I would say that your best bet is to go to a fire protection contractor and get their expertise, but I can give you a quick overview.
Your system is comprised of a sensor, your pipes, and the type of sprinkler head you choose.
Sensor: at what stage of the fire do you want to douse it? In order from early to later detection: Incipient phase uses an ionizing detector. The smoldering phase, where smoke particles are visible, uses a photoelectric detector. The flame phase uses a UV or IR radiation detector. The heat phase uses a fusible sprinkler head that is set to activate the heads at a certain temperature above the ambient room temp. My house has a sprinkler system that uses fusible heads.
The pipes can either be a wet or a dry system. Basically, wet means you have water in the pipes, ready to go on signal. Good: quick when you need it. Bad, need a propylene glycol mix if you are in a zone that freezes (my garage, for instance). A dry system has empty pipes, which can either get filed by the fire department running water into the system or by a preaction system, where the water is stored in a tank, the detector sends a signal that the pipes should fill, then the individual sprinkler heads open up when needed in that section.
The sprinkler heads can be crafted to your situation. Like I mentioned before, you could have the fusible head run the show. You can also have a mist head, which will leave less water damage. A deluge system has open heads on dry pipes, which can flood the area if needed.
Now this all presupposes that water is what you want. I don't know what you are burning, but there are four classes of fires to fight: A is ordinary combustibles, B is flammable liquids and gasses, C is electrical and D is metals. For a burning liquid fire, for example, you certainly don't want water, you want those heads to release a foam to effectively smother the fire. CO2 would cool the flame, but that would cause problems if you were stuck in there, too.
Whatever has the potential to burn requires the triangle of oxygen, heat, and fuel. Remove one of those, and you have no more fire.
For your problem of the kiln, I guess I am having trouble picturing it. It seems like a lot of money and trouble to install a fire suppression system if it is a small pottery kiln. For a more industrial kiln, I don't know...Perhaps talk to the kiln's manufacturer and ask what their clients typically do for fire protection. I don't want to lead you on the path of something expensive and unnecessary. Good luck!
Best Answer
[Nations vary, so these are US fire extinguisher type codes - A = wood and paper, B = grease and oil, C = Electrical]
It's always acceptable, it's just not the best choice - but if it's the only one you have and you can safely apply it, worth a shot - then if still safe, then go find a bucket and throw water at it (if its not got grease or electrical issues). Better yet, if you know the difference and can explain the difference to others in the house, pick up a nice type A (or AC these days - weird but available) water extinguisher and set it beside the BC extinguisher if the location is non-freezing - or pick up a bigger ABC powder unit for freezing locations or users that may just grab whatever there is without paying attention to the type of fire.
Generally "BC only" extinguishers are too small to do much good for an A fire - one difference in ABC dry powder types is that they are bigger, and have an A rating that's about a tenth of their BC rating. [Edit: they evidently do use a different dry chemical type, as well] Even a CO2 BC will knock back an A fire, but it will come right back when the CO2 runs out and oxygen returns to reignite the embers - still, it will have been knocked back.
ABC chemical and BC chemical
Looking at my current ABC dry chemical unit, it's rated 3 A, 40 BC (the number is larger for some arcane "size of fire that can be extinguished" system) so that one is not even a tenth of the BC rating. Thus, a small "kitchen" extinguisher that's 5 or 10 BC won't even rate a 1 A with that chemistry.
Remember in no case should you stick around to fight the fire if doing so is not clearly still safe - fire extinguishers are good for putting out small fires before they become big ones - big ones you leave and let the fire department put it out, remembering that being alive is worth more than all the stuff that's burning.