Detecting Gas Leaks with MQ-2

The MQ-2 is a semiconductor gas sensor sensitive to LPG, methane, hydrogen, and smoke. Here's an honest assessment of its capabilities and limitations for a DIY safety device.

The sensor requires a 24-48 hour burn-in period before readings stabilize. The output is a non-linear analog voltage that correlates to gas concentration but requires calibration in clean air for the Rs/Ro baseline. Temperature and humidity significantly affect readings — the sensitivity drops at low humidity and high temperatures.

For a safety alarm (not a concentration meter), the MQ-2 is adequate: set a threshold in clean air plus 20%, trigger an alarm above it. For accurate concentration measurement, a NDIR sensor (MQ-135 for CO2, Alphasense for industrial gases) is far more reliable. Never use a DIY sensor as the sole safety device for LPG or natural gas — use a certified detector in parallel.