An Introduction To Butterfly Valves

The butterfly valve belongs to a larger valve family, the quarter-turn valves. The “butterfly” part of the name derives from mounting a metal disc on a rod. The valve is closed by turning the disc and thus blocking the passageway the valve is set in. To open the valve, the disc is rotated by a quarter-turn, creating a nearly-straight shot for fluid to pass through. Most butterfly valves have a notch plate. This allows you to throttle the flow of fluid by opening the valve to a fixed increment. Notch plates typically offer you 10-12 different positions.

Butterfly valves are manufactured with a range of different features. Actuator styles, disc materials, seals, end configurations, and more can be modified to suit the intended use of the valve. Many different industries rely on butterfly valves. They can be found in industrial processing plants, water handling plants, paper mills, dry bulk conveying, food and beverage production, transportation, HVAC, and more.

The Butterfly Valve Advantages

While they share many qualities with ball valves, butterfly valves offer some distinct advantages to them. Butterfly valves are compact. With the right actuation (such as pneumatics), they can open and close with lightning speed. Discs are lighter than balls, and the resultant valve is lighter and easier to support. This means for a given diameter, a butterfly valve will be lighter than an equivalent ball valve. Butterfly valves also deliver noteworthy precision. Maintenance requirements are minimal.

 Potential Drawbacks Of Butterfly Valves

Because of its inherent design principles, a butterfly valve will always present some portion of its disc to the flow of liquid, even at its fully open position. This means that a pressure switch at the valve is unavoidable.

 Operation Of Butterfly Valves: Electronic, Manual, Pneumatic

Most butterfly valves are actuated in one of three ways: electronically, manually, or pneumatically. Pneumatic operation is the fastest. In an electronic valve, operation relies on signals sent to the gearbox. Butterfly valves can be either single or double-actuated, especially when they are pneumatic. In a single-actuated valve, the valve defaults to a closed position and requires a signal to open. If power is lost, it defaults to full closure. A double-actuated valve is one that lacks this feature; both opening and closing require an explicit signal.

Butterfly valves, particularly automated pneumatic ones, are highly durable and reliable. Valve lifetime is extended thanks to minimal wear. That means lower operating costs thanks to the valves’ minimal maintenance requirements.

For more in-depth information on butterfly valves, consider the topics addressed in the following articles: