Innovators at NASA's Glenn Research Center have designed a superior seal assembly that is durable and highly dependable in extremely harsh environments. This fault-tolerant design features a novel protective shroud that shields its interior seal element(s) from hazardous conditions that can quickly degrade the seal material and cause higher leak rates.
About 50” in diameter, Glenn's unique sealing system consists of multiple elements installed in a recessed rectangular sealing groove. The main sealing function is provided by an elastomer element (e.g., silicone) comprising one or more sealing wall(s) connected by a web. The wall(s) extend above the top of the sealing groove so they are compressed by the opposing mating surface during the sealing process. The retractable shroud element is installed between the wall(s), with its base resting atop the web of the sealing element.
The shroud is typically composed of an elastomer material to allow for flexibility (which is essential to retraction), but it can also be made from thin metal or plastic materials. When the seal is no longer in use, a pair of V-shaped shroud “arms” extend upward from the base of the seal to cover the wall(s). A thin metal retainer is installed on top of the shroud, and fasteners pass through holes in the retainer, shroud, and sealing elements to secure the system to the base of the sealing groove. Metal washers are installed in these holes to provide a load path between the metal retainer and the surface of the sealing groove.
The system can seal against either a flat metal surface or another seal of the same design. This sealing system has been designed to accommodate multiple sealing cycles and has exhibited extremely low leak rates, making it an attractive solution within a variety of industries from aerospace to agriculture.