resilient seated Archives

Advantages and Disadvantages of Centerline Butterfly Valves

August 16, 2022

Advantages of Centerline Butterfly Valves
The centerline butterfly valve adopts the centerline sealing structure, and the centerline of the disc sealing of the butterfly valve is consistent with the centerline of the valve body and the rotation centerline of the valve stem. The upper and lower ends of the butterfly plate near the

Double flange butterfly valve (16)

valve stem are designed as two smooth planes, and are in close contact with the valve seat gasket made of rubber to ensure that the medium does not leak from both ends; the outer edge of the butterfly plate is designed as a spherical outer edge, It should be ensured that the arc surface has a suitable surface roughness during processing, and the seat gasket should ensure that the sealing surface has a suitable surface roughness during molding. When the valve is closed, the butterfly plate rotates 0-900 degrees, and gradually compresses the valve seat gasket made of rubber, so that the elastic force formed by the elastic deformation of the valve seat gasket is used as the necessary sealing pressure to ensure the sealing of the valve.
The centerline butterfly valve is designed to reduce flow resistance:
1) The channel is designed as a full-diameter structure, which ensures the flow area of the valve and reduces the flow resistance when the fluid passes through the valve.
2) The butterfly plate adopts the disc-shaped streamline design, which can not only ensure the stress intensity in the center of the butterfly plate, but also ensure that the valve can obtain a larger flow coefficient and a smaller fluid resistance coefficient.
3) The valve seat sealing ring is designed as a soft sealing structure of rubber and resin skeleton (fixed sleeve), which is embedded in the valve body after being manufactured. The part of the inner ring higher than the inner cavity of the valve body adopts a streamline design to achieve the purpose of reducing the flow resistance.

Disadvantages of Centerline Butterfly Valves
Because of its own structure, the centerline butterfly valve can only be made into a soft-sealed butterfly valve, so the centerline butterfly valve can only be used in the working environment of low pressure and normal temperature, and is not suitable for high temperature and high pressure conditions.
The above is the introduction of the advantages and disadvantages of the centerline butterfly valve

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

What are the advantages of gate valves-resilient & metal seated

April 15, 2022

The gate valve has an opening and closing gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate

DN1000-DIN-F5-NRS gate valve-IS&Y (6)

valve is sealed by the contact between the valve seat and the gate plate. Usually, the sealing surface will be surfacing with metal materials to increase wear resistance, such as surfacing 1Cr13, STL6, stainless steel, etc. The gate has a rigid gate and an elastic gate. According to the different gates, the gate valve is divided into a rigid gate valve and an elastic gate valve.
Gate valve is a kind of valve with a large number of consultations every day. It is often used in water supply systems. The advantages of gate valves are:
1. Small flow resistance. The medium channel inside the valve body is straight, and the medium flows in a straight line. When the gate is fully opened, the internal resistance of the valve body channel is almost zero, and the flow resistance is very small.
2, opening and closing labor-saving. Whether the gate valve is open or closed, the movement direction of the gate is perpendicular to the flow direction of the medium, and the resistance of the gate to the lifting movement is also very small, and it is very labor-saving to open and close.
3. The full opening and full closing of the gate valve requires a long stroke, and the closing time is relatively long, which also makes the water hammer phenomenon less likely to occur.
4. The two sides of the gate valve channel are symmetrical, and the installation is not restricted by the flow direction of the medium, which is convenient for installation.
5. The shape is simple, the length of the structure is short, the manufacturing process is good, and the scope of application is wide.
6. Wide range of uses, gate valves are made of gray cast iron, ductile iron, cast steel, stainless steel, forged steel and other materials. Different materials can be used in different working conditions and environments, and have a wide range of applications.
Precautions for installation and use of gate valve
1. The handwheel, handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited.
2. The double gate gate valve should be installed vertically (that is, the valve stem is in the vertical position and the handwheel is at the top).
3. The gate valve with bypass valve should open the bypass valve before opening (to balance the pressure difference between the inlet and outlet and reduce the opening force).
4. The gate valve with transmission mechanism shall be installed according to the provisions of the product instruction manual.
5. If the valve is frequently switched on and off, lubricate it at least once a month.
6. The gate valve is only used to fully open and fully close the medium on various pipelines or equipment, and is not allowed to be used for throttling.
7. For gate valves with handwheels or handles, auxiliary levers should not be added during operation (if the sealing is not tight, the sealing surface or other parts should be checked and repaired). Turn the handwheel and handle clockwise to close, and vice versa. The gate valve with transmission mechanism should be used in accordance with the stipulations in the product instruction manual.

gate valve (3)

The difference between a metal seated gate valve and a resilient seated gate valve:

What are the differences between hard sealing gate valves and soft sealing gate valves? This article will introduce you.

material difference:
The material of the hard sealing gate valve body is mainly cast steel, stainless steel and forged steel. The gate plate and internal flow channel seal are all made of Stellite alloy accumulation welding.
The material of the soft-sealed gate valve body is mostly cast iron, the valve plate is covered with rubber, the appearance of the soft-sealed gate valve, and the valve wall of the flow channel side are all sprayed with electrostatic powder. Not only is the appearance beautiful, but more importantly, the smoothness of the flow channel and the inner valve wall ensures that the rubber-lined gate will not be affected by the roughness of the inner valve wall when opening and closing.

difference in use:
Soft-sealed gate valve is suitable for non-corrosive gas-liquid medium at normal temperature (≤80℃). Such as water, air, oil, water treatment sewage and other pipelines. And has a good sealing effect, almost zero leakage can be achieved.
The hard-sealed gate valve is suitable for high temperature (≤425℃) with slightly corrosive gas and liquid. Such as steam, heat transfer oil, sewage, petroleum, chemical industry, metallurgy, pipeline. Can have a certain degree of wear resistance.

To sum up, the difference between a soft-sealed gate valve and a hard-sealed gate valve is that the sealing performance of the soft-sealed gate valve is better than that of the hard-sealed gate valve, but the temperature and wear resistance of the hard-sealed gate valve is better than that of the soft-sealed gate valve. Each has advantages and disadvantages.

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

Video of resilient seated gate valve:

The role and application of gate valve

January 7, 2022

This article introduces you to the function of gate valve, and then understands the purpose of gate valve. The gate valve is a very important control component on the pipeline that transports the fluid medium. The structure of the gate valve is composed of a valve body, a valve cover, a valve stem, a gate plate, a sealing ring, and a driving device. The driving device is usually a hand wheel, and it can also be equipped with a pneumatic or electric actuator.

DIN-F4-BB-NRS-soft seated-wedge gate valve-DN100-PN16-copper holding ring-handwheel (3)

The gate of the gate valve is a disc shape, and the valve stem is driven to realize the opening and closing of the valve. The movement direction of the valve stem and the gate is perpendicular to the valve body passage and the direction of fluid flow in the pipeline. The gate valve has only two states, fully open and fully closed, so it can only be used to cut off the flow of the medium in the pipeline, and cannot adjust the flow rate. In addition, when the gate valve is opened and closed, the stroke distance of the gate is long. Although the opening and closing is labor-saving, it takes time. Therefore, the function of the gate valve is very suitable for use in pipelines that do not need to be opened and closed frequently, and used as a cut off or connected to the circulating medium in the pipeline.
The gate of the gate valve has two sealing surfaces. When the gate valve is closed, the sealing surface of the gate can be pressed against the seat on one side by the pressure of the medium to achieve sealing, which is self-sealing. The gate is basically a forced sealing type, that is, when the gate valve is closed, it needs to rely on the external force of the medium to force the gate to the valve seat to ensure the sealing performance of the sealing surface of the gate valve.
Gate valves can be divided into open-stem gate valves and concealed-stem gate valves according to their structural form. The functions of the two structural forms of gate valves are not much different, and the more difference lies in the use environment.
1. The stem of the rising stem gate valve is exposed, and the opening and closing state of the valve can be observed intuitively when the valve is opened and closed, so as to avoid misoperation. But also because the valve stem is exposed, the height of the rising stem gate valve, which is originally large in height, is even greater. Therefore, the rising stem gate valve is suitable for use in places that require a lot of operating space, and is not suitable for working conditions with narrow space.
2. The valve stem of the concealed stem gate valve is inside the valve body, so the on-off state of the valve cannot be directly observed, and another indicating device is required. However, because the valve stem is in the valve body, the volume of the dark-stem gate valve is smaller than that of the open-stem gate valve, and it is more suitable for use in occasions where the operating space is small and the location is limited and the pipeline is dense.
When the gate valve is fully opened, there is no obstruction when the medium flows through the inside of the valve body passage, and the flow resistance is almost zero. In addition, the valve body channel of the gate valve is symmetrical on both sides, the medium can flow in both directions, and it is not affected by the flow direction of the medium during installation. The gate valve has a wide range of applications due to its good manufacturing process. Gate valves have a wide range of uses, and are widely used in water conservancy systems, water supply and drainage systems, as well as petroleum, chemical, electric power, urban construction, and fire protection industries.

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

Video of resilient seated gate valve:

How many types of gate valves? gate valve classification

January 6, 2022

How many kinds of gate valves are there? Which gate valve is suitable for which occasion? How many kinds of gate valves are there?

Commonly used gate valves are as follows:

DIN-F4-BB-NRS-soft seated-wedge gate valve-DN100-PN16-copper holding ring-handwheel (3)

1. Gray iron gate valve: including gray iron open rod gate valve and gray iron dark rod gate valve, this gate valve is suitable for municipal construction, water treatment, water supply and drainage, water conservancy engineering and other fields.

2 ductile iron gate valve: usually for soft seal gate valve, and divided into exposed rod and hidden rod. This kind of gate valve is mainly used in sewage treatment, building fire control, water supply and drainage engineering and other municipal engineering pipeline.

Gray cast iron gate valves and ball valve gate valves are cast iron gate valves. These gate valves are mostly used in normal temperature and low pressure pipelines, and the medium used is mostly water.

3 carbon steel gate valve and stainless steel gate valve: these two kinds of gate valves are used in high temperature and high pressure pipelines, the use of medium for steam, oil and so on. Applications include petroleum, chemical, metallurgy and so on.

4. Knife gate valve: suitable for all kinds of fluid media such as pulp, mud, sewage, powder, syrup, coal pulp, ash, slag-water mixture, etc.

Knife gate valve (6)

The above are just a few common gate valves. In fact, gate valves are not only the above, according to the structure of gate valves, different standards, connection, drive, etc., can be divided into many types.

According to the structure:

1. Implicit stem gate valve: stem nut is placed inside the valve body, in direct contact with the medium, often fixed on the gate. Through the rotation of the stem, the stem nut drives the lubrication plate up and down to complete the opening and closing.

2. Plain stem gate valve: the stem trapezoidal thread is placed outside the valve body, on the upper part of the stem. By rotating stem nut, stem drives gate synchronous rise and fall, realize valve opening and closing, easy to identify the valve. On and off state to avoid misoperation.

3. Flat gate valve: the sealing face is parallel to the vertical center line, so the valve body is parallel to the sealing face on the gate. This valve is the most common type of double gate.

4. Wedge valve: the sealing face is at a certain Angle with the vertical center line, that is, the two sealing faces are wedge valves.

According to different standards: gb gate valve, American standard gate valve, German standard gate valve, Japanese standard gate valve.

According to the connection mode: flange gate valve, welding gate valve, threaded gate valve.

According to the pressure grade: high pressure gate valve, medium pressure gate valve, low pressure gate valve.

According to the driving mode: electric gate valve, pneumatic gate valve, manual gate valve.

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

Video of knife gate valve:

Video of resilient seated gate valve:

Application of Soft Seal Wafer Butterfly Valve in Sewage Treatment

December 28, 2021

The soft-seal wafer butterfly valve is now closely inseparable from various township sewage treatment plants. In the past agricultural villages, the sewage discharge facilities of farm households have not been transformed, resulting in the direct discharge of a large amount of domestic sewage, which seriously affected the lives of local villagers and

JIS 10K-wafer butterfly valve-backup seat (1)

threatened the ecological environment of rivers and rivers. With President Xi’s idea that “green water and green mountains are golden mountains and silver mountains”, the overall management of the city’s urban domestic sewage and the strengthening of the city’s ecological civilization construction are highly valued. While the construction of the township sewage treatment plant is in full swing, it is the important role of the soft seal butterfly valve in the sewage treatment.
Sewage treatment valves are generally soft-sealed butterfly valves, seat-sealed elastic gate valves, etc. If the sewage is acidic, it may be necessary to use a lining valve. It is very important for us to select the appropriate type of the soft seal butterfly valve according to different working conditions, so that it can be better used in sewage treatment working conditions. For example, when the chloride ion content in the water is 700mg/L, both steel-lined 4F and ordinary carbon steel butterfly valves can be used, while butterfly valves made of 304 and 316 are not good under this working condition because they cannot resist corrosion well.
For another example, a situation that many engineering pipelines in the north can encounter is that due to the low temperature in winter, the properties of many materials change at low temperatures, resulting in the loss of equipment or components. If the soft-seal wafer butterfly valve made of gray iron is selected in this case and the warmth is not well maintained, the valve will easily be broken by freezing. The major reason for this situation is that the weather is not considered in the pipeline design, which makes the system work abnormally. If the buried pipeline is buried deep enough and the exposed pipe fittings are insulated in place, this type of loss can be reduced. In winter in the north, facilities such as pipelines and valves are easily damaged. In addition to the low-temperature performance of the materials, there is another important reason: the water in the pipeline or pump is frozen. In the case of the same quality, the volume of ice is larger than that of the water, pipeline or pump. If there is water, the valve can easily burst. Under such working conditions, the manufacturers of soft-seal butterfly valve suggest that water treatment in the north, except that the pipeline is buried under the frozen layer, should first be insulated before the pipeline enters water, and ensure that there is water flowing or Empty the water after parking. If there is no more water, be sure to drain the water in the pipe. Otherwise, as long as there is still water after parking, there will be freezing cracks from the weak points of the pipeline or butterfly valve.
In the enquiry reception of Tanghai Valve, we also received customer inquiries regarding municipal sewage treatment whether it would be better to choose imported soft-seal wafer butterfly valves, but our suggestion is generally that municipal sewage does not need to be imported. Because the imported price is expensive and the delivery period is long, domestic valve manufacturers can do it. Generally, the use conditions of valves in sewage treatment plant projects are relatively low, and domestic valves not only meet the needs of use, but also save costs. A better domestic factory can meet the requirements, but the design institute generally chooses imported brands according to the situation.

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

Video of center-lined butterfly valve:

Resilient seated vs metal seated wafer butterfly valve

December 20, 2021

The soft-seal wafer butterfly valve contains two characteristics, one is that the sealing form is a soft seal, and the other is the connection method is a wafer. Wafer butterfly valves are divided into soft sealing butterfly valves and hard sealing butterfly valves. Soft seal means that one side of the butterfly valve sealing pair is made of metal

JIS 10K-wafer butterfly valve-backup seat (4)

material, and the other side is made of elastic non-metal material. The advantage of the soft sealing wafer butterfly valve is that it is made of non-metallic materials with certain strength, hardness and temperature resistance. It has good sealing performance, but its service life and temperature adaptability are relatively poor. In contrast, the hard seal wafer butterfly valve is made of metal, which can meet the process requirements of some corrosive materials. The hard seal has a long service life, but the sealing performance is relatively worse than that of the soft seal. The main differences between the soft-seal wafer butterfly valve and the hard-seal wafer butterfly valve are as follows:
1. The difference in structure: soft-sealed butterfly valves are mostly centerline. Hard seal butterfly valves are mostly single eccentric, double eccentric and triple eccentric butterfly valves.
2. Temperature resistance: soft-sealed butterfly valves are mostly used in normal temperature environments. Hard seal butterfly valve can be used in low temperature, normal temperature, high temperature and other environments.
3. Pressure: The soft seal wafer butterfly valve is only used for low pressure to normal pressure, and the hard seal can also be used for working conditions such as medium and high pressure, which is more resistant to high pressure.
4. Sealing performance: The soft sealing and triple eccentric hard sealing butterfly valves have better sealing

Double eccentric-wafer butterfly valve-D372F-150lbP-stainless steel (1)

performance. The triple eccentric butterfly valve can maintain good sealing under high pressure and high temperature environment.
In addition to the difference in product characteristics between the soft-seal wafer butterfly valve and the hard-seal wafer butterfly valve, their performance is also different, and they are used in different working conditions to adjust. The soft sealing wafer 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-seal wafer butterfly valves are mostly used in heating, gas supply, and gas, oil, acid and alkali environments.
With the widespread use of the soft-seal wafer butterfly valve, its features of convenient installation, convenient maintenance, and simple structure become more and more obvious. Products have also been continuously upgraded. For example, the electric soft-seal wafer butterfly valve, pneumatic soft-seal wafer butterfly valve, etc., which have been continuously developed in recent years, are used in more and more occasions, and gradually began to replace the more expensive electric power with some limited functions. Gate valves, globe valves, etc.

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

Video of center-lined butterfly valve:

Video of double eccentric butterfly valve:

Is a gasket needed for installation of the resilient seated wafer butterfly valve?

December 17, 2021

Before understanding the problem of adding gaskets to the soft-seal wafer butterfly valve, let’s take a look at the main working conditions of the soft-seal wafer butterfly valve. It can be applied to water supply and drainage, gas pipelines such as food, medicine, chemical industry, petroleum, electric power, textile papermaking, etc. It is used for regulating flow and intercepting medium. And has certain standards, as follows:

Wafer type butterfly valve with worm gear

Standards for soft-seal wafer butterfly valves:
Gauge manufacturing specification: GB/T 12238-2008
Construction length specification: GB/T 12221-2005
Connection flange specification: GB/T 9113
Pressure temperature rating: GB/T 12224-2005
Experimental inspection specification: GB/T 13927-2008
The soft-seal wafer butterfly valve is characterized by sensitive operation, labor-saving, and good sealing performance. So the reason for choosing the soft-seal wafer butterfly valve to a large extent is because of its good sealing performance. Then, in actual field application, we encountered a problem: Can the connecting surfaces on both sides of the soft-seal wafer butterfly valve function as a flange gasket? When installing the butterfly valve, is it necessary to add gaskets for sealing? With such a question, let’s first look at a live case.
A new batch of soft-seal wafer butterfly valves from a factory are used for acidic liquid pipelines. The soft-seal of the product is made very thick, and some of the soft-seal material is exposed to form a convex surface. May I ask if this kind of butterfly valve is installed? Also add gaskets for sealing? Through practice, we have seen that this situation can be added or not, but it is added for more insurance. Generally, new soft-sealed butterfly valves can be sealed without gaskets. If it is an old valve, it is necessary to consider the problem of aging. Soft-seal butterfly valves generally come with a gasket, which can not be installed, but it depends on the application of the soft-seal wafer butterfly valve. For example, in this case, if it is used in high temperature or corrosive liquid pipelines, in order to avoid personal injury, it is recommended to add high-pressure PTFE gaskets during flange connection, so that it can be safer and can be done once and for all. The purpose of adding gaskets is to protect the rubber-lined flange surface, because the replacement valve ring is more expensive than the replacement valve gasket. If the gasket is not added under bad working conditions, even if the flange does not leak, it is very likely that the valve will leak internally.
So in summary, whether the soft seal wafer butterfly valve needs to be gasketed depends on the chemical nature, temperature and pressure of the pipeline medium. Generally speaking, although the connecting surfaces on both sides of the soft seal wafer butterfly valve can play the role of flange gasket, it is recommended to add a gasket on both sides for safety. Because the butterfly valve will bump and bump a little during transportation and handling, it will produce an incomplete sealing surface, so it is recommended to add an extra gasket. Of course, there are other points of view that there is no need to add shims, and it is superfluous. Therefore, we can refer to a standard and then make a choice according to our specific working conditions, which can be based on the valve diameter, etc.: soft-seal wafer butterfly valves under 6 kg may not be added; 6-16 kg butterfly valves are recommended to add gaskets. Spacers below DN300 are 1.5mm; spacers above DN300 and below 1200 are 3.0mm. For more butterfly valve information, please contact Tanghai Valve’s online customer service.

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

Video of center-lined butterfly valve:

Troubleshoot reasons for pneumatic wafer butterfly valves

December 16, 2021

The pneumatic wafer butterfly valve has a beautiful appearance and is matched with a pneumatic actuator. The valve plate and the valve shaft can be connected without a pin, and the medium is completely isolated from the valve shaft and valve body, which is simple and easy to maintain. Pneumatic wafer butterfly valves are widely used in industrial automation systems in food, environmental protection, light industry, petroleum, papermaking, chemical, electric power and other industries. Pneumatic wafer butterfly valves are divided into soft seal and hard seal, and the two products also have their own different characteristics.

JIS 10K-wafer butterfly valve-backup seat (1)

The design features of the high-quality pneumatic wafer butterfly valve include: the valve body and end cover adopt dewaxing precision casting; the valve stem has an explosion-proof design; the standard air source interface can be directly connected to the solenoid valve; the cylinder inner wall anode hardening does not require secondary lubrication ; Switch position +/-5° stroke adjustment, easy to operate; 360°C any angle installation, etc. Its performance specifications are: nominal pressure: 1.0MPa-2.5MPa, nominal passage: DN32~DN600, applicable temperature: -20~+120 ℃. The hard seal will be higher. The soft-seal pneumatic wafer butterfly valve is used in normal temperature environment. The hard-sealed and soft-sealed pneumatic wafer butterfly valve can be used in low temperature, normal temperature, high temperature and other environments.
In use, we sometimes encounter the phenomenon that the pneumatic wafer butterfly valve does not work. Is it improper use or product quality? How do we troubleshoot the cause? Here is a reference. Pneumatic wafer butterfly valves are mainly composed of pneumatic actuators and butterfly valves. Pneumatic accessories are installed according to user requirements. Pneumatic accessories for on-off type pneumatic butterfly valves include solenoid valves and limit switches, adjustable type with positioners and filter decompression Device. Therefore, when the pneumatic wafer butterfly valve fails, it is necessary to investigate the cause one by one from each component.
The main points are as follows:
1. Pneumatic actuator:
(1) There is no air source and the air source is not opened (2) The air source pressure is insufficient (3) The cylinder piston is aging and fractured (4) The rack of the piston gear is worn (5) The single-acting actuator is rusted due to the long-term use of the spring;
2. Valve body:
(1) The valve stem is twisted or broken (2) The valve stem is rusted due to internal leakage of the medium (3) The medium has impurities and the valve plate and valve seat are stuck
3. Solenoid valve:
(1) If the terminal is loose or falling off, no electricity (2) The coil is burnt out (3) The solenoid valve is easy to get stuck when there are impurities or too little lubricating oil (4) Air leakage, the solenoid valve leaks and the air source pressure is insufficient;
4. Positioner:
(1) The air source is not turned on (2) In winter, the air source contains water and freezes causing the air duct and filter to be blocked (3) The regulator fails and the regulating mesh diaphragm is damaged;

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

Video of center-lined butterfly valve:

Advantages and Features of Center-lined Wafer Butterfly Valve

December 15, 2021

The centerline wafer butterfly valve is a kind of centerline butterfly valve, which has two characteristics of wafer connection and centerline sealing. Today, the advantages and characteristics of the centerline wafer butterfly valve are based on the flange butterfly valve. details as follows:

Wafer type butterfly valve with worm gear

Pressure Level
The centerline wafer butterfly valve generally does not have a high pressure, and cannot be made with a higher pressure level like the flange butterfly valve. The nominal pressure of flanged butterfly valves is higher than that of wafer butterfly valves.

Install
During installation, the centerline wafer butterfly valve is generally installed with a matching flange, and the flange butterfly valve does not need to be equipped separately. The valve bolt length of the wafer butterfly valve will be longer, so the construction accuracy is higher. Because if the flanges on both sides are misaligned, the bolts will be subjected to greater shearing force, and the valve is prone to leakage.

Repair and maintenance
The centerline wafer butterfly valve generally cannot be used in the end of the pipeline and the downstream occasions that need to be disassembled, because when the downstream flange is removed, the wafer valve will fall. In this case, another short section must be made for disassembly. The flanged butterfly valve does not have the above problems, but the cost will be relatively high. The wafer butterfly valve has no flanges at both ends of the valve body, only a few guide bolt holes, and the valve is connected with the flange at the end by a set of bolts/nuts. In contrast, disassembly is more convenient, and the valve cost is lower, but the disadvantage is that one sealing surface has a problem, and both sealing surfaces have to be disassembled.
Due to installation reasons, if you encounter a situation where you need to install a blind plate, this situation is actually quite often encountered. In this situation, the midline wafer butterfly valve can only be installed with transitional pipe sections or replaced with other types of valves. It is impossible to disassemble the blind plate on the center line of the clamp butterfly valve. It is necessary to add a pair of flanges to the straight pipe section behind the valve after stopping, and at the same time add the figure 8 blind plate to avoid insufficient position when the blind plate is added in the future.

Better tightness
The centerline wafer butterfly valve has a poorer sealing effect than the flange butterfly valve. For example, the transportation of slurry media causes blockage. The advantage of the center line to clamp butterfly valve is that it is easy to disassemble and assemble, but it will leak if it is not installed well. Flanged butterfly valves are expensive. The valve is equipped with flanges. The flanges on both ends of the valve are connected to the pipe flanges with bolts. The sealing performance is better than that of the clamp butterfly valve. Flange butterfly valves are easier to make eccentricity, and multiple eccentricities can achieve excellent sealing performance, but it is not easy to achieve a wafer butterfly valve. If the centerline wafer butterfly valve is a soft sealing butterfly valve, the rubber liner damage cannot be repaired on site, but the flange type can be repaired.

In summary, the centerline wafer butterfly valve has low cost and strong adaptability to installation space. The disadvantage is that the sealing performance is not as good as the eccentric butterfly valve and the flange butterfly valve, and the disassembly and maintenance will be slightly more troublesome than the flange butterfly valve. Under the condition that the medium pressure is not particularly high and the working conditions are ordinary, the centerline wafer butterfly valve is still a good choice from the comprehensive examination of cost, sealing performance, installation and maintenance.

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

Video of center-lined butterfly valve:

Is the EPDM butterfly valve suitable for water medium?

December 13, 2021

EPDM rubber butterfly valve fully meets the water working conditions and is a kind of soft sealing butterfly valve. It has excellent weather resistance, ozone resistance, heat resistance, acid and alkali resistance, water vapor resistance, color stability, electrical properties, oil-filling properties and fluidity at room temperature. It can be used in ozone-resistant, weather-resistant, and ultraviolet-resistant applications, but based on its own structural characteristics, EPDM butterfly valves have poor flame retardancy, oil resistance and adhesion. Now let’s take a look at the specific performance of EPDM butterfly valve:

wafer type butterfly valve, EPDM seat (10)

1. Low density and high filling:
The seat material of EPDM butterfly valve is a kind of rubber with lower density. A large amount of oil and filler can be added, so it can reduce the cost of rubber products, make up for the high price of EPDM rubber, and the physical and mechanical properties of the valve seat sealing surface are not greatly reduced after high filling.
2. Aging resistance:
EPDM butterfly valves have a common feature of rubber that is not resistant to high temperatures. It can be used for a long time at 120 ℃, and can be used briefly or intermittently at 150 to 200 ℃. However, manufacturers now also try to add suitable antioxidants to increase the temperature of the valve, and the EPDM butterfly valve cross-linked with peroxide can be used under more severe conditions.
3. Corrosion resistance:
EPDM butterfly valves have good resistance to various polar chemicals, such as alcohols, acids, alkalis, oxidants, refrigerants, detergents, animal and vegetable oils, ketones and greases. But it has poor stability in gasoline, benzene, etc. and mineral oil. Therefore, it is not suitable for oil, and its performance will decrease under the long-term action of concentrated acid.
4. Water vapor resistance:
EPDM butterfly valve has excellent performance in water vapor resistance. It is much higher than the performance of fluorine rubber, silicon rubber, fluorine silicon rubber, butyl rubber, nitrile rubber, and natural rubber under the same conditions.
5. Superheated water resistance:
The superheated water EPDM butterfly valve is also no problem, the mechanical properties change very little, and the volume expansion rate is low, but it is closely related to the vulcanization system used.
6. Electrical performance:
Compared with styrene butadiene rubber, polyethylene and cross-linked polyethylene, the electrical performance of EPDM butterfly valve is very close or even better, and it has good electrical insulation and corona resistance.
7. Flexibility:
In terms of elasticity, EPDM butterfly valves are second only to natural rubber and butadiene rubber, and can still be maintained at low temperatures.
8. Adhesion:
Due to the lack of active groups in the molecular structure of EPDM, the cohesive energy is low, and the rubber is easy to bloom, and its self-adhesiveness and mutual adhesion are very poor.

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

Video of center-lined butterfly valve: https://youtu.be/NuSZH_AJcwY

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