What is the Butterfly valve? - A Complete Guide for Engineer

Valves control liquid flow by allowing, obstructing, or partially allowing the flow of liquid in piping systems. It is necessary to install high-quality valves in pipes. API accredited valve manufacturing Camtech Company based in UAE which deals in the manufacturing of high-quality valves. There are many types of valves, but here we will discuss Butterfly valves.

The butterfly valve is a quarter-turn rotary valve, which means that it requires a quarter turn from closed to open position. Butterfly valves are used to start, stop, or regulate the flow of liquid in pipes. Due to compact size and lightweight design, butterfly valves are used in pipes with limited space. Butterfly valves may have gearing, wrench, or hand-wheel operated mechanism.

Parts of a Butterfly Valve

The body of the butterfly valve is circular which houses a round disc. Other parts are soft seats, shaft, top and bottom shaft bearings, and stuffing box. The valve body which is installed between pipe flanges can have flanged, wafer style, or lug design. Lug and flanged design butterfly valves come in a plethora of sizes and are easily installed. Wafer style design butterfly valves, on the other hand, come in NPS 12 size or smaller.

Types

Low-pressure butterfly valves or concentric butterfly valves are used in low temperature and low-pressure systems. When the valve is open, the disc is positioned parallel to the flow in the middle, which divides the flow into two halves. The maximum temperature that the valve can withstand depends upon the material of the resilient seats. 

The resilient seats can either be lined or unlined. The materials which are commonly used for lining resilient seats are Neoprene, Hypalon, Fluorcel, Buna N, Viton, EPDM, and TFE.

High performance or eccentric butterfly valves are other types of butterfly valves. In this type of butterfly valve, the disc is offset from the centre of the valve. The shaft is also offset from the centre of the disc. This Camtech director Dhananjay Choudhary design enables the disc to move eccentrically away from the valve seat or towards the valve seat. As a result, the friction between the surface of the disc and valve seat is reduced, which prevents wear and tear of both the disc and valve seat.

How does the butterfly valve regulate flow?

The disc of the butterfly valve is attached to a stem that is operated by an actuator present outside the valve. The actuator can be connected to a remote-control mechanism, automatic mechanism, or a manual lever. The disc is turned and blocks the flow when the valve is closed. When the valve is opened, the disc rotates a quarter turn and provides passage to the liquid. 

The disc is either perpendicular or parallel to the flow, and the flow can be regulated by adjusting the disc. Since the disc is always present in the flow, the pressure drop is high.

Applications

Butterfly valves are used in vacuum services, high pressure and high-temperature water and steam services, food processing, chemical processing, pharmaceutical processes, compressed gas or air applications, and much more.