Air quality sensor
An air quality sensor is a compact gas sensor for monitoring air with the task of detecting and measuring pollutants. An air quality sensor is often used indoors or in motor vehicles. Depending on the application, it can be installed in the flow to be monitored in ventilation systems or set up free-standing in rooms.
The pollutants can occur in the form of oxidizable or reducible gases z. B. nitrogen oxides , carbon monoxide , hydrocarbons or as vapors from benzene or gasoline . In the area of indoor air, volatile organic substances are particularly important.
Measuring principle and functionality
Air quality sensors are metal oxide semiconductor gas sensors (MOX) which change their electrical conductivity under the influence of gas. From this change in electrical resistance, it is possible to infer the presence and indirectly the concentration of a pollutant.
The sensor element is heated to a temperature in the range 300-400 ° C. The organic substances are oxidized to CO 2 and water on the surface , increasing the conductivity. In the case of reducible gases such as nitrogen oxides, the conductivity is reduced.
When used in the motor vehicle sector, fuel vapors are also detected among other pollutants. If a certain threshold value is exceeded, a recirculation switch is activated automatically . If the quality of the indoor air threatens to drop below that of the fresh air after a long period of time , air from outside is increasingly used. The automatic control takes over the air conditioning in the vehicle .
In interior rooms, the sensor can either be used to regulate a ventilation system or display the current air quality via optical displays, acoustic signals and the like, so that the residents can ventilate the rooms themselves if necessary.
Design and manufacturer
Air quality sensors are generally compact components with an electrical connector. You are u. a. available in different versions from Paragon and AMS . There are now numerous end-user products that have an integrated air quality sensor for the indoor air.
Web links
- Technical article Air quality sensor for needs-based ventilation of interiors, AppliedSensor (PDF; 195 kB)
Individual evidence
- ↑ S. Boller: Handbook of measurement and automation technology in automobiles: vehicle electronics, vehicle mechatronics . Ed .: Hans-Jürgen Gevatter, Ulrich Grünhaupt. Springer-Verlag, 2006, ISBN 3-540-29980-7 , 7th gas sensor technology, p. 81 ( online [accessed April 28, 2016]).