| 摘要 |
<p>A system of using a gas concentration detecting device (14) that conducts electricity increasingly for progressive concentrations of a gas being detected. A heating voltage cycle (16) is applied to a gas sensor element (14) to catalyse impurities on the surface and to cool down the sensor element (14) to a temperature at or above which the gas catalyzes. A sum of measured concentration levels is taken to gauge gas exposure over a time period. During a self-calibration routine, the sensor element output at each known concentration level is stored in nonvolatile memory (12). The stored calibration data is compared to values measured during normal operation to accurately detect gas concentration levels. Audible alarms (22) sound when the sum of measured concentration levels exceeds a hazardous level and a microprocessor (10) controls a three color LED (20) to emit a color pattern indicative of the concentration level of the gas.</p> |
