Running air lines underground

[bmwpower]

I can't remember the consenus on this...

Is it doable? Should you use metal, ie. copper?
What's the best way to remove/avoid water in the line?

I wanted to run an airline ~20 feet to my attached garage for things like tire fillup, etc.

 

[ron in sc]

I wanted to run an airline ~20 feet to my attached garage for things like tire fillup,

I'm going to be doing that but in reverse. Attached garage to new garage. I planned on using copper or having a lengh of hose made that I could screw on to connects at either end and run the hose or the pipe in conduit to protect it.

As for water in line not sure. I suppose I could get a refrigerated dryer next to tank and get rid of water before it becomes a problem.

Also I will not have to be concerned with ground freezing, although it was 30 degrees here this morning.

 

[OldCarGuy]

I have air supplied to Five garages. Four are connected underground using 1” diameter Goodyear hose that I pulled through 2” PVC gray pipe that I buried 36” deep. If and when the hose ages, it can easily be replaced. I don’t have any water problems because I have a 45 CFM refrigerant dryer installed. I also leave the system running all the time.

 

[1320stang]

Yeah, I was going to say to use electrical conduit with sweeps and just run a 3/8" air line thru it. If you wanted to get fancy, you could put it on a hose reel inside your shop and have a rope tied to the end, have another reel in your garage to pull the hose over from the shop.

 

[BowtieNut]

I'm sure I'll get scolded for this, but I just did the same thing with PVC. I figured it's underground anyways, so if it goes, it's not gonna hurt anybody. I only used PVC for the horizontal run in the bottom of the trench, and changed over to copper at the 90* elbow where it turns vertical to come out of the ground (so ALL pvc is 2' underground). I know I should have used copper for the whole thing, but I just couldn't justify the cost difference for my 80' run. My compressor and most of my work is done in the detached garage, so this is just for the occasional tire fill on the kids' bikes or our daily drivers.

The electrical conduit with air hose sounds like a good option too.

(Flame suit on)

 

[fefarms]

I ran underground lines in copper between shop buildings. It works fine; I put a drain valve at the low point (in a vault) as the line enters the second building to deal with water condensation.

With the current price of copper, I would not do it that way again. I recommend PEX-AL-PEX tubing such as Kitec or the Rifeng product sold by the blueridge company. This has an adequate pressure rating for compressed air, and does not shatter like PVC. The 5/8 tubing is adequate for 18 SCFM and costs around 50 cents per foot. Maybe 1/4 the current price of the equivalent copper.

 

[ron in sc]

I put a drain valve at the low point (in a vault) as the line enters the second building

I'd be interested to see how you did that could you post a photo of the vault?

 

[bmwpower]

I ran underground lines in copper between shop buildings. It works fine; I put a drain valve at the low point (in a vault) as the line enters the second building to deal with water condensation.

With the current price of copper, I would not do it that way again. I recommend PEX-AL-PEX tubing such as Kitec or the Rifeng product sold by the blueridge company. This has an adequate pressure rating for compressed air, and does not shatter like PVC. The 5/8 tubing is adequate for 18 SCFM and costs around 50 cents per foot. Maybe 1/4 the current price of the equivalent copper.

I take it one shop is higher than the other?

Does PEX get brittle? I'm assuming this would have to be installed in a sleeve.

 

[HoosierBuddy]

I can't remember the consenus on this...

Is it doable? Should you use metal, ie. copper?
What's the best way to remove/avoid water in the line?

I wanted to run an airline ~20 feet to my attached garage for things like tire fillup, etc.

If I did it, I would use polyethelyne gas pipe. That's what we use at work for natural gas mains and service lines. Normally they only run at about 60 psi, but the pipe is rated for 100 psi with a huge safety margin (since it's gas). I'd bring the ends up using anodeless service risers, essentially 4'-long 90's that transition you from PE to steel with NPT connections.

Phil

 

[fefarms]

The shops are the same elevation. I dug the trench to pitch the pipe downward towards the second shop. The drain valve is a simple manual ball valve at the far (low) end. The "vault" is a simple plasticirrigation valve box. From the drain valve, the pipe "tees" upward to enter the second shop high on the wall.

Pex is not inherently brittle like PVC. And it doesn't deteriorate over time (but keep it out of direct sunlight). If overstressed, Pex splits and leaks like copper rather than exploding like PVC. The specific product I use is Pex-al-Pex. This is a 3 layer sandwich of pex, aluminum, and pex. This has a higher pressure rating and better high-temp pressure rating retention than straight pex. At least some manufacturers specifically recommend it for compressed air, although some would prefer you to buy their more expensive specialty product rather than the all purpose plumbing/radiant heat version.

All pex is rated for (and commonly used for) direct bury applications. No sleeve is required. I supposed if your backfill were really rocky you might consider a sleeve.

 

[BuickFarmer]

Did anybody use black steel gas line. that's what I plan to use on about a 80 ft run with a drain at the low end. Can't imagine the gas line being a problem

 

[leadsled01]

Yeah, I was going to say to use electrical conduit with sweeps and just run a 3/8" air line thru it. If you wanted to get fancy, you could put it on a hose reel inside your shop and have a rope tied to the end, have another reel in your garage to pull the hose over from the shop.

Exactly what my buddy did 4 years ago. Still just fine.

 

[Lu47Dan]

If you were to use Black iron pipe underground with no coating on it , it will start to corrode and in a number of years it will develop a pin hole leak . Steel gas transmission and distribution lines have anodes attached to them , the anode is made from a metal that self sacrifices , in other words it corrodes easily , usually magnesium . This protects the steel pipe from corrosion . The Pex is the best option here for durability and ease of installation . But run a conduit for the pex to run in so if there would be a problem you could pull another line through with the old line . Dan (Plumber and Steamfitter from N/W Pennsylvania )