Water Activity Measurements with A Capacitance Manometer
John A. Troller · Journal of Food Science · 1983
ABSTRACT The design, use and performance of a capacitance manometer for the measurement of water activity (a w ) are evaluated. The device consists of a sensitive capacitance sensor for measuring the vapor pressure of a sample. This value is then divided by a known value for the vapor pressure of pure water at a specific temperature to obtain a w . Precision and accuracy of this Instrument are determined and compared to a conventional electric hygrometer. These parameters are similar to the hygrometer; however, the principal advantages of the capacitance manometer may occur in circumstances in which direct measurements of a w are required and situations in which contamination of hygrometric sensors could occur.