GB1325940A - Rotary mechanical face seals - Google Patents

Abstract

1325940 End face seals CRANE PACKING Ltd 19 July 1972 [27 July 1971] 35065/71 Heading F2B In a rotary mechanical face seal comprising an annular seal member 5 urged axially into facial sealing contact with a relatively rotatable axially fixed annular seat 3, as the member 5 moves axially due to facial wear, a cylindrical surface associated with that member telescopes with respect to an axially fixed cylindrical surface, the inner of the two surfaces having adjacent external contrastingly coloured annular bands 10, 11 positioned so that the boundary between them is normally covered but becomes uncovered to visually indicate when the wear is such that replacement is desirable. The seat 3 is clamped to a pump or housing 2 by a ring 4 and the member 5 is urged towards the seat 3 by a spring 8 and sealed to the pump or other rotating shaft 1 by an integral bellows 6 secured to the shaft by a clamping ring 7. A shroud 9 clamped between the spring 8 and ring 7 is partially enclosed by an extension sleeve 12 on the member 5 and has painted on its outer surface a white ring 10 and an adjacent red ring 11. When the seal member 5 is new and unworn the red ring 11 is covered by the sleeve 12. The member 5 moves to the left as wear occurs and eventually the red ring becomes visible indicating that replacement is shortly due. To facilitate correct loading of the spring 8 on initial assembly, a further coloured ring 13, for example blue, may be provided, the boundary between the white and blue rings being aligned with the end of the sleeve 12 at the correct setting. There may be further coloured rings, e.g. to indicate when the member 5 has reached its half-worn condition. In a modification, a set of coloured rings on the periphery of the seal member or a member moving with it is covered by a sleeve associated with the axially fixed part of the assembly.