How to detect the air permeability of ePTFE membrane?

1. Air permeability tester method:
Principle: Based on a certain gas transmission principle, the air permeability of the ePTFE membrane is evaluated by measuring the rate at which gas passes through the ePTFE membrane under specific conditions.
Operation steps: Cut the ePTFE membrane sample into a suitable size and install it in the test chamber of the air permeability tester to ensure that the membrane is installed tightly and leak-free. Set the test parameters, such as test gas (usually air or nitrogen), pressure difference, temperature, etc. Start the test instrument and let the gas pass through the membrane sample under a certain pressure difference. The instrument will monitor and record the gas permeation rate in real time. Calculate parameters such as air permeability and air permeability coefficient based on the test results to evaluate the air permeability of the membrane.
2. Constant pressure method:
Principle: Maintain a constant gas pressure on one side of the membrane, measure the flow rate or pressure change of the gas on the other side, and then calculate the air permeability.
Operation steps: Build a test system, including a gas source, a pressure regulating device, a test chamber, a flow sensor or a pressure sensor, etc. Place the ePTFE membrane sample in the test chamber, connect one side of the membrane to the gas source, and the other side to the atmosphere or connect to the pressure sensor. Adjust the gas source pressure to the set value, and record the gas flow through the membrane or the pressure change on the other side after stabilization. Calculate parameters such as air permeability based on the measured data.
3. Constant volume method:
Principle: A certain volume of gas is sealed on one side of the membrane, and the change in pressure on the other side after the gas passes through the membrane within a certain period of time is measured to obtain the air permeability.
Operation steps: Prepare a test chamber of known volume, install the ePTFE membrane sample at the partition of the chamber, and divide the chamber into two parts by the membrane. Fill one side with a certain amount of gas and record the initial pressure. Monitor the change in pressure on the other side within a certain period of time. Calculate parameters such as air permeability based on the ideal gas state equation and pressure changes.
4. Water vapor transmission rate test method:
Principle: In view of the special permeability of ePTFE membrane to water vapor, its air permeability is reflected by measuring the rate at which water vapor passes through the membrane.
Operation steps: Build a water vapor transmission rate test device, which usually includes a humidity control chamber and a drying chamber, with the ePTFE membrane sample placed in the middle. Maintain a certain high humidity environment (such as relative humidity above 90%) in the humidity control chamber, and maintain a low humidity (such as relative humidity below 10%) in the drying chamber. Measure the increase in water vapor in the drying chamber within a certain period of time by weighing or other methods to calculate the water vapor transmission rate.
5. Practical application simulation method:
Principle: According to the specific situation of the ePTFE membrane in actual use, simulate its working environment and conditions to evaluate whether the breathability meets the actual needs.
Operation steps: For example, for ePTFE membranes used in clothing, clothing samples can be made and let the wearer perform wearing tests under different sports states and environmental conditions. The breathability of the membrane is comprehensively evaluated through subjective feelings (such as whether it feels stuffy) and objective measurements (such as humidity and temperature on the skin surface). For ePTFE membranes used for heat dissipation in electronic equipment, they can be installed in a simulated electronic equipment heat dissipation structure to measure parameters such as temperature changes on the membrane surface and air flow during equipment operation to determine whether their air permeability can effectively meet the heat dissipation requirements.