Butterfly Valve Working Principle

[Mike]

A butterfly valve is a valve that can be used for isolating or regulating flow. The closing mechanism takes the form of a disk.

Operation is similar to that of a ball valve, which allows for quick shut off.

Butterfly valves are generally favored because they are lower in cost than other valve designs as well as being lighter in weight, meaning less support is required.

Butterfly Valve

The disc is positioned in the center of the pipe; passing through the disc is a rod connected to an actuator on the outside of the valve. Rotating the actuator turns the disc either parallel or perpendicular to the flow.

Unlike a ball valve, the disc is always present within the flow; therefore a pressure drop is always induced in the flow, regardless of valve position.

A butterfly valve is from a family of valves called quarter-turn valves. The butterfly is a metal disc mounted on a rod. When the valve is closed, the disc is turned so that it completely blocks off the passageway.

When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.

There are different kinds of butterfly valves, each adapted for different pressures and different usages. The resilient butterfly valve, which uses the flexibility of rubber, has the lowest pressure rating.

The high performance butterfly valve, used in slightly higher-pressure systems, features a slight offset in the way the disc is positioned, which increases the valve’s sealing ability and decreases its tendency to wear.

The valve best suited for high-pressure systems is the triple offset butterfly valve, which uses a metal seat, and is therefore able to withstand a greater amount of pressure.

Types

1. Concentric butterfly valves – this type of valve has a resilient rubber seat with a metal disc.
2. Doubly-eccentric butterfly valves (high-performance butterfly valves or double-offset butterfly valves) – different type of materials is used for seat and disc.
3. Triply-eccentric butterfly valves (triple-offset butterfly valves) – the seats are either laminated or solid metal seat design.

More info -

Butterfly Valves Construction, Types, Stem & Bonnet Assembly

[vignesh]

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.

When it comes to ordering butterfly valves for your specific application, you want to make sure that you are ordering from reputable and experienced company such as Valtorc International. Before you order, please know what element(s) you are dealing with, know the size needed, type of material and pressure flow, if possible. We can offer an assortment of trim features to ensure a perfect match for your particular valve needs.