Compressed air piping

[pkrankow]

Do you mean 30 inches or are you running through a mountain side?

Well, either way you could put a well like a sump well at the low end or both ends and use an automatic drain into the sump well and just pump it out with a sump pump. You could probably use the sump to bring service into the building and use a T instead of an elbow to bring the service up and out.

Phil

[mtnman]

Thanks, Phil. I thought of a sump well, and hoped there was a better idea. guess that will have to be it. I can come up with a removable cover to keep it safe and semi concealed.
it really is about 30 feet. the compressor has a nice location in a covered lean-to like shed on the outside wall of the existing "auto" shop of the house we are buying, but the smithy will be about 30 feet away, and I would like to be able to drive between the two buildings, so that's why am exploring running the pipe underground that far.

[pkrankow]

My bad, the run is 30 ft, not the depth of the run.

If you go to your local big box store they have plastic sump liners for about $30 each with lids and service openings. If you find a plumbing supply house you will have more options and better pricing. They come with solid bottoms so they can be dry or perforated according to the installation. The lid will support a persons weight as this is a safety requirement to protect children, adults, and pets. Lock the lid on before pouring the concrete or you may not have a lid that fits in the end. (I once almost got very unlucky, but the concrete hadn't cured yet so I was able to get the lid on.) Alternately there are other service covers available that can take vehicle weight and don't cost a fortune, but you will probably need to devise your own sump well liner.

With "dry" iron pipe or conduit you should not need to worry about frost and you should only need about 12 inches of soil on top of it to drive on, depending on your soil types, unless you are driving heavy equipment. If you rent a trencher (looks like an over sized chainsaw) you will be done in minutes at 24 inch burial.

Good luck
Phil

[mtnman]

Thanks!
this forum thing is pretty new to me, but it is great to be able to access all this great experience and knowledge. wish I had known about all this years ago...could have saved a lot of bruises and ....well, never mind! :D

[cami]

Make yourself a cyclonic air/water separator....or at least a drop/low spot to catch the moisture. Plumb a line into the bottom of the separator/low spot that comes out to a valve at ground level; give 'er a crank and let that compressed air do the work of bringing the moisture to the surface.

[BIGGUNDOCTOR]

Underground piping will work like a huge heatsink. I did a repair job on a 4 post lift at a Sears Auto Center that had underground piping. The first time I ran my impact gun it looked like I had hooked it up to a garden hose Water everywhere. Water traps on the compressor are not that effective, as the air is still too warm. Put traps downstream where the air is cooler, and easier to remove moisture from. Drain often in humid areas.

[pkrankow]

Underground piping will work like a huge heatsink. I did a repair job on a 4 post lift at a Sears Auto Center that had underground piping. The first time I ran my impact gun it looked like I had hooked it up to a garden hose Water everywhere. Water traps on the compressor are not that effective, as the air is still too warm. Put traps downstream where the air is cooler, and easier to remove moisture from. Drain often in humid areas.

That is part of why I suggested automatic water drains in one or both sump wells. Thanks for stating as such, it is important.

Phil

[wineslob]

Hi, first post here. (I'll put up one in the Introduction area also)
I designed and installed the system for the facility I'm in now about 20 years ago. It uses approx 1500 ft of 2" black pipe, 5000ft of 1" black pipe, and 2000 ft of 1/2" black for all the drops.
IF you can afford it use a refrigerated drier. HF sells one, but I don't know how the quality is. Put it in before any lines that go out to work areas.
The reason is, once you have water in the air and past the storage tank, it is VERY difficult to remove.
The system we use is a 100 HP IR rotary screw machine(rated at 450 cfm @ 100 psi). It feeds directly into a VanAir drier and then goes through a coalescing filter @ 30 microns.
Our air IS dry and clean, whats required for air tools, motors, etc.. to live a long life.

If you can't use a drier use an auto-draining coalescing filter. It's better than nothing. Wright-Austin makes some as does Lan-Air. Both work quite well.

Here's a good source: Air Liquid Separators for 99% Removal of Entrained Moisture Droplets 10 Microns and Larger

[waianvil]

In my shop I ran 1/2 inch copper with brass fitting for the outlets solder all the connections pressure at 120 lbs

[Sukellos]

I work for a major aerospace manufacturer. All of our compressed air lines are copper with soldered fittings. We use one huge Sullair compressor with a 4" line out to the hangars and from there it's run down to 3/4" or 1/2" lines at the point of use. We run at about 108 to 112 p.s.i.. There are drops with condensation release valves all over. I've never heard of using PVC for compressed air, but then, there are a lot of things I've never heard of.

[Bentiron1946]

I have designed industrial plants and never used PVC for any compressed gas at any pressure. That is not it's design purpose. I hve done several semi-conductor plants and PVC was not an option for air.

[Spears]

I won't make any suggestions to this thread, but I can tell you what I have seen. I took a job in a machine shop that used PVC plumbing pipe for air lines. In the 6th and 7th year, we had failures in the lines. These were explosions that sounded like a shotgun went off. Pieces of pipe separated and flew down from heights of 15 feet. A piece "feet" long hit the floor and was jagged. Far as I could tell the compressed air had left an oily film on the inside of the pipe over years and the chemistry changed which made things brittle. This may never happen, but can happen. I would never own a piece of property where something like this was constructed, but people are free to do as they wish. Good luck, Spears

[Pat Roy]

After too many decades in industry as an engineer doing a lot of piping projects let me recap what I think:

I would never use pvc in this application.
I would not use cast iron in this application, rather forged fittings.
I would use pipe sized such that there would not be appreciable pressure drop to the point of use.
If it is a long run from the compressor to the point of use I would consider placing an auxiliary receiver near the point of use.
Properly rated hoses are fine for portable tools.
Don't save a few bucks on material while take risks with everyone's safety. I don't care for how many years someone else has been lucky.

[Bentiron1946]

"I don't care for how many years someone else has been lucky"............AMEN! <_<

[Dragons lair]

Just a question for ya. Ever see a PVC line burst? We are talking grenade time here.
A 3/4" rubber line will beat ya badly.
Ken.

[Bentiron1946]

I guess that I'm sort of old fashioned, I just don't care for plastic pipe, I know that there are good ones out there but PVC is best used for low pressure applications, like irrigation pipe. I am not even one of these designers that liked to put it underground for water, it just failed to often. Now copper, steel, cast iron all good suitable pipe for underground application and steel and copper great for pressure lines and steel great for high pressure lines. Sometimes on steel underground you had to wrap and use sacrificial anodes but it usually held up well. We never specified PVC for anything except for ultra-pure deionized water and some drain piping, all exposed in an interstitial space. High pressure compressed air was in silver brazed copper for branch piping and mains were welded steel and low pressure compressed air was in silver brazed copper for branch piping and mains were black steel with screwed steel fittings.

[terrynewsmith]

yes i know your uncle brother ....ect used pcv pipe as a air line for xxx years it is a BOMB WAITING TO happen
i wasnt anywhere near mine when it blew up now replumbed with iron pipe
do google search for pcv air lines IT IS VERY DANGEROUS and doesnt show on xray

[ianinsa]

What is wrong with hdpe with push in fittings ? most of the world uses it these days!

Ian

[Bentiron1946]

I know that they use it for domestic water systems in houses now but it hasn't been approved for high pressure or even low pressure gasses in residential systems yet. It is used for high pressure natural gas lines and medium pressure up to the building underground but once inside it is still recommended that black steel pipe be use for natural gas or propane. It takes forever to move past somethings code wise here in the USA. I guess that I'm kind of conservative too in that if it ain't broke why fix it,schedule 40 black steel pipe with threaded cast iron fittings is a good choice for compressed air service up to 125 PSI and if necessary you can get pipe and fittings over schedule 40 for higher pressure than that.