Improving Accuracy and Precision of Water Activity Measurements with a Water Vapor Pressure Manometer

Accuracy and precision of water activity measurements using vapor pressure manometry can be significantly improved by taking into account the volume change that occurs when water is eliminated from the air‐water vapor mixture. It is shown that this can be done either by designing the apparatus according to a design constraint equation presented in this paper or by using a new equation to calculate water activity correcting for volume change.