GB941241A - Improvements relating to mechanical seals for rotating shafts - Google Patents

Abstract

941,241. Stuffing-box substitutes. FLEXIBOX Ltd. Oct. 5, 1962 [Feb. 12, 1962], No. 5229/62. Heading F2B. In a mechanical seal for a rotary shaft d comprising a main seal and a stand-by seal for use if the main seal is damaged, the stand-by seal comprises a stationary ring e which is normally held out of engagement with its cooperating rotary ring f by pressure of a spring v and is moved into engagement with the ring f by hydraulic pressure. The main seal comprises a stationary ring a and a rotary ring b secured to a sleeve c which rotates with the pump shaft d and to which the ring f is also secured. Liquid from the pump discharge is normally circulated around the main seal for cooling via pipes g and h, flow controller i, space j and return k to the pump suction. If the main seal fails liquid leaking past it flows into the space n around the stand-by seal and thence by pipe o into a tank p where it causes a switch p<1> to close a circuit and actuate a solenoid operated valve q to allow pump discharge liquid to pass to the space r behind a piston s which is moved by the hydraulic pressure against the spring v and via springs t moves a member u carrying the ring e to press the latter into sealing contact with the ring f and render the stand-by seal operative. If the stand-by seal is to be used for an extended period the valve q may be disconnected and a bypass valve q<1> opened or, alternatively, the piston s may be held in the operative position by screwing-in a sleeve nut y. The hydraulic pressure on the piston s may be obtained from an auxiliary pump driven by an electric motor operated by an increase in the liquid level in the tank p.