PRELIMINARY EVALUATION OF AN ACTIVE END-OF-SERVICE-LIFE INDICATOR FORORGANIC VAPOR CARTRIDGE RESPIRATORS

Data are presented on a microwatt chemiresistor microsensor for use wi th negative-pressure organic vapor respirators. This sensor would oper ate at or within a sorbent bed and detect parts per million levels of chemical vapors and/or gases as a function of sensor resistance. Senso rs were evaluated against four challenge concentrations of ethyl aceta te (750 ppm, 1000 ppm, 1500 ppm, and 2000 ppm). Direct comparison of b reakthrough times and curves for the chemiresistor microsensor and a s tandard infrared (IR) detector system were made. The chemiresistor sen sor responses were found to correlate well with the IR system. The eva luation showed that although the chemiresistor sensors were not as sen sitive as the IR detectors, they could be used if located inside the c harcoal bed. Thus, these sensors could function as organic-vapor detec tors and could be used in cartridge applications. However, further imp rovements in stability and sensitivity of these chemiresistor sensors is necessary.