Design & Implementation of an Automatic Fire Extinguishing System

Presentation on Design & Implementation of an Automatic Fire Extinguishing System

Introduction

Fire is the result of a chemical combustion reaction, typically a reaction between oxygen in the atmosphere and some sort of fuel. For the combustion reaction to take place, the fuel has to be heated to its ignition temperature.

Fire extinguishers are designed to remove at least one of these elements thus fire will die out. A fire extinguisher is absolute necessary equipment in any home or office. While there's a good chance that the extinguisher will sit on the wall for years, collecting dust, it could end up saving our property and even our life.

Objectives

1. Provide an automatic fire-extinguishing system which eliminates the disadvantages of the conventional complicated system
2. To enable easy installation or removal of the system in or from a region wherein automatic fire-extinguishing should be effected and
3. To allow a flexible arrangement of gas jetting nozzles according to the size and shape of the region.

Possible Outcome

The microcontroller based adjustable fire extinguishing system has been introduced. Experimental results showed that it provides-

1. Reliability
2. Applicable to different sizes of fire extinguisher
3. High controlling capability over them
4. It allows minimum of maintenance work
5. There is a greatly reduced of malfunction
6. The price-performance relationship is cost effective.

Experimental Design

Experimental Design

1. One fire-extinguisher placed at a desired location containing a fire-extinguishing gas under pressure and a gas jetting nozzle connected through a valve to bomb;
2. One fire sensor arranged at a desired location within said region;
3. An intermediate electric power supply source connected to automatic fire-extinguishing system being provided with a relay to receive an actuation signal from outside
4. And an electro-mechanical means for opening said valve, a gas jetting detecting switch for detecting gas pressure in bomb and a unit control circuit for controlling the actuation of fire-extinguisher

The main part of our project is the involvement of a microcontroller which is the Nucleus of the whole system. We use here PIC 16F84A microcontroller.

Signal conditioning:

The signal conditioning circuit is comprised with a led , transistor and a 741 operational amplifier. The output of the temperature sensor is low; it amplifies the output into a larger voltage signal.

The voltage is further reduced by a resistance to make it a measurable quantity for the comparator circuit. The output voltage is increased by amplifier as microcontroller sense the signal.

Programming:

The assembly language programming is shown below:

MAIN PROGRAM

main

Set up the Ports

TRISA = 255

TRISB = 0

Dim a as Byte

Wait ms 2000

main:

a = PORTA

If a > 0 Then

Wait ms 1000

a = PORTA

If a > 0 then go to alarm

End if

Go to main

alarm:

PORTB = 3

end

Interfacing is the final and most important part of the project. As there are various types of circuits introduced throughout the project it is also important to interface each circuit very carefully as each one has its own purpose.

A regulated power supply circuit which provides 5V dc for the circuit. Next the signal conditioning circuit connected with the solenoid valve is shown. Whenever there is a temperature variation, there is an output pulse results from the comparator circuit. This output is coupled to the microcontroller thereby send a signal to the Buzzer and relay. When relay operates, the solenoid valve is energized and then it is turned on.

References:

1. Operational Amplifiers and Linear Integrated circuits --- Robert F.Coughlin
2. “Microcontroller Technology: 16F84A”, prentice hall -2002.
3. Modern transducer interfacing handbook ----Daniel Sheingold
4. Fire protection ---Harris Corporation.

Submitted By Subir Das and Papan Dey