Flammable Gas Sensor MQ9 (Analog/Digital)

From the shop's description

Product Description MQ-9 gas sensor has high sensitity to Carbon Monoxide, Methane and LPG. The sensor could be used to detect different gases contains CO and combustible gases, it is with low cost and suitable for different application. The sensitivity of the sensor can be adjusted by using the potentiometer. Features Support both the output digital value and the output analog value. Good sensitivity to CO/Combustible Gas. High sensitivity to Methane, Propane, and CO. Long life and low cost Pin Connection: GND: Ground, Dout: digital output, Aout: analog output Vcc: 5V Simple drive circuit. How to Calibrate & Use MQ9 Gas Sensor w/ Arduino MQ9 Gas Sensor datasheet