Gas Leakage Correlation

A project has been carried out on the correlation of leakage measurements of different gases in specific conditions in bolted flanged assembly. The objectives were: • to check if the relationship between the leakage measurements of Helium, CO₂, refrigerant R134a and CH₄ would be similar to results of calculations that can be found when using correlation formulas, • to compare emissions of a typical laboratory fluid (Helium) with process fluids like methane, used in petrochemical plants, as well as CO₂ and R134a, used in the refrigeration industry. Referring to TA Luft and VDI 2440, which specify a unique test for the certification of gaskets, the configurations of the testing installation used consist of flanges assembled with either PTFE based, graphite or fibre based gaskets. Different gasket loads and internal pressure were applied in order to simulate molecular, intermediate or laminar leakage flow rates. This article describes the test configurations and shows the leakage measurement results. It also compares the ratios between the leakage values and the results that would be obtained by predicting the leakage of another gas and/or in other pressure conditions, using Poiseuille or Knudsen laws.