Abstract: Organizations such as the military, hazardous materialsunits, first responders and industries involved in theprocessing and manufacture of chemicals all haverequirements for specialized whole body protection forthose people in their organizations whose job it is towork with toxic chemicals on a day to day basis or inemergency situations. Currently, excluding chemicalbiological (CB) challenge scenarios, there is noroutine monitoring of the possible ingress of toxicchemicals within chemical protective suits. Underexisting national standards, swatches of the protectivesuit fabric are usually tested for chemicalbreakthrough and if they meet certain criteria, thesuit is considered to provide adequate protection tothe individual. Despite advances in protection levelresearch provided by full system protective clothingtests, inexpensive, real-time, sensitive and robustchemical monitoring systems for use both underprotective clothing and within a challenge environment,remains a technologically deficient area. This paperpresents the results of a preliminary assessment of thefeasibility of miniature detectors for monitoringreal-time volatile organic chemical (VOC) challengesunder chemical protective clothing and in closedenvironments where such suits are used. Nine gassensors of n-type semiconductor design (FigaroEngineering Inc) were assessed for their response to adichloromethane concentration of 560 ppm at atemperature of 23 degrees Celsius and relative humidityof 20%. Absolute voltage output, speed of response todichloromethane exposure, and time required to returnto zero, were considered. The top ranked sensor wasfurther evaluated for its calibration response to arange of dichloromethane concentrations up to 560 ppm.Variables that were considered include effect oftemperature and relative humidity, hysteresis andrepeatability. Increasing RH causes an increase in thezero output of the sensor with an approximate linearrelationship. The sensor response was characterized byminimal hysteresis, indicating that calibration valuesover the short term are very stable. Calibrationresponses measured on different days were in excellentagreement. !5
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