Moisture vapour transfer evaluation of waterproof protective jackets

In the textile industry, particularly within the protective clothing sector, moisture vapour transfer (MVTR) is a critical property that ensures the comfort and safety of workers. Waterproof protective jackets must balance the impermeability to water with the ability to allow sweat and heat to escape, thus maintaining an optimal microclimate for the wearer.

The evaluation of MVTR in waterproof protective jackets involves several key factors: the type of fabric used (e.g., breathable membranes), the design of the garment, and the testing methodologies employed. The primary objective is to determine how effectively a jacket allows moisture vapour to pass through while preventing liquid water from entering.

Testing for MVTR typically follows international standards such as ASTM F1868-20, ISO 13934, and EN ISO 17587. These standards provide precise protocols that ensure the reliability of test results across different laboratories. The tests are conducted under controlled conditions to simulate real-world scenarios, ensuring accurate assessment of a garment's performance.

For quality managers and compliance officers, understanding MVTR is crucial for meeting regulatory requirements such as those set by OSHA (Occupational Safety and Health Administration) in the United States or similar bodies worldwide. R&D engineers focus on improving fabric technologies to enhance both waterproofing and breathability. Procurement teams look at supplier data to ensure that purchased garments meet these stringent criteria.

Applied Standards
Standard	Year Published	Description
ASTM F1868-20	2020	Metric test method for determining the water vapor permeability of fabrics.
ISO 13934:2007	2007	American Society for Testing and Materials standard for measuring water vapour transmission rate (WVTR).

The testing process involves conditioning the specimen to a specific humidity level, placing it in a climate chamber with controlled temperature and relative humidity. The specimen is then exposed to a steady flow of air, and the amount of moisture vapour that passes through the fabric over time is measured.

Applied Standards

Use Cases and Application Examples
Standard	Application Example
ASTM F1868-20	MVTR testing of medical gowns in healthcare settings.
ISO 13934:2007	Evaluation of MVTR for industrial workers' protective gear.

Industry Applications

Military personnel in hot climates.
Pipeline workers exposed to harsh weather conditions.
Critical care nurses handling infectious materials.
Firefighters operating in high-risk environments.

Frequently Asked Questions

What is the difference between water repellency and moisture vapour transfer?

Water repellency refers to a fabric's ability to prevent water from penetrating, while moisture vapour transfer (MVTR) relates to how effectively it allows sweat or other moisture to pass through. Both properties are essential for protective clothing.

Why is MVTR testing important for workers in hot environments?

MVTR testing ensures that protective garments allow heat and moisture to escape, preventing overheating and potential health risks. This is particularly critical for workers in high-temperature conditions.

What role do breathable membranes play in MVTR?

Breathable membranes are key components that allow the passage of moisture vapour while maintaining water repellency. They enhance the comfort and performance of protective clothing by ensuring a suitable microclimate for the wearer.

Can you perform MVTR testing on all types of fabrics?

MVTR testing is applicable to most woven and non-woven fabrics, including those used in protective clothing. However, the type of fabric can affect the results, so it's important to choose appropriate standards.

How long does MVTR testing take?

The duration of MVTR testing depends on the number of specimens and the complexity of the test. Typically, it can range from a few hours to several days.

What are the consequences of poor MVTR performance in protective clothing?

Poor MVTR performance can lead to discomfort, increased risk of heat stress, and reduced effectiveness against environmental hazards. It can compromise the safety and comfort of workers.

What is the role of climate chambers in MVTR testing?

Climate chambers are used to control the temperature and humidity conditions under which specimens are tested. This ensures that the results accurately reflect real-world performance.

How do I choose the right standard for MVTR testing?

Choosing the appropriate standard depends on the specific requirements of your application. For instance, ASTM F1868-20 is commonly used in North America, while ISO 13934:2007 is widely recognized internationally.