Piping for compressed air

[John S]

I will soon be running the pipe for my new air compressor. I recently read about using copper pipe. Any thoughts on this?

[HWooldridge]

I use 1/2 or 3/4 black iron pipe. Strong, easy and cheap. However, copper is fine if you are good at silver solder.

[MoparNorm]

If cost is a concern, a lot of shops are now going to Schedule 80 (the gray pipe) PVC. It is good to 250 psi. Check the max output rating on your air compressor and pressure switch to be sure that your compressor does not exceed that rating. The pipe should be supported and/strapped at every 6' and at every change of direction. Be sure to run a "drip" leg and a filter to trap water.
MN

[RickL]

piping shop for air

Get black iron pipe its cheap and I would trust it a lot better then schedule 80 PVC.

I would suggest that you run minimum 3/4" pipe to your work locations and that for a water trap filter to work efficently you will need at least 25 feet of run prior to the first tap in order for the compressed air to cool enough to be trapped. If you do not then the water vapor will pass thorugh the filter.

There are several good sites about running air lines on the web.

Here are two that I suggest.

http://www.sharpe1.com/dr-pipe.htm
http://www.oldsmobility.com/air-compressor-piping.htm

There is another site on the web that I can not locate at the moment that recommends building a cooling tower, basically a U shapped set of piping using 2" line right off of the compressor and then reducing it down to your 3/4" line. Due to the sudden reduction in pipe diameter it creates a venturi effect which will then cool the air suffeciently for the water trap to work.

This is what I have set up in my shop and works fine with both sandblasting cabinet and paint gun for my truck.

Rick

[HWooldridge]

I have a two stage, 175 psi, 27 cfm compressor and it's in the barn with the shop about 75 feet away. The shop has an old 40 gallon industrial freon tank as an additional reservoir so I have 120 gallons of air capacity. The system is piped with 1/2" black pipe the entire way and is about 18" underground. The air tap comes out of the compressor, turns up, then turns down with a tee on the side feeding the shop and a drip valve at the bottom. Water collects in the tank and the leg but has never collected in the shop tank or lines. It's often 95 or hotter here with 60-75% humidity so there can be a lot of water in the air and I regularly blow off several quarts collected in the compressor tank and leg.

[RickL]

buried air lines

I have 3/4" about 36" below ground (frost line) I ran it inside PVC pipe. I have not finished the installation I have a Wayne 175psi 2 stage with a 60 gallon tank.

Definetly need a two stage when doing work on these trucks.

[John S]

thanks for all the info

[Denis]

Air Lines

One important consideration is moisture. To remove the water the air must be cooled. Copper tubing has a much better heat transfer rate than black iron. PVC is an insulator. I am planning a system for my garage and will run copper for this reason (dry air). The solder joints are another issue. If they are hard (silver) soldered no problem; but if soft (lead or tin) solder is used the joints should be kept below 200° or the solder may soften and come loose. An old AC condenser makes a good heat to cool the air as it leaves the tank.

[MoparNorm]

Most Paint Shops,

Use both filters and driers, before the air lines with an 'end of run' drier and filter again placed at the booth, or in the case of a home system, just before the (short) spray gun hose. The type of pipe, except for black iron which is prone to be very oily, will not matter much in that type of a system.
One word of caution, as a building contractor for over 30 years, I must caution that while copper is OK for use (although very expensive) the quality of the joints is of paramount importance! I have installed nitrogen lines that hold over 3,500 psi. I have seen a plumber KILLED while working with less than 65 psi water pressure. Be sure to carefully TEST all joints before putting the system into use. I would hate to think of a small child or a forum member being injured by a ruptured pipe. We normally test at 150% of operating pressure for 24 hours. If the system holds for that long without ANY loss of pressure, you are good to go.
MN