Wafer metal-seat Butterfly Valve Mental Seat butterfly Valve Concentric Butterfly Valve Concentric Butterfly Valve <<Butterfly ValveDesign Standard: API ... Manner: Hand wheel, worm wheel & worm screw, pneumatic driving, electric drivingButterfly ValveSingle Eccentric Butterfly ValveDesign Standard ... Lug, Wafer, Flange, Weld ConnectionDriving Manner: Hand wheel, worm wheel & worm screw, pneumatic driving ...