How does the waterproof and breathable valve achieve the effect of waterproof and breathable

The waterproof and breathable valve is made of expanded polytetrafluoroethylene as a breathable membrane body. It has a microporous structure at the microscopic level. It uses the order of magnitude difference between gas molecules, liquid and dust particles to allow gas molecules to pass through, while liquid and dust cannot pass through. , so as to achieve the purpose of waterproof and breathable.
The water is generated because the product absorbs water vapor under negative pressure during the working process, and water will appear in the inner shell when the water vapor condenses. After installing the waterproof and breathable valve, it passes through the filter of the waterproof and breathable membrane under negative pressure, and the inhaled air contains tiny water vapor, and the water vapor can also be discharged under positive pressure, which can achieve the effect of internal and external balance pressure difference , breathable and waterproof each other, water will not form.