A butterfly valve used for isolating or regulating flow in a pipeline is closed by a disc. Wafer style butterfly valves fit between flanges. Lugged style butterfly valves allow the valve to be installed between two flanges by using a separate set of bolts on each side of the flange. Double flanged valves have the flanges as part of the valve for situations requiring various flange classes. These are available in sizes from 50mm to 1200mm. Double flanged butterfly valves can be used for water and neutral liquids, are rated for full end of line duty and are suitable for vacuum conditions, buried and submerged services.

Shouldered end butterfly valves are available for reticulation of air and water. If the butterfly valve has a top flange manufactured to ISO5211 then a gear, pneumatic or electric actuator can be mounted directly on it.

Choices for seat materials are NBR, EPDM, Viton, PTFE, polyurethane or metal. This can be selected by fluid compatibility and seat tightness required on closing. Certain butterfly valves carry the WaterMark symbol for use in water supply systems.