GB1035607A - Improvements in or relating to rotary seals - Google Patents

Abstract

1,035,607. Mechanical seals. J. C. CARTER CO. May 13, 1965 [Sept. 30, 1964], No. 20295/65. Heading F2B. In a mechanical seal for a rotary pump shaft 12 and comprising two seal rings 41, 44 in facial sealing contact with each other, the contact face 45 of one, 44, of the seal rings has circumferentially spaced recesses 48, 49 therein arranged to alternately expose overlapping radial portions A, B, Fig. 4, of the contact face 42 of the other seal ring 41 to the surrounding atmosphere, without opening up leakage paths between the faces, whereby any loose grit particles on the faces collect in the recesses and are discharged to the surrounding atmosphere. The ring 41 is of graphitic carbon and is mounted in a carrier ring 19 secured to one end of a spring metal bellows 20 connected at its other end to a housing 17 sealed in the pump housing 13 by an 0-ring 25 and carrying rings 27 co-operating with a sleeve 18 on the shaft to minimize entry of foreign matter into the housing. The carrier ring 19 is slidably supported by three pins 38 fixed to the housing 17 and extending through apertures in the ring 19 which is urged to press the seal ring 41 against seal ring 44 by the bellows 20 and a spring- loaded pin 39 arranged diametrically opposite a seam 40, Fig. 2 (not shown), in the bellows. The seal ring 44 is fixed to the shaft and is of metal preferably case-hardened steel, the face 45 preferably being chrome plated. The recesses 48 and 49 are slots and blind holes respectively and, in use, wear particles of carbon P entering the slots 48 are centrifugally discharged into the pump chamber 14 whilst those P 1 entering the holes 49 are discharged by pressure to the low pressure side of the seal. For low temperature applications of the invention the face 42 may be conically dished inwardly from its outer to its inner periphery at ambient temperature to an extent such that the face becomes radial at the low operating temperature.