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.

 

[Lazy]

Hi
check out this setup for compressed air
http://www.garage-pak.com/

charlie

 

[Lazy]

Hi
check this out

http://www.lni.wa.gov/Safety/KeepSafe/HazAlerts/902.asp

Charlie

 

[Lazy]

Hi
One more

http://yarchive.net/metal/compressed_air_pipe.html

Charlie

 

[SPIKER]

the black pipe I was refering to is a line not pipe: when it blows up it does not splintere as a pipe would. it would form a bubble first then the bubble ruptures releasing the pressure. seen this happen before and there is TONS of plastic air lines, from 1/3" all the way up. that is what they use now for natural gas too, PLASTIC LINE not pipe. most of it is rated for much more than you would think. can be used for electrical water air or gases.

there is also lots of COPPER soldered piping but that has the tendency to burst appart if over pressurized.

forget the sch 40 stuff. run the plastic line, and keep it down below frozt or else run the out feed up hill with steel and add a drip leg prior to leaving the building, then leave an open pit with a drain dump at the incomming point of the new building if you are very worried about moisture buildup.

pesronally I wouldn't worry too much just leave a full port valve to dump a tank full of air prior to wintering over... the 1" stuff would have lots of room if some moisture did fill up in it.. and if you use it regularry then it probably would not build up but blow thourgh...

Mark M /forums/images/graemlins/ooo.gif

 

[GerardC]

I ran 1 1/2" diameter pipe and fished a rubber air hose through. Works great for me /forums/images/graemlins/grin.gif /forums/images/graemlins/wink.gif! G

 

[cisco]

Darn, I had to stop by this post, as the title caught my attention. About 15 years ago, I had to put in a second phone line when my wife and kids started bickering over the single line. I wanted such unlisted, so I wouldn't receive unsolicited sales calls on both my lines, but the phone company insisted, per their policy, that I assign a name for the phone book listing. So, I chose "Underground Airways", as such a business listed only in the white pages, in small print, couldn't possibly interest anyone. Wrong, per usual. I got folks calling for information about destinations and ticket prices. Stunned by the first few calls, I thereafter developed some amusing destinations - but, that's another story. Anyhow, thanks for stirring up the memory.

 

[fractal]

Just a few random thoughts. Sorry they aren't organized in any sane fashion..

Remember to design in condensation traps. You need a trap at the lowest point in the pipe. This suggests you will need to maintain the standard 1/4 inch per foot gradient in the air pipe you run to drain the water to one end where you can stub it out. This suggests you will have to have a pit for the stub and drain valve. Failure to provide a condensation trap will result in rusted pipe leading to failure.

Not wanting to deal with condensation related rust is one reason people want to use plastic pipes. There do appear to be plastic pipes certified for compressed air. Schedule 40 water pipe is NOT one of them.

I had an old 1 1/2 gallon compressor I got cheap when I was given the 6hp, 30gallon compressor I now use. My kids wanted a way to fill their bike tires. I started looking at how to run a pipe from the compressor to the front of the garage. After much thinking I dug the old 1 1/2 gallon job out of the pile and set it up in the front of the garage. It works great for them. Makes me wonder if you really need a big air compressor at both locations. Maybe you can get away with a smaller one at one location or the other.

If you do decide to run an air line from your garage to your utility shed, consider installing an air tank in the shed. This can reduce the size of the air line you need to run. You can get a 5 gallon air tank for 20 bucks at harbor freight ( http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41712 ) and other places. Bigger ones are not that much more. You might be able to scrounge a tank from a shot air compressor if you are good at scrounging.

There are frequently threads on wiring shops. There is one now not far from this one on the forums. Given that you know you will need 110 and 220, many of us would suggest you install a sub pannel in your utility shed. Runs over 150 feet say you go up one size in wire. Thus while a 60 amp sub would normally require #8 awg, you should use #6 to keep the voltage drop under 5% for full load operation.

Any 110v outlet in your shed needs to be GFI protected.

I have not seen any 220v GFI units here in the US.

If you do take the time to run a full sub to the shed, maybe it makes sense to put a smaller air compressor out there, or haul one with you when you go.

Another thought is .. if you do decide to run a big honkin pipe between the shed and your garage, and you do decide to run a decent amount of power to your shed ... My big air compressor is L O U D. If I had a shed 150 ft from MY garage with a big honkin air pipe and decent power. I would surely move my compressor to the shed..

As usual, ymmv.

 

[EddieWalker]

After reading all the posts and links, I'm recosidering using Sch 40 for my air line. Maybe copper is the way to go.

 

[MossRoad]

Don't know about the air line, but around here on the electrical...

You can run one circuit to an outbuilding. If you want two circuits, you must install a sub panel. The reasoning was they don't want two possible paths for the electric. Check with your local codes.

I always wanted to run air from my garage to my house. It would be very handy in the basement some days. /forums/images/graemlins/smile.gif

 

[PJ_Kravetz]

It looks as though I will use copper in the garage, PVC underground to the shed and copper in the shed.

As for the electrical, I am going to run #8 into a single 20 amp 220V outlet. I can then just pull one hot wire fro a duplex 110V outlet and 1 4' light. No sub panel or anything else to wory about.

Thanks for all the suggestions!

P.J.