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Home / Blog / What is water vapor transmission rate (WVTR) and the test method ?
What is water vapor transmission rate (WVTR) and the test method ? August 26,2020.

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


There are many industries where moisture control is critical. Moisture sensitive foods and pharmaceuticals are put in packaging with controlled MVTR to achieve the required quality, safety, and shelf life.

water vapor transmission rate WVTR MVTR

In clothing, MVTR as a measure of breathability has contributed to greater comfort for wearers of clothing for outdoor activity. The building materials industry also manages the moisture barrier properties in architectural components to ensure the correct moisture levels in the internal spaces of buildings. Optoelectronic devices based on organic material, generally named OLEDs, need an encapsulation with low values of WVTR to guarantee same performances over the device lifetime.


Water vapor transmission rate WVTR




At present, there are mainly 3 methods to analyze WVTR which are Infrared Sensor Method, Electrolytic Sensor Method and gravimetric method.


Method

Infrared Sensor Method

Electrolytic Sensor Method

Gravimetric Method

Standards

ASTM F1249

ISO 15106-2

GB/T26253

TAPPI T557

JIS K7129

ASTM E398-2013

BS EN ISO 15106-3-2005

YBB 00092003-2015

GB/T 21529-2008

DIN 53122-2

ASTM E96

ASTM D1653

ISO 2528

JIS Z0208

TAPPI T464

DIN53122-1

Test Principle

The principle of infrared detector is adopted. Fix the pre-processed sample in the middle of the test cavity. The sample divides the test cavity into upper and lower chambers. Relatively stable humidity flows in the upper cavity of the film, and dry gas flows in the lower cavity of the film; Under the action, water molecules diffuse through the sample into the dry gas on the other side, and are carried by the flowing gas to the infrared detector. The water vapor concentration measured by the detector is analyzed to calculate the water vapor transmission.

Using electrolytic sensor principle. Fix the pre-processed sample in the middle of the test chamber. The sample divides the test chamber into upper and lower chambers. Relatively stable humidity flows in the upper chamber of the film, and dry gas flows in the lower chamber of the film; Under the action, water molecules diffuse through the sample into the dry gas on the other side, and are carried by the flowing gas to the electrolysis sensor. The water vapor concentration measured by the sensor is analyzed to calculate the water vapor transmission.

The test specimen is mounted in the test dish which contains water or desiccant inside. The test dish is placed in the test chamber with stable temperature, humidity and air flow. The water vapor permeates through the specimen and into the dry side. By measuring the weight changes of the test dish periodically, water vapor transmission rate and other parameters can be obtained.

GBPI WVTR Instrument

WVTR Tester W405

water vapor transmission rate

WVTR Tester W203

Moisture vapor transmission rate

WVTR Tester W303

water vapor transmission rate

Test range

0.005~500 g/m2·24h(film and sheet)

0.001~100g/(m2 ・ 24h)

0.01~10000 g/ m2 · 24h

Resolution ratio

0.001 g/m2·24h(film and sheet)

0.001g/(m2 ・ 24h)(film and sheet)

0.001 g/ m2 · 24h


We can help you select or customize the proper unit for your test requirements.

For more infomation, please contact:
Email: info@gbtest.cn
Skype: janice9695
Tel: +8613539758284
whatsapp: +86 13539758284

water vapor transmission rate-GBPI.pdf:Download
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