Butterfly valves as they are a cost-effective solution for on/off operations as well as modulating the flow. Thay are simple and easy to understand as they operate by means of having a rotating disc to control the flow. They can be controlled electrically, pneumatically, or by hand utilizing alocking lever or gear wheel for easy opeartion.

VSN Butterfly Valve is one of the most compact and light-weight valves. Used for a wide range of applications, the choice of seat, lining and disc options has increased significantly over recent years making the valve a popular choice. 

Butterfly valves are quick opening valves that consist of a metal circular disc or vane with its pivot axes at right angles to the direction of flow in the pipe, which when rotated on a shaft, seals against seats in the valve body. They are normally used as throttling valves to control flow. Unlike ball valves, butterfly valves do not have any pockets in which fluids may become trapped when the valve is closed