Under Ground Air

[PJ_Kravetz]

What would be the best (cheapest?) method to run a permanet air line underground from the 80 gal. air compressor in my garage to my utility shed 150 feet behind my house?

Has anybody had any luck running air through PVC? I know it is not recommended, but I have heard of people doing it.

Also, what size wire (AWG) would I need to run for 1 110V and 1 220V outlet? Remember it is approx. 150'

Thanks!

P.J.

 

[RHughes]

I once worked in a shop with air lines plumbed almost completely with sch 40 PVC pipe. We never had any trouble with it. I believe the air presure was regulated to about 80 lbs for our equipment.

 

[SPIKER]

I would say you could run the 1" 160 PSI black line available just about everywhere as a water line. air water not much diffeance.

and if you run one might as well run 2 so the wires can go into the other. for that distance 20 amps needs to be 10 gage minimum and if 220 then go with 8 ga and then you need 2 hots one N and one Green Wire (4 total) that will make sure you only need to do it once and less fussing run it off a 30 amp double pole breaker and put a small panel in the shed keeping the N and the G sepperated and add a NEW ground rod at the shed and tie it to the Green, DON't TIE the N and G together.

Mark

 

[higgy]

If 220 10 gauge should be fine, also he should make sure there is enough capcity to handle the starting inrush on the breaker curcut. With 20 amp 10 gauge will go to approx 250 feet with 220.

 

[BobReeves]

Here is a wire size calculator..
Wire Size

 

[higgy]

Bob. reat link.

and This did make me think abiut the curcut that I just ran, I was incorrect. The pump that I was running is only 11 amps with a start inrush of 5 amps which is why I could use the 10 gauge. Man my brian is in pain. /forums/images/graemlins/blush.gif

 

[EddieWalker]

Lots of shops use Sch 40 to run air lines. I've never heard it not being recomended. Why wouldn't it be alright?

Your max air preasure is going to be around 120 pounds, but even twice that you'd be WAY under what Sch 40 can handle.

I'm running half inch Sch 40 about 30 feet to have an outside fitting off my compressor with a dedicated hose for tractor work. I love my air grease gun.

The only reason I'm using half inch is it's a tite fit through my rafters.

Don't mess around with the black tubing, too much hassle with the fittings and eventually it always leaks.

Good Luck,
Eddie

 

[Henro]

<font color="blue">Lots of shops use Sch 40 to run air lines. I've never heard it not being recomended. Why wouldn't it be alright? </font>

I forget why it might not be alright...but I remember reading that plastic is more of a thermal insulator than copper, for example, so if you would use copper tubing the air coming out of the compressor cools quicker, and moisture drops out sooner, which is better for your air tools and especially better if you are painting.

Of course, proper drip legs and drain valves are needed too...otherwise the point is moot.

One question about running the air a distance under ground, even in plastic is what will happen to the condensate? If there is not a low spot to drain condensate out, that undergound leg may end up being filled with water...I suppose it could be blown out by opening a valve full at ground level...something to think about.

 

[kevinj]

Check any industrial safety group, osha etc. Plastic pipe is not permitted in most areas. There is a new product out which I understand is air rated. Water will not explode since it is not compressable. Air is compressed and will send plastic spears in all directions if a pipe fails.

 

[ns_in_tex]

I ran 3/4" schedule 40 PVC, underground to most of my barns and has been in for about 12 years now.

I think what is dangerous, is when exposed, it might send a piece through the air like a bullet from the air force, if the pipe is broken.

My solution to this was either convert to steel pipe before coming above ground, or protect so no strain could ever be exerted on the exposed pipe.