Abstract: A sight glass assembly comprising a first housing section having an opening therethrough, mountable on a vessel wall having an opening therethrough so that the first housing section opening registers with the vessel wall opening, the opening of the first housing section having an enlarged section, a second housing section cooperable with the first housing section, having an opening therethrough registered with the opening in the first housing section, the opening in the second housing section having an enlarged section disposed in opposed relation to the enlarged section of the opening in the first housing section, a lens disposed across the openings having the periphery thereof disposed between the housing sections and received within the enlarged sections of the openings in the housing sections, a sealing ring assembly disposed in the enlarged sections of the housing section openings, included a rigid compression ring and a resilient packing member, the compression ring being engageable with one of the hous

Abstract: A sight glass assembly comprising a housing structure having a circular opening therethrough, the opening having an enlarged section, a lens disposed across the opening and having a peripheral portion received within the enlarged section of the housing structure opening, a sealed ring assembly disposed in the enlarged section of the housing structure opening, the sealing ring assembly comprising a rigid compression ring and a resilient packing member mounted on the compression ring, the packing member having an L-shaped cross-sectional configuration including a wall portion mounted on an inner side of the compression ring and engaging the periphery of the lens and a flange portion mounted on the compression ring and engaging the housing structure, and means mounted on the housing structure and engageable with the compression ring for urging the compression ring against the packing member, causing the packing member to expand radially, thereby effecting a seal between the housing structure and the periphery of