Project5: smoke and fire (flame) alarm detection arduino.
Fire in your home or workplace is a disaster for everyone so being informed before you could have some serious injuries is very important. The goal for this project was to make a fire detection system who's even been able to detect a fire in second's in places where the risk of fire is very high like boiler rooms, electric cabinets, oil and fuel storage, ect......... This project could only be used in a home environment because of laws and certifications but is a very good supplement of the battery suplied single smoke detectors you probably have already.
For the smoke detection we use conventional optical smoke sensors who works from 10-24Volts and who are connected in a loop with a supervision resistor of 2K7. The system is made for a loop till 15 sensors with the possibility to have 5 detectors simultaneously in alarm,, after that the protection fuse will blown, but when you have 5 detectors in alarm you have already a serious problem. The arduino detect also if the loop is ok so when there is one detector disconnected from his socket you will hear every 10 sec a short beep. The system works with a normal powersupply ,of 18-24vdc but is expandable with accu's and a accu charger if the normal grid fails. You can connect the alarm output to a sirene, 433mhz transmitter to transmit a alarm wireless and so on, use your imagination and you can expand it like you want.
For the detection of a flame we use a IR phototransistor with a diffuser for daylight like the omron sfh314. After a few tests we seen that sunlight was a problem so to exclude this problem a flame will only be detected when it flickers , that's 99% the case when a flame burns, it is never steady except a small candle light , and the infrared signal is also not steady so to detect this we use this behavior to measure the differences in the IR signal , amplified it and with some comparators and a timer function each flickering of the flame will react as a 2 sec alarm., that's more than enough time for the arduino to react and give the alarm. The detector sees the starting of a small lighter flame within 1.5meter from the sensor and reacts instantly in a alarm. Bigger flames will be detected on a larger distance. The circuit is made to connect several fire detectors on the same input through a open collector output. This detector can only detect yellow fires from, normal materials, oil, fuel ect... It will not detect bleu flames like gas, hydrogen and other special fuels therefore you need also a UV detector who is not in this scope of the project, allmost all of the fire's in a home environment burn filthy yellow/red who radiates a lot of Infra red signals.