GB538326A - Pressure controlling device for use in raising sunken ships by compressed air - Google Patents

Abstract

538,326. Raising sunken ships; fluid-pressure servomotor systems. ZULVER, C. June 20, 1940, No. 10622. [Class 68 (ii)] [Also in Group XXIX] In raising sunken ships by replacing water by compressed air a desired ratio between internal and external pressure is maintained by operation of main valves controlling air pressure inside the ship through a fluid-pressure servomotor system comprising pilot valves operated by a piston subjected to the difference between internal and external pressures. The piston, which may comprise parts 5, 6 of different diameters to enable the internal pressure to be maintained somewhat higher than the external pressure, is subjected on its upper side to the air pressure within the ship through a pipe 3, and on its underside to pneumatic pressure equal to the hydrostatic pressure, a valve 15 controlling a supply of compressed air from a pipe 20 in accordance with the hydrostatic pressure applied to a diaphragm 13 being provided for the purpose. Upward movement of the piston under excess external pressure operates a pilot valve 33 to cause opening of a main valve 54 admitting compressed air from a supply 52 to the ship at 1. Downward movement of the piston on decrease of external pressure operates the pilot valve to cause closing of the main valve and at the same time operates a second pilot valve controlling a second main valve which permits escape of air from the ship. A third pilot valve also operated by the piston 5 may be provided to control the speed of the compressers supplying air to the ship.