A seal that can be used alone or as a containment seal for another seal includes a primary ring (36) and a mating ring (30), the primary ring being axially shiftable relative to a rotating shaft (12) and the mating ring being axially fixable relative to the rotating shaft, a biasing mechanism (500) that urges the primary ring toward the mating ring, and an annular flexible sealing membrane (100). The membrane includes a flange portion (102) disposed at least partially between the biasing mechanism and the primary ring, a coaxial portion (104) that is axially fixable relative to the shaft, and a flexible connection portion (106) positioned within a radially inward extent of the flange portion and connecting the flange portion to the coaxial portion. At least one of the mating ring and the primary ring includes grooves formed on a face thereof that cause the formation of a gas film to develop between the primary ring and the mating ring that keeps the primary ring and the mating ring from contacting each other in operation.