Application
The Water Vapour Permeability Tester is designed to evaluate the resistance of textiles and textile composites — particularly activewear fabrics — to water vapour penetration. This device is essential for measuring the breathability and comfort of clothing materials. It consists of eight containers with water reservoirs, a standard permeable fabric cover, sample holder rings, and a precision drive system. The tester operates in a conditioning room or conditioning chamber, and the wet-cup setup can be adapted for different testing methods.
What is Water Vapour Permeability of Fabric? Water vapour permeability refers to the ability of a fabric to allow water vapour to pass from one side to the other due to a difference in water vapour pressure. This property is a key indicator of a fabric’s breathability and its ability to manage moisture, making it crucial for evaluating the performance of clothing, especially sports and outdoor apparel.
Testing Method
Testing Principle:
A test specimen is sealed over the open mouth of a test dish containing water, and the entire assembly is placed in a controlled environment. After an equilibrium period to establish a water vapour pressure gradient across the sample, successive measurements of the assembled dish are taken. The rate of water vapour permeation through the fabric is then calculated based on these readings.
Water Vapour Transmission Rate Calculation The water vapour permeability index is calculated by comparing the water permeability of the tested textile against a reference fabric under standardized conditions. The water vapour permeability of the fabric is derived from the water vapour transmission rate, using appropriate unit conversions and established formulas.
Testing Method
The accuracy of water vapour permeability results depends on the selected test method and environmental conditions. This instrument is portable and simple to operate, designed for testing fabric permeability in natural environments. For controlled environmental testing, the VIT165B model offers additional capabilities.
