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Discussion Starter · #1 ·
My compressor is going to be about a hundred feet from the shop and I am trying to determine the best way to get the air from the compressor to the work area.

I am thinking of running 3/4" black iron pipe underground from the storage shed that houses the air compressor to the shop.

What do you think? Could I get by with 1/2" pipe, or am I undersized with 3/4" for that length?

Any suggestions welcome!!
 

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the 3/4 would be fine because you are talking about psi. So you are going to have the same amount of air pressure with either size line. The air hose you use is probably only 3/8's anyways. Can you put a storage tank in the shop area to hold air closer to the work area. Make sure that underground line don't freeze up on ya in the winter time. You might have to put it in the ground like 3 or 4 feet.
 

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Discussion Starter · #3 ·
I am in south texas, so we don't get much cold weather. Could I go with PVC for the underground sections?

I am looking for ways to cut down the cost of buying so much iron pipe..about $17 per 10 foot lengths at HD or Lowes.
 

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I wouldn't, but If you did. end the PVC right b4 it runs into the buildings, and bury it deeper than you normally do.. compliance for Air/water snowmaking ( 175 PSI at the caps ) uses a special flexible PVC, but is 8' in the ground.. this is cold temps.. as long as theres a foot or so of soil between you and the pipe, I guess it would be safe
 

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Don't plumb with PVC. I did with "shattering" consequences. I tried to go cheap with PVC, then decided that it wasn't safe after reading some articles. When I loosened it from the wall clamps to remove, it broke up in many small pieces - and had only been up a few weeks. I believe that 3/4" copper is 10-12 bucks a ten foot length (the price came down this spring) and it's the best for cooling your air. Don't forget that you need a good dryer at the outlet end as well to knock out any water carry over. Scrimp now, and you'll regret it later. Half inch is good, but three quarter is better - some air tools are real air hogs and need lots of volume. Black iron as you said, is a good alternative, but if it's buried, I would be concerned with rust within a few years if you live in one of Texas' wet areas.
 

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I'd put galvanized pipe underground. It will last your lifetime. The bigger the better. Bigger pipe will slow the air velocity through the line lessening the amount of contaminants that will be carried through. Run the pipe uphill at least 1/4" per foot from where it goes into the ground to the outlet. Put a Pipe T at the low point in the ground with the T pointed down. Use a brass compression fitting to copper tube from the bottom of the T to the surface of the ground. Put a petcock or ball valve on the end above the ground. This way you can drain any moisture that may collect in the underground line. Air pressure will blow it out. I would at least put a oil/water separator in line before it goes into the ground.
 

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Do it once, do it right

I'd go with copper. Not much more than galvy, may be cheater today.

Copper is naturally rot-resistant, you're not counting on a coating. And soldired fittings done right, and it's easy to do them right, last forever with no leaks inlike a mechanical fitting.

Just my opinion for what it's worth.
 

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One downside to running an airline underground is the moisture condensation because of the cooler ground temp. The line can filll with water pretty quickly. We used to put a blowwoff line from the lowest point up with a ball valve to get rid of the condensation. Just a thought for you to think about.
 

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1/2" copper will be sufficient if you use only one tool at a time. You can run a healthy sand blaster or paint gun using the 100' 1/2 Cu line. You can run 3/4" Cu if you have overkill tendancies. The water will condense in the underground line which is a good thing. Some buy expensive coolers to do the same thing. You must however plan how to remove the condensed water. Some will have issues with freezing once we win war on global warming. If you are sure it won't freeze underground then a cheap water separator can easily remove the water post a 100' run. You should slope the 100' run (more than 1/4" per foot if possible) to a low point drain.

If you are really on a budget, you can buy a cheap 100' air hose followed by a few ft of Cu pipe and water separator/low point drain.
 

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47 Coupe said:
One downside to running an airline underground is the moisture condensation because of the cooler ground temp. The line can filll with water pretty quickly. We used to put a blowwoff line from the lowest point up with a ball valve to get rid of the condensation. Just a thought for you to think about.


Downside? DOWNSIDE?? :confused: You have got to be kidding! That is one of the main plus sides to running that line underground, you WANT the line to cool the air and condense the moisture vapor into liquid, that's why we WANT to run long lines and use Copper when possible. A refrigerated separator works by cooling the air before it enters the separator which is exactly what running that line underground will accomplish.
 

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You said any suggestions were welcome, so........can I ask why you don't just get another compressor and put it in the shop where you want it? I guarantee you'll spend less money on another compressor, and have less problems than trying to dig a trench and run 100 ft.of air line to another building.

I had a similar problem, only it involved running 150 feet of heavy electrical wire to power my garage. I ended up putting in a separate electrical service from a nearby power pole. I have a separate $20.00 electric bill for my garage every month which is $7.00 more than it would cost me if the power came from my house. But,......I got to put in 200 amp service which I wouldn't have been able to do had I run a wire.
 

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61bone said:
Put a Pipe T at the low point in the ground with the T pointed down....copper tube from the bottom of the T to the surface of the ground. Put a petcock or ball valve on the end above the ground. This way you can drain any moisture that may collect in the underground line. Air pressure will blow it out.
Don't put filter underground.
Put filter/water separator down stream of the underground pipe.
 

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001mustang said:
Don't put filter underground.
Put filter/water separator down stream of the underground pipe.
Actually, you want the separator before it goes in the ground to remove any liquid oil or water before it goes underground. A t'd in blowdown will remove any condensation that develops in the pipe. Give it a hit about every 2 hours of use. Another option is to put in a pneumatic blowdown that will give it a hit every time the compressor cycles. These can be used on the separator also. Use a dessicant drier where it comes out of the ground to get any residual vapor before it goes to distribution lines. This system will give you air that is almost clean enough to breathe. Put oilers on the tool outlets and a filter/drier on the spraygun/booth outlet. Don't use the same hose for tool and painting.
:)
 

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Liquid separator

A liquid separator will not remove uncondensed water. That's why I suggested putting liquid separator down stream of underground pipe. The water will condense in underground pipe then can easily be removed by low point drain and down stream water separator.

The 100ft downward sloping underground pipe actually functions as an effective water separator in itself (remember to keep it drained). With this long underground run it will render unnecessary a desiccant filter in most situations.

I have a desiccant filter system but have found it unnecesary for painting. My downward sloping Cu lines effectively removes the condensed water.

It wouldn't hurt to put an oil separator upstream of 100' line. I didn't and have not had a problem.
 

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Hey please remember the compressor is located 100 feet away from the shop. He wants to bring air into it. Putting the line underground is the most logical option, unless there is some way of running the overhead.
The cooling effect of the ground is a bonus, not his primary goal.
 

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I think running the line underground is a dandy idea but there must be some provision for draining the water from it where it comes into the shop. If the line reaches the shop at a low point and then must rise up to separator/regulator/outlet this could cause a problem so a drain must located at the lowest point. Also be careful not to allow the line to sag anywhere along it's length which could easily happen even with black or galvanized when using lengths like that. A low spot along the length of the pipe can be especially troublesome since it will allow water to collect that can not be drained, this water will be expelled in spurts when it reaches a certain level in the pipe. What is so annoying about this problem is that the air may seem to be dry most of the time but as the water collects in the low spot it will restrict the air flow until it reaches a point at which it will pick up most of the water and shoot it out of the line almost like a water hose for a few seconds. After this happens all may seem ok for a while but the cycle will start all over again and you never know when the water will come shooting out! :mad: Of course this need not be a problem at all since it is simply a matter of keeping that line straight and keeping the slope fairly constant.



BTW, there is arguments both ways as to which direction to slope the pipe but IMO either direction will be just fine as long as the drain can be placed on the low end. In all probability the slope here is going to be determined by the location of the compressor to the shop so just slope it whatever direction is convenient, just place that drain at the lowest point.
 
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