Butterfly valve

Unlike a ball valve, the disc is always present within the flow, so it induces a pressure drop, even when open.

When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid.

In the case of triple offset valves the seat is made of metal so that it can be machined such as to achieve a bubble-tight shut-off when in contact with the disc.

A lug-style butterfly valve used in dead end service generally has a reduced pressure rating.

Lugged valves are extremely resistant to chemicals and solvents and can handle temperatures up to 200 °C, which makes it a versatile solution.

But when it is in the rotation, the pockets allow dropping a defined amount of solids,[2] which makes the valve suitable for dosing bulk product by gravity.

In the pharmaceutical, chemical, and food industries, a butterfly valve is used to interrupt product flow (solid, liquid, gas) within the process.

With advances in material manufacturing and technology, butterfly valves could be made smaller and withstand more-extreme temperatures.

After World War II, synthetic rubbers were used in the sealer members, allowing the butterfly valve to be used in many more industries.