GB1518583A - Sealed assembly - Google Patents

Abstract

1518583 Sealing VSES TEPLOTEKHNICHE NI INST IM FE DZERZHIN 10 March 1976 09587/76 Heading F2B A sealing means, for sealing an annular gap between two components which may be fixed or rotate relative to one another, the annular gap operating media at different pressures, comprises a liquid sealant 4 and, in a recess 6 concentric with the gap 3, a fine-grained packing 5 which is compressed in the recess, has a polycapillary structure and is resistant to wetting by the sealant 4. The resistance to wetting ensures that the sealant 4 in the capillaries has a very high surface tension which opposes the pressure p 1 of the medium to be sealed. In the embodiment shown in Fig. 1, the seal is between a pair of flanges, on the left-hand side of the figure the higher pressure p 1 being on the outside and acting on the surface of sealant 4, and on the right-hand side the higher pressure p 1 being on the inside. The sealing liquid 4 may be the medium sealed (Figs. 2 and 3, not shown). The fineness of the grain of the packing 5 may increase from the low pressure side to the high pressure side. In the embodiment shown in Fig. 6 the sealant 4 is separated from the packing 5 and communicates with it through the gap 3, the packing 5 being held compressed in its recess 6 rather than compressed by the pressure p 1 as in the embodiment of Fig. 1. Teeth 14 of an annular projection 7 maintain sealing should the sealed members 1 and 2 move slightly apart. There may be packing 5 on each side of sealant 4 (Figs. 4 and 7, not shown). A seal for a horizontal rotating shaft 29 in a housing 30 enclosing the higher pressure p 1 is shown in Fig. 9. Sealant 4 is disposed in a chamber surrounding the shaft and is restrained from rotating with the shaft by ribs formed by notches 31 in a bush 26, the bush 26 being between rings 24 which compress the packing 5 in spaces 6 and 6a. The pressure p 1 is communicated to the surface of sealant 4 on one side of a flange 32 through an aperture 34. A liquid 36 which is capable of wetting the packing 5 and also acts as a lubricant is received in an annular reservoir 35 and pumped by a pump 39 ta the right-hand portion of seal 4. The pump 39 is switched on by a sensor 44 of the level 41. An embodiment for a vertical shaft is also described (Fig. 10, not shown). The packing 5 may be graphite powder and the sealant 4 can be of molten tin or molten Wood's alloy and may contain bronze powder to increase the surface tension. Water can also be used with graphite.