compressor air lines

**Master Brian** · 10-05-2009, 08:47 AM

I am wanting to setup outlets for my compressor, so that I can plug my air tools in without having to run long hose everywhere.

Most of this will take place inside of my 1-1/2 car garage, but I am toying with the idea of also running a line into my house and into the mechanical room in the basement.

I should note the garage is not attached, it sits about 10' off the house, but I have an area I can easily bury the line and bring it into the house.

What have others found that works well? I was thinking of using PVC, someone mentioned the grey plastic pipe, but a google search just brought up to use black metal pipe. Here is a link to that site.

When I had my drive re-poured last year, I ran metal pipe under ground and terminated it in my garage and at the edge of a box-out crawl space. I did that so that if I ever wanted gas to heat my garage, the line would already be there. I suppose I could use that and then when I get done remodeling or if I ever wanted gas in the gargage, I could switch it's use back over.

Thoughts???

**Gary Swart** · 10-05-2009, 09:06 AM

Absolutely do not use any kind of PVC for compressed air. PVC becomes brittle overtime and is prone to burst under air pressure. I know it is tempting because it is easy to assemble and cheap to buy, but you are tempting fate if you use it. Without getting into the professional air lines that are excellent but very expensive, there are two acceptable media that you can use. Black iron and copper. My personal choice is copper because it does not rust and is much easier to install. Copper assembles like PVC except joints are soldered rather than being solvent welded. Black iron will rust and while probably not rust to the point of leaking air for many years, it will produce some rust inside that could contaminate tools, especially paint guns.

**jadnashua** · 10-05-2009, 09:14 AM

It's amazing how much water can accumulate in the bottom of an air compressor after running on a hot humid day. Stay away from steel or iron. Even with a dryer, you'll be constantly allowing some moisture into the line, and rust is inevitable. And, as noted, using PVC is tempting fate...the shards can kill.

**Master Brian** · 10-05-2009, 10:27 AM

Well, PVC is definately out for me.

I actually was also wondering about pex as well. It's very strong, wouldn't be many joints along a long run, and it's flexible, which equals easy to run. Though I've thought about it, I am 99% sure I wouldn't use it.

The link I attached above, suggests staying away from copper because the joints can come loose. I question that, as it's used for water and I'm fairly certain my water pressure is around 90psi in my house. Of course my compressor goes to about 120psi and I plan on a 2stage once I get my garage setup.

I would think the black pipe would rust as well, but in my area they use it for gas and it seems to hold up, here is what they say....

Use Black Iron Pipe only. We do not recommend galvanized metal pipe, as galvanization can come off the inside of the pipe, clogging
separators and regulators. Do not use plastic pipe, as plastic will not help cool the air; and glued joints often separate. Avoid copper
tubing, as it is easily damaged; and soldered joints can come loose under pressure (Safety Hazard). Use 1/2" pipe for up to 75 feet of
horizontal runs of pipe from your compressor. Use 3/4" pipe for horizontal runs of over 75 feet.

So, at this point, I guess I am leaning towards copper or black pipe, unless someone else has a good suggestion. Hmmm.....

**iminaquagmire** · 10-05-2009, 12:16 PM

Unless I had a separate industrial dryer before it entered the black pipe, I'd use copper. Your other option is either DOT air line or high pressure hose, but I think I'd just use copper.

**Gary Swart** · 10-05-2009, 01:23 PM

My copper air lines have been holding strong for several years. I question that pressure will cause the joints to fail. I you have 90 psi in your home, that's way too high. 60 to 65 psi is plenty. Higher and you risk rupturing hoses to the washer and toilets, that much pressure is also hard on faucets and valves. You should seriously consider a pressure regulator valve and a thermal expansion tank so the pressure can be lowered. FWIW, I run 50 psi and feel that that is plenty of pressure.

**jadnashua** · 10-05-2009, 03:25 PM

Pex might work. The pressure it can handle depends on the temperature. You'd have to read the individual specs for the type you are interested in. Because it is flexible, starting and stopping air flow could cause it to whip around, which could wear a hole in things. Could do that with copper as well, so proper clamping and routing is critical.

**Gary Swart** · 10-05-2009, 08:58 PM

My compressor is connected to the copper line with a high pressure hose to absorb vibration and movement of the compressor.

**dgold** · 10-08-2009, 06:12 PM

I've seen PVC used many times. I'm not endorsing it by any stretch, just that I've seen it used successfully in industrial applications. At cool temperatures and in smaller diameters, it has a fairly high burst strength. While I have no data to back this up, I would think PEX would fail safer than PVC since it's a less brittle material - would be interesting to test it. Personally, I'd use 1/2" copper.

One of the big downsides to plastic vs metal (other than a potential safety issue) and why I personally wouldn't use plastic, is that it's a much better insulator than metal. Metal, being much cooler than the heated compressed air will encourage condensation along it's interior and if routed properly can help ensure extremely dry air at the outlet. Dry air is typically wanted - especially if you intend to use any kind of spray equipment. If using air tools, dry air is still wanted, but a lubricator may be added after the regulator.

When plumbing for air, keep in mind where that water will go. If you have a giant "U" or trap in the ground, which it sounds like you may, eventually water it will build up in this trap until you eventually have accumulated a giant slug of water. If this slug of water is then driven through an air tool with a vane motor, it will undoubtedly destroy the tool. Somehow, you need to cool the air below it's dew point before sending into your underground plumbing. Don't let anyone tell you that a non-desiccant moisture filter will pull the moisture out of the air. They don't dry (dehumidify) the air, they only remove liquid water.

**Gary Swart** · 10-08-2009, 06:27 PM

I have to question that you have seen PVC used for compressed air in industrial applications. OSHA would put an immediate stop to it. As far as it being used by many individuals, I know that is true, but just because many do it hardly makes it safe. If you want to take the chance, that's your business, but don't try to justify an unsafe practice just because it's cheap and easy.

**Lakee911** · 10-08-2009, 06:43 PM

I like and have used black iron pipe. Copper would be good too.

hj · 10-09-2009, 06:47 AM

Copper tubing will withstand any safe air pressure in your system, "Coming apart" is not a danger with copper, it would just cause a loss of pressure. Catastrophic, spontaneous, pipe failure and the shrapnel it causes is the danger with plastic pipes.

**Cass** · 10-09-2009, 06:51 AM

I can't wait till the first guy comes along and wants to use PEX for compressed air...

**Master Brian** · 10-09-2009, 09:10 AM

Originally Posted by Cass

I can't wait till the first guy comes along and wants to use PEX for compressed air...

I have questioned whether it would be ok or not. It would seem a quick, inexpensive and easy to run option for a home setup.

With that said, I have read that plastics create too much water buildup that can't be removed via water seperators, so it is not an option I am willing to try.

Although it is relatively more expensive than the copper, especially since I have lots of copper sitting unused in my house after switching to mostly Pex water lines, I think I will go the Black Pipe Option. I think I found an easy to run underground spot to come into my house via the garage and it will not contain any vertical runs except for possibly one section inside the house, which I can place a valve to purge the line of any pooled water on occaision.

Thanks for the feedback and for helping me decide what option to go with.

I did speak with my neighbor, who is also interested in running a line inside his garage and I think he's going to go PVC. Needless to say, I am a bit concerned now about helping him with any jobs in the vicinity of the air line.... Maybe I'll offer him my copper!!

**Lakee911** · 10-09-2009, 12:38 PM

Originally Posted by Master Brian

With that said, I have read that plastics create too much water buildup that can't be removed via water seperators, so it is not an option I am willing to try.

How do you figure? I would think it would be the opposite since plastic is a better insultor...no?