WHAT IS A BUTTERFLY VALVE?


WHAT IS A BUTTERFLY VALVE?

There are various butterfly valves being utilized in every industry imaginable. The butterfly valve, aka quarter-turn valve, is one of the most popular and economical valves. You may not realize it, but you encounter butterfly valves on a daily basis. These valves, made of carbon steel, cast iron, stainless steel or plastic, are being utilized in many applications where assorted types of fluids, gas, air, steam are being controlled by shut-off or throttling. This valve is excellent for shut-off applications and the disk can completely block the passageway for fluids.

The body of a butterfly valve is comprised of a metal disk with a rod that runs through the disk. The rod is connected to an actuator or a manual lever which controls the disk turning it parallel or perpendicular to the flow. Depending upon the application, the disk can be made of plastic, steel, carbon steel or stainless steel. There are different options of actuators for this valve: pneumatic, electric and electro-hydraulic, manual and a gear type.

There are 3 types of butterfly valves. The standard butterfly valve is the concentric butterfly valve. The disk is metal with a rubber seat. Next, is the doubly-eccentric butterfly valve consists of various types of material for the disk and seat. This one is more of a high-performance valve. Lastly, the triply-eccentric butterfly valve (known as triple offset butterfly valve) is utilized when the application requires tight shut-off when gas or oil are involved. Being the most of expensive of the butterfly valves, the seats are typically laminated or metal in design.

Butterfly valves can be wafer or lug style. You will see wafer style valves installed when the valve is between pipe flanges. Lug style simply means that there are holes machined so that it can be bolted to the flange. These valves are typically used in HVAC applications, water systems, OEM, or irrigation for positive shut-off. Lug style will be a bit more expensive and are used at the end of the line.

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