The response time of the multi gas detector represents the response speed of the gas sensor to the detected gas. In principle, the faster the response, the better, that is, as soon as the gas sensor contacts the measured gas or the gas concentration changes, the resistance of the device will change to its determined resistance. But it actually takes some time to reach a stable value. The response time tres is defined as the time required for the resistance to reach 90% of the stable resistance value at this concentration after the element contacts the measured gas. It is defined as the response time and is often expressed as tres.