The 47 800-ton vessel Altair of the Compagnie Navale des Pétroles (C.N.P.) was the first oil-tanker to be equipped with a hydraulic remote-control system of cargo valves. The vessel was delivered at the beginning of May 1959. The opening and closing operations of the valves were controlled from a central panel which was fitted with manually operated directional control valves. The panel was located in the cargo valves' remote-control room which also housed the indispensable remote-controlled level-indicator board. Since then the application of hydraulic remote-controlled valves has become widespread and has taken one of two forms : that of a centralized control system or that of directional control valves located on the deck. Remote-controlled valves are either gate valves operated by a hydraulic cylinder, or butterfly valves operated by a hydraulic rotary actuator. The application of remote-control also allowed the setting up of the ‘free-flow’ system which uses hydraulically operated bulkhead valves. The first ‘free-flow’ oil-tanker was the Sirius of the C.N.P.; it was delivered in 1961. At present it appears that there exists an ever-increasing trend towards automation in the loading and unloading of tanker cargoes. This is accomplished by electrically operated directional control valves, which are connected with electrically programmed systems or with electronic servo-controls.
A Study of Single-Stage Electro-Hydraulic Control Valves : 2nd Report, Servovalves
