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Butterfly Valve

» Butterfly Valve

Butterfly Valve

NTGD is an industrial butterfly valve manufacturer selling four types of butterfly valves. Our valve factory produces high-performance metal seals and butterfly valves for high-pressure industrial applications.

NTGD is also a provider of two types of eccentric butterfly valves, the double and triple eccentric. The double eccentric form is mostly used in power generation and petrochemical applications, while the triple eccentric is used in more demanding industrial applications.

The butterfly valve comes from the family of the quarter-turn valve. It is named for its butterfly disk, which serves as a gate to open or shut the valve. The butterfly valve looks identical to the ball valve. The benefits of NTGD butterfly valves include reliability, simple working, and fewer maintenance needs.

TRIPLE OFFSET BUTTERFLY VALVE

 

Definite Guide to Butterfly Valves

The butterfly valve is a flow control device that utilizes a rotary disk to control the flow medium in a system. Disk stays in the passage but because it’s very thin, offers very less resistance to the flow.

Butterfly valve technology has grown significantly over the last half-century, and also its industrial popularity. This popularity is due to its quarter-turn operation, the tight closure, and its availability in a variety of design materials and sizes.

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.   The wafer-design body and comparatively lightweight minimize the expense and installation cost, equipment, piping support, labor, and time of installation.

 

What Are Butterfly Valves Used For?

Initially, butterfly valves are used for water applications only, but improvements in designs and materials have made it possible for them to be used in growing industrial fluid applications. Nowadays, butterfly valves can be used in almost any plant handling many fluids.

Some of the industrial applications for which Butterfly valves are used, are Supply of water, wastewater treatment, Lube System, Fire protection services, Food processing, pharmaceuticals, and many more.

 

Butterfly Valve Parts

  • Body: The valve body houses the operating parts of the valve and is built to fit in between the flanges of the pipe systems. There are various body shapes whose variations are discussed further. Lug and wafer are the most common body styles.
  • Disc: The disk is the flow closure component of the butterfly valve. Many changes in disk design have emerged relative to disk and stem alignment to enhance flow, sealing, and operational torque.

The disk is similar to a plug, or a ball. Rotating the disk with a one-quarter or 90-degree turn opens and shuts the butterfly valve.

  • Stem: The stem attaches the disk to the actuator, also called the wheel or the handle. The stem transmits the rotation of the handle to the disk. The actuator cannot manually open or shut the disk without it.

The stem is shielded from the media in most resilient seated projects, allowing for effective material selection in terms of cost and mechanical properties.

In high-performance designs, the stems are in contact with the media and must thus be compliant and have the requisite strength for seating and disk removal from the bench.

  • Seat: A resilient butterfly valve employs an interference fit between the disk outer edge and the seat to ensure shutdown. The seat material may be made from a wide variety of various elastomers or polymers. The seat may be fixed to the body or it may be pushed or locked.

In the case of high-performance butterfly valves, the sealing can be created by an interference-fit seat or a line-energized seat design, where the pressure within the pipe helps it to maximize the interference between the seat and the disk outer edge. The commonly used seat materials are polytetrafluoroethylene (PTFE) or reinforced PTFE (RTFE) due to a broader functionality and temperature range.

Metal seats are also provided in high-performance butterfly valves. These metal seats facilitate the use of a butterfly valve at a much higher temp. up to 1,000 degrees, F. Fire-safe variants are also provided that include the shut-off of the valve well before a fire, and the metal seal ensures sealing during and after a fire.

  • Actuator: The actuator is a mechanical device used to move or control a process or system. An actuator as part of an actuated butterfly valve is generally a mechanical system that takes energy, normally produced by air, electricity, or liquid, and transforms it into some kind of motion.

There are three main designs when it comes to actuator failure:

  • Fail Open is used to prevent overpressure when there is a loss in pressure.
  • Fail closed design is used in steam injection wells to prevent uncontrolled seam as it is extremely dangerous.
  • Fail in place is utilized where at the time of actuator failure, the processes cannot be shutdown.

 

How Does a Butterfly Valve Work

A butterfly valve is one of the quarter turns valves that are used for shut-off or regulating services when placed in a pipeline. They house a ‘butterfly’ or a disc that looks like a butterfly that is connected to a stem rod which rotated the disc to close the valve when it is turned to a position perpendicular to the flow.

 

Consideration While Buying The Butterfly Valves

When choosing a butterfly valve for your service, you will need to decide a few things before you check the technical specs of the valve. These specific details are the application of the valve, the type of fluid, the mode of operation, and the mode of installation listed below.

  • Application of butterfly valves decides a type of valve that should be employed for the given work, check if the valve is to be used for control or restrict the flow.
  • A fluid that is to be used in the system: Butterfly valve can handle liquids or gases and not the bulk solids. You need to know the property of the medium if it’s corrosive in nature or not, so for this, the body material of the valve should be stainless steel and for normal uses like water, carbon steel, or cheaper alloys can be used.
  • You also need to know about the Mode of Operation that is how you want to operate the valve. Operations of the valve can be manual, semi-automatic, or fully automatic. This can be considered after knowing the location and accessibility of the valve.
  • Some more consideration before you choose a perfect valve for your use is capacity, Level of precision, operating life, and pressure drop.

 

Butterfly Valve Types By Body Design

  • Lug Butterfly valve: The lug body has outward projecting lugs to have bolt holes that complement those in the pipe flange. Lug type valve can be utilized for dead-end services or can also work without downstream piping.

LUG TYPE BUTTERFLY VALVE

  • Wafer Butterfly Valve: The wafer body has no lugs. The wafer valve is located or you can say that it’s sandwiched between the flanges of the pipe and the flange bolts circle the body. In Wafer type bodyweight of the piping is not directly transferred to the valve and wafer type valve is less expensive than a lug type valve.

WAFER TYPE BUTTERFLY VALVE

  • Flanged Butterfly valve: The end connection of this type butterfly valve is flange, which is according to standard ASME or DIN

FLANGED TYPE BUTTERFLY VALVE

 

Butterfly Valve Types By Disc Closure Design

  • Concentric Butterfly Valve: The concentric butterfly valve is regular or widely used. The shaft is situated in the middle of the plate. During opening or closure, there are portions of the disk that are either in-contact or touching the seat.

Low-pressure applications are typical uses of this valve. These valves are also known as a central butterfly valve, a centreline butterfly valve, or a resilient-sealed valve.

CONCENTRIC BUTTERFLY VALVE

  • Double Offset Butterfly Valve: The double eccentric butterfly valve has 2 offset valves compared to the concentric butterfly valve. The first offset is the shaft which is located not in the middle of the disk, but behind the disk. This offset would allow the valve to have a continuous sealing surface on the disk.

The second offset is the shaft positioned not in the middle line of the piping, but slightly to the right side of the centerline. This arrangement would make the seat feel less pressure than the concentric butterfly valve and therefore extend its life.

DOUBLE OFFSET BUTTERFLY VALVE

  • Triple Offset Butterfly valve: The triple eccentric butterfly valve is a 3 offset valve compared to the concentric butterfly valve. Much as a double offset butterfly valve with 2 offsets, this triple offset also has the same offset except that it has one extra offset which is a conical form bench. This conical-shaped bench would complement the disk that has already been manufactured to match the seat.

TRIPLE OFFSET BUTTERFLY VALVE

This arrangement would mean that the seat does not have pressure or friction when closing or opening. This arrangement would therefore result in the valve having a bubble-tight application and a much longer life than a double-offset butterfly valve. 

 

Butterfly Valve By The Material

  • PVC Butterfly Valve: PVC butterfly valves are now commonly used as they are cost-effective. They can be lightweight, but this type of material also has a high structural capability, making them suitable for applications with low to moderate strain. PVC will not react to most fluids and gases, compared to metal materials which give a prolonged lifespan.
  • Cast iron Butterfly Valve: If metal is a commodity choice, cast iron is a popular choice for industrial applications. Compared to PVC, cast iron can handle higher temperatures and pressure conditions, making it a safer option for industrial applications.

 

Butterfly Valve Types By Actuation

There are two ways by which a Butterfly valve can be operated i.e. Manually (using a lever or a handle) or Automatically (using an actuator). These actuators can work using electrical power, hydraulic, or using pressurized air.

  • Electric Butterfly valve: An electric actuator is used to operate the valve here. An electrical actuator is a mechanical system used to transform electricity into kinetic energy in a single linear or rotational movement.
  • Hydraulic Butterfly valve: Hydraulic actuators are used when a large amount of force is required to operate a valve. The main design for the hydraulic actuator is a piston-type design.
  • Pneumatic Butterfly valve: Pneumatic actuators are generally used to monitor processes requiring a fast and precise action since they do not need a significant amount of motivating force.

 

Difference Between Butterfly Valve And Ball Valve

Butterfly valves are cost-effective and usually smaller than other types of valves. A butterfly valve with a wide diameter pipe is way smaller than the equivalent of the ball valve.

Butterfly valves do not close as fully as ball valves and are not used to regulate the flow of gas. Ball valves show a reliable seal.

In high-pressure systems, the ball valve can have superior cutting properties as well as little difficulties in rotating or requiring a pressure balancing scheme.

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    NTGD Valve (China) Co. LTD
    North Avenue Zhuqu Town ,Weishi County, Kaifeng, Henan,P.R.China
    Email: sales@ntgdvalve.com
    Website:www.ntgdvalve.com

    NTGD Valve (UK) Co. LTD
    ADD.: 19,King Street, Gillingham, England ME7 1EO
    Email: sales@ntgd.co.uk