Pipeline burst valves are butterfly valves and are generally restricted solely to flow control applications but in the Penstock Valve systems used in Hydro stations the butterfly valve is essentially used to protect the powerhouse in case of rupture. These are designed to withstand large forces encountered during closing under excessively high flow velocity. The entire structural design of the valve is based on rupture velocity of the pipeline. Under this condition, the valve closure develops large reaction forces caused by hydraulic torque generated by large flow velocities in the pipeline. The cost of the valve is very sensitive to rupture velocity. These valves help ensure pipeline safety and provide protection against harm to environment. Equipment , or people.
Typically the valve system would have aggregates like the Bypass Valves, Air Release Valves, Anti Vacuum Valves , Trip Mechanism and Over Velocity Sensing Devices.
The most important control interlock and actuation element of the penstock system is the Over Velocity sensing device and trip mechanism. The primary function is to monitor the flow velocity through the penstock valve and generate a mechanical/ electrical signal in the event the flow exceeds the pre-set value. The required action is to convert the signal into a mechanical force large enough to be able to release the latch mechanism, so as to initiate valve closure.
Modern trends are to provide a Programmable Logic Controller (PLC) system which would communicate with the main PLC system within the main control panel and provide all operational information and receive control commands. The PLC system controls and monitors the shutoff valve on the basis of a stored digital program of instructions .