Flow control orifice Might be used for certain control valves where the flow opening might be changed by removing a mechanical piece and replacing it by a different piece with other measurements for the opening. Different zizes of orifices (openings) can also be selected under fabrication for some regulation or control valves, to suit (together with suitable formed closing member (cone, clack etc)) a best possible regulation of a given flow spectre.
Flow control orifice can be found as the flow opening closed by the valves closing member, might also be part of a construction placed inside or outside the valve, for instance in a separate, throtteling disc outside and/or far from any valve.