running underground compressed air line to detached garage

[dexter-]

Been trying to plan my underground tubing run to a detached garage. I want to use Duratec 1/2" (similar to Pex-Al-Pex) inside a 1 1/2" diameter PVC conduit. I will be running another conduit to house the electrical supply wires in the same trench. The electric conduit will be at 18" deep and the air lines will be installed deeper (approx 24") then covered with ground with the electrical conduit above it. I want to slope the air line towards the detached garage and install a sump pit of some sort right before the air lines travel upwards into the garage. Not sure if I want to use a 18 x 30 poly sump basin or build a cement block pit(cheaper than the first option, but more work). The sump basin would contain a condensation trap and the fittings needed to branch from this to the air supply. My question is.......I live a climate in the North East U.S. tht gets quite cold winters. If I get any appeciable condensation in the air line and/or trap setup within the underground pit is there a danger of this freezing? Is this really worth all the trouble, work and digging? I can probably, for the same cost of running an underground line, get a 30 gal oil- lubed compressor for the new garage and just deal with noise of a running compressor out there rather a 60 gal compressor in my basement with an underground line . Any thoughts? What would you do?

 

[dwm]

I don't think 24" is below the frost line in your area. Check your local codes.

Personally, I'd plan for a second compressor. Run 240V to the garage with as thick wire as you can afford. My detached garage, built in 1975, only has 120V run to it and the wire is not thick enough for me to run my small 120V compressor; the voltage drop with more than 10 amps of current is too high. It'll pressurize once if I completely drain the tank first, but after that it won't restart and the breaker will trip. Unloader valve is fully functional, but the wiring to that garage is too thin.

 

[Outlawmws]

Why run the hose inside the PVC? PVC (Sch 40 or above) is used to run airlines all the time...

Run a vapor trap between the compressor and the line, and you should be OK...

 

[SLOCOBRAR]

i,ve got 3/4 stainless tubung buried in between my attached and detatched sheds. no probs even in the winter. i run the air comp. in the garage i,m not working in,unless sandblasting i,ll run both

 

[mtkst19]

why not build a outdoor compressor shed off the garage? this keeps the noise outside in a contained room that you dont hear inside the building and is not loud enough to upset neighbors.. all places i have worked at have done this. compressor is outside. with the air plumbed into the building.

 

[bsaint]

Why not do what you want? In Massachusetts its against the law to use PVC as air piping. Running it underground is a good idea. Its like an all natural air dryer.

 

[dexter-]

SLOCOBRAR, do you have any type of trap or blow off for condensation in the lines?
BSAINT, im only using the PVC for a conduit to run the air piping inside of. Im afraid of my rocky soil puncturing the air line, so I want to protect it with conduit. The air tubing itself is PEX type tubing with an aluminum core. Its designed for compressed air applications.

 

[buildmyown]

For the little bit of water that forms in an air line I wouldnt even worry about it. Its not going to frezze solid like a water line will worst case you might get some frozen drops on the inside of the line.

 

[dwm]

Just my opinion, but it truly ***** to have a buried pipe burst. You don't want to have to dig it up again, so if you're going to bury air line, bury it below the frost line.

I've seen sprinkler lines burst that were blown out with air at the end of the season. All it takes is enough water pooling in one spot. It's humid here, plenty of water comes out of my automatic tank drain as well as my filter and drip leg valves.

There's not a chance in hell I'd bury a compressed air pipe at 24" here in southeast Michigan, even if I had a very good dryer at the feed end. Frost heave would risk cracking the conduit and the pipe inside it. I don't think I could get a licensed contractor to even consider it. Might be different where you are, which is why I suggested checking your local codes. I've seen decks here that have had footings at 30" depth (which doesn't meet code) heave so much they rip the ledger board off of the house and rise above the door sill.

 

[darkk]

I have buried electrical service *inside grey electrical plastic conduit* from my main garage to my storage garage. My compressor is in the storage garage. I just ran a good quality 1/2" goodyear rubber air hose inside the electrical conduit with the wiring. No problems there.

 

[Roots]

I've regularly dealt with exposed to weather control air lines in Northern climates. Condensation traps and heaters are always required, and there is often still problems. Personally, I think it might be a bit more troublesome than it's worth. Additionally, you'd still require a large compressed air storage tank at the remote location to handle the volume, pressure drop, and thermal stress. At best, you might have a reasonably quiet work room, but you'd almost certainly have more into it than just buying a compressor and attempting to muffle it some.

 

[Milton Shaw]

Don't do the compressor shed outdoors in Pennsylavnia , You will have the bottom of the tank freeze up and eventually fill the tank with ice as it won't defrost until spring. The Auto drain assemblies don't like freezing weather. Also once it fills to the outlet and freezes you won't have air either. (had a friends machine shop compressor lines freeze here in Knoxville, Tn.)

 

[dexter-]

sounds a little discouraging... I was afraid of the freezing possibility in the winter. I definitely dont want to spend the extra time and effort to dig the trench down to the frost line(40" in my area) and dont want to take the chance and spend all the money and time only to have the freezing problem. Looking at the possibility of using a 30 or 60 gal oil lubed compressor in the detached garage, but not sure of the electrical demand of one of these compressors. What if I run a $50 1/2" rubber air hose instead of the more expensive Duratec tubing inside of a PVC conduit? I can put a ball valve inside the basement to shut off the air when not using it. I can install a general purpose regulator/filter to collect any moisture in the detached garage and omit the condensation trap. For periodic use maybe OK? Shut off the ball valve in the basement when finished working in the garage to isolate the underground hose when not in use. Cheaper initial installation this way and if it fails no big loss........?

 

[rodm1]

How often will this be used?
How far is the run?
Will a coxreel work?
What brand of compressor?
What is the shut of pressure?

You will be getting a pressure drop that you might have to worry about. But my thinking is you could run a large PVC pipe set up and use a coxreel and pull and retract the hose in Winter, Summer just leave it set up.

 

[canuckian]

I briefly contemplated doing this....very briefly. The time and effort involved plus the things that can cause issues down the road greatly outweighs the benefits IMHO. my solution was to have the bigger compressor in the shop you do most of your work in and buy a smaller one for the other garage for infrequent use. I have a smaller wall mounted unit in the attached garage for small stuff like inflating tires, running an impact, ratchet, etc and a horizontal oiled unit in the detached shop that will do pretty much anything I need it to besides maybe running some painting setups - only guessing that as I've never looked into it.

 

[Jim C.]

why not build a outdoor compressor shed off the garage? this keeps the noise outside in a contained room that you dont hear inside the building and is not loud enough to upset neighbors.. all places i have worked at have done this. compressor is outside. with the air plumbed into the building.

Seems like a reasonable idea, versus burying lines, sump pits, etc. Just my opinion.

Or, like the original poster said, just put a compressor out in the garage. That's probably the easiest solution.

Jim C.

 

[dexter-]

been researching all of the possible options and dont think I want to take the chance and bury an underground system with all kinds of complicated traps and sump pits only to have it fail or freeze in the winter. Looked at buying a small compressor for the detached garage, but dont think I will have enough electrical capacity to run one along with a large 240 volt electric heater(24 amps draw) and a turbine HVLP system(13 amps)the lighting etc. (running a 60 amp sub panel out there) I definitely like the idea of installing a large PVC conduit, maybe 2" or 3" diameter and getting a good quality hose reel and run a high quality 1/2" ID air hose through the conduit. I can keep it installed in the conduit probably from March through November without any problems with freezing condensation, then simply pull it when the low temps arrive. Since I will only need air out there occaisionally during the winter I can either pull it back through the conduit or just run it outside into the garage on the ground temporarily when I need it. Good idea...............thanks for all the input. I looked at Coxreels and they are just a bit too pricey for me, but Reelcraft has a nice 50 foot unit that would fit my budget.

 

[Norcal]

I have buried electrical service *inside grey electrical plastic conduit* from my main garage to my storage garage. My compressor is in the storage garage. I just ran a good quality 1/2" goodyear rubber air hose inside the electrical conduit with the wiring. No problems there.

Yeah there are problems with what you did, "foreign" piping/systems is not allowed to share electrical conduits. Just like it's also not allowed to strap voice/data lines to the outside of conduits either....

 

[Aceman]

I have buried electrical service *inside grey electrical plastic conduit* from my main garage to my storage garage. My compressor is in the storage garage. I just ran a good quality 1/2" goodyear rubber air hose inside the electrical conduit with the wiring. No problems there.

Are those your words or the electrical inspector's?

It should be said, there's nothing wrong with using conduit as a sleeve as long as nothing else is in it. People do it all the time for air, water, and grease lines. But, not if there are actual wires in it.

So, does your air hose come out of your panel?

 

[SpiderGearsMan]

go up , not down , trapped water

 

[mtkst19]

Don't do the compressor shed outdoors in Pennsylavnia , You will have the bottom of the tank freeze up and eventually fill the tank with ice as it won't defrost until spring. The Auto drain assemblies don't like freezing weather. Also once it fills to the outlet and freezes you won't have air either. (had a friends machine shop compressor lines freeze here in Knoxville, Tn.)

i live in pa. never had this issue at any of my jobs current or past. is it possible for stuff to freeze--yes. but being my current employer has had it outside for 11 years in a shed that was built when the building was constructed and my last employer for 18 years in a lean-to setting which shielded it from rain and snow but no wind-- it is very doable.