US Patent 7426936 Fully independent, redundant fluid energized sealing solution with secondary containment

A redundant sealing system with secondary containment for preventing leakage of fluid along a valve shaft is provided. The system comprises a first set of dynamic seals, a second set of dynamic seals, an auxiliary barrier fluid chamber, and a barrier fluid indicator. The first and second set of dynamic seals are in spaced relation to each other a distance equal to or further than a maximum stroke length of an actuatable valve stem. The auxiliary barrier fluid chamber is interposed between the first and second sets of dynamic seals. The barrier fluid indicator has a piston in a primary barrier fluid chamber. A first face of the piston is exposed to the auxiliary barrier fluid chamber. A second face of the piston is exposed to a barrier fluid and inhibited from fluid communication with the auxiliary barrier fluid chamber by a dynamic seal in the first set of dynamic seals.