The MQ-9B is a CO and CH₄ gas-detection sensor from Winsen. The sensing material of the MQ-9B is SnO2, which has a low conductivity in clean air. It detects carbon monoxide (1.5V) by cycling between high and low temperatures. The sensor’s conductivity gets higher as the CO and CH₄ gas concentrations rise. The sensing range is 10-500ppm CH₄. A simple circuit makes measuring this change in conductivity and turning it into data fairly straightforward, but it does require some calibration. For easy Solderability, use our Gas Sensor Breakout Board. https://elecena.pl/product/17194926/dual-gas-co-and-ch4-detection-sensor-mq-9b 2020-09-25 https://elecena.pl/product/17194926/dual-gas-co-and-ch4-detection-sensor-mq-9b 2022-02-21