MQ7 GAS SENSOR

A GAS sensor or a GAS Detector is defined as a chemical sensor that detects/measures the concentration of gas in its vicinity. A gas sensor is a simple drive circuit that interacts with gas to measure concentration. MQ7 sensor is ideal for detection of Carbon Monoxide (CO) concentration in the air such as portable gas detectors or in other industrial applications. Carbon Monoxide is a toxic, colourless, odourless, flammable gas that is slightly less dense than air.MQ7 is a Tin oxide semiconductor sensor designed explicitly for Carbon Monoxide (CO) concentration detection. It offers very good sensitivity and a fast response time. MQ7 Gas sensor measures CO concentrations ranging from 20 to 2000 ppm providing lower conductivity in clean air.MQ7 works by detecting the CO concentration of the cycle at high and low temperatures and detecting CO at low temperatures (heated by 1.5V).

Analogue resistive output is provided by the sensor with conductivity higher along with the gas concentration rising. The resistance varies inside the sensor on the detection of carbon monoxide. Under the high temperature (heated by 5.0V), the other gases adsorbed under the low temperature are cleared. We just need to power the heater coil with 5V, add a load resistance. As a result, the sensor and load resistor in the module form a potential divider and connect the output to an ADC or a simple OPAMP comparator. Thus the CO content was detected by measuring this resistance. Therefore the lower the sensor resistance, the upper the voltage reading is going to be. MQ7 sensor designed to operate at temperatures ranging from -10 to 50°C. And consumes less than 150 mA current at 5 V.

Applications of MQ7 CO Gas Sensor:-

• Domestic gas leakage detector
• Industrial CO detector
• Portable gas detector