Sensors for CO-indoor Monitoring

CO-sensors and sensor systems for indoor use should meet several specifications regarding their sensitivity, cross-sensitivity and stability. A reasonable approach for the development of CO indoor alarm or monitoring systems is to comply with BS 

CO-concentration Alarm not earlier than Alarm not later than 

7860 or EN 50291 or equivalent standards. The hazardousness of CO is a function of exposure time and concentration. Therefore alarm systems should give a delayed optical and acoustical alarm scaled according to the indoor CO-concentra-tion. Details are listed in Tab. 5.8. 

EN 50291 also determines the limits of cross-sensitivities to H2, C02, NO, S02, ethanol and hexamethyldisiloxane. The latter is known to cause poisoning of pel-listors and metal oxide sensors. 

Suitable methods for CO indoor monitoring are based on using metal oxide sensors (chapter 5.3.2.1), electrochemical cells (chapters 5.3.2.3 and 5.3.2.4), pellis-tors (chapter 53.2.2) and optical methods (chapter 5.3.2.5). An overview of CO-sensors and systems is given in Tab. 5.9. 

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