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Check valve and its working principle

July 30, 2020

What is check valve?

Check valve refers to a valve whose opening and closing parts are circular discs and rely on its own weight and medium pressure to generate actions to block the back flow of the medium. It is an automatic valve, also called check valve, one-way valve, return valve or isolation valve. The movement of the disc is divided into lift check valve and swing check valve. The lift check valve is similar in structure to the stop valve, but lacks the valve stem to drive the valve disc. The medium flows in from the inlet end (lower side) and flows out from the outlet end (upper side). When the inlet pressure is greater than the sum of the weight of the disc and its flow resistance, the valve is opened. On the contrary, the valve is closed when the medium flows back. The swing check valve has a disc that is incline

tilting disc check valve body (2)

d and can rotate around the axis, and its working principle is similar to that of the lift check valve. The check valve is often used as the bottom valve of the pumping device to prevent the backflow of water. The combination of check valve and stop valve can play a role of safety isolation. The disadvantage is that the resistance is large and the sealing performance is poor when closed.

Working principle of check valve:
Check valves can also be used to supply pipelines for auxiliary systems whose pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

The function of this type of valve is to only allow the medium to flow in one direction and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow.

Among them, check valves belong to this type of valve, which includes swing check valves and lift check valves. The swing check valve has a hinge mechanism and a valve flap like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve clack can reach the proper position of the valve seat surface every time, the valve clack is designed in a hinge mechanism so that the valve clack has enough space for rotation and makes the valve clack truly and comprehensively contact the valve seat. The valve clack can be made of metal, or inlaid with leather, rubber, or synthetic covering, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall back to the seat and cut off the flow. According to the conditions of use, the valve disc can be an all-metal structure, or it can be in the form of a rubber pad or a rubber ring inlaid on the disc holder. Like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve, and the flow rate of the swing check valve is restricted.

Detailed introduction of soft sealing butterfly valve-(3)

July 28, 2020

Features of soft sealing butterfly valve:

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

1. Small and light, easy to disassemble and repair, and can be installed in any position.

2. The structure is simple and compact, the operating torque is small, and the 90-degree rotation opens quickly.

3. The flow characteristics tend to be straight, and the regulation performance is good.

4. The connection between the butterfly plate and the valve stem adopts a pinless structure, which overcomes possible internal leakage points.

5. The seal can be replaced, and the seal is reliable to achieve two-way sealing.

6. The butterfly plate can be sprayed with a coating layer, such as nylon or PTFE, according to user requirements.

7. The valve can be designed as flange connection and wafer connection.

8. The driving mode can be manual, electric or pneumatic.

Problems in the use of soft sealing butterfly valves:

1. Due to the principle of the triple eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat is to press the valve plate against the valve seat by the torque of the transmission device. In the state of positive flow, the higher the medium pressure, the tighter the sealing extrusion. When the flow channel medium flows back, as the medium pressure increases, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the seal begins to leak.

2. Due to structural conditions, this structure is not suitable for valves with a diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.

3. Since the multilayer soft and hard stacked sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium will wash its sealing surface positively, and the soft sealing tape in the metal sheet sandwich will directly affect the sealing performance after being washed.

high-performance soft sealing butterfly valve, characterized in that: the valve seat sealing ring is composed of multiple layers of stainless steel sheets on both sides of the soft T-shaped sealing ring.

The sealing surface of the valve plate and the valve seat is of an oblique cone structure, and the oblique cone surface of the valve plate is welded with temperature-resistant and corrosion-resistant alloy materials; the spring fixed between the adjusting ring pressure plate and the adjusting bolt of the pressure plate are assembled together. This structure effectively compensates for the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under the medium pressure, and solves the sealing problem of the valve in the two-way interchangeable medium conveying process.

The sealing ring is composed of a soft T-shaped multi-layer stainless steel sheet on both sides, which has the dual advantages of metal hard and soft sealing. It has zero leakage sealing performance regardless of low temperature and high temperature. The test proves that in the positive flow state of the pool (the flow direction of the medium is the same as the rotation direction of the butterfly plate), the pressure of the sealing surface is produced 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 oblique cone surface of the valve plate and the sealing surface of the valve seat are pressed, the better the sealing effect.

Therefore, unlike the prior art, the utility model does not install a soft and hard multilayer sealing ring on the valve plate, but directly installs it on the valve body. Adding an adjustment ring between the pressure plate and the valve seat is a very ideal two-way hard sealing method. . It can replace gate valves and ball valves.

In the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the driving device. With the increase of the reverse medium pressure, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation energy stored by the spring of the adjusting ring after being loaded compensates for the tight pressure of the sealing surface of the valve plate and the valve seat Play the role of automatic compensation.

Detailed introduction of soft sealing butterfly valve-(2)

July 28, 2020

There are many types of soft-sealed butterfly valves, which can be divided into the following categories according to different forms:
Classified by structure
Classified by structure

(1) Center sealing butterfly valve

(2) Single eccentric sealed coal valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

(3) Double eccentric sealing butterfly valve

(4) Triple eccentric seal valve

Classified according to the sealing surface material:

(1) Soft sealing butterfly valve.

1) The sealing pair is composed of non-metallic soft material to non-metallic soft material.

2) The sealing pair is composed of a metal hard material and a non-metal soft material.

(2) Metal hard seal butterfly valve. The sealing pair is composed of a metal hard material to a metal hard material.

Classified according to the sealing form:

(1) Forced sealing butterfly valve

1) Elastic sealing butterfly valve. The specific pressure of the seal is generated by the valve plate squeezing the valve seat when the valve is closed, and the elasticity of the valve seat or valve plate

2) External torque sealing butterfly valve. The seal specific pressure is generated by the torque applied to the valve shaft

(2) Pressurized sealing butterfly valve. The specific sealing pressure is generated by the pressure of the elastic sealing element on the valve seat or valve plate

(3) Automatic sealing butterfly valve. The sealing specific pressure is automatically generated by the medium pressure.

Classified by work pressure:

(1) Vacuum butterfly valve. Butterfly valves whose working pressure is lower than the atmospheric pressure of the standard reactor.

(2) Low pressure butterfly valve. Butterfly valve with nominal pressure PN<1.6MPa.

(3) Medium pressure butterfly valve. Butterfly valve with nominal pressure PN of 2.5-6. 4MPa.

(4) High pressure butterfly valve. A butterfly valve with a nominal pressure PN of 10.0-80.0MPa.

(5) Ultra-high pressure butterfly valve. Butterfly valve with nominal pressure PN>100MPa.

Classified by working temperature:

(1) High temperature butterfly valve. t>450 C butterfly valve

(2) Medium temperature butterfly valve. 120 C＜t＜450 C butterfly valve

(3) Normal temperature butterfly valve. One 40C<t<; 120 C butterfly valve

(4) Cryogenic butterfly valve. One 100＜t＜一40 C butterfly valve

(E) Ultra-low temperature butterfly valve. t＜一100 C butterfly valve

Classified according to the connection method:

(1) Wafer butterfly valve

(2) flange butterfly valve

(3) lug butterfly valve

(4) Welded butterfly valve

Detailed introduction of soft sealing butterfly valve-(1)

July 28, 2020

The butterfly plate of the soft sealing butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation reaches 90°, the valve is fully opened. The characteristics of the new type of high-life stainless steel butterfly valve and the problem of the butterfly valve during use, this type of valve should generally be installed horizontally in the pipeline.

Problems in use of soft sealing butterfly valve:
1. Since the multi-layer soft and hard stacked sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium will wash its sealing surface positively, and the soft sealing tape in the metal sheet sandwich will directly affect the sealing performance after being washed.

2. Due to structural conditions, this structure is not suitable for valves with a diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.

3. Due to the principle of the triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat depends on the torque of the transmission device to press the valve plate against the valve seat. In the state of positive flow, the higher the medium pressure, the tighter the sealing extrusion. When the flow channel medium flows back, as the medium pressure increases, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the seal begins to leak.

high-performance soft sealing butterfly valve, characterized in that: the valve seat sealing ring is composed of multiple layers of stainless steel sheets on both sides of the soft T-shaped sealing ring.

The sealing surface of the valve plate and the valve seat is of oblique cone structure, and the temperature and corrosion resistant alloy material is built up on the oblique cone surface of the valve plate; the spring fixed between the pressure plate of the adjusting ring and the adjusting bolt of the pressure plate are assembled together. This structure effectively compensates for the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under the medium pressure, and solves the sealing problem of the valve in the two-way interchangeable medium conveying process.

The sealing ring is composed of a soft T-shaped multi-layer stainless steel sheet on both sides, which has the dual advantages of metal hard and soft sealing. It has zero leakage sealing performance regardless of low temperature and high temperature. The test proves that in the positive flow state of the pool (the flow direction of the medium is the same as the rotation direction of the butterfly plate), the pressure of the sealing surface is produced 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 oblique cone surface of the valve plate and the sealing surface of the valve seat are pressed, the better the sealing effect.

In the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the driving device. With the increase of the reverse medium pressure, when the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation energy stored by the spring of the adjusting ring after being loaded compensates for the tight pressure of the sealing surface of the valve plate and the valve seat Play the role of automatic compensation.

Therefore, unlike the prior art, the utility model does not install a soft and hard multilayer sealing ring on the valve plate, but directly installs it on the valve body. Adding an adjustment ring between the pressure plate and the valve seat is a very ideal two-way hard sealing method. . It can replace gate valves and globe valves

Difference between Soft seal gate valve and hard seal gate valve

July 28, 2020

Soft seal gate valve and hard seal gate valve are two major categories in the gate valve series. Hard seal and soft seal can sometimes compensate for each other, and

13 gate-valve-5

sometimes they are independent of each other. So what is the relationship between soft seal gate valve and hard seal gate valve? What are the main differences? Next, the editor of Tanghai Valve will solve these mysteries for everyone.

1. Sealing material

Soft seal gate valve: the seal pair is made of metal materials on one side and elastic non-metallic materials on the other side, which is called “soft seal”. This kind of seal has good sealing performance, but it is not resistant to high temperature, easy to wear, and has poor mechanical properties.

Hard seal gate valve: The two sides of the seal pair are made of metal materials or other harder materials are called “hard seals”. This kind of seal has poor sealing performance, but has high temperature resistance, abrasion resistance and good mechanical properties.

2. Structure mechanism

The hard seal gate valve is a seal between metal and metal, and the sealing ball and valve seat are both metal. Machining accuracy and craftsmanship are more difficult, and are generally used in high pressure, usually above 35MPa. The soft seal gate valve is a seal between metal and non-metal, such as nylon\tetrafluoroethylene, and the manufacturing standards are the same.

3. Equipment selection

The selection of soft and hard seal gate valves is mainly based on the process medium, temperature and pressure. Generally, the medium contains solid particles or wears or the temperature is higher than 200 degrees. It is best to use hard seals. Valves with a diameter greater than 50 have a larger pressure difference and consider opening the valve torque. , When the torque is large, the fixed hard-seal ball valve should be selected, and its sealing level can reach 6 regardless of the soft or hard seal.

3. Conditions of use

The soft seal gate valve generally has a very high seal, while the hard seal can be high or low according to the requirements; the soft seal needs to be fireproof, because the material of the soft seal will leak at high temperatures, while the hard seal does not have this problem; Seals can generally be made at very high pressures, but soft seals cannot; soft seals cannot be used in some situations due to the problem of the flowing medium. Finally, hard seal valves are generally more expensive than soft seals. As for manufacturing, there is little difference between the two, mainly the difference between the valve seat, the soft seal is non-metallic, and the hard seal is metallic.

Through the above introduction, I believe everyone can understand the difference between soft seal gate valve and hard seal gate valve. With the continuous development of China’s industrial market, it is necessary to understand the difference between soft seal gate valve and hard seal gate valve, which may not only affect Production efficiency may also greatly affect economic efficiency

Difference between soft seal butterfly valve and hard seal butterfly valve

July 28, 2020

The difference between soft seal butterfly valve and hard seal butterfly valve:

A butterfly valve hard seal refers to a “hard seal” in which both sides of the seal pair are made of metal materials or other harder materials. This kind of seal has poor

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

sealing performance, but high temperature resistance, wear resistance, and good mechanical properties. For example, : Steel + Steel; Steel + Copper; Steel + Graphite; Steel + Alloy Steel; (The steel here may also be cast iron, cast steel, alloy steel or surfacing, sprayed alloy).

The soft seal seal pair is made of metal materials on one side and elastic non-metallic materials on the other side. It is called “soft seal”. This kind of seal has better sealing performance, but it is not resistant to high temperatures, easy to wear, and mechanical Poor performance. Such as: steel + rubber; steel + tetrafluoropolyethylene; etc. The soft sealing seat is made of non-metallic materials with certain strength, hardness and temperature resistance, with good sealing performance, zero leakage, but life And the adaptability to temperature is relatively poor. The hard seal is made of metal, and the sealing performance is relatively poor, although some manufacturers claim that it can achieve zero leakage. The soft seal cannot meet the process requirements for some corrosive materials, and the hard seal can solve it! These two types of seals can complement each other. In terms of tightness, the soft seal is relatively good, but now the tightness of the hard seal can also meet the corresponding requirements! The advantage of the soft seal is good sealing performance, but the disadvantage is that it is easy to age, wear, and has a short service life. The hard seal has a long service life, but the tightness is relatively worse than that of the soft seal.

The main differences in its structure are as follows
1. The difference in structure

Soft seal butterfly valves are mostly centerline type, and hard seals are mostly single eccentric, double eccentric, and triple eccentric butterfly valves.

2. Temperature resistance

The soft seal is used in normal temperature environment. Hard seal can be used in low temperature, normal temperature, high temperature and other environments

3. Pressure

Soft seal low pressure-normal pressure, hard seal can also be used in medium and high pressure conditions

4. Sealing performance: The soft sealing and triple eccentric hard sealing butterfly valves have better sealing performance. The triple eccentric butterfly valve can maintain good sealing under high pressure and high temperature environment.

In view of the above characteristics, the soft sealing butterfly valve is suitable for the two-way opening and closing and adjustment of ventilation and dust removal pipelines, water treatment, light industry, petroleum, chemical and other industries. Hard-sealed butterfly valves are mostly used in heating, gas, gas, oil, acid and alkali environments.

With the widespread use of butterfly valves, its features of convenient installation, convenient maintenance and simple structure become more and more obvious. Electric soft-sealed butterfly valves, pneumatic soft-sealed butterfly valves, hard-sealed butterfly valves, etc. have begun to replace electric gate valves and globe valves in more and more occasions.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Introduction of U-shaped flange butterfly valve

July 27, 2020

What is U-shaped flange connection butterfly valve?
The U shaped butterfly valve is simple in structure, small in size and light in weight, and consists of only a few parts. Moreover, it can be opened and closed quickly

U-type flange butterfly valve, ductile iron, DI, center line,

by rotating 90°, and the operation is simple. At the same time, the valve has good fluid control characteristics.
The butterfly plate of the U type butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation reaches 90°, the valve is fully opened.
The butterfly valve is simple in structure, small in size and light in weight, and consists of only a few parts. Moreover, it can be opened and closed quickly by rotating 90°, and the operation is simple. At the same time, the valve has good fluid control characteristics. When the flange butterfly valve is in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body, so the pressure drop generated by the valve is small, so it has better flow control characteristics. The butterfly valve has two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be embedded in the valve body or attached to the periphery of the butterfly plate.
Valves with metal seals generally have a longer life than valves with elastic seals, but it is difficult to achieve a complete seal. Metal seals can adapt to higher operating temperatures, while elastic seals have the defect of being limited by temperature.
If the butterfly valve is required to be used as a flow control, the main thing is to correctly choose the size and type of the valve. The structure principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, water treatment, etc., but also used in cooling water systems of thermal power stations.
Commonly used butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipe flanges. Flange type butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flanges.
When in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body, so the pressure drop generated by the valve is small, so it has better flow control characteristics. The butterfly valve has two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be embedded in the valve body or attached to the periphery of the butterfly plate. Valves with metal seals generally have a longer life than valves with elastic seals, but it is difficult to achieve a complete seal. Metal seals can adapt to higher operating temperatures, while elastic seals have the defect of being limited by temperature.
If the butterfly valve is required to be used as a flow control, the main thing is to correctly select the size and type of the valve. The structure principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, water treatment, etc., but also used in cooling water systems of thermal power stations.
Commonly used butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipe flanges. Flange type butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flanges.

Triple eccentric multi-level hard sealing flange butterfly valve

July 27, 2020

The triple eccentric multi-level hard-sealed flange butterfly valve is a valve designed with the principle of three-dimensional knitting. The product is composed of

triple eccentric butterfly valve-wafer-butt weld (1)

main components such as valve body, butterfly plate, multi-level valve seat, valve stem, and transmission mechanism. It is widely used in the pipelines of corrosive media such as metallurgy, electric power, petroleum, chemical industry, air, gas, combustible gas and water supply and drainage.

Overview of Triple eccentric multi-level hard sealing flange butterfly valve:
Triple eccentric multi-level hard-sealed flange butterfly valve is a long-life, energy-saving butterfly valve. Its structure adopts three-dimensional core design principle, the valve seat adopts a multi-layer structure compatible with hard and soft sealing, exquisite processing and advanced technology. This product is composed of main components such as valve body, butterfly plate, multi-level valve seat, valve stem and transmission mechanism. It is widely used in the pipelines of corrosive media such as metallurgy, electric power, petroleum, chemical industry, air, gas, combustible gas and water supply and drainage.

Use of Triple eccentric multi-level hard sealing flange butterfly valve:
The triple-eccentric multi-layered hard-sealed flange butterfly valve has the characteristics of simple structure, small size, light weight, low material consumption, small installation size, rapid switching, 90° reciprocating rotation, and small driving torque. It is used to cut off, connect, and adjust tubes. The medium in the road has good fluid control characteristics and close sealing performance. It is widely used in the pipelines of corrosive media such as metallurgy, electric power, petroleum, chemical industry, air, gas, combustible gas and water supply and drainage.

Features of Triple eccentric multi-level hard sealing flange butterfly valve:

The triple eccentric multi-level hard sealing flange butterfly valve adopts the three-dimensional eccentric principle design, so that the space movement trajectory of the sealing surface is idealized. There is no friction and interference between the sealing surfaces, and the sealing material is selected properly, so that the butterfly valve can be sealed. Performance, corrosion resistance, high temperature resistance and wear resistance have been reliably guaranteed. Its main features are as follows:

1. The opening torque is small, flexible and convenient, labor-saving and energy-saving.

2. The three-dimensional knitting core structure makes the butterfly plate tighter and tighter, and its sealing performance is reliable and leak-free.

3. High pressure resistance, corrosion resistance, wear resistance, long service life, etc.

Adopt standards:

Our products use advanced manufacturing technology, and strictly conform to API, DIN, BS, EN, GB and other international standards.

The main technical parameters
Nominal diameter DN (mm) 50～2000
Nominal pressure PN (MPa) 0.6 1.0 1.6 2.5 4.0
Test pressure Strength test 0.9 1.5 2.4 3.75 6.0
Seal test 0.66 1.1 1.76 2.75 4.4
Hermetic sealing test 0.6 0.6 0.6 0.6 0.6
Leakage rate <0.1×DNmm/s (in line with GB/T13927-92 standard)
Applicable temperature Carbon steel: -29℃～425℃ Stainless steel -40℃～600℃
Applicable medium: air, water, steam, gas, oil, acid, alkali, salt with weak corrosive medium, etc.
Drive form: Worm gear drive, pneumatic drive, electric drive

Installation instructions of double eccentric butterfly valve

July 24, 2020

Installation instructions of double eccentric butterfly valve:
1. Before installation, you must carefully check whether the valve’s mark and certificate of conformity meet the requirements for use, and clean it after verification.

Double eccentric-wafer butterfly valve-D72F-150lbP-stainless steel (3)

Uninstalled valves should be stored in a dry room. Valves stored for a long time should be cleaned regularly, dried and coated with anti-rust oil. Blind plates shall be used to protect the flange sealing surface at both ends of the valve.
2. Install according to the flow direction of the medium; horizontal installation is preferred.
3. The connecting bolts of the butterfly valve and the pipeline should be tightened several times in the diagonal direction during installation, and no single piece should be tightened at a time to prevent the flange connection from leaking due to uneven force.
4. When installing the butterfly valve, the butterfly plate should be in the closed position to prevent debris from entering the valve cavity and scratching the sealing surface. When the user wants to test the pressure, be sure to install the flange pair on both ends and test the pressure.
5. When connecting the valve to the pipeline, it is required to use butt-welded steel flanges or special butterfly valve flanges on the pipeline. If flat-welded steel flanges are used, the inner hole of the flange must be the same size as the inner hole of the gasket to ensure the effective sealing surface of the gasket.
6. When the electric butterfly valve leaves the factory, the opening and closing stroke of the control mechanism has been adjusted. In order to prevent the direction from being wrong when the power is turned on, the user must manually move to 1/3 of the closed position before turning on the power for the first time. And check whether the direction of the indicator plate is consistent with the opening direction of the valve.
7. When the valve is in use, if any malfunction is found, stop using it immediately

Tanghai Valve is the best manufacturer of double eccentric butterfly valve in China. We produce the best quality products with competitive low prices. Main products: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Classification and features of Eccentric butterfly valves

July 24, 2020

Eccentric butterfly valves are divided into single eccentric butterfly valves, double eccentric butterfly valves, triple eccentric butterfly valves, and variable eccentric butterfly valves. Contrast with concentric butterfly valve. A butterfly valve whose stem axis deviates from the center of the disc and the center of the body at the same time, and the sealing pair is an oblique vertebra is called an eccentric butterfly valve.

high performance-double eccentric-butterlfy valve-wafer-lug-flanged (5)

Structure classification of eccentric butterfly valve:
Single eccentric butterfly valve
In order to solve the problem of the extrusion of the butterfly plate and the valve seat of the concentric butterfly valve, a single eccentric butterfly valve was produced. Its structural feature is that the shaft center of the valve stem deviates from the center of the butterfly plate, so that the lower end of the butterfly plate no longer becomes the rotation axis. Disperse and reduce the excessive squeezing between the lower end of the butterfly plate and the valve seat.
Double eccentric butterfly valve
On the basis of the single eccentric butterfly valve, the double eccentric butterfly valve is the most widely used double eccentric butterfly valve. Its structural feature is that the axis of the valve stem deviates from the center of the butterfly plate and the center of the body. The double eccentric effect enables the butterfly plate to be released from the valve seat immediately after the valve is opened, which greatly eliminates unnecessary excessive extrusion and scratching of the butterfly plate and the valve seat, reduces the opening resistance, reduces wear and improves The life of the valve seat is improved.
Triple eccentric butterfly valve
To withstand high temperatures, hard seals must be used, but the amount of leakage is large; for zero leakage, soft seals must be used, but they are not resistant to high temperatures. In order to overcome the contradiction of the double eccentric butterfly valve, the butterfly valve was eccentric for the third time. The so-called third eccentricity means that the shape of the sealing pair is not a positive cone, but an oblique cone.
Variable eccentric butterfly valve
The uniqueness of the variable eccentric butterfly valve is that the valve stem shaft where the butterfly plate is installed is a three-segment shaft structure. The three-segment shaft type valve stem has two shaft sections concentric, and the center line of the central shaft is offset from the two ends of the axis by a center distance , The butterfly plate is installed on the intermediate shaft section. Such an eccentric structure makes the butterfly plate a double eccentric shape when in the fully open position, and a single eccentric shape when the butterfly plate rotates to the closed position. Due to the effect of the eccentric shaft, when close to closing, the butterfly plate moves a

triple eccentric butterfly valve-lug

distance into the sealing cone surface of the valve seat, and the butterfly plate matches the sealing surface of the valve seat to achieve reliable sealing performance.

Features of eccentric butterfly valve:

The butterfly valve and the upper and lower valve shafts are connected by special-shaped holes and special-shaped shafts. During the opening and closing process of the butterfly plate, the function of the butterfly plate floating up and down, left and right, without a pin link, reduces the interference area between the butterfly plate and the valve seat. Thereby greatly reducing the torque. The floating structure of the butterfly plate realizes the single eccentric manufacturing process and the use function of variable eccentricity.
There is an over-position stopper for the butterfly plate in the inner cavity of the valve body to ensure that the butterfly plate is not in place when it is closed.
Bushings are used between the upper and lower valve shaft holes of the valve body cavity and the upper and lower valve shaft holes of the butterfly plate to prevent large particles in the medium from entering the valve shaft holes.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Posts

Check valve and its working principle

Detailed introduction of soft sealing butterfly valve-(3)

Detailed introduction of soft sealing butterfly valve-(2)

Detailed introduction of soft sealing butterfly valve-(1)

Difference between Soft seal gate valve and hard seal gate valve

Difference between soft seal butterfly valve and hard seal butterfly valve

Introduction of U-shaped flange butterfly valve

Triple eccentric multi-level hard sealing flange butterfly valve

Installation instructions of double eccentric butterfly valve

Classification and features of Eccentric butterfly valves

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