GB789680A - Improvements in and relating to shaft sealing arrangements - Google Patents

Abstract

789,680. Stuffing-box substitutes. PARSONS & CO., Ltd., C. A. April 12, 1956 [April 21, 1955], No. 11513/55. Class 122 (5). A shaft sealing arrangement comprises a sealing means 10, 11 which prevents leakage of fluid along the rotating shaft 4 where it passes through the wall 6 of an enclosure containing the fluid, a supplementary seal 12 for preventing the escape of fluid from the housing 6 when the shaft is stationary and the seals 10 and 11 are not functioning, and means 14 for moving the shaft axially to bring an O-ring 28 on a collar 13 into sealing contact with the wall 6 to form the supplementary seal 12. As shown, the shaft 4 of the blower 1 is driven by a prime mover 6a and enclosed in a housing 7. The seal 10 is of labyrinth type and the seal 11 is of the liquid-film thrust-collar type, comprising a sealing ring 15 which is maintained in contact with the face of a collar 18 by springs 17. An annular groove 19 in the sealing face 16 of the ring is fed with oil under pressure from a reservoir 20 via holes 21, 22 to the face 16. Radial grooves extending outwardly from the groove 19 carry most of the oil from the sealing face 16 but a small amount flows inwardly over an ungrooved inner portion of the face to a clearance 24 around the shaft and thence to a collecting space 25 for separation from the working fluid. U-shaped sealing rings 26 prevent the leakage of oil from the annular space 27 between the ring 15 and housing 7. Maintenance access to the latter rings 26 or to the sealing face 16 may be achieved without reducing pressure or evacuating the enclosed blower system, by moving the shaft, when stationary, axially by the means 14, to close the seal 12, so that the upper part of the housing 7 may be removed for the withdrawal of the shaft bearings 8 and 9. The collar 18 can also then be moved along the shaft and the U-rings 26 withdrawn and cut away; new rings housed in a container 31 are then moved into place along the shaft. The seal 11 may be replaced after withdrawing the bearing 9 while the shaft is supported by a strap placed immediately to the right of the bearing. After replacing the seals, the shaft is moved back to its original position by the means 14 which, if the pressure in the enclosed system is high, may be augmented by the introduction of a pressurized fluid into the space 5 between the labyrinth seal 10 and the collar 13.