Labthink Testing Instruments has researched and developed the third-generation Perme W3/060 water vapour transmission test system.
This is a gravimetric WVTR tester, which is said to replace the manual cup method of performing water vapour transmission rate tests according to gravimetric principles (ASTM E96 and ISO 2528).
Before, according to the gravimetric standards, operators would buy analytical balance, a constant humidity and temperature chamber, WVTR dishes and other components.
The operators would put the dishes (with samples) in and out of the chamber frequently to weigh the changes.
During the new procedure, while the dish is taken out of the chamber to the room, the water vapour in the air will coagulate onto the out-surface of the dish; the operator will rub it off and then balance dish.
During the testing, the dish goes to and fro between the different conditions.
