A butterfly valve controls fluid flow in a large pipe using a disc that turns in quarters. Imagine a thin metal disc that flutters like the wings of a butterfly along a fixed axis. As you open or close, the valve allows (or stops) a material to flow down a pipe. A butterfly valve has four parts – the valve body, disc, seat and stem.
The valve body:
The body of the butterfly valve holds all the other components in place. It fits into the flange of the large pipe. Generally, there are two types: wafer and lug. The prior comes with a flexible seal and prevents backflow. The latter has inserts along the circumference. It allows for bolt passages.
The material used to make a valve body varies. For instance, a corrosion-resistant valve will have stainless steel, nickel alloy or titanium alloy valve body. On the other hand, environments that are not corrosive use a carbon steel valve body.
The disc is connected to the valve body. It is the gate that restricts the flow of fluid. Like the body, the material it is made of depends on the valve application.
The seat is a strong elastomer that lines the internal part of the valve body. It can also be made of metal. The primary function of the seat is to secure the disc in place and prevent leak. A soft seat is made of rubber or O-rings. A metal seat is made of stainless steel or Inconel
The most protected part of a butterfly valve is the stem. It lies inside the disc. Think of it as a shaft that links the disc to the actuator. When the stem is initiated, it rotates. The action is then transmitted to the disc, which helps the valve open or close.
Any piping system that needs to deliver large volumes of fluids typically utilises butterfly valves in India. They are not used for dry solids because their structure is delicate. The flow of bulk solids either chokes or breaks them.