As these days, everything going automation, then why don’t we design an automation for controlling exhaust fan in accordance to smoke and flammable LPG gas present in environment? Here, I am going to design such system to control exhaust fan in industry. Here I will used microcontroller to take decision when to turn OFF or ON exhaust fan. The decision will be take according to the output of LPG gas sensor and the smoke sensor. Smoke sensor that II will use here is an optical sensor. Such type of sensor detect smoke by sensing the intensity of light that passing across a passes of smoke. And we will use MQ6 sensor module to sense LPG gas present in environment. To run an ac exhaust fan, we have to switch 220V ac supply using small DC voltage. For such scenario, I we use 12V DC electromagnetic relay.

1. Microcontroller atmega8
2. LPG sensor MQ6
3. Smoke sensor (IR optical sensor)
4. Transformer 12-0-12, 500ma
5. LM7805
6. Diodes
7. Resistors
8. Capacitors
9. LEDs
10. 16x2 LCD display
11. PCB
12. AC fan
13. Electromagnetic relay
14. transistors
15. Soldering iron, soldering wire, soldering paste
16. Connecting wires

1. Industrial usage
2. This can be used in offices
3. Cinema halls
4. Hospitals and schools
5. This can be use in public transportation like trains and buses
6. In kitchen

1. No used of manual switching off/on
2. Sensor based automatic controlling
3. Sensors are very cheap and easy to used and replace
4. System cost is low
5. Low power consumptions
6. Very accurate controlling because of microcontroller
7. Due to its low cost and liability, it can be used any place even in domestic area.