A GAS sensor or a GAS Detector 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. MQ-9 Carbon Monoxide, Methane and LPG Gas Sensor Module is ideal for detection of Carbon Monoxide and Methane Gas in the air such as portable gas detectors or in other industrial applications. Carbon Monoxide is a toxic, colorless, odorless, flammable gas that is slightly less dense than air.MQ9 is a Tin oxide semiconductor sensor designed explicitly for Carbon Monoxide (CO) concentration detection. It offers very good sensitivity and a fast response time. MQ9 Gas sensor measures CO concentrations providing lower conductivity in clean air.MQ9 works by detecting the CO concentration of cycle high and low temperature, and detect CO at low temperature (heated by 1.5V).
An analog resistive output 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), it detects Methane, Propane, combustible gas, etc, and 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 detected by measuring this resistance. Therefore the lower the sensor resistance, the upper the voltage reading is going to be. MQ9 sensor designed to operate at temperatures ranging from -10 to 50°C. And consumes less than 150 mA current at 5 V.
Applications of MQ9 CO Gas Sensor:
- Domestic gas leakage detector
- Industrial CO detector
- Portable gas detector