CHEMICAL SENSOR SELECTION AND OPERATION GUIDE 283 Table 7.2. Comparison of various types of gas sensors T YPE OF GAS SENSOR C ATALYTIC P ARAMETER Sensitivity Accuracy Selectivity Response time Stability Durability Maintenance Cost Suitability for portable instruments S EMICONDUCTOR e g p e g g e e e COMBUSTION T HERMAL E LECTROCHEMICAL g g g p b p g g p CONDUCTIVE I NFRARED ABSORPTION g g b g g g e e g b g b g g g g g g e e e p g e p p b e, excellent; g, good; p, poor; b, bad.