Permeation in Seals – Polymeric Sealing Materials and Gas Impermeability

Abstract

All elastomers and plastics are permeable to liquids, gases and vapours. Permeability is therefore an important factor for determining the suitability of these materials for specific sealing applications. When elastomeric seals are used to separate different media from each other for instance, permeation may impair the performance of the equipment. Direct measurements of the amount of permeate that penetrates an elastomeric sealing material are often impossible due to constraints. In these cases standard measurements supported by numerical methods (CAE) may be utilised to predict media loss. This paper discusses the mechanisms and principles of the diffusion and permeation of gases, liquids and vapours and how they can be applied to forecast the performance of elastomeric sealing materials under service conditions.