Quick-opening sight glass assembly

A sight glass assembly comprising a first housing section having an opening therethrough, mountable on a vessel wall having and opening communicating with a fluid contained therein so that said housing section opening registers with said vessel wall opening, said first housing section having an enlarged section including a lens seating surface and a packing bearing surface, said packing bearing surface being inclined relative to a longitudinal center line of said first housing section opening, a second housing section having an opening therethrough registered with said first housing section opening, said second housing section opening having an enlarged section including a lens seating surface and a packing bearing surface, said packing bearing surface being inclined relative to said longitudinal center line, said lens seating and packing bearing surfaces of the enlarged opening section of said second housing section being disposed in opposed relation to the lens seating and packing bearing surfaces of the enlarged opening section of said first housing section, a lens disposed in said housing openings, interposed between said seating surfaces, a packing member disposed in said enlarged opening sections, said packing member engaging said bearing surfaces and a periphery of said lens and means for urging said packing bearing surfaces together whereby said packing is caused to expand laterally to place said lens in lateral compression and to provide a fluid tight seal between said housing sections and the periphery of said lens.