Sight glass assembly capable of withstanding high pressure - has packing member exerting uniform compressive force about periphery of lens

摘要

A sight glass assembly includes a housing structure mountable on a vessel for containing fluid. The housing structure has a through opening. The latter has an enlarged section providing a shoulder. A face plate has an opening registered with the opening in the housing structure, mounted on the housing structure so that a portion of it is disposed in opposed relation to the shoulder. A lens disposed in the enlarged section of the opening in the housing structure is interposed between the shoulder and the portion of the face plate. A packing member is disposed in the enlarged section of the opening between the housing structure and the periphery of the lens. The packing member is hollow and filled with a fluid.