor O/A & Ramco BandsawLincoln 225 ACSnapOn AD HoodMiller XMT304/22AHypertherm Powermax 1650 G3Lincoln Idealarc DC600 w/Extreme 12 VSMiller Digital Elite "Joker"
Reply:I weld up fittings, lines and manifold type things all the time, as long as the internal air volume of the component isn't huge (think container or air tank) then it's not really a problem at all, the worse that could possibly happen even with a catastrophic and immediate failure would be like blowing an air hose but without even the whipping effect, truth is it's not going to fail like that anyway, even if you welded the hell out of it. larger tanks contain a lot of energy and the wall thickness-container size ratio is very low, here the wall thickness-containment ratio is so high that a smaller fitting like this could see way more than just 150psi before any danger of rupture at all.miller 330a bp TIGmiller dynasty 200DX TIGmillermatic 185 MIGthermal dynamics cutmaster 101 plasma cuttersnap-on YA5550 plasma cutterhypertherm powermax 30 plasma cutterbaileigh CS225 cold sawetc....