Butterfly Valve |

What Are Butterfly Valves?

A butterfly valve is a shut-off valve with a relatively simple construction. In closed position, the disc blocks the valve bore while in open position, the disc is turned to allow flow. A quarter turn takes the valve from fully open to fully closed position, or opposite, and thus the butterfly valve allows for quick opening and closure.

Butterfly valves have many advantages over other types of valves, such as an economic design that is built of fewer parts which makes it easy to maintain and repair.

Butterfly Valve Advantages

Easy and fast-opening : One of the major advantages of using butterfly valves is that it offers complete closure or opening of the valve. The function can further be simplified by using a gearbox which can be attached to the stem of the valve.
Highly Economical : The design of the butterfly valves requires fewer materials; hence the cost incurred in manufacturing is less. Comparatively, the wafer type design is less costly than the lug type design.
Compact Design : Due to the compact design, butterfly valve designs do not require much space when compared with the other types of valves.
Better reliability : Butterfly valves are well-accepted by various industries because it needs reduced maintenance. It has a longer life than other types of valves and therefore the direct operating cost is reduced.

Butterfly Valve Working Principle

Components of Butterfly Valve

A - Bushing

B - O-ring

C- Stem / Shaft:
Valve shafts, also known as stems, are the components that connect the disc to the actuator mechanism and transmit torque through themselves.

D - Disc:
There is a disc attached to the valve body that acts as a gate to stop or throttle fluid flow; this can be compared to a gate on a gate valve or a ball on a ball valve. Bores are usually cut into the disc so that the stem, or shaft, can be received. In order to enhance flow, sealing, and/or operating torque conditions, many variations in disc design, orientation, and material are available.

E- Seat:
Seen as a lining to the internal body of the butterfly valve, the seat is a type of rubber (EPDM, NBR, FKM, etc.) or metallic seal for preventing leakages. The design of the butterfly valve seat may differ from different manufacturers. It may even be locked, pressed, or bonded into the body of the valve.

F- Body:
Located between the pipe flanges, the body of the butterfly valve holds all the other parts of the butterfly valve in place. It can fit two pipe flanges —— flanged, lug, and wafer connections are the most common.

Applications of Butterfly Valve

Butterfly valves are present in almost all industries that need flow control.
These could be the following:

Steam
Chemical
Plumbing
Marine
Sea Wafer
Slurry Application
Water Supply
Wastewater Treatment
Hydro Power Plant
Corrosive Applications
Oil and Gas Industries
Fuel Handling Systems
Cooling and Circulating Water
Agricultural Irrigation

Butterfly Valve Types By Valve Body Design

Wafer Type Butterfly Valve — Concentric Butterfly Valve

Wafer butterfly valves are designed to be installed between flanges, with a short face-to-face dimension in relation to the pipeline diameter. These valves cannot be used for dead-end service, which requires additional isolation valves when shut down for maintenance. Wafer options are lighter and cheaper than lug style and often used in lower pressure applications.

Lug Type Butterfly Valve — Double Eccentric Butterfly Valve

Lug butterfly valves are designed to be bolted to one or both flanges using fasteners threaded into lug protrusions on the valve body, with a short face-to-face dimension in relation to the pipeline diameter. These valves can also be used in dead-end service depending on seat design but may be de-rated and can be heavier than wafer style.

Double Flange Butterfly Valve — Triple Eccentric Butterfly Valve

Double flanged butterfly valves are designed with flanges on both ends of the body to secure the valve to mating flanges on the pipe with bolts or studs and nuts. They can be used in dead-end service; Double-flanged butterfly valves are more popular in butterfly valves with larger sizing.

Butterfly Valve Types By Material

{}Flange butterfly valve

Flange butterfly valve bronze disc used for seawater.

Flange butterfly valve ny

Flange butterfly valve nylon disc

Worm gear flange butterfl

Worm gear flange butterfly valve, a good flange butterfly valve

Butterfly valve EPDM coat

Butterfly valve EPDM coated disc can be used for sea water

Electric flange butterfly

Electric flange butterfly valve is a automatic butterfly valve.

Stainless steel flange bu

Stainless steel flange butterfly valve use for sea water.

Butterfly Valve Types By Actuation

Manual Butterfly Valve

Manual butterfly valves are of two types: lever handle and gear butterfly valves but the basic process of usage remains the same. Manual operating valves are used in smaller spaces and systems to effectively regulate media flow.

Automatic Butterfly Valve

Automated butterfly valves are divided into electric butterfly valves and pneumatic butterfly valves, remote control valve, allowing you to implement automation applications more easily and quickly, and improve production efficiency.

Butterfly Valve Types By Disc Closure Design

Concentric / Zero Offset Butterfly Valve

In the concentric valve design, the stem passes through the center of the gate into the pipe bore which is also located at the center of the valve. To seal the flow, concentric valves should have a very flexible seat rubber because the disk touches the seat first when rotated in a quarter turn.

Since the disk and the seat are always in contact, the body of the valve is less prone to corrosion as the media flows. It only touches the seat that acts like a sleeve.

The concentric butterfly valve is regular or widely used. Low-pressure applications are typical uses of this valve. These valves are also known as a central butterfly valve, centrerline butterfly valve, resilient seated butterfly valve, rubber seated butterfly valve, or soft seated butterfly valve.

Double Eccentric / Double Offset Butterfly Valve

In double offset butterfly valves, the stem axis is offset behind the centerline of the seat and the body (first offset), then the stem axis is further offset from the vertical centerline of the valve (second offset). When the disc is opened, the seat is lifted from the seal; this reduces the friction during the first and last 10 degrees of the valve opening and closing, respectively. This results in a smoother valve operation, better sealing capability, and longer service life than the zero offset butterfly valve.

Like zero offset butterfly valves, double offset butterfly valves use a soft seat. They are available in moderate pressure and temperatures ratings, which are capable of withstanding higher pressures and temperatures than the zero offset butterfly valves in liquid and gas pipelines.

Double offset butterfly valves are typically used in water purification, wastewater treatment, HVAC, and fire protection systems.

Triple Eccentric / Triple Offset Butterfly valve

In triple offset butterfly valves, an angular offset in the body sealing cone axis is made in addition to the first two offsets (third offset). This is accomplished by using the right-angled conical profile of the seat coupled with a matching profile at the disc edge. This offset eliminates the contact of the seat and the disc during valve opening and closing, hence, friction is also eliminated. Contact only occurs during the full closure of the butterfly valve; this also acts as a mechanical stop to prevent the disc from rotating further.

The design of triple offset butterfly valves requires the use of metal seats. they can withstand high temperatures and high fluid pressures; this minimizes valve wear, longer life.

Triple offset butterfly valves are ideal in handling high-pressure and superheated steam, high-temperature liquids and gases, and corrosive chemicals that cannot be handled by butterfly valves with soft seats.

Difference between concentric, double-offset, and the triple-offset butterfly valve

Concentric (Zero-Offset) : The shaft is located in the center of the disc.

Double-Offset : The shaft is offset form its body center line + shaft offset form pipe center line.

Tripple-Offset : The shaft is offset form ites body center line + shaft offset form pipe center line + conical offset shape in its seal and disc connection.

Butterfly Valve Types By Seat

Butterfly valves can be metal-to-metal seated, soft seated, or with a fully lined body and disc.

Soft or Resilient Seated Butterfly Valves

Resilient seated butterfly valve (also known as concentric butterfly valve). The stem is centred in the middle of the valve disc, exerting a high degree of contact with the rubber seat to effect a seal, for all industries with less critical applications and low pressure systems. The seat material may be made from a wide variety of various elastomers or polymers, such as EPDM, Buna-N, PTFE(Teflon)/RPTFE, VITON, etc.

Metal Hard Seated Butterfly Valves

Between the body and the flavor of metal seated butterfly valves use a sealing surface made of metal.triple offset design to prevent seat wear, superior performance, lower maintenance, and a longer life for your valves. Mainly used in industries that work under extreme pressure and temperatures.

Considerations When Buying Butterfly Valves

There are many factors to consider when buying industrial butterfly valves.

Flow Medium

Perhaps this is the most important consideration. The media that flows through the valve greatly affects the lifespan of the valve. Furthermore, the wrong kind of media may cause damage to the valve. Some media are corrosive, others are abrasive.
Some have high-pressure levels while others have low temperatures. Knowing the media and how it works with the valve material is an important consideration.

Pipe Considerations

Butterfly valves should be able to handle the weight of the piping system：The valve diameter with the same size as the pipes can withstand high pressure. But when the valve diameter is smaller than the pipe’s, there is the tendency for the valve to bend. The bending may cause external and internal leakage.

Materials Used

The material of the valve body, disc, and seat should be able to withstand the corrosiveness of the passing medium. For example, use corrosion-resistant materials if the media is acidic. High-pressure media uses valves made of an alloy that can resist high temperature and pressure levels.
Choosing the wrong kind of material means shorter valve lifespan.

Actuation

Whether manual actuation is the best option or not, actuation is also a factor worth considering. Process pipelines require large valves. Manual actuation is not suited for a large valve. Instead, use pneumatic or automated valves.

End Connections

The end connections of the valves often follow that of the pipe. Having said that, compatibility is of the two is vital. A flanged end valve is not the required one when the pipe employs a thread.

Industry Standards

Butterfly valves follow certain standards. With that in mind, there are standards for the material of the valve. There are standards for the end connections. It is important that butterfly valves follow the rigid regulations imposed by international bodies. This ensures safety and proper valve installation.

Choose Reliable Butterfly Valve Manufacturers

Choose reliable butterfly valve manufacturers is the focal point when thinking of buying industrial butterfly valves.
High quality butterfly valve manufacturer should provide the customer with the right valve. Responsible for informing the customer about the industry standards and other considerations. He should be able to provide the right product with the right price point. He should also aware of customer needs, the right type of valve for a particular industrial application,Save costs, save time, and provide perfect product after-sales service.

Whether you are looking for manufacturers of butterfly valves, high performance butterfly valves, and butterfly valves of every type, VALFLO is the premier source for you.
As one of the leading butterfly valve manufacturers in China, VALFLO VALVE exports best-quality butterfly valves at the competitive rates.
Request A free quote: sale@valflovalve.com

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