Running a liquid seal dry is commonly one of the quickest ways to shorten its life. Mechanical seals can, however, be designed to operate successfully without a liquid fluid film. Gas barrier seals have noncontacting seal faces that lift off during operation independent of what’s happening in the seal chamber; wet or dry. In the case of containment seals, the seal faces are designed to run dry under normal operation and also handle process liquid during upset events.
Gas barrier seals provide users the benefits of zero process emissions, no process contamination by liquid barrier fluid, a simplified support system, and low power consumption. Containment seals running behind wet seals provide proactive safety by directing process vapor leakage to a collection system, minimizing environmental emissions, and by having the ability to take over if the inboard seal fails.
Gas seal technology pioneered in compressor seals is applicable to pumps and other rotating equipment by taking into account the same aerostatic and aerodynamic forces acting on the seal faces. Flowserve’s Precision Face Topography is the essential ingredient that establishes a strong and stable gas film. Unidirectional Advanced Pattern Groove (APG), bidirectional wavy face and hydropad designs are most common in pump seals. Both pusher and metal bellows seals employ the advantages of gas seal technology for a variety of services.
