The capacitance of the sensor changes based upon the number of water molecules in the air. Rotronic measures water activity with a thin film capacitive sensor. In each case, Rotronic instruments are designed to maintain stable temperature through the use of large thermal mass or active thermal control for the AwTherm. Rotronic provides measurement solutions for both applications. In situations where ambient temperature cannot be controlled or where you wish to test samples at temperatures away from ambient, a temperature controlled system should be used. Many standards require measurements to be made at a specific temperature. Measurements can only be made when the product sample, sample holder and measurement sensors are at stable temperatures. Water activity is sensitive to temperature. Rotronic devices have embedded Aw Quick software to perform this process quickly and repeatedly.Ĭross section HC2-AW with WP-40 Temperature control Water activity can be measured in two ways: either via a predictive model or by waiting until the water vapor pressure and the temperature have reached equilibrium within the measurement chamber. Only then is the system closed and equilibrium can be achieved. Important: the probe and sample holder must form a tight seal. Close the lid or place the measurement head on the sample holder. Place the sample cup into the sample holder.Ĥ. Important: Do not allow the sample to touch the measurement probe head! Contamination of the measurement head will falsify all subsequent measurements made with other product samples.ģ. The less air in the container, the faster the time to achieve equilibrium. Recommendation: fill up to within 3 mm of the rim if possible. Place a sample of the product to be measured into a Rotronic sample cup (14 or 40 mm deep). This includes temperature and sample preparation.Ģ. As a qualitative measurement it is important that variables are eliminated when performing measurements.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |