Electric 50Hz Metal LPG Gas Leakage Detector, Certification : CE Certified

Listing ID #964148

LPG Gas Leakage Detector is an ultra-sensitive LPG sensor that generates loud beeps when it senses any gas leakage. LPG Gas Leakage Detector detects vapors of liquefied petroleum gas anywhere between 200 and 10,000 ppm and drives a piezobuzzer to catch attention for immediate action. The buzzer beeps until the concentration of gas in the air decreases to a safe level. The circuit uses an MQ6 gas sensor, which is designed to sense LPG, propane, and isobutene gases. LPG gas is supplied in pressurized steel cylinders. As this gas is heavier than air, when it leaks from a cylinder it flows along floor and tends to settle in low spots such as a basement. This can cause fire or suffocation if not dealt with. Here is a circuit that detects the leakage of LPG gas and alerts the user through audio-visual indications. Fig. 1 shows the circuit of the gas leakage alarm. As per its datasheet, it has high sensitivity to propane, butane, isobutene, LPG, and natural gas. The sensor can also be used to detect combustible gases, especially methane. This circuit has been tested with LPG gas and is found to work satisfactory. Whenever there is LPG concentration of 1000 ppm (parts per million) in the area, the OUT pin of the sensor module goes high. This signal drives IC2, Hex Invertin Bufferr, Current-limiting resistors R5 and R4, respectively. LED D1 glows and the alarm sound to alert the user of gas leakage.
Circuit and working :
 Fig. 1 shows the circuit of the LPG sensor. The circuit is built around 5V voltage regulator 7805 (IC1),  gas sensor MQ6 &IC2, Hex Invertin Bufferr  and a few discrete components MQ6 is a six-pin gas sensor that can detect very small traces of LPG in the air and has a swift response time. However, it has very less sensitivity to alcohol and smoke. The sensor has output is in the form of resistance. As indicated in Fig. 1, the pins of MQ6 are H, A and B, two each on either side. H pins are for the heater with no polarity. Input pins A or B and output pins A or B can be connected either way round. The coil heater inside the sensor can be easily heated with 5V DC. If pin A is connected to 5V, DC Both A and B pins can be shorted. In short, H pins are connected to positive and negative rails, A or B pin to 5V DC, and B or A for output. The resistance value of MQ6 is different for various kinds and concentration of gases. So when using this sensor, sensitivity arrangement is very important. For accurate detection, it is necessary to calibrate the sensor for 1000 ppm of LPG concentration in the air with load resistance of about 22 kilo-ohms. Output from the sensor is connected to the base of transistor T1, which acts as a switch to trigger the alarm generator built around IC2. IC2 is Hex Invertin Bufferr. Transistor T1 controls the pin 12 of IC2.Working of the circuit is simple. When the sensor detects LPG in the air, its output becomes high and transistor T1 conducts. R2 is indicated by LED1. The circuit works off 12V DC from a battery (BATT.1) or you can use an adaptor. IC1 provides regulated 5V DC supply for the sensor and IC2.