What size CO2 fire extinguisher did you buy?

As my laser build starts taking shape, I’m trying to decide what size CO2 fire extinguisher to buy for it.

How big a CO2 fire extinguisher did you buy for your laser cutter?

What size would you buy if you were doing it over again, and why?


I must check at the makers tonight to see just what fire extinguisher we have. Hopefully not a dry powder type, I’ve seen what they can do to the inside of a laser cutter (not a cheap K40 either!)


Michael… I guess it depends on how big of a fire you expect… I have also determined that a c02, or preferably a halon extinguisher is a must. Dry extinguishers were never on the list. I think anything that can produce enough volume to fill the machine with gas should stop anything, assuming the fire is not reigniting.

I’m looking at a 2.5 lb. model or this 1.4 lb model. Small price difference, but size might be a factor.

Halon is proven around electronics, enough air to breath but not enough for fire to burn. At least in MHO that’s the direction I’m leaning. (8’)

I have very strong opinions regarding Halon.

Halon production was banned in 1994 as a potent and long-lived greenhouse gas, and it’s toxic. It makes sense to use halon for applications where there should never be a fire (e.g. on board aircraft) and any fire is an immediate threat to life, but I think it’s not appropriate to use it where a fire is expected to be likely in normal operation, as with a laser cutter.

I neither want to contribute to global warming by unnecessarily releasing a greenhouse gas, nor wish to expose my family to toxic gas. One reasonably likely reason for a flame-up would be if the exhaust fan fails, which would mean I would be concentrating a known toxic gas in my house. My data center training included that if the halon release alarm sounded, drop everything and get out the door immediately to avoid breathing it.

CO2 won’t damage the laser cutter, and is normal for use with laser cutters. I think that environmental and financial cost are two very good reasons for this normal.

My intent is to get one that is large enough that I can put out a fire before it damages the laser cutter, and still have enough left to use again to keep using the laser cutter in the same session, before getting it recharged.


Good point about it’s a greenhouse gas problem, one I didn’t know. When I went through the training as a field engineer working almost entirely within computer facilities they never mentioned anything about it being toxic. In fact they did have a room for us to go in an breath it to show us you could breath… Of course that doesn’t mean it wasn’t killing us… :frowning: Most of those applications were low concentrations levels. But as you point out it’s manufacture was banned in 1994 because it’s ozone depletion is apparently massive. Count this one out… Funny these are for sale, usually when the production is prohibited the use is also prohibited.

My only reason to depart from CO2 was that the it caused a great amount of moisture to condense when it was released and I replaced many boards that were damaged by CO2, according to the customer. Halon also can cause burns from cold, but I never saw the condensation. Don’t see how it could be any different. Maybe I wasn’t observant enough.

My area was in the desert southwest and the humidity is in the single digits most of the time so it seems like ti would be more of an issue in humid areas. I’ve been out of the field for 30 years… if that indicates anything…

I think you could flood a laser cabinet with very little co2, especially if you could trigger it with the covers closed.

I had no doubt that I had to have something for fires… Glad you started the thread… Hope for good suggestions… Take care…

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My data center training was around the turn of the millennium, was probably less detailed (I was responsible for part of a lab) and I have no idea whether my training was industry standard. I’m curious, though; what kind of boards were damaged by water? I remember around the same time you are talking about, the advice was “shower with your keyboard” to clean it. I heard of cleaning flux off circuit boards in a dishwasher dedicated to the purpose. Was there some sort of environmental contaminant such that an acid or base created a corrosive solution or something like that?

I did think about an integrated system plumbed into the air assist and even thought about trying to automate it. My enclosure is about 750 liters. It looks like CO2 is a little less than 2g per liter at atmospheric pressure. Ignoring stoichiometry for a moment, if replacement were perfect that would be around 375g of CO2. A 24oz CO2 paintball canister would be nearly two full changes of air (680g). It wouldn’t be a perfect change, but then as long as the stoichiometry changes enough to not support combustion for a bit while it cools down (helped by expanding CO2) that’s probably OK?

But I’m guessing that I’d need a lot more than that if I have the lid open. Therefore I was thinking about 10lb as a reasonable size portable fire extinguisher.

I’m assuming that a fire could be bad for the optics and if I have a fire there’s a substantial chance that I’ll be replacing lens and/or mirrors if nothing else.

Most of the time the problems were in peripheral equipment such as tape handlers and disk drives. In one instance a fire was near a tape handler and they used their CO2 on the fire. The closest handler had multiple card failures the ones on each side each had one card failure. I still have trouble connecting that incident because the cooling was cold air coming from under the floor up into the machines. This should have eliminated most of the CO2 that was in the area. Compared to everything else in the area the gas was release in the low pressure area, never should have reached the machines innards anyway.

I could see where the ‘smoke’ had left the IC, but nothing else was there. I ran this up through engineering where I worked as to why we had so many failure with CO2 extinguishers. Initially told it was condensation. Never did get an answer. They went to Halon, so you could get out of the area, and it wasn’t an issue any longer.

I believe you’ve got it right, except for opening the door. A few nozzles on the inside and a short burst, the whole cabinet won’t support combustion.

I don’t like opening doors with burning things inside, you’re always adding that little bit of extra oxygen…

When I was a police officer, I always thought that firemen were nuts since they ran into a burning buildings, they thought we were nuts because we went after bad guys who shot at us…

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Combustion products are often corrosive, I’ll put my money on that. I wonder if a Halon flood just extinguished the fire faster than hand-held (?) CO2? :thinking:

It’s not an exclusive choice. A hand-held extinguisher is a non-negotiable item; integrated fire suppression is optional and not on my list for first light. (Though I do have an unused 24oz paintball CO2 canister for reasons that don’t involve paintball.)

Also, this is made of aluminum extrusion, so there is a lot of room for air to get in; it’s not really airtight, so more O2 will get in even with the door closed.

I’ll keep thinking about an integrated system, though.

(Maybe I should make one of those new DIY O2 concentrators, and then use O2 as cutting gas and the N2/CO2 mix left over as shield gas. :stuck_out_tongue_winking_eye: )

Enough flow for enough time and any leaks won’t matter… :slight_smile: Quite right about no reason you can’t have both. I’m sure I’ll have a hand held long before an ‘installed’ ideal system. Although it makes me wonder how horrible could it be for a diy project? Wonder what it would cost to set up an emergency controlled ‘burst’ of CO2 system.

Sounds like right up your alley (8’) Can’t wait to see how you solve it… :slight_smile: :upside_down_face:

And now we’re back to the original topic!

After all the You must buy a CO2 extinguisher for your laser advice here I was rather expecting that someone would own up to having, you know, actually bought one. And maybe have an opinion about size… I’m running into the same problem on twitter, too. :grin:

I’m doing my best to keep the thread alive, but no takers (8’)

Isn’t that how it seems…catch 22