The FHA-Series humidity sensors work with ALMEMO® series indicators and data loggers to provide accurate measurement of relative humidity, temperature, dew point, mixture ratio, enthalpy, and partial vapor pressure. The capacitance sensor used in the FHA-series contains a glass substrate with a humidity-sensitive polymer layer between two metal electrodes. The absorption of water in the thin film changes with relative humidity, and therefore changes the capacitance between the two electrodes. The measuring signal is directly proportional to the relative humidity and is independent of changes in atmospheric pressure. Standard sensor cable length is 5 feet.