Stewart & Stevenson Oiltools, Inc.

Terry W Pollard

David P Herd

Jack Whiteman

A hydraulic control system for controlling a plurality of remotely positioned hydraulically actuated underwater devices by a single hydraulic control line extending underwater. A reference hydraulic manifold is connected to the single control line and a signal hydraulic manifold is connected to the single control line. A pilot actuated hydraulic control valve is connected to each of the underwater devices controlling the flow of actuating fluid thereto. The pilot of each valve is connected to both the reference manifold and the signal manifold, but the pilot of each of the valves is actuated by different pressure levels in the signal manifold whereby the underwater devices may be controlled in a predetermined sequence by applying predetermined pressure levels to the single hydraulic control line. A pressure regulator is positioned in the control line upstream of the reference manifold to maintain the reference manifold at a predetermined pressure level. Time delay and fail safe circuits are provided in the reference manifold and signal manifold. In one embodiment the hydraulic control valves are connected to provide one mode of sequencing the underwater devices. In another embodiment the hydraulic control valves are connected to provide a different mode of sequencing.

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Houston, TX, United States of America

Terry W Pollard