The Vacuum Method is a key application of the differential pressure technique used to measure the diffusional permeability of Technical Textile products. Here, the permeation cell is separated into two distinct chambers by the specimen. Both chambers are initially evacuated, after which one side is filled with a testing gas at 0.1 MPa while the other side remains under vacuum. This creates a pressure difference of 0.1 MPa across the specimen. The testing gas permeates through the film into the low-pressure side, inducing a pressure change there. The permeability can then be calculated based on this pressure variation, providing important data for the evaluation of various materials in Technical Textiles.