Air Compressor Plumbing

[Stan Thigpen]

I am planning to run air overhead in my shop for greater access when using my air tools. I plan to use 3/4" copper water line which I have left over from removing a hot water baseboard heating system years ago. Is there any reason that I cannot use compression fittings to connect the sections of copper? I would rather not do any soldering in the rafters if I can avoid doing so. Will using 3/4" pipe have any effect on my pressure or volume? Where should I mount the regulator, at the compressor tank or where the rubber hose attaches to the copper tubing? My compressor is a 3 hp 220 volt 20 gal roll-around unit.

[Greg Scott]

Stan,
You wont have any pressure or volume issues but you will gain a little capacity because of the extra storage you'll gain from the 3/4" pipe. I can't answer the compresssion fitting question though.
Greg

[Dennis Peacock]

Stan,

I think you need L2 grade copper piping for compressed air supply lines. Don't hold me to it, but I believe that L2 is the correct grade of copper.

[Jim Becker]

Type L or K for air...leave "M" on the racks. The compression fittings should work, but this is a great opportunity to learn how to sweat pipe...with no water involved, too.

[Dennis Peacock]

Type L or K for air...leave "M" on the racks. The compression fittings should work, but this is a great opportunity to learn how to sweat pipe...with no water involved, too.

Yea....that's it......type "L"......Thanks Mr. Becker!!!! :rolleyes: ;)

[Rob Russell]

I'd sweat the joints - it's really not a big deal, even up "in the rafters" as you note. It'll cost you a lot less, too. The compression fittings get expensive. This is a gret way to practice sweating joints. Just make sure they're clean, flux 'em and sweat away.

Remember to have your taps come off the top of the main feed line so any condensation in the main pipe stays in the main pipe. You might want to consider a moisture bleeding valve by your quick connects (QCs).

Make sure you run a rubber hose/flexible connection between the compressor and piping. That's as a vibration isolator. I also have a water trap mounted on the compressor, so if I ever take it somewhere the water filter goes with the compressor, with a QC mounted on the output side of the filter. A short connector with appropriate male and female QC fittings goes to the hard plumbing. The hard plumbing starts with a male QC fitting into a ball valve. The reason for that is it makes it really easy to disconnect the compressor from the hard plumbing. The ball valve means you can shutoff the otherwise open male QC which would send a loud blast of air out as soon as you pop the female QC. This way, close the ball valve, disconnect the female QC and then you can crack the ball valve to gently bleed the air out of the plumbing.

Here's a pic.

Rob

[Larry Browning]

Stan,
At the risk of starting an argument with Jim B and Dennis P. I think the pipe you have on hand will work just fine. If you were installing this is an industrial enviroment then the heavier walled pipe is a must, but for the hobbiest, type "M" is fine. You are not going to run more that 150-180 psi are you? Type M is rated for about 300psi or so. And even in the unlikely event that you do spring a leak, it won't blow up like the pvc could, so there really isn't a safety risk here. Go price the type L and K and see if you don't agree with me. Oh, and sweat those joints! It's easier, cheaper, stronger and more fun to do.

Larry

[Steve Stube]

Allow me to copy my post from elsewhere on this topic.

Shop Air Lines is frequently discussed so I decided to show a bit of my air line installation. I’m not saying this is the only way, nor am I saying it’s the best way to do it, I’m only offering this info as the way I did it. I have run all air lines in the walls with one exception which I will show. I used ¾” copper for the main line running 48' down the middle tucked up tight next to the wood plate between the 8" WF I-Beam and the second level 2 X 12 floor joists. There are three ¾” drops from this main line. One under the stairs to tie into the compressor and one at each end of the shop for exterior use, presumably for sand blasting at these locations outside. Off of the main line I "T"ed and reduced to ½” copper lines aimed up ~6 inches and then "T"ed again to make runs in both directions in the floor joist space to the outside wall spaces between the 2 X 6's at right angles to the main line. Once in an outside wall I "T"ed again feeding both the upper level and lower level at that point. (Sorry that this "T" is hardly visible, in the photo but it is just above the wall double plate). The drops from this point in the outside walls (there were some exceptions to this on interior walls) were rigid copper but because my upstairs sidewalls are angled (knee walls) I used soft copper for the risers to the second level wood shop and electric rooms. There were a couple of places where feeding soft copper lines worked best (Read, no room for making solder joints and it snakes thru places that were already enclosed, i.e. a blind 90. Remember that freshly annealed it feeds like electrical runs.) in the interior walls and at the East end wall so that is what I used. The branch lines were terminated with sweat 3/8" male fittings screwed into SS Eel's or Tee's. The “T” bracket was used were both sides of an interior wall fed from the same drop. The SS fittings were welded to 1/8" x 1" x 5" straps with mounting holes to secure them to 2 X 4's spanning between studs at the appropriate height. The SS fittings were bushed down to ¼” SS pipe that feeds thru the wall into the room. I have already shown the typical air outlet in an attachment in this thread where a ½” SS washer was added as a final to the opening. Okay, I thought it looked kind of nice too. I have 18 openings in all making air very accessible throughout the shop. I tested the system under pressure for a few days before enclosing any part of it. Guess what – not a single leak.

Photos; The main ¾” line above the beam, a riser and the slip joint for the final main line fit up.

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAirbranchriser.jpg (http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAirbranchriser.jpg)

Two more risers, soft copper coming toward you (beginning of the bend is visible) where it makes a loop to feed down the wall on the right in the picture. A “T” is used on this drop to feed two rooms. The “T” riser on the right is ¾”, ¾”, ½” because it goes away form us, thru the 2 X 12 header at the top of the stairs and then drops into the space under the stairs where the compressor is located (later).

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAiroverMR1.jpg (http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAiroverMR1.jpg)

Next is an outside wall where the “T” is only slightly visible above the wall top plate. Soft copper goes up from the “T” and rigid down to the bracketed outlet.

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAirLineteewwalldrop.jpg (http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopAirLineteewwalldrop.jpg)

A shot from the bathroom shows another drop from the backside of the bracketed mount. This is over a bench area on the other side of the wall.

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopBathPlumbing2.jpg (http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/ShopBathPlumbing2.jpg)

Here is one of those EXCEPTIONS I mentioned where air is fed down a post without first going thru a riser. The outlet on this post will probably be used more than any other with the possible exception of the outside ¾” line drops. A collection point that is trapped and filtered when necessary.

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/AirLineatBeam.jpg (http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/AirLineatBeam.jpg)

I would talk to the painter about sloppy work but I know he has some nice crown molding to hid the bo bo. I see I could have wiped the solder joints a little better too.

I'm adding a couple more items to round out the shop air installation (I hope). I have set up to use disconnects at each outlet and have several regulator/filter units (floaters) I can plug in where needed.

http://img.photobucket.com/albums/v19/ceethese/Lab%20Cabinets/ShopAirtypical.jpg (http://img.photobucket.com/albums/v19/ceethese/Lab%20Cabinets/ShopAirtypical.jpg)

3 Floaters shown. I have provided permenant mount regulators for items like the mister for milling machine etc.

http://img.photobucket.com/albums/v19/ceethese/Lab%20Cabinets/PortableAirReg.jpg (http://img.photobucket.com/albums/v19/ceethese/Lab%20Cabinets/PortableAirReg.jpg)

BTW, the ball valves I use are the purge type so you do not have to disconnect under pressure.

Last a shot of where the system is/will be fed from under the stairs. I have a larger 10 HP compressor but it won't fit this space so I'm looking for a 5 HP commercial unit to replace the one in the photo. A drop pipe w/drain and flex connection will complete the air hookup. The open electrical box is wired for 40 Amp 240 V which will handle the 5 HP.

http://img.photobucket.com/albums/v19/ceethese/Shop%20Photos/Under_Stairs_1.jpg

[Bob Worrel Jr.]

Is PVC not an option? Will it hold up to 120 PSI?

[Steve Stube]

PVC is not an option I would consider but some folks do use it. With PVC in compressed air lines there are several considerations. The top ones pretty much include the safety considerations - temperature, crazing (due to oil in the system from a compressor) and blunt force trauma. They are 1.) will your local code allow it, and 2.) Will your insurance company cover a loss (or even insure you) where PVC has been used for compressed air lines. My 2 cents.

[Jim Becker]

Is PVC not an option? Will it hold up to 120 PSI?PVC is not an option. Both OSHA and the Army Corps of Engineers forbid it and I believe code does, too. PVC can be easily shattered by an accidental blow and when under pressure those sharp shards can kill. Further, it is my understanding that the pressure rating on PVC is for liquids and doesn't apply to gasses. I can't cite the source, but I know that I've seen a number of what appeared to be intelligent posts on this over the years. I have no reason to doubt them.

Some folks do use PVC for this successfully, but IMHO, it's a risk I wouldn't consider. Copper or iron pipe is the best bet for an air system in the shop, both for function and safety.

[Dennis Peacock]

Stan,
At the risk of starting an argument with Jim B and Dennis P. I think the pipe you have on hand will work just fine. If you were installing this is an industrial enviroment then the heavier walled pipe is a must, but for the hobbiest, type "M" is fine. You are not going to run more that 150-180 psi are you? Type M is rated for about 300psi or so. And even in the unlikely event that you do spring a leak, it won't blow up like the pvc could, so there really isn't a safety risk here. Go price the type L and K and see if you don't agree with me. Oh, and sweat those joints! It's easier, cheaper, stronger and more fun to do.

Larry

Hey Larry,

You ain't gonna get an argument out of me. :p ;)
To each his own as I now say. Shoot....you're talkin' to a dude who has run about 100' of 3/8" air hose to the center of the shop and coil/uncoil every time I want to use air. I really need to run some air lines but, that too takes money that I don't have right now.

[Bob Reeve]

When running your main line from the compressor you should leave some distance before you mount your filter. This is to allow the air to cool and the water vapor to condense. Make sure to mount the regulator after the filter. This keeps water and particulates out of the regulator. Hope this helps

Bob

[Steve Stube]

Bob,


When running your main line from the compressor you should leave some distance before you mount your filter. This is to allow the air to cool and the water vapor to condense.
I prefer to filter air as it leaves the compressor tank to catch any blow-by oil from the compressor. I filter and trap at outlets of the system as well but I consider that first filter at the tank to be the most important. I see no reason to contaminate any part of the piping system as would be the case following your recommendation. Traps are somewhat effective in removing moisture from the air. Chillers and dehydrators (air dryers) can also help. Are you saying you count on a filter to remove water? Tell me how.

[Bob Reeve]

Steve,

I work for Coilhose Pneumatics and their engineers recomend using a common filter unit to catch the bulk of water that leaves the tank. They also recomend using a coalescing filter or a dryer to remove the remaining water if using the line for painting or spraying finish's.

The comment about leaving a distance from the tank can be accomplished by running a flex line (rubber hose) from the tank outlet to the wall up high. Then snaking copper tubing, either flexible or with 90 degree fitting back and forth across the wall. This way you can get many feet of tubing in a small space, let the water condense and then mount the filter.
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Make sure to mount the regulator after the filter. I have gone on many service calls where the regulator is mounted first and has gone bad because the water washes the lubrication out of the regulator.

Also make sure to run any over head lines at a slight slope away from the compressor and have the last drop come off the bottom of the tubing and go down to a mechanical drain. Make all other drops come up off of the top and then make a u-turn and go down. This makes sure all the water ends up in the drain and not the tools you are using.

Bob

[Gerald Bailey]

Stan, The smartest thing I did when installing my air system was to mount a hose reel on the ceiling in the center of the shop. I used a reel from HF on sale for $39.95 (on sale)complete with 30 ft of 3/8 inch hose. Have used it for about 2 years with no trouble. I can reach the end of the hanging hose and it is always close no mater where I am in a 26x26 shop. Dont have to fool with a hose when I'm finished just let it retract and its out of the way till I need it again. I used compression fittings (copper) and have only had one small leak, quick pull with a wrench and it was fixed. One other thing, put a good ball valve at the outlet of your compressor. That way if you did develope a leak while you are not in the shop the compressor wont be kicking on and off. I have a habit of shuting the valve along with the lights in the shop when I leave.
Good Luck with your installation, Bill

[Stan Thigpen]

Thanks for all your suggestions & obversations. Bob R - what is that on the J-box in your illustration?

[Rob Russell]

Thanks for all your suggestions & obversations. Bob R - what is that on the J-box in your illustration?

Stan,

I assume you mean me, not Bob.

The junction box was in a box of stuff I picked up at a tag sale for a buck or 2. I believe that it had a transformer in it and the terminal strip was for 24v power takeoffs.

I just used that stuff to mount the compresser receptacle because I had it, that made it cheaper than buying new and it used something from those boxes of "stuff I could use someday" that we all have.

Rob