A butterfly valve is used to control the flow of a certain object. Both the mechanism and structure of this valve is similar to that of a ball valve. It has a spherical disk with a hole and has a rod running through it so that when the valve is open, the flow will happen. When the valve is close, the flow is obviously, blocked.
The technology of the butterfly valve has evolved gradually throughout time and its usage has become more popular nowadays. This valve comes from the family of quarter turn valves in different sizes, intended for different uses and handling different levels of pressure, the greater the size of the valve, the higher the pressure that it can handle (you can know more this at butterfly valve selection guide article). In coherence with all mechanical devices, this piece of equipment has different parts or components that contribute in its functionality and usefulness in everyday life.
The first part of the valve to be tackled is the disk. Since this valve is a flow control device, it incorporates the use of a rotating disk which serves as the passageway of the material that the valve controls. An early use of these devices was mainly in controlling the flow of water. This makes sense since the valve is designed and can definitely be used to regulate and isolate the gush of water. Nowadays, these valves are also used to regulate the flow of chemicals in certain factories and also used to control the entry and exit of air in a carburetor of a car.
Typically, this valve has four main components, namely: the body, seat, operator or valve handle, and disk. High performance valves like this usually have a body that would usually fit in between two pipes. Most common body designs are the lug and the wafer. The lug type has these protruding lugs that provide bolt holes, while the wafer type does not have these protrusions and instead, is placed in between the pipes flanges and this in turn surrounds the bolt holes. Both types have their equal share of advantages and disadvantages. The wafer type costs less, but this design does not transfer the weight of the piping system directly through the body. And the lug type is more expensive, but allows removal of downstream piping.
Next up on the list is the seat of the valve. This seat utilizes the interference fit between the edge of the disk and the seat to provide shutoff for the valve. The seat may either be bonded to the body or locked in. The materials of these are usually made out of polymers or in some cases, out of metal. Having these metal seats would allow resistance up to a higher temperature.
The disk, as illustrated earlier, acts as a passageway for the valve. Many variations and attempted experiments on improving the disk have showed capabilities such as improving the rotation of the disk and quality of the disk itself and sealing and increasing the level of torque. Last but not the least is the operator or the valve handle. Obviously, this is used to operate the valve in increasing or decreasing the flow. This is an important component since without this; the butterfly valve would not be much a valve, would it?