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need to run long length of pipe from air compressor

12K views 33 replies 15 participants last post by  oldred 
#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!!
 
#27 ·
001mustang said:
That is a good drawing. I like the exaggerated slope.

The lines should be sloped as much as practical to assure water is actually drained. I have seen specs of 1/4" per foot which can lead to water build up like previous poster said.

I prefer to slope line to compressor to assure that OIL as well as water drains into compressor tank.

One problem I saw with the drawings is the first leg from compressor outlet is not sloped and the pressure gauge (PI) is susceptible to flooding. A flooded PI will surely get freeze damaged if ambient temp drops below freezing. Must mount PI above water level.
A little more here. Up here in N.E. Wisconsin it can get to 20 below, and I have had it below freezing in the garage.

The compressor kicks in around 125 psi and out at 175 psi. I always have 125 or over on it below freezing or not, never a problem.

I don't know how many have looked at the drawing, but it doesn't have any dessicant cannisters or air dryers, its pretty basic and not that expensive to put up, although time consuming, once its in you forget it, clean dry air.

Rob

http://www.1969supersport.com
 
#28 · (Edited)
I agree Rob.

I have similar setup and found my desiccant dryer and water separator is not needed with proper piping.

I would avoid any horizontal piping near the compressor.

I had one PI that got water inside and lost calibration when it froze. I installed that PI on a vertical nipple and it works perfect. If you are unlucky the PI will get water inside and freeze.
 
#29 ·
shad9876 said:
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!!
You didn't say what your compressor rating was... HP &/or CFM. Assuming about 5HP, I'd suggest 1" galvanize pipe minimum.
For less than 5HP, �" minimum. For such a long 100' run, you may need 1" to prevent a severe pressure drop.

Choosing the correct size of air-pipe:


This compilation might help ---> DIY Series ~ Tools: Air-compressor & Piping Installation

Here are some things to keep in mind ---> Air Compressor Piping Diagrams and Tips.
Keith Dickson - OLDSmobility.com said:
Air Compressor Piping Rules Of Thumb:

After leaving the air compressor, air line pipe goes straight up the shop wall as high as possible.
This helps minimize any water from leaving the compressor and traveling through the pipe.

Slope main lines at least four inches (10 cm) per 50 feet (12.7 m) of pipe away from air compressor so
that condensate travels with the flow of air and away from the compressor.
As warm air leaves the compressor, it cools and thereby condenses as it travels through the pipe.

This water vapor, a problem in itself, can also cause scaling and rusting inside the piping.
Install drop legs for condensate removal.

The first air drop should be at least 25 ft. (6.4 m) from the compressor although 50 feet (12.7 m) is optimum.
This allows the compressed air to cool to room temperature so any condensation can occur before it gets
into the water separator.

Take-off comes from the top of the main air supply line at each air drop.
This reduces the risk of water and other contaminants from traveling down the drop into the water separator.

Use carbon steel pipe as discharge pipe material. Never use PVC or ABS. (PVC is easy to work with, but will not allow the hot air to cool quickly enough to condense the water in the compressed air.
Also, in case of a compressor regulator failure, if the PSI inside the line were to go above the rated safety capacity, the plastic pipe won't just split, but will actually explode, producing razor-sharp projectiles which are sure to damage property and person.)


Consider using Schedule 40 black iron, galvanized, copper, stainless steel, or anodized aluminum.

Size the pipe for maximum CFM required. This will equal full load production plus future expansion plans.
(See chart above)
My $0.02¢
 
#30 · (Edited)
001mustang said:
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 tendencies.
If you run one tool at a time you will be hard pressed to use all the air a 100ft 1/2" line can provide, regardless of compressor size..

http://www.goodyearrubberproducts.com/files/Dixon/DixonCatalog/DixonCatalog1.Page528.pdf

100' 1/2" pipe will flow 54 SCFM at 100 PSI with a 10% DP.
 
#31 ·
#32 ·
I would also recommend at least a 1" galvanized line, but if you can afford it 2" would be even better...100' ft is a long way and the less restriction the better.
 
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