An Actionable, Introductory Guide To Butterfly Valves

When you need a low-cost valve that shuts off tightly to allow for fluid flow, a butterfly valve is the answer. But these easy-to-install valves are so much more. With this introductory guide, we help you learn the basics, from what is a butterfly valve to what applications it can be used for in India.

What Is A Butterfly Valve?

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:

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:

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 stem:

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.

Where Are Butterfly Valves Used In India?

Countless industries in India make use of butterfly valves. Just some of the niches and sectors are:

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.

Why is a butterfly valve called a quarter-turn valve? The disc of a butterfly valve rotates to 90 degrees, i.e., a quarter of a turn. That’s why these regulated rotary valves are also known as quarter-turn valves. They operate very similar to ball valves but are a bit lighter and far less costly. The direction of the flow of fluid they allow can be:

Linear
Bi-directional

Butterfly valves can run using any of the following:

a solenoid
an electric motor
a pneumatic actuator
a hydraulic piston and cylinder

What are the benefits of using butterfly valves?

Butterfly valves are one of the most affordable valves compared to others like gate valves, ball valves, side valves and others. They are also easy to handle. The benefits butterfly valves bring to you are:

They are simple to install.
The operation is swift and easy.
They offer very low-pressure loss.
They are lightweight and compact.
They require almost nil maintenance.

What Are The Major Types Of Butterfly Valves?

There are three primary types of butterfly valves based on the offset design. Although all of them perform similar functions, they are built for different operations.

Zero-offset valve

The stem of these butterfly valves has no offset. They seal due to the interference between the disc and the rubber seal at the disc edge. They are also known as rubber seated or concentric butterfly valves.
The rubber seat covers the body of the valve. It ensures that no part touches the fluid, maintaining purity. Such valves have up to 250 PSI pressure rating, the lowest possible. Their heat capacity is 204°C.

Double offset valves

So called because there are two offsets, these are high-performance valves. The offset is placed at the bore and where the body and seat seal. This makes the seal more durable, so such butterfly valves are used for large capacities and viscous mediums.

High-performance butterfly valves can withstand heat up to 648°C and have a pressure capacity of 1440 PSI. For the first 10 degrees of closing and opening, these valves have cam-action.

Triple offset valve

These valves are ideal for high-pressure systems because they have a pressure capacity of 1480 PSI and can tolerate heat up to 648°C.

Designed to work in varying environments, triple offset butterfly valves have lower emissions. The most advanced of butterfly valves, they have three offsets. Two are at the centre. The third offers cam action and conical sealing at right angles.

Conclusion:

Butterfly valves are extremely useful for industrial application. But you need reliable butterfly valve manufacturers in India to get the best possible option for you. So, before you order butterfly valves, dig into the company reputation. See if they have proper certifications. What are the price tags, and do they cover warranties? Lastly, ensure that they provide you with great after-sale services like repairs and maintenance!

Oilway valves have been manufacturing and supplying butterfly valves in India for years. Please get in touch for the best performance valves in the market!