Fire safety  

RE: Fire safety

Most use a Rpi3 or 4 to run OctoPrint host software that enables live cam views via the web.  As for securing a fireproof box with extinguisher, there are extinguishers with switches that open when the extinguisher triggers from heat.  This can be used to open the 24v using a simple low voltage relay disconnect circuit -- avoiding any mucking with mains wiring.  You'll probably want an inert gas extinguisher, rather than one of the solids based units which will destroy the printer.  There are nic e small marine units that are designed for engine cabinets and fight fuels like diesel (and burning ABS).

RE: Fire safety

The aerosol generator shouldn't destroy the printer. Do you have link to the marine unit?

I don't mind mucking with the mains. I wanted to cut the mains in case the power source is the problem. No mains, no power to feed the fire.

RE: Fire safety

What about those fireballs? I saw pictures where people installed those into enclosures, or right above. Advantage is it seems to be fairly effective against fire. Disadvantage is it seems to be fairly effective against fire 😀  meaning there has to be flame for igniting cord and causing ball to explode. It would be better to prevent fire in first place, take action while it's smoking.

RE: Fire safety

I haven't gotten around to it (or running unattended prints) yet, but I purchased a mains smoke detector with interconnect for that purpose; it will output a signal on a third wire if there's an alarm condition, which I plan to use together with something mechanical and simple, like a bistable relay or emergency shutoff to kill power to the system. 

RE: Fire safety

@crawlerin

Those were my first idea about what to use.

1. They are not cheap

2. The contents makes a mess

3. They explode

4. Propably demages the printer

4. The contents seems to be toxic

All in all, I would say it's better then nothing, but still.

RE: Fire safety

I put my printer in a cabinet with one of these things over it:

I don't mind it getting ruined in the unlikely event of a fire, better that than burning my house down.

Of course, I don't know what it takes to pop one of these things. Presumably it's designed for a flaming grease fire. Maybe a smouldering electrical fire could spread beyond the cabinet by the time the Firestop goes off.

RE: Fire safety

Posted by: @masto

I put my printer in a cabinet with one of these things over it:

I don't mind it getting ruined in the unlikely event of a fire, better that than burning my house down.

Of course, I don't know what it takes to pop one of these things. Presumably it's designed for a flaming grease fire. Maybe a smouldering electrical fire could spread beyond the cabinet by the time the Firestop goes off.

I recall looking at those a while back. Apparently the track record for them even with their intended use is questionable. Not sure I'd trust it for something like a printer where the use case is even more marginal.

RE: Fire safety

@hawwwran

I finally got around to reading some of the literature for the fire suppressant sticks you posted a link to.  They claim an aerosol but they are really just another way of distributing a powdered chemical suppressant (2. In the presence of fire, the potassium carbonate (K2CO3) which is the active agent in the condensed aerosol medium undergoes thermal dissociation, forming unstable potassium free radicals (K*) which act as chemical chain reaction inhibitors).  

Chemical extinguishers with chemical mixes tend to make a nasty mess when the go off.  The chemicals tend to bake onto hot surfaces and become what you might consider a ceramic coating - one that is extremely difficult to remove.

Marine extinguishers generally use a form of gas, usually a hydrofluoro-something - though most no longer use halon, instead they use HFC-227, which is better on the environment (causes no ozone depletion).  https://www.fireboy-xintex.com/cg2-fire-extinguisher/

RE: Fire safety

@tim-m30

Well, it's aerosol, not gas. I've seen a video where they show the resulting powdery coat. They smeared it off a glass with finger. Didn't seemed like a big issue. Still nasty, but better then explosion released powder. I will look more closely on the gas supressant. Looks really good. One of the function the aerosol has is that it's safe for human to be in. If that's the same for the gas and if they have electronically triggered can, then it looks really good.

RE: Fire safety

The gas extinguishers work to an extent by displacing oxygen ... but mainly use the chemical route to reduce flames.  Human safe - but in my computer training was told you only have a short time to get out of a room filling with Halon. It won't kill you, but can render you unconscious if the saturation is too high; all said though, do you want to be in a room full of smoke and combustion byproducts?  So when the alarm sounds, head for the exits. 

But for small enclosures that shouldn't be an issue.  If it were, I'd be just as concerned about powdered aerosol inhalation.  

The surfaces I'd had to deal with when the chemical extinguisher was used were hot, and the chemical dust was baked on.  Cool surfaces did clean up fairly well: but hot surfaces: not so much.  Almost like the chemicals etched onto the ceramic and glass surfaces.  The SO was cooking and had a fire in an oven running at 200C, oil spilled out and flashed on the heating elements.  Leaving the door closed to smother the fire never occurred to her and she grabbed the extinguisher and pulled the trigger.  Dust everywhere.  We never did get the inside of the oven clean.

RE: Fire safety

@tim-m30

Haha, the oven story sounds too real 😀

The aerosol does not displace oxygen. That's one of the safety features. I hoped it ituld be cleaned off easily. If it sticks to hot surfaces... All hot surfaces in my box are ruined anyway in cas case of fire. I was more concerned of false positive trigger damages or small fire trigger damages. This seems to work pretty well. I did not find any gas canister replacement for what I have, but in case it exists and is cost effective in conparsion, it sounds good. 

RE: Fire safety

TBH, I have to agree to some extent with that; if the fire's severe enough to warrant triggering fire suppression, salvageability of the printer be damned. $750 for a new printer is cheaper than a new house or your life because your suppression was inadequate.