Testing Principles and Applications of Waterproof, Moisture Permeability and Air Permeability Testing of Textiles

The Testing Principle of Textile Waterproof Performance Test

The testing principles of textile waterproof performance testing mainly include hydrostatic pressure method and water immersion method. The hydrostatic method assesses the water resistance of textiles by applying hydrostatic pressure to the textile surface and observing the penetration of water on the textile surface. Specific steps include:

Sample Preparation: Prepare the textile sample to standard size, ensuring that the sample surface is flat and free from damage.
Installation of the test device: The sample is placed in the test device, ensuring good contact between the sample and the test device.
Hydrostatic Pressure Application: Gradually increase the hydrostatic pressure by means of a hydrostatic pressure gauge until the water begins to penetrate the textile surface.
Data recording: The value of the applied hydrostatic pressure and the time at which water penetration of the sample occurs are recorded.
Analysis of results: Evaluation of the water repellency of the textile based on the value of the hydrostatic pressure applied and the time at which water penetration of the sample occurs.

The dipping method involves spraying the samples with a specific amount of pure or deionised water by fixing the samples in a ring fixture and ensuring that the fixture is at an angle of 45 degrees to the horizontal. At the end of the spraying process, the water resistance of the fabric is assessed by comparing the change in the appearance of the sample with the description and graphical representation of the water-soaked condition to determine the water resistance of the fabric.

Applications of the Textile Waterproofing Test

The applications of textile waterproof performance testing are very wide, mainly including the following aspects:

Textile quality control: Through hydrostatic testing, textiles with better waterproof performance can be screened out to ensure that the products meet the quality standards and improve product quality and market competitiveness.
Textile research and development: assessing the impact of different materials and processes on the waterproof performance of textiles, optimising the choice of materials and production processes to improve waterproof performance.
Environmental protection: assess the environmental impact of textiles in terms of waterproof performance, screen environmentally friendly waterproof textiles and reduce environmental pollution.
Specific application areas: such as outdoor products, sportswear, medical supplies, etc., to ensure the waterproof performance of textiles in specific application areas.

In addition, with the development of material science and textile engineering, hydrostatic pressure method will achieve higher testing accuracy and faster testing speed, and be applied in more fields, such as environmental protection, medical treatment, outdoor products, etc.

The basic principle and operation method of textile waterproofness test

The basic principle of textile waterproofness test is to assess the waterproof performance of textiles by applying hydrostatic pressure on the textile surface and observing the penetration of water on the textile surface. Specifically, the hydrostatic pressure method assesses the water resistance of textiles by applying gradually increasing hydrostatic pressure to the surface of the textile until water begins to penetrate the textile surface and recording the value of the hydrostatic pressure applied.

Method of operation

Sample Preparation: Prepare the textile sample to standard size and ensure that the surface of the sample is flat and undamaged.
Installation of the test device: The sample is placed in the test device, making sure that the sample is in good contact with the test device.
Hydrostatic pressure application: Gradually increase the hydrostatic pressure by means of a hydrostatic pressure gauge until the water starts to penetrate the sample surface.
Data logging: Record the value of hydrostatic pressure applied and the time at which water penetration of the sample occurs.
Analysis of results: Evaluation of the water repellency of the textile based on the value of the hydrostatic pressure applied and the time at which the water penetration of the sample occurs.
Test standards for textile water repellency testing

Representative test standards include:

AATCC127-2014 ‘Water Repellency:Hydrostatic Pressure Method
ISO811-1981 ‘Textile fabrics I Determination of water repellency hydrostatic pressure test
AATCC22-2014 《Water repellency:Spray test
ISO4920-2012 ‘Determination of surface moisture resistance of textile fabrics (water immersion test)’.
GB/T4745-2012《Test and evaluation of textile waterproof performance of water-soaking method

Application areas of textile waterproofness test

Textile waterproofness test is widely used in the following fields:

The textile quality control: to ensure that the products meet the quality standards and to screen out textiles with better waterproof performance.
Textile research and development: to assess the impact of different materials and processes on the waterproof performance of textiles, and to optimise the selection of materials and production processes.
Environmental protection: assessing the environmental impact of textiles in terms of waterproof performance, screening environmentally friendly waterproof textiles.

Testing Principle of Textile Moisture Permeability Test

The testing principle of textile moisture permeability test mainly includes moisture permeability cup weighing method, moisture absorption method and evaporation method. Moisture permeable cup weighing method is through the formation of a specific humidity difference between the two sides of the fabric at a certain temperature, water vapour through the moisture permeable cup in the specimen into the dry side, through the determination of the amount of change in the weight of the moisture permeable cup over time, so as to find out the water vapour permeability of the fabric and other parameters.

Moisture absorption method is to put anhydrous calcium chloride in the moisture permeable cup, the moisture in the environment through the unit area of the specimen, anhydrous calcium chloride absorbs water. The evaporation method is to put deionised water into the moisture permeability cup, and the deionised water will pass through the unit area of the specimen and evaporate part of the water.

The application range of textile moisture permeability test is very wide, mainly used to detect the moisture permeability of film, sheet, paper, cardboard, textiles, non-woven fabrics. In addition, quality control organisations can also test the moisture permeability of textile products on the market by using this equipment to ensure that they comply with standards.

Advantages and disadvantages of different testing methods:

Moisture Permeability Cup Weighing Method: This method is simple to operate and is suitable for all types of fabrics, but takes a longer time to obtain accurate data.
Moisture absorption method: using anhydrous calcium chloride to absorb water, applicable to fabrics with a thickness of 10mm or less, but need to control the temperature and humidity conditions.
Evaporation method: use deionised water to evaporate part of the water, also applicable to fabrics up to 10mm thick, but need to control the ambient humidity and wind speed.

Standards of different countries and regions:

China: GB/T12704-91
USA: ASTME96
Japan: JISL-1099
UK: BS7209
Canada: CGSB-4.2No.49-99E

These standards and test methods together constitute a complete system of textile moisture permeability testing, ensuring the accuracy and reliability of the test.

Textile Moisture Permeability Test Application Scope

Moisture permeability testing of textiles has a wide range of applications, mainly including the following aspects:

Clothing fabrics: Moisture permeability testing is widely used in various clothing fabrics, such as sportswear, protective clothing, mackintoshes and so on. Through the test, the breathability and comfort of the fabrics can be assessed under sports or bad weather conditions.

Medical products: Waterproof and breathable fabrics also have important applications in the medical field, such as trauma dressings and surgeons’ work clothes. These materials keep wounds dry and prevent bacterial infections.

Packaging materials: Moisture permeability testing is also applicable to moisture-proof packaging materials to ensure that the packaging materials can effectively regulate the internal humidity and protect the products during storage and transport.

Basic Principle and Operation Method of Moisture Permeability Testing

The basic principle of Moisture Permeability Test is to calculate the water vapour permeability rate and water vapour permeability index by covering the specimen with a petri dish containing water in a constant temperature and humidity environment and measuring the weight of water vapour permeating through the fixed specimen area after a certain period of time.

The method of operation includes the following steps:

Sample preparation: Select a suitable fabric sample to ensure that it meets the testing requirements.
Installation of the sample: Fix the fabric between the upper and lower test chambers and clamp it.
Setting test parameters: set the test temperature, temperature control accuracy and other relevant data according to the testing requirements.
Start test: Start the switch, test the fabric according to the set parameters and count the relevant data.
Data processing and analysis: the microcomputer system will automatically count the testing data and evaluate the moisture permeability of the fabric through analysis and processing.

Standards and equipment for moisture permeability test

The standards of moisture permeability test include BS7209, BS3424, ASTME96, GB/T12704, ISO2528, JIS1099 and so on. The commonly used test equipment is the textile moisture permeability tester, which is able to calculate the moisture permeability by measuring the weight change of water vapour through the specimen in a constant temperature and humidity environment.

Testing Principle of Textile Air Permeability Test

The testing principle of the Textile Air Permeability Test is based on the formation of a certain pressure difference on both sides of the fabric, and then determining the flow rate of air through the fabric for a certain period of time, or stabilising the flow rate through the fabric at a constant flow rate, and determining the pressure difference between the two sides of the fabric under these conditions. This method is based on the ability of a gas to pass through a fabric under a pressure difference to be evaluated.

Test Procedure for Textile Air Permeability Testing

The test procedure usually consists of the following steps:

Secure the fabric sample to the sample holder, ensuring that there are no wrinkles or slack.
Set the pressure difference, usually 100 Pa.

Start the test apparatus and record the volume of gas passing through a unit area of fabric per unit time.
Repeat the test three times and take the average value.

Applications of Textile Air Permeability Test

The range of applications is very wide, mainly including:

Textile industry: for assessing the air permeability of various textiles, such as fabrics, non-woven fabrics, etc.
Clothing industry: for testing the breathability of clothing fabrics to assess their comfort and functionality.
Medical textiles: Breathability has a significant impact on patient comfort and health, so medical textiles also need to be tested for breathability.
Automotive interiors: Breathability testing is also required for automotive interior materials to ensure passenger comfort and health.

Technical parameters for textile breathability testing

Technical parameters may vary between different models and manufacturers of textile air permeability testers, but generally include the following:

Differential pressure test range: e.g. 0~1000 Pa
Differential pressure resolution: e.g. 0.1 Pa
Tne differential pressure accuracy: e.g. 0.25% Pa

The flow measurement range: e.g. 0 to 30 L/min
Flow rate resolution: e.g. 0.1 L/min
Flow rate accuracy: e.g. 2% L/min
Sample size: e.g. 5cm×5cm or ф12mm≤d(diameter)≤ф71mm, etc.
Test area: such as 20cm² (other areas can be customised)
Gas specification: clean compressed air (gas source provided)
Power supply: e.g. 120VAC±10% 60Hz / 220VAC±10% 50Hz (choose one).

The basic principle and operation method of textile air permeability test

The textile air permeability test measures how breathable fabrics are. It does this by measuring the volume of gas that passes through a unit area of the fabric per unit time at a set pressure difference. The test principle is to create a pressure difference across the fabric. It measures the volume of air that passes through the fabric in a unit of time at that pressure difference. This is the fabric’s air permeability.

Test Method

Prepare the sample:

The lab must pre-moisturise the sample, per the standards, before testing it. This is usually done at 20±2℃, 65±2% humidity, and standard pressure to achieve equilibrium.

Setting test conditions:

Set the test area and pressure difference, usually to 100Pa.

Fix the sample:

Fix the fabric sample on the sample holder, make sure there is no wrinkle or slack.

Start the test:

Start the test instrument. Then, record the gas flow through the fabric per unit area per unit time.

Repeat Test:

It is usually necessary to test three times and average the results for accuracy.

Test Equipment for Textile Air Permeability Test

The Textile Air Permeability Tester is a device. It tests the air permeability of fabrics. It tests fabric air permeability by simulating different usage conditions. For example, it simulates heavy sweating during exercise, which results in wet clothes. The test equipment usually includes a gas flow meter, a manometer, and a test chamber. It also includes a sample holder.

Application Scenarios of Textile Air Permeability Testing

Textile air permeability testing has many uses in textiles. For example, sportswear and outdoor clothing must be breathable. It is key for comfort and function. Testing equipment can assess fabric breathability. It can guide product development. Also, the medical textiles sector tests breathability. It ensures patient comfort and health.

 

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