Valves Components and Operating Principle
As a common piece for equipments in fluid processing facilities, sanitary valves are different in types, shapes and sizes. However, they all basically consist of some of the parts defined as follows:
- Body: the framework that holds everything together and serves as the pressure boundary.
- Bonnet: the cover on the valve body. During valve manufacturing, the internal parts are put into the body and then the bonnet is attached to hold everything together inside. Some types of valves (ball valve for example) don’t have this part.
- Handle and Actuator: the handle is mainly used to manually open or close the valve; the actuator, pneumatic or electric, is used to automatically or remotely control the valve. Some valves, check valves and relief valves for example, have neither handle nor actuator because they automatically control themselves from the inside.
- Disc/Ball: a movable obstruction inside the body that controls the flow through the valve.
- Stem: the part that transmits the motion of the handle/actuator to the disc/ball.
- Packing: the seal between the stem and the bonnet that prevents leakage.
- Seat: the seating surface for the disc/ball.