Mechanical seal assembly for glass-lined mixer tanks

Claim 1

A corrosion-resistant unit package mechanical seal assembly for sealing a rotatable shaft which extends through an opening in a tank wall, said seal assembly being removable as a unit by sliding movement along said shaft, said unit assembly including: a. a fixed annular upper stationary seal face having means for receiving the ends of draw rods for removal of said unit; b. a corrosion-resistant annular lower stationary seal face; c. a holder having an annular central hub portion and upper and lower collar portions; d. means securing said hub portion to said rotatable shaft at a point approximately midway between the faces of said upper and lower stationary seal faces; e. said upper and lower collar portions of said holder being spaced radially from said rotatable shaft forming upper and lower annular spaces therebetween; f. said upper and lower collar portions having internal projections; g. annular upper and lower rotatable seal faces within said upper and lower annular spaces and having external slots receiving said collar projections; h. spring means within said annular spaces forcing said upper and lower rotatable seal faces toward said upper and lower stationary seal faces, respectively; i. annular seal means between said lower rotatable seal face and said rotatable shaft, and j. an annular spacer-and-support sleeve secured to an depending from said upper stationary seal face external to said rotatable seal faces and isolated from contact by fluid from said vessel, k. said spacer-and-support sleeve having means at its lower end for supporting said lower stationary seal face and for preventing rotation thereof.