What Are Butterfly Valves?

7 October

What is a butterfly valve?

Simply put, it’s a valve with a design that resembles a butterfly’s wings. In the centre of a butterfly valve, there’s a large rotating disc—often stainless steel in FlowCon IVC valves—which controls the flow of liquid or gas.

How does a butterfly valve work?

There are three common butterfly valve types based on how they are operated:

• Lever – A manual squeezable lever rotates the disc a quarter turn to open the valve. This operation suits only smaller butterfly valves (up to DN150), since larger ones become difficult to open manually.

• Gear – A gearbox with a protruding wheel is fitted on top of the valve. Like a steering wheel, it’s rotated to operate larger valves with less effort.

• Actuator – An actuated butterfly valve uses a control system to send signals to an internal motor, which adjusts the aperture to open or close the valve automatically.

These three types of butterfly valves allow flexible operation depending on system design and user requirements.

What is the difference between semi-lugged and fully lugged butterfly valves?

This refers to the shape of the body, where you’ll find “lugs”. These are looped tags on the edge of the body. A semi-lugged valve from FloControl will have four lugs, two each near the top and bottom of the disc. These are more suited to the middle of a pipeline, as it can only be bolted between two flanges. A fully lugged valve has eight lugs and is more suited to the end of a pipeline. If a semi-lugged valve is fitted to the end of a pipe without another flanged pipe being attached, it will fall off.

Where are butterfly valves commonly used?

Butterfly valves are found in a huge variety of projects, and are a big part in controlling the flow of liquid or gas. We at FloControl provide them largely for hydronic systems with HVAC (heating, ventilation and air conditioning) systems being big users of FlowCon IVC butterfly valves. You’ll also use them regularly if you work in construction of the oil and gas industry, fire protection industry, and marine industry. Anything that requires precise control of large scale liquids or gas will deal with butterfly valves.

How do I select the right size and material for my butterfly valve?

The size of the butterfly valve refers to the size of the disc. For example, a DN65 butterfly valve will fit onto the flanged end of a DN65 pipe, so while the disc itself measures 65mm across, the body of the valve is much larger. Always refer to the data sheets for exact measurements to ensure it will fit in your system.

The material of our butterfly valves is generally a ductile iron body with a stainless steel disc, but make sure to check the data sheets as it can very. In some instances we use cast iron as this is good for low-pressure HVAC systems but we have moved most of the products to a stronger ductile iron body.

Can butterfly valves be used for both on/off and throttling applications?

Yes. Actuated butterfly valves are able to do this automatically and make minute adjustments to the valve to allow for effective throttling. But manual valves also have this functionality. On the lever-controlled butterfly valve, for example, there is a metal notched disc under the handle, and you can stop at any point in your turn and slot the lever into an angle. This can then be locked in place with additional parts. Check the data sheets for flow rates to make sure you can get your desired output. You will find our actuated butterfly valves in our Control Valves range.

FAQS

What is a butterfly valve and how does it work?

A butterfly valve uses a rotating disc to control fluid flow. When turned, the disc either blocks or allows passage, regulating flow in both manual and automated systems.

What are the main types of butterfly valves?

The most common types of butterfly valves include lever-operated, gear-operated, and actuated butterfly valves. Each type is used based on system needs and size.

What is a butterfly valve used for in HVAC systems?

In HVAC systems, a butterfly valve is used to regulate water or air flow, offering precise control in heating and cooling processes.

How does a semi lugged butterfly valve differ from a fully lugged one?

A semi lugged butterfly valve is installed between two pipe flanges, while a fully lugged butterfly valve has additional lugs allowing it to be mounted at the pipe end.

Can butterfly valves be used for throttling?

Yes, both manual and actuated butterfly valves are suitable for throttling applications, making them versatile for various flow control needs.

Are there different materials used in butterfly valves?

Yes. Butterfly valves can be made from ductile iron, stainless steel, or cast iron, depending on pressure levels and application.

What are butterfly valve types commonly found in industrial applications?

Industrial systems often use butterfly valve types like lug-style, wafer-style, and flanged valves, depending on the piping layout and system design.

What size butterfly valve should I choose?

Choose a butterfly valve size based on pipe diameter and flow requirements. Always refer to technical data sheets for accurate fitting.

Can a butterfly valve be installed in any orientation?

Generally, yes. However, the valve should be installed as per manufacturer recommendations to ensure optimal performance and avoid wear.

Do butterfly valves support automated control?

Yes. Actuated butterfly valves are widely used in systems that require automation for precision, such as HVAC, fire safety, and industrial flow control.

I’ve got so many more questions!

Get in touch with our technical team or our sales team on the Contact page and we’ll happily help you out with any additional questions you might have about the intricate workings of our butterfly valves and whether they are suitable for your project.