Predicted Effects of Bearing Sump and Injection Pressures on Oil Labyrinth Leakage

New information and an enhanced understanding concerning the oil vapor contaminant leaking through non-flooded oil labyrinth seals are provided. The results were obtained using a finite-volume Navier-Stokes computer code that was extended to include the concentration transport equation. The minimum (i.e. critical) pressure and flow rate at which un-contaminated buffer gas must be injected to prevent oil vapor from leaking to the process gas was determined for a range of seal geometries and operating conditions. It was found that the variation of the critical buffer-gas injection pressure with bearing gas and process gas pressures, for example, was surprisingly small for the cases considered. In addition, the bearing gas and oil vapor flow rates for a wide range of bearing and injection (where present) pressures and geometries were determined for both buffered as well as non-buffered seals.Copyright © 2001 by ASME