Definition(s)
Control Valve (Surface Control System)
A valve mounted on the hydraulic manifold which directs hydraulic power fluid to the selected function (such as annular BOP close) while simultaneously venting the opposite function (annular BOP open).
Source: API SPEC 16D, Specification for Control Systems for Drilling Well Control Equipment and Control Systems for Diverter Equipment, Upstream Segment, Second Edition, July 2004. Global Standards