Fire detection and CO2 release inside server closet

Hello

We have been renovating and I managed to snatch a closed for our network devices. These include a run-over MacBook Pro (still working perfectly, just without screen), a NAS, a four external harddrives, a 24port Switch and probably some more stuff with the time.

This may get hot, so I have bought two 200mm fans to blow air inside (from the bottom) and suck it out (from the top). Other than that, since the whole closed and our house in general (its over 120yo) is made of wood, I want to prevent a fire to happen.

My idea is the following. Having an Ethernet Arduino coupled with rechargeable battery (as backup power source), a fixed tone siren, a smoke/fire sensor and a mechanical seal valve attached to a CO2 tank.

As soon as smoke/fire is detected: - the Arduino tries to send out a message/mail over Ethernet. (may not work if the switch was the fire cause, but its a Netgear GS724T, so this shouldn't happen) - Turn on the siren for a few seconds (depending on the time of day, the one from Seeedstudio is extremely loud) - Cut the power to the fans - Open the valve of the CO2 tank and flood the closet with CO2.

I have two remaining open questions: - Is there a valve that can be controlled with an Arduino? Like an solenoid gas valve but for higher pressure (about 800psi). - The smoke sensor MQ2, can it also be used to detect fire or is this more used to detect gases like propane etc?

A few questions:

1) Do you have homeowner's insurance? 2) As part of these renovations, did they include removal/upgrade of the electrical service (if not, you want to do that -first-)? 3) Instead of a sensor, why not hook into a smoke detector (aka - something designed for the job)? 4) Regarding the valve: I'm sure such a thing exists, if you're willing to pay for it...

All in all, provided your electrical service is up to spec, and you haven't did any modifications to the hardware in a way that would compromise their cases to the point that they wouldn't fail "gracefully" (that macbook is suspect, of course, but you have to be the ultimate judge of its safety), you shouldn't have any problems with a fire, even if something failed. In all the years I've been using, working, and such computers, etc - I have never seen one catch fire; the closest I've ever seen was a motherboard that shorted out against the chassis; in that case, there was a minor bit of smoke and the power supply shut down immediately.

Any heat generated by the components isn't going to be anywhere near enough to catch anything on fire, even if you didn't have the fans (but the fans are a good idea). I personally think you may be overthinking this out of a sense of paranoia about a possible fire. I won't say it is impossible, just highly improbable (unless you overload your circuits, and your electrical service in total is somewhat questionable; in a house that old, it should be inspected to see if it is completely up to code for today's needs and practices).

What you're adding is causing another fire risk. If you need a fire extinguisher system I suggest you get a proper commercial one. For example you can get a firetrace system that will release CO2 or AFFF if the temperature gets hot enough. But better to design your server closet so that the risk of fire is negligibly small in the first place. If you ever do actually get a fire, letting off a CO2 cylinder in there is not certain to put it out and you still run the risk of the house going up - getting an email to tell you is small comfort.

If you have any components that are at risk of overheating then store them on non-flammable shelves without anything flammable above or below them. Fit a smoke alarm (and service it regularly). Check the temperature in normal use and don't leave equipment locked away if it's getting hot.