I need some ideas on detecting fire from a distance. This is for a fire fighting bot. I've tried a pyroelectric sensor but it seems to give a digital output based on heat movement. LM35 works fine but the range is very limited. Any other ideas?
hmm... I've used a thermocouple and solid state sensor combination to detect heat at my house's home made bbq. But the response time for my system wasn't imperative.
Thermocouples can be pretty slow, but they have a linear relationship and they have a big temperature range. They are super expensive as well. Only reason I used it, was I got mine for free cause I managed to salvage some that were being thrown out at where I work.
Do you know the range of temp you will be trying to measure?
use some form of Infrared like these do :-
They are rather expensive, but pro flame detectors work in the uv rather than the ir end of the spectrum. Strange but true!
Detect a match striking more than 15ft away in a sunny room...
Will a smoke sensor be much help? It's obviously not directional.
Thanks all... Does anyone know how to build a fire detection sensor with a IR pair? Eveything else seems very expensive
There's an obvious solution here. Just process the video data and extract whatever possibly descriptive video information and associate it to various objects/ideas in its imaging database and if there's a fairly good match with "fire objects", then it's likely a fire. Couldn't get simpler. ;D
I never thought it might be as simple as that.. Infact, i'm now thinking of integrating a GSM modem with this setup so it call the fire dept to extinguish the fire rather than the bot putting it out 
That could be a problem, if your bot calls the fire dept and it's a false alarm, the fire dept may send you a big bill and in some cases it may be illegal and you may get into legal trouble
Also, if you have frequent false alarms they won't show up when there is a real fire!
Good luck 
lol! now getting back to the discussion seriously...
I've managed to detect it with IR reciever. But the range is limited say 4 inches. Now how can i improve this? i have a brianwave - How bout hacking the Sharp Ir distance sensor? i tried it without hacking and there was no change in the input. But i presume it should be possible as it is supposed to have a good range. Anyone ever tried this?
I think you want a differant IR sensor ..
IR heat wave lengh , not just you can`t see.
You could hack two consumer type / household smoke detectors to let your arduino know when they detect smoke
One with an ionization sensor and one with a photoelectric sensor, if they both go off then you almost definitely have smoke present and probably a fire
If I were building a bot like that I would use the two types of smoke detectors, a CO or other gas sensors and a camera and would SMS and send myself a picture and the sensor readings to one or more cell phones and a terrestrial email address
Have you seen http://www.windmeadow.com/node/45 ?
Andrew
@Andrew Cool Thanks for the link
I'm infact looking at using 3 sensors - smoke + temp + uv but within a very low budget. Also i think a smoke sensor and temp sensor cant do much if the fire is at a distance. unless i buy a expensive ir thermal heat sensor. i do have a couple of co2 sensors so that shouldn't be a problem.
You can get consumer type smoke detectors for $5-10 each and you should be able to hack them
A CO detector would cost about $15
A DS18S20 temp sensor costs about $4-$5