I have been lasering with a 130w laser for almost 10 years now and have been mostly lucky. I added an 80w Fiber laser to my stable and had my first fire with it.
I built an enclosure for it from Dibond- a signshop product which has aluminum faces and either a corrugated or sold plastic core. It would have been easier to cut out panels from acrylic which we have in abundance and laser often, but I am a cautious old fart and the alum faced material is normally coated white and looks professional. So far, so good. I mocked up a 2.5 inch high velocity fan thru the bulkhead into the enclosure and used plastic flex tubing similar to a vac cleaner hose with a 3D printed [PETG] intake to get close to the ablation point.
I am hoping that you guys can see this coming- a hot spark ignited in the hose and with the wonderful airflow moved down the hose to the nearby fan housing.
It was a nice blaze- I have had a Halogen fire extinguisher strapped to the end of my CO2 laser [right next to the Fiber laser] which did a great job of extinguishing the flame without any powder residue. It has been a several week long cleanup, which was pretty nasty in the early stages, but I am getting to make a lot of changes for the better and have some actual aluminum flex tubing which should eliminate that particular issue. I am flame testing everything- the aluminum tape used for furnaces is actually very fire-resistant [the glue melts but is not a real problem] I had a piece of cheap alum flex ducting which actually burns- they line it with clear plastic to make it harder to puncture, I also have a new extinguisher to replace the other one, altho halogen is no longer easily available. Please consider all possibilities for fire, before you have your fire. Gene
Hi.
An important reminder, thanks for sharing Gene.
For stuff like lasers and other sensitive electrical equipment, halon extinguishers would be ideal, but as You said, those are somewhat hard to get nowadays.
And for a good reason, but unfortunately there’s no eqvivalent substitute, at least not cheaply.
Co2 is IMO the next best option, but does have its issues as well.
And the availability of smaller Co2 extinguishers is somewhat poor, at least over here.
And bigger ones are darn expensive.
NOT A SUBSTITUTE FOR A REAL, APPROVED EXTINGUISHER, but I printed and tested this:
and I was pretty amazed how well and how long time it actually performs adequately.
That particular 3D design could be improved in many ways, but it does work as-is.
Regards,
Sam
Thank you Sam- I downloaded the .stl s to look at into Fusion 360. If you are not comfortable with modifying 3D files, I would be happy to- I enjoy it. The pivot on the trigger lever seem crude at first glance. I assume the CO2 bottles are meant to be triggered and closed repeatedly so one could test it? This could be a first line of defense before going to a messy extinguisher. Gene
I just reread your post and noticed you are Finnish- I grew up in a small German town in Minnesota which is surrounded by small Finnish towns- spent 6 years in the local Army National Guard with a lot of Finlanders- they know how to have fun…
I thought the same thing. When I get around to printing it, I was going to replace the pivot arrangement with a through hole and use a pin, maybe one like the trigger lock pin.
not so small town called Bloomington, but I spent a lot of my youth with my grandparents in Lake Crystal, which had a mix of Swedish, Norwegian and German farmers. My grandfather would regale us with his best “Sven and Ollie” jokes.
I spent my formative years in Wadena, my mom and her peeps were Scandinavians and my dad’s were German. I even spent 2 years in the local Votech school- we studied very early computers and electronic technology- it has served me well. And I still play with anything technical in my dotage. Have been in the northern suburbs ever since [65 years].
Hi.
You’re welcome Gene.
Thanks for the offer, but I really do need to brush up my few decades dormant 3D modeling skills 
.
It sure seem to, but it does work.
The leverage ratio of the trigger is enough for the rather light valve in the soda maker cylinder to operate, but:
Was my intention as well.
I’d use the same 4mm brass rod as the plunger, with spring-keepers on each end obviously.
Yes.
I’ll write a more thorough “Tips and Tricks” thread when the time permits, but in short, one gets ~10 approximately 5 second long bursts that have ~15 seconds between them one after another, before things start to dwindle down (in 0 deg C ~80 rh).
At the start, 5 seconds equal ~40g of CO2, around 10th cycle, ~15g CO2.
To get the bottle “empty”, it took an additional 2 minutes or so to get the gasflow to die down, with around 1 minute of downtime when I weighed the bottle and wrote down the weights.
Empty in quotes, because there was quite a lump of dry ice in the bottle, and the weights didn’t match.
My Flir E5 thermal camera is limited to -40C, and the bottle was a lot colder than that even when it had sat a good few minutes as I remembered that I should have monitored the bottle temperature as well, and went to fetch the camera .
The handle was -10C with no cold brittleness.
The thing is, a CO2 bottle and the valve like that is not intended for continuous operation (the ones in the actual fire extinguishers are), and furthermore, the cross sectional area of the expanding gas path is somewhat irregular and therefore the gas velocity varies along the path, so the passage will clog sooner or later when operated continuously.
We sure do.
Unfortunately we tend to absorb alcoholic beverages like sponges while having fun, and that can lead to all sorts of pequliar incidents.
Regards,
Sam
As much as I love to build most anything- I am going to buy a CO2 extinguisher, they are really cheap. Thanks all. Gene
I purchase a 5lb co2 extinguisher from a restaurant distributor.
Price has gone up… I think I paid a bit over $100 for it a few years back.
Doesn’t hurt to let the Internet do your walking for this kind of stuff. Maybe you can find it at a lower cost.
I am thinking of adapting one of these to each of my 2 laser enclosures. It is 800psi and a down-blast should snuff out any flames.
The SF-A9 has a flame detector, but I am adding a 175 degree alarm thermostat to the S30 box.
I replaced my aluminum-can leaking ABCDE units with SS canister versions, but I wonder what that ionic fluid would do to my aluminum parts on the laser.
Comments welcome…
Amazon, $35: DiversiTech GG-1 Drain Gun with Flexible Hose Pipe for A/C Condensate Lines, Air Conditioner Cleaner, Clears HVAC Clogs, Charcoal Grey
Keep in mind what’s happening.
If you dump 800 psi into your enclosure … the size of your cabinet, lets assume 1’ on each side (144 sq inches) which is very small. I’m sure yours is much larger, so my numbers are more than conservative.
We’ll use a 4 sides and a top for 5 * 144" or 720 sq inches. At 800psi it would put 288 tons of pressure on the enclosure… assuming a short ton being 2000lbs.
Just need to ensure it doesn’t have a chance to build up any pressure within the cabinet… or it will come apart.
It would be nice if you could post a photo your creation for us to see and behold 
That 800psi is in what looks like a 20ml cylinder. Not much chance of blowing the doors off. It is e really small volume of gas in the cylinder. These things are made to blow the crud out of A/C drain lines, which are Schedule 20 PVC.
Yes images will be provided. 
I will do that Jack- still rebuilding after my fire- When I built the enclosure I had no clue what it should look like- so I am trying to improve what I can without starting over. Should be getting pretty close this weekend- I will take pix when it is pretty again, Gene
Understand… most of us here love a good diy…
Got them today. They are labeled 16g. Anybody know how much volume 16g of CO2 at 800psi will occupy at 15psi? V
Google AI advises
- 16g CO2 at 900psi:
A 16g CO2 cartridge typically contains about 20 cubic centimeters (cc) of CO2 at 900psi, which is roughly 62 bar.
- 16g CO2 at 15psi:
If the 16g of CO2 is released to 15psi, it will expand to a much larger volume, depending on the temperature. A rough estimate would be around 1080 cc.
Appears to be about a liter…?
I guess I could fire one into a big baloon to get a better idea.
Actually, I really do have a clogged A/C drain line. That will be my first test.
Hi.
That’s the standard ballpark procedure when finding out gas volumes and flow rates.
Since You’ll most likely be using pear shaped party balloons, the Archimedes procedure will help with the volume calculation.
The AS answer posted above is grossly incorrect though, so ~10l (/~2,6 USgal) plus balloon will probably save You from doing unscheduled laundry 
.
Regards,
Sam
But it was an estimate, no? I did a calc using computed moles and got about 8 liters as the result. But yours was an estimate too, right?
8L would be just about right for my cabinet sizes. However, I am a bit reluctant to build a fire in one to see how it works. 
C’mon, it’s for science! 
No guts, no glory. lol