Humimeter RH2 Water Activity Meter (aw)
The water activity of products, especially food products, indicates the amount of unbound water in a material. This quality factor, also called aw value, depends on the water vapor pressure in the material, the current temperature and the vapor pressure of the surrounding water. The humimeter RH2 enables the quick and easy determination of water activities. Thanks to the large sample volume, even larger sample quantities can be measured in a short time. The simple operation ensures cost savings in the process and error-free determination of water activity. Simply place the material in the measuring camera and close it. After an appropriate conditioning time, the water activity can be read directly on the display of the meter. The time required to reach moisture equilibrium depends heavily on the material to be measured, as well as on the temperature. For example, hygroscopic materials such as cornflakes assimilate in a considerably shorter time than whole corn kernels. In this context it is important that the sample has the same temperature as the measuring chamber – a high temperature difference prolongs the conditioning time. The material-dependent conditioning time is a physical phenomenon and cannot be shortened artificially.
Typically the conditioning time varies from 5 minutes to about an hour.
Moisture equilibrium is reached when the displayed measured value no longer changes over a period of several minutes (e.g. 10 minutes, changes less than 0.002 aw).
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