Some gases are both flammable and toxic

For example, carbon monoxide (CO) has a toxic and lethal concentration far below its explosion limit. When the concentration in the air reaches 500ppm, it is already dangerous to human breathing but has not yet reached the explosion limit. Therefore, when monitoring CO, it is always monitored. toxicity and does not fall within the scope of flammable gas monitoring.

Similar gases include ammonia (NH3), hydrogen sulfide (H2S), etc.

Volatile organic compounds (VOC) are generally carbon, hydrogen and oxygen compounds that can burn. In the same way, these compounds are too toxic and cannot even be measured as ordinary toxic gases with electrochemical sensors. They can only be monitored with PID sensors.