Dual-butterfly non-return valves

The word butterfly in the name of dual-butterfly non-return valves describes the structure of the valve rather well. In the middle, there is a closing axle, and there are hemisphere-formed closing flaps symmetrically on both sides of the axle.

Otherwise, as in case of competitors, GESTRA uses two separate axles and each closing flap is secured with two separate closing springs, as generally no closing springs are used at all. The robust structure aims at protection from the damages of the valve caused by small water hammers. If water hammers are extensive in the system, the BB dual-butterfly non-return valves can be fitted with special hydraulic dampers.

Non-existing flow resistance

The absolute advantage of the dual-butterfly non-return valve is its low flow resistance that is only a few millibars, depending on the flow rate. In other models, it can be one hundreds of times higher.

BB dual-butterfly non-return valves are available from different materials as well as coated for seawater use.


  • DN 50-300
  • PN 16-40
  • Laippojen vu00e4liin
  • Pronssi, C22.8, AISI 316

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