Correlation of Gaseous Mass Leak Rates Through Micro and Nano-Porous Gaskets

The present work deals with theoretical and experimental studies of gaseous flow through tight gasket. The paper presents an innovative approach to accurately predict and correlate leak rates of several gases through nano-porous gaskets. The new approach is based on the calculation of the gasket porosity parameters (D_H, N) using a model based on a first order slip flow regime. The model assumes the flow to be continuum but employs a slip boundary condition on the channel wall. Experimental measured gas flow rates were performed on gaskets with a microscopic flow rate range and isothermal steady conditions. The flow rate is accurately measured using multi-gas mass spectrometers. The gasket porosity parameters in the developed leakage rate formula were obtained experimentally for a reference gas (helium) for each stress level. In the presence of these statistical properties of a porous media the leak rates for different gases can be predicted with reasonable accuracy. It was found that the approach that considers the slip flow with the first order combined to the molecular flow covers the prediction of flow rates at the microscopy level and down to 10⁻⁸ mg/s very well.