Short description
The inserted sample divides the permeation cell into an upper and a lower part. In the upper part of the permeation cell, a constant water vapor pressure (relative humidity) is set via saturated salt or via defined sulfuric acid solutions. The carrier gas (nitrogen 3.5) is pre-dried in the WDDG and then fed into the lower part of the permeation cell. The carrier gas stream takes the water vapor permeated by the sample and passes it through a Keidel electrolysis cell. There, the amount of water vapor is quantitatively recorded. The electronics register the current flow and display the water vapor permeability directly in the corresponding unit (grams of water per square meter of sample area and day) via a 7-segment display.
The duration of a test depends on the water vapor permeability of the inserted specimen. At the beginning of the test, the displayed value increases continuously. You can follow this increase via a compensation recorder and stop the measurement when the final measured value is reached (no further increase).
The temperature of the sample can be adjusted between -25°C and 80°C via an external bath thermostat.
