Air leakage in seals with application to syringes

We study the leakage of air in syringes with Teflon coated rubber stopper and glass barrel. The leakrate depends on interfacial surface roughness, viscoelastic properties elastoplastic coating. measured rates are compared to predictions a simple theory for gas flow, which takes into account both diffusive ballistic multiscale contact mechanics determines probability distribution separations. shows that flow (leakage) channels so narrow is mainly (the called Knudsen limit). implications container closure integrity discussed.