Gas detector response time
The response time 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 value of the device immediately changes to its determined resistance value. But in practice it always takes a while 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 is in contact with the gas to be measured. It is defined as the response time and is commonly expressed as tres.
Gas detector recovery time
Different from the response time, the recovery time represents the desorption speed of the gas sensor to the detected gas, also known as the desorption time. Again, I hope this time comes as soon as possible. The recovery time trec is defined as the time required for the element to be separated from the detection gas until the resistance value recovers to 10% of the resistance value in normal air. It is defined as the recovery time and is represented by trec.
Gas sensors and their classification
A sensor refers to a device or device that can be measured and converted into a usable output signal according to a certain law, usually composed of a sensitive element and a conversion element. Among them, the sensitive element refers to the part of the sensor that can directly feel or respond to the measured; the conversion element refers to the part of the sensor that can convert the measured sensed or responded by the sensitive element into an electrical signal suitable for transmission or measurement.
Gas sensors mainly include semiconductor sensors (resistance type and non-resistance type), insulator sensors (contact combustion type and capacitive type), electrochemical type (potentiostatic electrolysis type, galvanic battery type), as well as infrared absorption type, quartz oscillation type , fiber type, thermal conductivity type, surface acoustic wave type, gas chromatography, etc.
Zero drift
Zero drift refers to the phenomenon that when the gas detector is used for a period of time or applied to a new environment, the indication value of the detector in clean air or in an environment without such gas is greater than (positive drift) or less than zero (negative drift).
