Water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance. It is a measure of the permeability for vapor barriers.

Here we introduce one important method to test it- The Gravimetric Method. It included two methods: The desiccant method(dry cup method) and the water method (wet cup method). These two tests are similar in setup but the service conditions are different and the results are not comparable. Here we will talk about the dry method in details.

1. Principle

In the Desiccant Method the test sample is sealed to the open mouth of a test dish containing a desiccant, and the assembly placed in a controlled atmosphere. By weighing we can get the rate of water vapor movement through the sample into the desiccant.

2. Standard

ASTM E96/E96M-2016, ASTM D1653-2013, GB/T 1037-1988, GB/T 16928-1997, TAPPI T464， ISO 2528-1995，DIN53122-1，JIS Z0208-1976， YBB00092003-2015

At present, ASTM E96 is the most comprehensive standard on cup method being compiled up. W501-W533 water vapor permeability analyzer of GBPI strictly conforms this standard.

3. Applied to:

1) Plastic film, composite film, aluminum foil, aluminized film,etc;

2) Sheet, panel, rubber, ceramics,etc;

3) Packaging containers, such as:glass, bottle, cans, boxes, etc;

4) Expanding application: solar panel, LCD film, medical patch, etc.

GBPI supply different type water vapour permeability tester with advance technology,below introduce one of our hot sellling WVTR Tester W201 Competitive advantage

Advanced technology

Temperature control: International advanced electromagnetic technology, program controlled, auto heating and cooling; and no need of external accessories. Precision: 0.1℃.

Humidity control: Dual gas flow method(dry gas and humid gas), high precision (1%RH) and stable flow.

Carrying cutting-edge ARM controlling system, can run independently without computer

High efficiency

With three different test modes of high, medium and lower barriers, can test films with different barrier property.

Measurement precise up to 0.001 g/m2•24h, can test high barrier materials, such as aluminum foil.

By adding adaptive accessory, can test water vapor transmission of various containers such as bag, bottle, can and bowl.