Water Activity Probes

Rotronic Measurement Solutions

Water activity – a measure for the energy status of the water in a system’ specifies the relationship between the water vapour pressure of a product and the saturation pressure of pure water at the same temperature. It is stated in ‘aw’ in the range 0…1 aw and is an important indicator for product quality in the industrial production of, for example, plastics. The determination of water activity is also very important in the food, tobacco, pharmaceutical and cosmetics industries. Water activity should not be confused with the water content – the ‘chemically bound’ water – of a product.