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What Is a Butterfly Valve?

    VW Butterfly Valves are the best solution to intercept pneumatically or gravity-fed dry powders or granules within various bulk solids handling and processing facilities.

    VW Butterfly Valves consist of an individual block made of die-cast aluminum and carbon or stainless steel disc with shafts and a sealing elastomer. An adjusting lever or electric or pneumatic actuators can be connected to the valve. The three WAM-type actuators can be fully interchangeable. The driveshaft can be interchanged (standard: DIN 5482; alternative: ISO 5211), and universal connections to different sizes of flanges lead to a variety of designs.

    Is a butterfly valve a valve?

    Butterfly valves are shut-off valves with a reasonably simple design. When closed, the disc block the valve bore, while in the open position, the disc rotates to let flow. A quarter turn can take off the valve utterly open to closed, or the opposite so that the butterfly valve can allow rapid opening and closing.

    Resilient Seated Valves

    A butterfly valve that is seated and resilient features a rubber seat between the outside dimension of the disc and the inside walls of the valve. The seat is connected mechanically to the valve’s body, and the disc is an interfering fit with the seat when it is in when it is closed. The valves have an automatic shut-off feature and can take on more pressures. Common ways the seat is connected to the body include dovetail joint chairs or cartridge seats. They also have a bonded seat.

    Design for Disc Closure

    In this class, two types of valves are concentric and eccentric. This classification is based on the position of the stem about the disc and the angle at which the disc shuts.

    However, the shaft of an eccentric butterfly valve does not travel through the disc’s centerline; instead, it is placed in the background. Eccentric valves can be classified into double-offset, single-offset, triple-offset, and single-offset valves. These are made to decrease the disc contact and seal until the valve has been completely shut. The aim is to extend the service life of the valve.

    The triple offset model is the most efficient of all three and is employed in critical situations. In general, eccentric valves have higher pressure ratings, and they are more prone to wear.

    Dovetail Seats

    Dovetail connections are made by using a male dovetail made by casting or machining into the wall surrounding the valve. The seat is fitted with a female dovetail formed inside its diameter, which can be inserted onto the male dovetail of the body. When compressed by two pipe fittings, the seat is locked in its place. This seat design should not be used for vacuum applications because the seat isn’t bonded to the body and may be removed and away from the body. This may cause the disc to squeeze and cut through the seating while shutting the valve.

    Cartridge Seats

    The seats with cartridge designs are made of a solid metallic or phenolic resin circle molded into the seat. The inside of the valve and the outer dimension of the seating area are smooth. The inside wall’s diameter is less than the external dimension of the seat. The seat is pressed against the body and is secured by this interference fit. Cartridge seats can be able to handle higher pressures than dovetail seating and also work in vacuum applications.

    Bonded Seals

    Bonded seats are either glued or injected into the body. They cannot be repaired if the seat wears out or is damaged. They can make the most significant pressure and vacuum of rubber-seated valves. Often, they are also the most affordable flexible butterfly valves.

    Building a Butterfly valve body

    The body of a butterfly valve is different. The most affordable is the wafer design fitted between two pipeline flanges. A different type is the lug wafer model is secured between the two pipe flanges using bolts that connect the two flanges and then pass through holes within the valve’s casing. Butterfly valves can be found with flanged ends that are conventional to bolt onto pipe flanges and threaded ends.

    What are the different types of BUTTERFLY VALVES?


    The distinctive design of triple offset valves can prevent galling and scratches between the seat of the metal and the disc made of metal. The seal will only contact the seating at the time of total closure. Triple offset valves are typically used in areas that require bi-directional shut-off. For instance, they are used in oil and gas Chemical factories, LNG/NPG terminals, as well as tanks, and shipbuilding. They can also be used for heavy or dirty oil to avoid extrusion.


    Butterfly valves made of wafers have been made to keep a seal against bi-directional pressure differentials to avoid backflow in systems intended to flow in a single direction. This is accomplished with an extremely tight seal, for example, a gasket, an o-ring that is precision machined, and a smooth valve face on both the upstream and downstream faces of the valve.


    Lugged butterfly valves feature threaded inserts on both ends of the valve body, allowing the valve to be installed with two sets of bolts but no nuts. The valve is positioned between two flanges, using an individual set of bolts per flange. This allows any part of the piping system to be removed without disrupting the opposite side.

    Lush butterfly valves used in dead-end services generally have a lower pressure rating. A butterfly valve that is lugged between two flanges will carry 150 psi of pressure. However, the same valve mounted to one flange will be rated at 75 psi for dead-end service.


    Butterfly valves are among the most frequently used valves on the marketplace due to their plethora of efficiency, low cost, and easy operation. In the absence of high-pressure applications and in situations where the flow capacity must be maintained at a certain level, butterfly valves could nearly always substitute ball valves.

    The industries in which butterfly valves can be used are food, pharma and chemical, water supply, and fuel handling. Their bigger sizes make them suitable for handling slurries and other low-pressure liquids that contain massive amounts of solids.

    When choosing a butterfly valve, you must be aware of your particular requirements and specific applications. When possible, get expert advice when navigating the market to avoid errors.

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