Shop Air Compressor System Design & Plumbing [Complete Guide]
I Love Shop Air
Gimme some air, please!
I love having air conveniently available in my shop. I use it to run all manner of hand held air tools, a blast cabinet, and it’s very important for the CNC Machines in my shop to have clean dry compressed air. I started with a Sears Craftsman compressor that sat below a 50 foot coiled hose reel like you’d find in an auto repair facility.
The hose reached pretty well throughout my shop, but I wanted to take the next step and get a bigger compressor and plumb in a more permanent and convenient air distribution system. For one thing, it’ll clean up dragging that silly reel hose all over, and for another, the current compressor is very loud. It’s so loud, that sitting right next to it where my CNC controls are, I used to put on my hearing protection muffs until the tank had filled.
So, I ordered a new 5HP industrial stationary compressor from Eaton, installed it in some crawl space that is removed from the workshop, and plumbed in an air system using black pipe. I couldn’t be happier with the results. The workshop is now very quiet except for the slight hiss of a little air leaking here and there. In addition, I have a lot more air capacity when I want to run really air-hungry tools like my blast cabinet.
This page chronicles the choices and the installation of my shop’s air system.
The original air system and Craftsman compressor. The manifold was built with the knowledge I would eventually want to link it up to a compressor located elsewhere…
Air Compressor Installation
That Sears Craftsman 2 hp 33 gallon vertical compressor had done an excellent job for me, but I wanted a better compressor. I wanted a stationary/fixed compressor with more horsepower, and my choices basically boiled down to whether to purchase a 2 stage model or get crazy and buy a rotary screw compressor. The latter, BTW, are truly the cat’s meow. They’re much quieter, last forever, and produce ridiculous amounts of air very efficiently. There’s just one unfortunate drawback, and that is price. A lower end rotary screw compressor costs about $3500 whereas a nice 2-stage compressor is more like $1200. For my budget, that made the decision easy.
I wound up buying an Eaton 5 hp 2-stage 60 gallon unit. The offer a choice of colors, so I selected Ford Blue. This unit will put out 17 CFM @ 175 psi, which is more than enough for my needs considering the old compressor pretty well did the trick without running out of oomph and had less than half the capacity.
Compressed Air System Design
Shop Air Line Choices
There are several approaches to choose from when it comes to plumbing.
You could use copper tubing, sweat soldered together. I have seen the majority of good home air systems done this way. Another approach is threaded black pipe. This is the strongest approach in terms of its ability to handle pressure. Our local Orchard supply will cut the pipe to length and thread the ends for free as well, which is nice.
The other nice thing about using copper or black pipe is that I can just run down to the hardware store and buy a fitting or more pipe if I need to add something to my system. In addition, I note that Harbor Freight has an inexpensive electric pipe threading machine available, so I took the black pipe approach.
Pex Plumbing & Rapid Air Systems vs Copper or Black Pipe
I went with hard line for my system, but another approach that’s hugely popular is to use Pex Plumbing. One of the most popular brands for Pex Plumbing is Rapid Air. These kits are available on Amazon and many other places and are super easy to install:
Rapid Air System w/ 1/2″ Line: About $75 on Amazon…
A Rapid Air System with 1/2″ line like the one I picture above is about $75 on Amazon. With push-on connectors and flexible hose they may be the easiest thing yet for DIY’er to install.
For me the advantage of hard line was bigger capacity pipe and durability. But the downside is more difficult installation and chasing down leaks in the pipe threads.
Avoid PVC Air Lines!
One approach to be avoided in any case is PVC pipe, which has a tendency to become brittle and eventually burst while spreading dangerous shrapnel in the shop.
Air Compressor Plumbing
Part of the deal with getting a new compressor is I have promised the old compressor to my brother. So as not to keep him waiting too long, I wanted to place the new compressor into service just as the old one was and build the distribution system to run from that location back to where the compressor will eventually be located. I will admit this is somewhat backwards, but if you’ve read these pages for very long, you will realize I have to plan my projects on the notion they will move in fits and starts and the overall elapsed time can sometimes be long for the easiest things.
Lastly, I want to added a refrigerated dryer to my system. Drier air is better from every standpoint, and a refrigerated dryer does a good job getting most of the moisture out of the system right up front. Harbor Freight makes one of these too that is very reasonable, and I have heard good recommendations for the unit on a number of boards. I took a look at one the last time I was in their store and it looked pretty well made so far as I can tell.
Here is my plan with respect to the distribution system for my shop:
As you can see, a fair amount of the system is designed to eliminate any water. The dryer should pull the lion’s share of moisture out of the system, but I’m still planning to slope the overhead distribution line (1″ black pipe) and provide water drains at the low points. The individual drops will be 1/2″ black pipe, except for the drain drops which will be 1″. The valves will all be ball valves. I need to find a source for the filter/oiler/regulator assemblies, but the system is pretty simple in its design.
Note: A good and cheaper alternative to a dryer is to simply add an aftercooler to your compressor system. It won’t get the air quite as dry, but even if you add a real refrigerated dryer later, it is a worthwhile addition.
I’ve been advised that there needs to be a pretty good filter upstream of the dryer to keep the crud out of it. A coalescing filter is what Eaton recommends and others have mentioned a 5 micron or better filter of some sort.
For the individual stations, I found these Wilkerson units that combine a filter, regulator, and oiler on eBay for a good price:
Wilkerson R08-02-F0G0 Filter/Regulator/Oiler…
These are 1/4″ NPT fitting units. I bought a couple of extra of the Wilkerson units because I may be expanding my shop at some stage and wanted to have some spares.
For the main filter right of the compressor, I went with a SMC NAF4000-N04, which is 1/2″ NPT:
How it Turned Out
Typical air drop. Drain at bottom, individual valves for each outlet, and a filter/regulator unit for each outlet…
Got a hard to reach place? Just use flexible air hose. This run goes up and over a garage door and was much easier and cheaper than running black pipe over what was a pretty long distance to get to one air drop…
Here is the air distribution for my CNC mill. One line supplies all functions…
All functions at this point consists of my coolant mister, a handheld nozzle, and my little butterfly impact wrench…
Try to Test Out Sections of Your System for Leaks
I went with black pipe, and luckily tested sections for leaks. There were a few! I was also lucky to have done this before actually bolting things down. I waited until all leaks were fixed before bolting down each section.
Use Pipe Dope, not Teflon Tape!
Pipe Dope seals better than Teflon tape. Most places actually prohibit use of the tape on gas lines for this reason and because the tape can break off inside and wedge in a valve seal which makes the valve leak. However, soldered copper seals even better. If I had it to do all over again, I would be very tempted to go for the copper!