Predicting Gasket Leak Rates Using a Laminar-Molecular Flow Model

The tightness characterization of gaskets used in static seal applications, such as bolted flanged connections, is achieved by performing leakage tests with a single fluid, usually a gas like helium. Attempts made in the past to predict gasket leakage with other gases had limited success unless the leak flow regime through the gasket was predominately laminar, which is not the case with most of the gaskets. In this work, a new gasket leak flow model that combines both molecular and laminar flow regimes is developed to predict the gasket leak rate under different pressures and with different gases. The Laminar-Molecular Flow (LMF) model is first constructed around a reference pressure for which the fraction of the total leakage that occurs through laminar flow channels is established. This fraction is computed using a simple leakage test performed with one gas and at least two different pressures. The model is then tested against experimental leak data obtained from two different gaskets and four gases and is shown to produce accurate predictions.