The pre-processed sample is placed between the upper and lower test cavities, clamped in place. Initially, the lower cavity (lower chamber) of the pressure difference permeability tester is evacuated. Next, the entire system is vacuumed. Once the specified vacuum level is achieved, the lower test cavity is sealed, and a certain pressure of test gas is introduced into the upper cavity (upper chamber) of the permeability tester.

The device ensures a constant pressure difference (adjustable) on both sides of the sample, causing the gas to permeate from the high-pressure side to the low-pressure side of the pressure difference permeability tester under the action of the pressure gradient. By monitoring and processing the internal pressure on the low-pressure side of the tester, the various barrier parameters of the tested sample can be determined.

The principle of the pressure difference method is utilized in the design, where pre-processed samples are placed between the upper and lower measuring surfaces. A constant pressure difference is formed on both sides of the sample. Under the action of the pressure difference, gases flow from the high-pressure side through the sample to the low-pressure side. The air permeability of the sample is calculated based on the area of the sample, the pressure difference, and the flow rate.