A valve that can be used for regulating or isolating the flow is called a butterfly valve. This valve is used to open or close the circular butterfly plate, which rotates with a pungent and is used as a cut-off valve. A butterfly valves manufacturers suggest that the valve can be designed to have the function of paragraph valve and adjust the disc.
The more and more used valve in the low pressure caliber pipes is cast iron butterfly valve. The closing mechanism proceeds further in the form of a disk. The operation of a butterfly valve is quite similar to that of a ball valve, which allows a quick shut off. The reason behind butterfly valves being commonly favored in the industry is that they are lower in cost as compared to the other valve designs as well as lighter in weight. Therefore, it requires less support. In the center of the pipe, the disc is positioned, through which the rod is connected to an actuator passes. The actuator, as it starts rotating, turns the disc either perpendicular or parallel to the flow. The disk is always present within the flow, which is not the case with a ball valve. Therefore, regardless of the valve position, a pressure drop is always induced in the flow.
Structure of the butterfly valves
The structure of the butterfly valve is very simple, small in size and light in weight with only a few parts in them. According to butterfly valves manufacturers, only 90-degree rotation is required for the valve to be opened and closed quickly. The electric valve, at the same time, has good fluid control characteristics. The thickness of the butterfly plate is the only resistance when the medium flows through the valve body and the valve is in a fully open position. As a result, the pressure drop generated by the valve is very small and thereby it has better flow control characteristics. When the valve is closed, the disc is turned in such a way that it fully blocks off the passageway. In case the valve is fully open, the disc is rotated with a quarter turn, hence ensuring that an almost unrestricted passage of the fluid is allowed. The valve, in some cases, may also be opened incrementally to throttle flow.
Butterfly valves are most economical for large lines in water treatment, chemical services, and fire protection systems. General sizes available of the valve are 2” to 48′, although for certain butterfly valves manufacturers sizes up to 96” are available. The butterfly valve is an economical choice for larger line sizes due to the valve design, including a small face-to-face dimension and lower weight than most of the other valve types. Face-to-face dimensions and pressure ratings of the butterfly valves are complied with ASME, which enables the valve to be easily retrofitted in line regardless of the manufacturer. The ASME pressure classes followed by most of the butterfly valves manufacturers include 150, 300, and 600# allowing a maximum pressure of 1500 psi.
Butterfly valves can be configured accordingly, i.e. it can be configured to operate either manually, electronically or pneumatically. The electronically operated valves need a signal to the gearbox to both open or close. Whereas for pneumatic valves, it can be either of the two sides – single or double actuated. Also, they operate the most rapidly amongst others. Butterfly valves also come in with different styles and shapes. Large pump lines and front suctions are two examples of butterfly valves that offer high performance across various systems. This was a detailed description concerning butterfly valves and its various operating principles, structure, and applications.