Comparison of wetness sensing methods during atmospheric exposure

Abstract

This paper reports on the results of a set of experiments that examine TOW determinations using three indirect sensing methods during short-term outdoor and laboratory atmospheric exposure. The objective of the study was to better elucidate the accuracy and comparability of TOW determination methods. Replicate sets of indirect resistance and galvanic multi-electrode sensors along with inert gold surfaces were exposed to an outdoor coastal marine environment followed by laboratory humidity chamber exposure. Output was compared between sensor types and to optical micrographs of the sensor and inert surfaces during exposure. Cumulative TOW estimates varied widely between the different methods. Results indicate that output of the resistance-type sensors was dependent on aerosol loading and surface wettability. Additionally, sensor output and optical microscopy indicated that the outdoor exposed sensors remained wet down to at least 13% RH, far below the ISO 9223 TOW threshold. Show more