Fire Extinguisher Warning

A couple of years ago, I purchased a couple of multiple class fire extinguisher. They were based on using deionized (non-conductive) water and some sort of additive.

About 3 months ago, one started leaking through some corrosion on the bottom. I tossed it and moved the spare to the holder on my laser box. Last week, I discovered the second one did the same thing.

These units have an aluminum canister and appears to not be able to resist chemical action on the aluminum. Had I used it, I wonder what would have happened to the aluminum components of my laser.

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Hi.

Thank’s for pointing that out.

From an engineering point of view, combining aluminium and water is always a really bad idea, storing stagnant water under pressure in an drawn aluminium container ranks as one of the worst imaginable.
No matter what additives are used.

Extruded would be only marginally better, the cast varities the best, but the manufacturing costs are prohibitive in consumer grade products.
Same goes for internal coatings, too expensive to be used in consumer grade products.

The drawing (and extruding) process(es) requires an certain pureish aluminium alloy, as well as produces all sorts of uneven material hardening effects that weaken the corrosive resistance in all metals.

Nothing, You would’ve cleaned the liquid off soon after using the fire extinguishing liquid.
Water+pressure+time is the cause of the pinhole-corrosion in the canister.
OTOH, had You used powderous or foam type fire extinguishing materials, in all likelihood Your laser would’ve been toast.

Haven’t gotten around to actually make one, but the way I see it, the only feasible fire extinguishing method for hobby lasers is to use slow release displacing CO2, Argon or CO2/Argon mix.
Even though I do have both kinds in large containers for welding and could use those, for multiple reasons I thought about building the system around a Soda Stream CO2 container, rather than a pack of small CO2 cartiridges that those kind of systems are usually based on.

The slow release is IMO the key, a fast pressure drop of a gaseous material is highly endothermic reaction, and while that reaction will extinguish the fire by cooling it, it will also cause thermal stresses onto the materials.
Those rapid thermal stresses will bend the ways and/or the frame, and in a case of a CO2 laser, the tube probably doesn’t have to be inspected whether it still works or not :wink:.

Regards,
Sam

:finland:

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As far as I know, fire extinguishers have an expiration date. (Here at the company, by law, everyone is reviewed annually). If by “couple of years” you mean two years, then something strange has indeed happened.

As @LSS mentioned, water and aluminum never produce good results. (I must have hundreds, yes hundreds, and this time it’s not a translation problem) of pictures that prove it.

Any beer can is guaranteed to have more internal protection against corrosion than these extinguishers.
I don’t know if they will be as efficient, but if you shake them vigorously before opening I believe they will perform remarkably well.
Furthermore, if the expiration date is coming to an end, you can always give the content another use than throwing it away.
Taking into account all the precautions of today:
DO NOT TRY THIS AT HOME.

Errr,… what does “OTOH” mean?
I have a conventional fire extinguisher next to the machine for emergencies. I know that fire extinguishers can render the machine useless. But I’d rather render the machine useless than the house. Also, I have the machine located next to a window, which could be useful if I want to throw the whole machine out the window. (whether for fire reasons or not.) :innocent: :grin:

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“On the other hand.” Basically it is viewing the situation from the opposite perspective. Commonly used to block a rebuttal.

I appreciate all this advice about aluminum and water. Where were you guys when I ordered the units.

Seriously, aluminum canteens have been used for water storage for more than 100 years. Being pressurized makes no difference. It was the chemicals that did the corroding. I knew neither that the container was aluminum nor that the contents were corrosive. Amazing that hindsight is 20/20 vision, no?

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Hi.

They do, and in the case of those “camping-”, “trekking-”, “just-in-case-” rattle-can varities, that date may be as near as one year.
Or nothing at all, if the can has sat on the shelf for that year.

Unlike in the bigger, more convincing varities, there’s seldom any indicators for the pressure either, so there’s no way of knowing whether they’re actually pressurized or not.
IOW, whether they actually work when the need arises or not.

One IMO rather important thing to keep in mind is also the fact that the actual time to empty a can like that in order to extinguish the flames is just a few seconds.
Couldn’t find that exact extinguisher online, but it’s usually in the ballpark of 2-6 seconds.
So no matter the reason a fire extinguisher of any kind is needed or required, it’s also advisable to buy one extra, light a small fire, and find out how it actually works.

As will any other can intended to hold beverages.
Save for the intention to sell more units, there’s no reason why there couldn’t be a similar lining in these kind of fire extinguishers as well.

Like @MikeyH said, On The Other Hand.
One of the acronyms/initialisms I do like to use rather frequently, even though I’m probably a hair (or lack of it) too old that it would seem natural :slight_smile:

Absolutely true, but that’s a preplanned choice, people seldom understand what a mess a conventional foam or powder fire extinguisher makes.
If I had to choose, I’d pick a CO2 extinguisher for the possible lasering fires every time over the other varities.

Not at all a bad plan either.

:grinning:

Sure, but not thin, uncoated drawn ones.
It’s all about the metallurgy, and choosing the correct alloy for the intended purpose.
And the alloy dictates the manufacturing method.
Even the most common aluminium additives Silicon and Magnesium, will render the alloy difficult, unfeasible, or plain impossible to be drawn.
I don’t have the exact figures, but if I was a bettng kind, I’d be willing to bet that 99.99% of the aluminium canisters are drawn.

From an engineering viewpoint it does.

It’s possible -even though improbable- that the chemicals expedited the corrosion, my money is still on the water being the major culprit.

You won’t get an argument from me there, that’s absolutely spot on.

On the positive side, those cans were rendered useless before You had to use them :slight_smile: .
Now You can choose more suitable ones, and since You made the issue public, there’s a good chance that You saved someone elses money (not to mention machine, house, etc.) in the process.
And that’s a definitive win in my book.

Regards,
Sam

:finland:

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Well then…
I never studied chemistry, but I know that aluminum (Al) in its pure state oxidizes. I know that water is (H2O) Hydrogen and Oxygen Which makes me realize that if there is oxygen in contact with aluminum there will be corrosion. :innocent:
Now getting into the subject in a more serious way, I often say “There are no arguments against facts”.
It’s true that I’ve seen a lot of aluminum corroded by water, but it’s no less true that aluminum utensils have been used to store water for hundreds of years (that’s what they say because I’m not even 100 years old yet). :smiley:
In my opinion it will be due to two main reasons:
1 - Aluminum containers were and still are used to transport or store water for short periods of time, that is, they are not in permanent contact with water (which must have a higher concentration of oxygen than air, I am completely unaware of whether this is the case or not). Furthermore, I believe that they had and have some kind of treatment when the objective was to be in contact with water.
2 - Today’s aluminum is more of an aluminum alloy, it is not pure as before and I believe that this is reflected in the quality of the final product. For some purposes it is better but for others it is worse.

I should definitely take your advice. I’ve never needed to use a fire extinguisher, I’m aware that the smaller it is, the more I have to take into account the discharge time. But 2 seconds is only enough to put out a match…
What I had no idea was that they unloaded in such a short time.
If I were to use it, I would press the “trigger” for a few moments and move around the flames as needed. No pressing the “trigger” and waiting for it to end.
The ones I have actually have a pressure gauge, but from what I know, there’s nothing stopping the pressure gauge from getting stuck and not showing the real pressure. (this is because they are cheap extinguishers, of course)

Acronyms and I have never gotten along very well, but I admit that they are very useful. :grin:

Here in Portugal, as far as I know, these extinguishers are not sold in “compact” format. For industrial use only. But I could be wrong. It’s something I’ll figure out.

In my opinion, only CO2 and Halon are acceptable. However, I just notices Fire Blankets are a possible alternative.

@parsec , I would love to be get a CO2 unit for 45 euros ($46). Here, the cheapest are about $150 USD.

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Hi.

If directed correctly and the fire is a small one, 2 seconds is plenty.
Takes a lot of skill though, as do the larger varities as well.
So if there’s a chance to test how an fire extinguisher works, I urge everyone to take it.
During those few seconds, an unbelievable mess is created.
But, probably we all agree that the mess is always a better alternative than a burned down building.

That’s the correct way, but often the smaller ones don’t have that option.
When the trigger is pressed, a hollow needle punctures a metal membrane and the can empties.

The 2Kg one @parsec linked is plenty for a diode laser fires.

Or, if You’re a DIYholic like me, the first Google hit:

Requires a 3D-printer though.

While it works as-is, the design isn’t optimal IMO.
The discharge nozzle should resemble more like the ones on @parsec 's link in order to handle and direct the expanding CO2 better, and the channel from the cylinder to the nozzle should be removable.
Removable, because plastics -especially printed ones- become rather brittle rather fast when flash-freezed.

Regards,
Sam

:finland:

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Hi.

Agreed.

The problem with Halon is that those have been banned in most places, and for good reasons.

True as well, but not quite as easy to put out a machine fire with a blanket, compared with CO2.

Regards,
Sam

:finland:

High pressure control valve made with a home 3D printer? Trust it not, I am.

Hi.

Since the makeshift handle is not acting as the control valve, but rather as the means to actuate the valve in the container and a passage to direct the expanding gas, I for one would as long as the printing material was chosen correctly of course.

True, should the passage freeze shut and clog up for some reason near the nozzle opening, or the full canister emptied at one go, then something would probably give.
From the video it seems that the velocity is high enough to suspect that while the nozzle shape could use some improving, the channel is correct enough.

It would be easy enough though to design a some sort of safety feature that directs the gas stream away from the operator, should the the pressure rise uncontrollably inside the handle.

Another IMO important safety feature would be to put a sock over the container. Especially if used long and hard, freeze-burns are pretty much guaranteed if the container is handled with bare hands.

Didn’t download the files (yet) so I don’t know exactly, but it seems from the pics that the actuating pin is shrouded as it should, in order to keep it from jamming from the extreme temperature changes.

In any case, a some sort of plastic is probably the best material to make such a handle/actuator, any kind of metal would probably have to be coated/lined to prevent it from freezing shut and/or the actuating pin to jam.
Milling one out of a block of Nylon or Teflon would probably work as well, but it makes the fabrication significantly harder, not to mention much more expensive and more time consuming.

Regards,
Sam

:finland:

Thank you one more time!!! :+1:
This extinguisher (2Kgs) is like the ones I have at work place who are checked every year.
What I will look for is much smaller, maybe 0.5Kgs. I am not sure, because after @LSS mention earlier I will need to know for how long it last in terms of extinguish time 2 or 3 seconds of discharge time is very risky, almost useless.

If you say so…
That’s why I consider 2 seconds almost useless. I have no practice at all :smiley:

This is why I love this forum and these people, in just a few threads I have learned more about the subject than I have learned in life. :ok_hand:

I had no idea, and there it is, if I needed to use it in an emergency I would take an approach counting on being able to control the way the extinguisher discharged, if I was caught by surprise with it discharging completely at once I don’t know if I would be successful. Thanks!!!

I only read this moments after replying to @parsec.
Yes, it seems like a lot to me, but only because for the purposes of the work I do in my profession, these are the ones indicated by the competent entities, I deduce that the 0.5 kg approx. be more suitable for the purpose of laser machines. (like mine of course)

@MikeyH I hope you’re taking all of this into account too, because I’m probably not the only one learning from a topic of yours. :wink: