Multiple laser - shop air question

[David Sabot]

We have 7 lasers in our shop, and are looking into running shop air instead of individual compressors.

Ideally, we would like 60+ PSI for each machine.

My question is what is the best way to make this work? Do we run a single line from a large compressor with T junctions to each machine with a pressure gauge and regulator? Do we run multiple lines out of the compressor to each machine?

Any pics, advice, diagrams, etc. you could provide would be invaluable.

Oh, last question, is there a calculation to figure out how large a compressor we would need to feed X machines Y psi?

[Scott Shepherd]

60 PSI on each laser? What in the world are you cutting. I ran tests a long time ago and I never found a noticable difference on most materials. If you need 60 PSI on 7 lasers you are going to need a beast of a compressor.

Why so high on the PSI? Trotec's built in compressor is very low, something like 10 PSI max.

[David Sabot]

We are only cutting through 1/4" birch, but we have been doing tests with various PSI and have found at around 60 we can blast through our material with no burn marks, a super clean cut, and increase our cutting speeds over 2 times.

[Scott Shepherd]

Have you tried Nitrogen?

You'd need to figure out how many SCFM each laser is using. That's based on the diameter of the tubing and nozzle, I suppose, and then multiply that by 7. At 60 PSI, that's a ton of air. Probably close to 4-5 SCFM, I'm guessing. That would mean you need 35 SCFM at 60 PSI. That's a serious industrial compressor, something like a screw compressor.

I think you could probably get by with a couple lines that fed into a few machines each.

[Kev Williams]

I'm going to assume you're using a cone-tip on your lenses with the air blowing thru the cone? If so, it's no wonder you need 60psi of air... If this is true, do yourself a favor and rig up some external air delivery so you can focus high pressure air thru thin tubing...

My LS900 factory air setup-
414362
-a length of .093" ID air line runs to the machine and terminates with some 3/16" OD copper tubing. I have 125 psi feeding the line, and with the valve wide open, it blows some hard air, but it's not that MUCH air, the size of the feed line restricts the flow, less air wasted.

My Triumph's 'I-chucked-the-cone-the-first-day-and-made-this' air setup ;)
414363
Note the high tech paperclip 'hose clamp' :D - hey, it works, a small piece of clear hose connects the copper nozzle tube to the plastic feed line, making it adjustable, and my Chinese diaphragm pump pushes a nice stream of a air, and the small copper tube restricts the flow near perfectly, notice there's no air valve, don't need it using the 'fish tank' pump :)


With small tubing you'll likely find that 25psi will give you more usable air PRESSURE than 60psi thru a nose cone, and use a lot less air doing it.

I have a big 80 gallon Coleman air compressor that's around 20 years old, and at least a dozen air lines all over the place. Something similar should be plenty to supply your machines, as long as you can restrict the high-volume flow...

[Gary Hair]

I can't find the diagram but there was a website I found with some great info about running shop air and the various connections needed. What they recommended was to run a single copper line all around the shop then "T" off of it into a water trap and then into the machine. The reason for a trap on each machine was because the length of the line and how much cooling the copper provided would guarantee that moisture would condense and you certainly didn't want it condensing on/in your equipment. If I can find the picture I'll post it, otherwise I'll sketch something up to show the basics.
Steve (Scott) is right about the compressor, 35-40 CFM would be needed if you run all of them at the same time. You can buy a rotary screw with that capacity for somewhere around $3K and it will provide tons of air all day long and way quieter than any piston or diaphragm compressor.

here is a link to a picture - it's very important to run the "T" up from the main line so you don't force water into the laser. A drain is critical as well, you'd be amazed at how much water still makes it to the end of the line!
https://3.bp.blogspot.com/-kkn-nYhqrfA/Vv-ohOGVV5I/AAAAAAAACZA/YOzoyflPLNY8LztBFcFptM7LzH6-5EyIg/s1600/air%2Bcompressor%2Bplumbing%2Bdrops.jpg


We have 7 lasers in our shop, and are looking into running shop air instead of individual compressors.

Ideally, we would like 60+ PSI for each machine.

My question is what is the best way to make this work? Do we run a single line from a large compressor with T junctions to each machine with a pressure gauge and regulator? Do we run multiple lines out of the compressor to each machine?

Any pics, advice, diagrams, etc. you could provide would be invaluable.

Oh, last question, is there a calculation to figure out how large a compressor we would need to feed X machines Y psi?

[David Sabot]

For some reason I can't view your images :(

[Scott Shepherd]

For some reason I can't view your images :(

Images are only visible for paid contributors ($6 a year) now. The format changed a while back.

[Kev Williams]

Because copper tubing IS conducive to causing condensation to form is a good reason NOT to use it. My old man ran copper tubing everywhere for air lines, over the years I disconnected near all of it and replaced it with various types of basic air hose-- not because of condensation problems, it was simply due to changing needs. But the added benefit has been zero water in our air lines, EXCEPT one; the main line coming in goes into my saw room and to a tee-- the straight shot of the tee is connected to a hose in the room, that most of which lays on the cool cement floor; the right-angle shot of the tee, pointed up, feeds the rest of the place. The hose on the floor is all downhill from the compressor, and collects and condenses what seems to be 99.9% of the moisture in the air from the compressor, there's almost always water in that line, I just blow it out occasionally.

FWIW, awhile back I found the air dryer on my compressor was cracked and leaking, so I picked up a new one, but ended up needing some pipe reducers- so at the time I needed to get back to work and I just reconnected the line without a dryer. I later picked up the adapters, but I still haven't installed the new dryer. That was 9 months ago, and I've seen no increase in water in the 'wet' air line. If anything, I've seen less. And still no moisture in any other air line.

Another irony, I never see water in my compressor's air dryers? There's never been even a drop of water in the dryers on my 2 big compressors (I have a 60 gal HD Husky out at the boat harbor), even though there's nearly always water in the wet line at home. While the dryer's jars are dry, the tanks aren't! I have to wonder what good is an air dryer that doesn't capture any water? The air-line-on-a-cool-cement-floor seems to be best water catcher I've found...

pics--
LS900-factory nozzle
http://www.engraver1.com/help/an4.jpg

Triumph-Macguivered up nozzle
http://www.engraver1.com/help/an3.jpg

I'm not suggesting anyone do away with air dryers or 'accepted procedures' on running air lines, just relaying my experiences. :)

[John Lifer]

I would go with pex myself. Keep your air below 60psi and it will be there till you want to take it out. I think most is rated for 100 or 120 psi water use (I don't have any laying around I can look at) but it can easily be cut and moved if you wanted to rearrange a layout and it's probably 20% of copper. I still use my little chinese aquarium pump. It probably puts out 5 psi. Works fine for me.

[Gary Hair]

Because copper tubing IS conducive to causing condensation to form is a good reason NOT to use it
That's exactly the reason to use it Kev. You want to condense the water out before it gets to your equipment and copper lines are the best way to do that.


Another irony, I never see water in my compressor's air dryers?

That's due to the air being hot coming right out of the compressor. Hot air holds more moisture than cool air and you can't remove the moisture until you cool it down, so having a moisture trap on your compressor is a total waste, it needs to be the last thing before the equipment. A case in point - I had a 70hp diesel rotary screw compressor and connected up a $500 air/oil/water separator within about 5' of the outlet off the compressor. I would get at the most about a 1/2 pint of water an hour from this setup. After calling the manufacturer they recommended moving it to the end of the 100' air hose instead, giving the air time to cool down and release the moisture. After that I would get pretty close to 3/4 gallon per hour and virtually no more problems with moisture in my pressure pot (sandblaster).

[Gary Hair]

I would go with pex myself. Keep your air below 60psi and it will be there till you want to take it out. I think most is rated for 100 or 120 psi water use (I don't have any laying around I can look at) but it can easily be cut and moved if you wanted to rearrange a layout and it's probably 20% of copper. I still use my little chinese aquarium pump. It probably puts out 5 psi. Works fine for me.

Pex lines are ok for air but the fittings are not, at least according to various websites I have read. There are a few products that are made for compressed air, but not the same pex and fittings that are used for water.

[Bill George]

Exactly what Gary said. Copper or black iron pipe. Drop down the wall, set a T on its side and come out with your air fitting, out of the bottom of the T 6 or 8 inch nipple, install a blow down valve. Every so often blow all those valves open and dump all the water out. Ideally when you run your main, come off the TOP or SIDE of that main with your drops so the water does not just run down into your air drops. Don't forget to drain the air compressor tank.

I do not know about PEX for air lines, but I know that OSHA will fine you big time if you use PVC in an industrial location. I have seen PVC break open and scatter shrapnel all over. I think the age and the vibration work hardens it. As a pipefitter I have refused to replace PVC air lines,

[Gary Hair]

I have seen PVC break open and scatter shrapnel all over.

There used to be people that swore copper would explode and send metal shrapnel and that it was so much more dangerous than plastic. I watched a video about 10 years ago where they tested copper vs pvc and how they burst when overpressurized as well as punctured or crushed. Both violently released the air but the copper just mushroomed out and send virtually no shrapnel flying and the pvc literally exploded into pieces that would really cause you to have a bad day. The final test was inside a cardboard box, a rather large refrigerator size box, there were no holes in the copper test but the pvc looked like Swiss cheese. That was plenty to convince me to stick with copper, and I got pretty good at sweating a joint after plumbing my garage with a complete closed circuit with 3-4 drops on each wall...

[Scott Shepherd]

Totally agree with Gary. Moisture is controlled by a properly designed system. It cannot be eliminated purely on the fact of what's happening to the air, the temperature of the air as it's running through a room temperature pipe, etc. I think I recall the image Gary referred to. It showed the proper way to plumb in any type of system and it explained the logic behind it all. You want a trap at all the termination points.

I know it's all off topic from the original post but still good info to talk about.