| SB- 5: CO methane sensor Using both high and low sensor temperature in the periodic temperature change method (same operation method as the SB-500), it is possble to detect both CO and methane selectively with sngle element. Fig shows a typical temperature dependency characteristic of the SB- 5. When the sensor is operated with high/low periodic operation (Fig 10), sensor sgnal changes according to the temperature dependency characteristics. By detecting the sensor signal at sufficient timings (at a high temperature for methane and at a low temperature for CO), selective detection of both methane and CO has been achieved. Figs 11 and 12 show the senstivity characteristics of the SB- 5, at high temperature and at low temperature signals respectively. Using this concept, development of CO or methane, or both CO and methane detectors can be developed using the same sensor and circuit. |