Design and construction of an automatic low-cost fire alarm.

Abstract

An automatic fire alarm system is designed to detect the unwanted presence of fire by monitoring the radiations from any burning material at any given temperature. Fire is a reaction in which fuel molecules become oxidized. By oxidation, we mean the burning of flammable materials in presence of oxygen. Fire is the visible effect of the process of combustion. The circuit consists of an IR Sensor as the major component connected to resistors, led bulb and battery source. IR flame detector consists of ultraviolet (UV) and infrared (IR) sensors that are joined together in a single apparatus. UV sensors work by detecting the UV radiation emitted by the flame. The main radiant emission band for hydrocarbon fueled fires ranges between 4.3 and 4.4 microns, it is an infrared emission that the IR sensors can detect with ease. The energy released by the burning of the CO2 at a resonance frequency of 4.3 microns enables the IR Sensor to detect the emission. Most fire detection technology focuses on detecting heat, smoke (particle matter) or flame (light) the three major characteristics of fire. All of these characteristics also have benign sources other than fire, such as heat from steam pipes, particle matter from aerosols, and light from the sun.