Butterfly Valves

What is a butterfly valve used for?

Butterfly valves are used to regulate and throttle process flow in a partial, fully open or closed position. Butterfly valves are a popular choice when space is limited.

How do butterfly valves work?

Butterfly valves are operated by either a lever, gear operator, electric or pneumatic actuators. There is a stem with a disc (commonly made out of stainless steel) connected to it and the valve opens and closes when the stem rotates. A butterfly valve disc is always present in the process flow even in an open position, so a pressure drop will always occur.

What type of valve is a butterfly valve?

Butterfly valves come from a family of valves called “quarter turn” valves. Meaning that it only requires a quarter turn to fully open or close a butterfly valve. This makes them particularly easy and economical to actuate.

What is the difference between ball valve and butterfly valves?

A butterfly valve and ball valve are designed differently. A butterfly valve has a disk connected to a stem and a ball valve consists of a ball with a hole through it.

Do butterfly valves have a flow direction?

Butterfly valves are bi-directional meaning that the flow can go either direction through the valve. Concentric butterfly valves are bi-directional and the disc is symmetrical. Double and triple offset butterfly valves are also bi-directional however they do have a preferred direction of flow due to how the seat and disc is designed.

Can a butterfly valve be installed backwards?

It is possible to install a butterfly valve backwards as they are bi directional. Double and triple offset butterfly valves do have a preferred direction of flow so it is best to install these according to the flow direction of the pipe media.

How do I know if my butterfly valve is open or closed?

To determine whether your butterfly valve is in an open or closed position you can observe the position of the lever handle on top of the valve or an indicator on a gearbox. The lever is used to open or close the valve and when the lever is parallel to the pipe work the valve is open. When the lever is perpendicular to the pipe work the valve is in a closed position.

Why is it called a butterfly valve?

The butterfly valve gets its name from an operation similar to a butterfly. A butterfly’s wings (the disk in the valve) move around its body (the centre axis of the valve). A butterfly valve often has a cast iron body or ductile iron body. The disc materials is commonly stainless.

How many types of butterfly valves are there?

There are three main types of butterfly valves: Concentric, double offset and triple offset. Concentric butterfly valves are most commonly used in lower pressure and lower temperature applications. The type of butterfly valve you should use for best performance is dependent on the pressure, temperature and fluid. Concentric butterfly valves are best suited to low pressure. Double offset are suitable for higher pressure, while the triple offset butterfly valve is better suited for high temperature applications. When the temperature exceeds the limits of soft seats the use of a metal seated triple offset valve should be used. We stock a range of butterfly valves including wafer and lugged resilient seated variants.