I've heard that about copper piping, but I've always been worried about it being so thin, and something falling on it and tearing it apart. I'm also not sure what the pressure rating is on the copper stuff. I'm only bringing this up because I'll be converting to hard lines soon, and I was going to use steel. Copper is a lot cheaper and if its a worthy option well then I will seriously consider it.

Thanx

Madmike33

 

Have you priced copper lately? Copper is in short supply world wide due to newfound Chinese demand for appliances. 1 inch type L copper "pipe" is running $2.13 a foot. 1.25 inch black pipe (roughly equivalent flow capacity) is running $1.58 a foot retail, and may be available "surplus" for half that. (Steel prices have gone up too, but not as much as copper).

I would prefer the copper due to cleaner operation, but find myself tempted to go down to the local steel yard to see if they've got some rusty surplus.

 

Madmike33,
Don't worry about the copper being too thin. Even Type M, the thinnest wall at 0.032" (3/4" dia.) will take the compressed air pressure. The rated internal pressure for Type M drawn copper tube is 611 psi at 100 psi (3/4" dia.). This is from Table 3c of the Copper Tube Handbook published by the Copper Development Association. That is over 200 psi with a 3X safety factor. The weakest point in the system is the soldered joint and the max. recommended pressure is 500 psi for 100F temperature for 1/4 "-1" sizes. That's using 95-5 Tin-Antimony solder. 50-50 Tin-Lead solder is a weaker joint; but you won't be able to find that solder at Home Depot or Lowe's or your local hardware store. The Plumbing Code doesn't allow lead solder in water systems for obvious reasons.

If you don't want anything falling on it to dent or ding it; then put it where it won't be damaged. Run it along the wall up close to the ceiling and put in vertical drops where you will be using it. When you do your piping, fab most of it up on the bench, where you can control the soldering of the joints and then do the minimum amount of joints when you are on a ladder or in a tough position.

With copper pipe the different wall thickness tubes are labeled K, L and M. K has the inked label in green, L is blue and M is red. K is the thickest wall, next is L and M is the thinnest. Wall thickness varies with tube size.

This should alleviate your concerns.

Phil

 

fefarms,
Yes, copper is more expensive lately. All commodities fluctuate in price. The difference in the price of steel and copper will even itself out with the problems you will pay to fix with the steel pipe. The steel WILL corrode, especially if you go get some "rusty" surplus. Don't be tempted by the lower price. Copper will be far less problems for you. I've replaced too many steel air lines with copper to recommend anything else but copper. And copper will be easier to install. Soldering a copper joint is about 1/4 to 1/3 the time that it takes to do a threaded steel joint. And if you were to go to the expense of galvanized steel pipe, you still get the corrosion because where ever you cut and thread the pipe the zinc is cut off exposing raw steel and the threads and cut ends will corrode, still giving you the rust in the system. Use copper in compressed air systems. Remember, water is the universal solvent and you will get water in a compressed air system.

Phil

 

Thanx for the good read AZAV8, I will definately think twice before using the steel piping.

Madmike33

 

I'll go with copper as it will be a short run anyway.

One more question on mounting these things. Any easy way to do this, or is it a drill the whole (concrete floor), sitck a bolt in it and cement it in excersize?

 

Just another data point: about a year ago, I installed a short run of black pipe from my compressor to my workbench. I am *still* chasing down air leaks -- I've got it to where it will hold 80 PSI but leak under higher than that. It's OK for my purposes, but...if I had it to do again, I'd probably go copper.

 

You can buy compressor mounting pads from grainger or ebay or the local compressor store. These are waffle pattern rubber with a steel backing plate. They act as vibration isolators to keep the compressor from rattling your teeth out by telegraphing through the floor. Or you can scrounge around -- I used some left over aircraft shock donuts, but even pieces of old tire would work.

I don't think much of trying to bolt a compressor to a concrete floor with wedge anchors. It seems like the vibrations would "work" the anchors and eventually loosen them. I used lag screws to bolt my IR 60 gallon vertical to a couple of 2 foot lengths of 6x6 wood timber to form a wider mounting pad, then added a couple lengths of chain to the nearby wall. (Oregon is overdue for a subduction zone earthquake, and those vertical compressors are tippy). The wood helps to reduce the noise and vibration transmitted down into the floor. A lot of guys just use the pallet the compressor is shipped on as the mounting base; since the compressor comes already bolted to the pallet. Uses a lot of floor space, though.

It is very difficult to reach the compressor tank drain at the bottom center of a vertical tank. It helps to get the compressor up off the floor with the mounting arrangement, and leave yourself enough room to get your hand in there and spin the drain. You can replace the cheap drain valve the compressor comes with with a cable operated tank drain (meant for air brake tanks on trucks) that make this daily maintenance a lot easier. Or you can get fancy and put in an automatic drain.

And I have to agree with the post about threaded joints leaking. I always have trouble with NPT joints. Teflon tape, RectorSeal, big pipe wrenches, they always seem to leak. Copper it is, despite the cost.

 

Throw the teflon tape away! If you want leak free pipe joints the only way to go is Locktite pipe sealant. You can even screw the joints together hand tight and they wont leak.

Teflon tape works OK on hydraulics and water but don't expect it to be leak free on a gas.

 

In my experience of plumbing half a dozen shop and automotive air systems, teflon tape works fine when you have good pipe threads to work with. Unfortunately, buying iron pipe at home depot doesn't usually get you precise fits, and the dope can definitely take up the slack well.

That said, my entire truck on-board air system is plumbed with red brass pipe and brass fittings (a mix of cast red and forged or barstock yellow) and teflon tape. I'm generous with the tape and have no leaks in any of the 2 dozen taped joints. I've gone a month before without using a tool or the air horns and have seen no indication that even 1 nitrogen molecule has slipped out. The only joint I have dope on is tank's inlet check valve, I used the loctite brand stuff already recommended. I never expect to have to undo that joint, but the whole rest of my truck air system is a continual work in progess.

I've added these comments because I've seen that teflon tape often gets unfairly blamed. A lot of the time it's crappy threads that are the real problem. There is a very noticable difference between a made-in-china $0.79 iron Home Depot pipe elbow and a $5 made-in-USA LEE fitting.