Helium gas permeability measurements of polymeric membranes using the difference method

This paper presents a new permeation measurement facility based on the difference method, which is shown to be capable of measuring gas fluxes through different polymeric membranes. In order to correct for the background pressure increase in the measurement chamber, a reference chamber has been adapted and connected to it. The permeation flux was examined by measuring the pressure difference between the reference and measurement chambers. Pure helium permeation was performed through polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) membranes using this method. The uncertainty of the permeability was evaluated. The results show that the introduction of reference chamber can mitigate the influence of the residual pressure in the measurement chamber. This new method allows simplified and visualized measurement of the permeation fluxes.