A while ago, someone described their air system. Compressor upstairs, 3/4" copper line runs down to a second smaller tank under the bench. (a flex line from the compressor to the copper line) Then a line (3/4" copper) back up to the ceiling, across the shop with drops at the various locations for connectors. (each drop continued past the "T" for the connector as moisture "traps" with drain valves at each location. Then for air tools and painting; a drop to a wall mounted air dryer (has it's own drain. The reason for the second tank under the bench was it helped cool the air (and added some more capacity) AND it had a moisture drain as well. As a safe guard, the copper (3/4") was run INSIDE black iron pipe at any locations that something might run into the air line drops. (the black iron pipe was just a shield, not holding air) As far as bending galv pipe; it is a lot of work and the flaking of the galv coating will leave particles in the lines.
Its serious buisnees. People might have gotten away with it but it will catch up to them. Im a licended irrigator and use it daily. 30 psi of water will shatter it after so many times of water hammer. Be carefull.
Add me to the no votes on PVC, I've witnessed failure (within feet of the shrapnel) and could drone on about why it is a poor material choice for compressed air systems over time.
I'm a mechanical engineer and have specified pipe for all manner of piping systems for 29 years. DO NOT USE PVC, CPVC, ABS, PE OR ANY OTHER THERMOPLASTIC PIPE FOR COMPRESSED GAS SYSTEMS. THIS INCLUDES COMPRESSED AIR SYSTEMS. Those of you who have used PVC in compressed air systems and haven't had and accident are lucky! Your burst pipe is just waiting for the right size pressure spike. You WILL have a pipe burst on you with sharp fragments flying everywhere. People will get hurt if they are in the line of fire. PVC fragments make nasty, jagged wounds and eye wounds are very difficult to repair. If you don't want rust flakes in the system, use copper, either Type L or K. Type K is the heaviest wall copper. The nuclear power industry uses copper for its instrument air systems. The steel and galvanized pipe will rust over time. Orient your tees for the drops so the branch goes up. That way any water in the line will flow along the bottom of the main. Slope the main so it will drain. When I specify pipe for air systems in auto shops, I specify copper. Galvanized and steel have to be threaded and that will cost about 20% more than copper to install in a commercial shop. With galvanized pipe, the threading cuts off the zinc coating leaving uncoated steel. The threaded joints will rust. Soldering pipe is easy if done correctly. NIBCO and Oatey even have info on their web sites on how to solder copper pipe. I taught myself how to solder pipe. Me an engineer and you know what pipefitters say about engineers. We won't repeat those things here. I've ranted enough about compressed air systems and PVC. Don't use it. Somebody WILL get hurt. Philip E. Maynard, P. E. AZ registration No. 18696 A.K.A. AZAV8
good topic, good discussion...I am planning on redoing some things in my shop soon and this is interesting. Why not use air hose to connect between to drops, etc.? It would seem easy to just throw hose over the rafters and plumb it in where needed but I sure there must be a reason why this wouldnt work?? Thanks- another question, if I were to plumb in an extra tank, how would I do it? On which tank would the regulator, pressure switch, etc. go?? thanks-
Yep: the smaller the ID & the longer the hose/line the greater loss of pressure (when the air is flowing). ~ Paul aka "Tha Driver" If you can't take the heat, get out of the nuclear reactor.
Hose is considered a consumable item. Use it as a main distribution line and it will sag between supports and keep water trapped...continually flex, chafe and eventually burst, which will mean it will thrash around like a rabid snake in your loft, kicking dust and God knows what else everywhere...it will limit available air flow due to the small diameter...you can't set it up for vertical taps without splicing into a hard fittings anyway... Using hose to plumb your shop is just too wrong to even keep answering the question. Besides...the only reason rubber hose is used ANYWHERE is due to the need for a flexible continuation between the distribution line and the tool. Its only JUST adequate for that purpose. "another question, if I were to plumb in an extra tank, how would I do it? On which tank would the regulator, pressure switch, etc. go?? thanks-" The pressure switch can remain on the original compressor. Nothing needs to be changed. I mounted my additional tank under a work bench opposite the compressor. Air p***es thru a copper line, over my garage door header and then down to the lower inlet of my additional lay down 60 Gal tank. Air leaves this tank from a higher outlet and directly into a water separator. From there it goes to a simple manifold/regulator unit that gives either regulated air or full pressure at the flip of a ball valve. From the manifold, the copper air line again goes to the ceiling and across the front of the shop to the far corner where it drops down to a drain leg. Half ways down the drain leg a TEE in the tube sends pressure along the full wall with 3 top mounted taps...ending in another drain leg at the back of the garage. I have an additional water separator that plugs into whichever tap I am using at the time. Pros and cons... PROS..... NO water at all when painting. NONE. The additional tank works as a giant heat sink and removes at least 90% of the water vapor before it even gets to the first separator. This is a hobby shop...not a full time operation though. Eventually the additional tank would heat up and not work as well. I've never reached that point. My compressor is mounted inside the garage. With the additional tank I turn off the compressor when painting...paint a full coat over the vehicle and then, once the overspray has cleared, I turn on the compressor and let both tanks refill as I fill the gun etc for the next coat. No worries of a vapor explosion OR clogging the compressor/motor with paint overspray. Turn the comp off and go with the next coat etc... NOT a HVLP gun either BTW... CONS....The compressor won't refill both tanks without running for a longer period than I like when I'm running a DA. So I redesigned the manifold to allow single or dual tank operation and I only use dual tanks for painting. Perhaps using a 30 gal reserve tank would make it a non-issue. On the single tank I get some water vapor...eventually...but my quick and dirty manifold mod pulls the air from the second tank INPUT line when I'm using the single tank! Thats too close to the compressor for the normal vapor to condense, so its an expected problem. Eventually I'll be redesigning it to feed the full shop on the single as well as the dual tank so then I can take air off a tap further down the line. Should have no problem with vapor then at all. Should be done before the fall. I'm THINKING about running a homemade condenser coil inside my shop fridge IF I still get some moisture...I really don't think its gonna be a problem though. All in all I'm happy with how the setup has worked... a few additional mods will make it perfect for my needs.
Because of overhead doors and man doors being on the wall that I run my (copper) air line across; the line is at the ceiling. (with an down slope to the end that has a drain valve) So .. if I run DROPS down from the overhead line and go lower than the outlets and come back up, (the shape of a "U"; a 90 deg, a "T" and another 90) then UP to the outlet; then have a drain valve at the bottom of the "U" (the "T" ); would that work?? (better) I have 6 drops that I could modify easily. I already have moisture traps off the bottom of the existing outlets made from one (1) and a 1/2" copper pipe, 8 inches long. (3/4 to 1 1/2 and 1 1/2 to 1/2" reducers with drain valves on the ends)
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