SHAFT SEAL

摘要

A valve stem seal has a fixing region (7) with a flange (9) for mounting in a valve housing, and a flexible seal region (19), with an external groove (17) between these regions to permit the region (19) to flex relative to the fixing region (7). The fixing region (7) has a small radial clearance from the valve stem and acts as a bearing for the latter. The region (19) is an interference fit on the valve stem and has internal labyrinth seal grooves (21). The seal may be made of metal or of plastics material such as PTFE. If made of metal, the region (19) preferably has external grooves (23) in a diamond pattern to provide increased flexibility. The region (19) is externally exposed to the pressure of the fluid in the valve housing so that the seal is self-energizing.