Advanced Methods for Predicting Elastomer/Fluids Interactions

Abstract

The method of predicting seal swell previously reported by this laboratory, has been extended to include three-dimensional solubility parameter concepts. Techniques for analysis and the calculation of the partial solubility parameters in consistent dimensions have been formulated for pure liquids, binary mixtures of known composition, and multicomponent mixtures of unknown ingredients. Although the quantitative analysis of swell requires analyzing seven or more variables simultaneously, it can be represented with two dimensional graphs in the region of greatest interest to the hydraulics engineer by observing a few simple rules. With this scheme, it is possible to predict, with 97% accuracy, whether a particular fluid/elastomer combination will meet a specification limit of 25% maximum swell. This has been demonstrated on 975 combinations of 15 vulcanized elastomers and 133 pure liquids.