A hydrogen permeation test bench for pressures up to 1000 bar and a temperature range of 0–85 °C was developed and set up at HyCentA to characterize the permeation properties of polymer materials and evaluate their suitability for hydrogen storage and infrastructure applications.

This test setup adheres to the ISO 11114-5 standard, with the exception of omitting the wire mesh between sample and sinter plate, as the sinter plate used in this setup provides the required uniform and smooth contact surface for the sample. On the upstream side, a polymer sample is subjected to pressurized hydrogen, which permeates through the sample to a certain degree. The downstream side is purged with nitrogen, which takes up the permeated hydrogen and transports it to a thermal conductivity sensor for detection. The hydrogen pressure on the upstream side is kept constant.

To minimize possible edge-effects and other interfering effects, a sample diameter of 150 mm is necessary. The outer part of the sample is needed for sealing, leaving a diameter of 80 mm as effective test diameter.

Permeation tests were performed at 400 and 800 bar on HD-PE samples with a thickness of 2 mm. The tests were carried out at a temperature of 25 °C. From the obtained data, the permeation parameters permeability, diffusion coefficient, and solubility coefficient were determined. Five tests were conducted for each permeation pressure level to evaluate accuracy and uncertainty of the test setup.

For a hydrogen permeation pressure of 400 bar at 25 °C, the permeability of the HD-PE samples resulted in 6.58 ⋅ 10^-16 mol/(m⋅s⋅Pa), the diffusion coefficient in 1.26 ⋅ 10^-6 cm²/s, and the solubility coefficient in 5.23 ⋅ 10^-6 mol/(m³⋅Pa). For 800 bar, the permeability was 4.64 ⋅ 10^-16 mol/(m⋅s⋅Pa), the diffusion coefficient 0.94 ⋅ 10^-6 cm²/s, and the solubility coefficient 4.93 ⋅ 10^-6 mol/(m³⋅Pa).

The measurement curves showed a high level of repeatability, particularly in the 400 bar tests. For both permeation pressure levels, the maximum deviation of any measurement point from the mean value was smaller than 5 %, indicating minimal error and a high degree of accuracy and reproducibility in the measurement of the hydrogen permeation parameters.