The structure and working principle of the butterfly check valve

The structure and working principle of the butterfly check valve

The wesdom butterfly check valve overcomes the calibre and pressure drop limitations of swing and disc check valves. The butterfly check valve has a flap that is split in two and hinged in the middle so that the two discs can only swing in one direction and the discs are pressed against the seat by a button spring mounted on the hinge.

In order to be able to have a hinge in the centre of the flow channel, a fixing pin needs to be fitted on the outside, this causes leakage in the valve, the design can be improved by fitting it on the inside, the fluid can then be sealed inside the valve body and will not leak to the outside. If the root of the disc wears the seat during normal operation, frequent opening and closing of the butterfly check valve will quickly lead to damage to the seat. To overcome this problem, the root of the disc is lifted when the valve is first opened and the disc only rotates around the strand.

Working principle of the wesdom butterfly check valve

The double adjustable flap construction uses two spring loaded flaps (half valve braid) suspended from a central vertical chain pin shaft. When the fluid starts to flow, the flaps open under the combined force acting on the centre of the sealing surface. The point of action of the spring-loaded support force, which acts in the opposite direction, is located outside the centre of the valve face, allowing the root of the valve to open first. This avoids the friction on the sealing surface that occurred in older conventional valves when the flap opened and eliminates wear on the components.

When the flow rate slows, the torsion spring automatically reverses, allowing the valve flap to close, moving closer to the valve seat, reducing the distance and time of travel for closure. When the fluid flows backwards, the valve flap gradually moves closer to the body seat and the dynamic response of the valve is then greatly accelerated, reducing the cumulative effect of the water hammer phenomenon and thus achieving impact-free performance. When closed, the spring force point of action allows the top of the valve flap to close first, preventing galling at the root of the flap and allowing the valve to maintain its sealing integrity for longer.