Three magnetic fluid seals custom engineered to meet specific application objectives are discussed. These seals are: a belt edge seal, a large diameter seal and a centrifugal seal. Extensive experimental data were acquired on the first two seals to determine their performance characteristics. Some of these test results are compared with the theoretical expectations. Numerical computations are made on the centrifugal seal to Predict its sealing capabilites.Presented at the 34th Annual Meeting in St. Louis, Missouri, April 30-May 3, 1979