Production Field of Flanged Butterfly Valve and Resilient Seated Gate Valve

Packing List of ZECO Valves

1. Low Resistance Silent Check Valve DN150-250

2. Resilient Seated Gate Valve DN50-250

3. Flanged Concentric Butterfly Valve DN50-200

4. Iron Gate Valve DN50-200

5. Y Strainer DN150-250

6. Flapper Swing Check Valve DN80-150

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What is a Concentric Butterfly Valve?

Also known as a concentric design, this is common in general service “resilient seated” or “rubber seated” butterfly valves. The stem and disc are centered in the seat of the valve, all of which are centered in the body of the valve. The disc is in constant contact with the seat.

An advantage of this valve is the media going through the valve will not contact the body, since the seat is constructed as a sleeve or cartridge inside of the body.

Concentric butterfly valves are used in basic and specialty liquid and gas applications up to 200 PSI and up to 400 deg F. The zero offset butterfly valve can handle chemicals, coatings, food, some solids, and abrasive applications.  

The Concentric butterfly valve is available in epoxy-coated cast iron and stainless steel with multiple seat materials such as Buna, EPDM, VITON, Teflon, Natural rubber, and others.

What is a Double Offset Butterfly Valve?

The double eccentric offset butterfly valve can also be called the high-performance butterfly valve or double eccentric butterfly valve. This valve is suitable for thicker media that have high pressure because its design does not allow too much contact with the disc and seat.

Features of Double Offset Butterfly Valve

The balance of this valve is in the stem placed behind the circular disc. It allows the disc to self-adjust to the center, ensuring tight sealing. Even when the valve is fully opened, the valve does not touch the soft seat, ensuring a longer service life.

What is a Triple Offset Butterfly Valve?

The triple offset butterfly valve incorporates the two offset points of the double, but it also has a third point of offsets. Relating this time to the sealing points rather than the shaft, the point of sealing on the disc and seat are both machined into an offset conical profile. This allows it to operate fully without any contact until the point of full closure as a mechanical stop. Therefore both the sealing components can be made of metal without the need for an elastomeric element.

Features of Triple Offset Butterfly Valve

As a butterfly valve, it also belongs to the quarter family. It is also lightweight and easy to operate. Installation is also a breeze since there is less pipe bracing needed. Replacement of seat rings is also easy as this valve is top-entry.

The triple offset butterfly valve has a low torque so there is no need to have larger valves. That being said, this means higher savings costs. This valve has zero leakage closure on both ends.

The introduction of soft seats increases the value of the valves. Aside from being fire-safe due to the metal seats underneath the soft ones, the valves can now self-center because of the elastomeric seat material.

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How to choose these four?

Concentric butterfly valve, single eccentric butterfly valve, double offset butterfly valve and triple offset butterfly valve reflect the fact that the opening and closing process is more and more labour-saving and the wear and tear of sealing surface is less and less. By setting the rotating shaft position of the butterfly valve plate, the sealing and opening state of the butterfly valve can be changed.

Concentric Butterfly Valve

A concentric butterfly valve is characterized by the same position of stem axis, butterfly centre and valve body centre. Generally speaking, the concentric butterfly valve is used as much as possible if concentric butterfly valve can be used in principle. The concentric butterfly valve is a conventional product because of its low requirement of sealing both in structure and operation. In order to overcome extrusion, scratch and ensure sealing performance, concentric butterfly valve seats are basically made of elastic materials such as rubber or polytetrafluoroethylene, which are soft-sealed butterfly valves.

Double Eccentric Butterfly Valve

Double eccentric butterfly valve is the most widely used. The structure features that the axis of the stem deviates from both the centre of the butterfly plate and the centre of the valve body. It deviates from two central positions and is called double eccentric butterfly valve. Many double offset butterfly valve are linear seals. Friction occurs between the disc plate and valve seat when the sealing surface is closed. The sealing effect is very good. It has the characteristics of small area and strong pressure. After the valve is opened, the butterfly plate can quickly detach from the valve seat, greatly eliminating the unnecessary over-extrusion and scratch between the butterfly plate and the valve seat, reducing the opening resistance, reducing wear and tear, and improving the service life of the valve seat.

Triple Eccentric Butterfly Valve

Triple eccentric butterfly valve undertook the third eccentricity on the basis of the double offset butterfly valve. The shape of the sealing pair is not a positive cone, but an oblique cone. Most of them are short distance force and surface seal. The stem shaft of a triple eccentric butterfly valve is a three-section axis structure. The two-axle segments of the three-section axle stem are concentric, and the centre line of the axis of the central segment deviates from the axis of both ends. The butterfly plate is installed on the middle axle segment. Such an eccentric structure makes the butterfly plate double eccentric in the fully open position and single eccentric in the closed position when the butterfly plate rotates. Because of the eccentric axis, when closing, the butterfly plate moves a distance into the sealing cone of the seat, and the sealing surface of the butterfly plate and the seat coincides to achieve reliable sealing performance. It makes up for the contradiction that the hard seal is poor in sealing and the soft seal is good in sealing but not high temperature resistant.

When to use concentric butterfly valve and when to choose the double eccentric butterfly valve or triple eccentric butterfly valve, it mainly depends on usage habits and budget. If it is not an extreme working condition, the concentric butterfly valve is usually chosen, whereas concentric butterfly valve is chosen as far as possible. Because concentric butterfly valve is simple in structure and relatively economical in price.

Zeco Valve Group Co., Ltd. provides you with various of butterfly valves. Welcome to buy them!

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What is Triple Offset Butterfly Valve?

A triple-offset butterfly valve has three separate offsets. Two of these apply to the location of the shaft with respect to the center line of the bore and the center line of the disc/seat sealing surfaces. While the third offset is the design in the axis of the seat cone angle.

Triple Offset TECHNOLOGY

• Zero Offset: The Disc rotates around the center axis, allowing for a potential 360-degree rotation. Sealing is achieved by the Disc deforming the soft seal. This results in full friction through the full operating cycle.
• Double Offset: To allow displacement of the seat, the shaft is offset from the center line of the disc seat and body seal (offset one), and the center line of the bore (offset two). Thus creating a cam action during operation to lift the seat out of the seal. This results in friction during the first 10 degrees of opening and the final 10 degrees of closing.
• Triple Offset: The third offset is the geometry design of the sealing components. The sealing components are each machined into an offset conical profile resulting in a right-angled cone, which ensures friction-free stroking throughout its operating cycle. Contact is only made at the final point of closure with the 90-degree angle acting as a mechanical stop. This results in no over-travel of the disc seat.

THE BENEFITS OF TRIPLE-OFFSET VALVES

• ‘Cam-action’ and ‘right-angled’ conical sealing design ensures the metal sealing components are never in contact until its final degree of closing. This results in repeatable sealing and vastly extended valve life.
• Metal-to-Metal sealing ensures bubble-tight shut-off, resulting in zero-leakage performance.
• Suitability to harsh media because the construction of the valve features no elastomers or materials typically affected by corrosion.
• The geometric design of sealing components provides friction-free stroking throughout the valve. This extends the valve life and allows a lower torque actuator to be fitted.
• There are no cavities between sealing components, resulting in no clogging, low maintenance, and extended valve life.

Application of Triple Offset Butterfly Valves

At present, a butterfly valve, as a component used to realize the on-off and flow control of pipeline systems, has been widely used in the petroleum, the chemical industry, metallurgy, hydropower, and other fields. In the butterfly valve technology known to the public, its sealing form is mostly used in the sealing structure, in sealing material like rubber, polytetrafluoroethylene, etc. Due to the limitation of structural characteristics, it is not suitable for high temperature, high pressure, corrosion resistance, wear resistance, and other industries. An existing more advanced butterfly valve is a three-eccentric metal hard seal butterfly valve, with the valve body and valve seat as the connecting members, valve seat sealing surface welded with high temperature and corrosion resistant alloy materials. The multi-layer soft stacked sealing ring is fixed on the valve plate. Compared with the traditional butterfly valve, this kind of butterfly valve has high-temperature resistance and is easy to operate, without friction when opening and closing. Moreover, the butterfly valve is automatically closed when the torque of the transmission mechanism increases to compensate for the sealing, which improves the sealing performance and extends the service life of the butterfly valve. However, there are still the following problems with the use of this butterfly valve:

• 1. As the multi-layer soft-hard overlapping sealing ring is fixed on the valve plate when the valve plate is normally open, the medium forms a frontal scour on its sealing surface, and the soft sealing belt in the interlayer of the metal sheet is scoured, which directly affects the sealing performance.
• 2. Restricted by the structural conditions, this structure is not suitable for valves with a diameter less than DN200, because the overall structure of the valve plate is too thick and the flow resistance is high.
• 3. Because of the principle of a three-eccentric structure, the sealing surface of the valve plate and the seat between the seal is driven by the torque of the valve plate pressure to the seat. In the positive flow state, the higher the medium pressure is, the tighter the sealing extrusion will be. When the medium is flowing upward, the pressure of the medium increases, along with which the positive pressure value between the disc and the seat is lower than the pressure of the media, and the seal begins to leak. 

The high-performance three-eccentric bidirectional hard sealing butterfly valve is characterized in that the seat sealing ring is composed of two layers of stainless steel plates on both sides of the soft t-shaped sealing ring. The sealing surface of the valve plate and the valve seat is an inclined conical structure, and the high temperature and corrosion-resistant alloy material are surfacing welded on the inclined conical surface of the valve plate. The spring fixed between the adjusting ring pressure plate and the adjusting bolt assembly on the pressure plate is arranged together. This structure effectively compensates the tolerance belt between the shaft sleeve and the valve body and the elastic deformation of the valve stem under the pressure of the medium and solves the sealing problem of the valve in the process of two-way interchangeable medium transportation.

The use of soft t-type two sides of the multi-layer stainless steel sheet seal ring has the double advantages of hard metal seal and soft seal and, regardless of low temperature and high temperature, has zero leakage sealing performance.

The test proves that when the pool is in a positive flow state (the flow direction of the medium is the same as the rotation direction of the butterfly valve plate), the pressure on the sealing surface is generated by the torque of the transmission device and the action of the medium pressure on the valve plate. When the positive medium pressure increases, the tighter the extrusion between the valve plate’s oblique conical surface and seat sealing surface is, the better the sealing effect is.

When in reverse flow, the seal between the disc and the seat forces the disc against the seat by the torque of the drive device. With the increase of the reverse medium pressure, the unit positive pressure between the valve plate and the seat is less than the medium pressure, and the adjustment ring spring in the load after the storage of the deformation can compensate for sealing, the tight pressure of the valve plate and seat sealing surface plays an automatic compensation role. Therefore, the utility model is not like the existing technology, which installs the soft and hard multi-layer sealing ring on the valve plate, but directly installs it on the valve body, and adding the adjusting ring between the pressure plate and the seat is a very ideal two-way hard sealing way. It will replace gate valves and globe valves.

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What are Centric Butterfly Valves?

Centric butterfly valves are mainly used in the construction of facilities located inside closed buildings. Here, this butterfly valve type demonstrates its advantages, as it is more favorably priced and needs less space than a flanged butterfly valve.

Features of Concentric Butterfly Valves

• Suitable for both gaseous and liquid service
• Positive shutoff bi-directionally
• Direct mount automation

Applications of Centerline Butterfly Valves

• HVAC
• Chemical/Petrochemical Processing
• Food and Beverage
• Power and Utilities
• Pulp and Paper

What is a Double Flanged Center Line Butterfly Valve?

Double flange butterfly valve used for regulation and flow sectioning in water supply facilities, plumbing, irrigation, etc. It has low head loss due to a hydrodynamic design of the disc, it is 100% watertight and needs no gaskets to be installed.

According to different structural forms, it can be divided into middle line butterfly valve, single eccentricity butterfly valve, double eccentricity butterfly valve, and three eccentricity butterfly valve. The middle line butterfly valve is usually sealed with a soft seal. Eccentric butterfly valve with hard seal. The three-eccentric butterfly valve is the best performance valve at present, both soft sealing butterfly valves have excellent sealing performance, and hard sealing butterfly valves have high temperature, high-pressure corrosion resistance characteristics.

According to the different connection forms, it can be divided into dual butterfly valve, flanged butterfly valve, welded butterfly valve, screw butterfly valve, clamp butterfly valve, and so on. So do you know how it came about?

We are a professional Flanged Center Line Butterfly Valve Supplier, we provide flange center line butterfly valves, welcome to contact us!

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