Inflammable gas leakage detector

Arrest Fire...!!!!!

DANGERS OF INFLAMMABLE GASES LEAKING

Some of the inflammable Gases are not toxic. But they are extremely flammable and will cause an explosion; it will also kill you by asphyxiation if it leaks into an enclosed space and deprives you of oxygen. In case of methane it only becomes poisonous when it forms part of another gas and is subject to certain circumstances. The bad news is that this happens quite often.

Don’t worry…. Here is a solution for detecting the inflammable gas leakage. The circuit uses a gas sensor which can detect the presence of LPG, Propane, Methane and Hydrogen also other combustible streams. 

MY CIRCUIT PROTOTYPE

                                                                       

CIRCUIT DIAGRAM

SEMICONDUCTOR SENSOR FOR COMBUSTIBLE GAS

Sensitive material of MQ-2 gas sensor is SnO2, which with lower conductivity in clean air. When the target combustible gas exist, the sensor’s conductivity is higher along with the gas concentration rising. These electronic circuit converts the change of conductivity to correspond output signal of gas concentration. MQ-2 gas sensor has high sensitivity to LPG, Propane and Hydrogen, also could be used to Methane and other combustible steam, it is with low cost and suitable for different application.

 

MQ2 SENSOR

CONFIGURATION

 

BASIC TEST LOOP

 The above is basic test circuit of the sensor. The sensor needs to be put 2 voltages, heater voltage (VH） and test voltage (VC). VH used to supply certified working temperature to the sensor, while VC used to detect voltage (VRL) on load resistance (RL) whom is in series with sensor. The sensor has light polarity, VC need DC power. VC and VH could use same power circuit with precondition to assure performance of sensor. In order to make the sensor with better performance, suitable RL value is needed.

            The Op-amp HT17358 is designed in a comparator mode which compares the signal received from the sensor to a threshold value. When the input increases by threshold value the output of comparator goes high which drives the transistor and thereby the LED. This invokes the oscillator circuit for generating Alarm. The circuit for oscillator is designed using the Schmitt trigger IC CD 40106. That drives the Buzzer to produce alarm.

           Also the relay is driven by the output of the transistor BC547. Which makes the external water pump to run and pump water in case of fire ignition or connects to another indicator or warning system which depends upon application of the circuit in different situations.

CIRCUIT DIAGRAM OF POWER SUPPLY

 

SUPPORTING DOCUMENTS

            Download complete document here.

Good Luck.

Regards

Sooraj Shenoy.