The team managing education services for the Fisher brand of valves and instrumentation has a lot of really good videos on valve basics. You’ll find these on Emerson’s Fisher Valves & Instruments YouTube channel.
For example, a recently posted video, What are the Components of a Butterfly Valve?, provides an under 2-minute look at what makes up a butterfly valve and differences in types of valve.
It opens describing a butterfly valve‘s three basic components—a disk, shaft and valve body. A simple swing through design has a centered shaft on which the disk swings open or closed to control the flow of fluids through it.
Seals made of elastomers or other materials are added to the interior of the valve body when flow shutoff is required. Friction can be a concern where the disk makes contact with the seal repeatedly over time.
To reduce friction, high-performance butterfly valves. In these designs the drive shaft is offset from centerline of the valve body. The disk rotates away from the seal. Most of the high-performance butterfly valves have interchangeable seals with different materials depending on the type of fluid flowing through the valve.
Another consideration for the seal material selection is the required valve leakage class for the application.
Learn more at the Fisher Valves & Instruments YouTube channel or visiting the Training – Valves, Actuators & Regulators area on Emerson.com.