Need To Know About Pressure Relief Butterfly Valve Castings

Pressure relief butterfly valves are flow controlling devices which isolate or regulate the flow of any fluid. Its closing mechanism is a rotating disk, unlike the ball valve. With its expanding usage throughout different industries, butterfly valve castings are very high in demand, globally. So, let’s take a quick look at the basics of these valves to understand their relevance.

How does it operate?

The basic principle of operation is identical to that of a ball valve, which allows for a quick shut off of flow. But usually people are more biased towards the former because of their comparatively lower cost than the latter. In addition, butterfly valves are lighter in weight, hence requiring much less support. A butterfly valve’s basic functioning design is:

• A disc is placed at the centre of a pipe.
• A rod passes through that disc to an actuator placed outside of the valve.
• By rotating the actuator, the disc can be turned parallel or perpendicular to the flow.
• Unlike the ball valve, due to the constant presence of the disc within the flow, there is a pressure drop induced even when open.

The butterfly valve belongs to the group of quarter-turn valves. While operating, the valve completely opens or closes with the rotation of a quarter turn of the disc. The “butterfly” comprises nothing but a disc made of metal, which is placed on a rod. The disc is twisted at the time the when the valve remains closed and this ends up blocking out the passageway, whereas, when completely open, the disc on the valve gets a quarter turn rotation, to allow the fluid flow in an unhindered manner. The valve can be opened in a gradual increasing method, to enable throttle of the flow.

Different Kinds of Butterfly Valves

There are different kinds of butterfly valves available to suit different pressures and usages. The most common kinds are-

• Wafer-style butterfly valve: This type of butterfly valve has a designed to keep up a blockage against pressure gap that is bi-directional, to stop it from flowing back in systems that are meant to have unidirectional flow.
• Lug-style butterfly valve: In these types of valves, both ends of the body have threaded inclusions which enable installation of the valves into a system that has just two bolt sets, without any nuts. This setup allows either sides of the piping arrangement to be disconnected without affecting the other side.
• Rotary Valve: These kinds of valves comprise a variation of the basic butterfly valve where pockets are included in the butterfly as an alternative to being flat.

Usage of Butterfly Valves in Industries

• Butterfly valves are frequently used in the chemical, pharmaceutical as well as the food industry.
• These valves are also used by firefighters on their hoses to limit their pressure.
• These are also abundantly used on front and rear suction ports, tanks and water pumps.
• In case of specific valves, it is possible that the valve may perform additional functions; e.g.-cast iron butterfly valves not only act as a regulatory device but can actually stop and start the flow as desired.

Due to its low cost, high functioning and simplicity of installation, butterfly valves have been replacing ball valves in their several usages (like the petroleum industry). But it is important to make sure that the valves used in these industries are manufactured according to the CGMP (Current Good Manufacturing Practice) guidelines. In different industries, butterfly valve castings are preferred and appreciated alike, by virtue of their efficiency and simplistic design.