ball valve Archives

High platform ball valve and ordinary ball valve

June 17, 2021

The difference and selection of high platform ball valve and ordinary ball valve
High platform ball valve, the so-called high platform means that the ball valve adopts the ISO5211 manufacturing standard. A square or round flange and the ball valve are cast into one piece, and the end of the platform is higher than the outer edges of the flanges at both ends, which is not only conducive to easy installation Pneumatic actuators, electric actuators and other actuators can greatly improve the stability between the valve and the actuator, and the appearance is more beautiful and refined. The high platform usually called york or bracket.

Pneumatic electric high platform ball valve

Electric high platform ball valve Pneumatic high platform ball valve
The high platform ball valve is an evolution of the conventional ordinary bracket ball valve. The difference between it and the ordinary ball valve is that it can be directly connected to the drive actuator without installing a connecting bracket, while the ordinary ball valve requires the bracket to be installed before the actuator can be installed. . In addition to avoiding additional bracket installation, because it is installed directly on the platform, this greatly improves the stability between the actuator and the ball valve.
The advantage of the high platform ball valve is that it can directly install pneumatic or electric actuators on its own platform, while ordinary ball valves require additional valve connections. This may occur due to loose brackets or excessive coupling gaps. As a result, the valve is affected in use, but the high platform ball valve will not have this problem. Its performance is very stable during operation.

Schematic diagram of high platform ball valve

In the selection of high-platform ball valves and ordinary ball valves, the internal structure of the high-platform ball valve is still the principle of opening and closing, which is consistent with the ordinary ball valve. In addition to the advantages described above, when the medium temperature is relatively high, it needs to be adopted The connection bracket is to protect the normal use of the actuator and prevent the heat transfer of the medium from causing the actuator to be unusable.

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

Electric ball valve principle | Electric ball valve working principle

June 15, 2021

Electric ball valve principle | Electric ball valve working principle
The electric ball valve is mainly composed of an electric actuator and a ball valve. The cock body is a ball with a 90-degree rotation. Electric ball valve is not only a good product for throttling, blocking, cutting, on-off, and diversion, it is also the first choice in the flow control system. It has many characteristics such as pressure resistance,

electric ball valve

temperature resistance, corrosion resistance, low flow resistance, long service life, and wide application range. To
The working principle of the electric ball valve: The electric ball valve mainly relies on the adjustment of the electric current in the electric actuator to operate the ball valve. The input and output signal of the electric actuator is 4-20mA and the standard signal of the 220VAC power supply. The motor group drives the gear and worm torque to control the opening and closing of the ball valve, to distribute and change the flow direction of the medium or to adjust the proportional degree of the spool rotation, namely The opening of the valve is proportional to the control fluid, or percentage.
Electric ball valve application:

electric V type ball valve

The electric ball valve does not need to be operated manually, but is operated intelligently. In the production process, the environmental site determines all the factors. Electric ball valves used in high pressure, high temperature or low pressure and low temperature environments are different. The following points should be noted:
1. For low temperature and low pressure, the material does not need to be adjusted too much.
2. In the case of high pressure and high temperature, high temperature and high pressure resistant materials should be used as the electric ball valve material, such as stainless steel and alloy, which can withstand high pressure and high temperature.
3. The internal parts of the electric ball valve need to be replaced to reduce the damage to the valve core, and it is also conducive to the flow of the medium and avoid the coking and blockage of the electric ball valve.
4. When the electric ball valve is opened, some machinery to avoid vibration can be installed to prevent the internal structure of the electric ball valve spool from being damaged when it is opened.

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

Ball valve model preparation method/code name establishment

June 11, 2021

Ball valve model preparation method/code name establishment in China.
With the rapid development of my country’s industrial modernization, the use of valves is also increasing. Ball valves have the advantages of fast opening and closing speed, and not only can switch and cut off, but also control flow, etc., and become the most widely used valve type. one! However, due to the wide variety of ball valves, including the use of pressure, temperature and control methods, the corresponding ball valve models are also different. In order to avoid errors in the selection of the user, and to ensure that the ball valve can be used normally, more instruments Self-Control Valve Company hereby provides instructions for the preparation of ball valve models for everyone to understand and recognize!

Pneumatic electric high platform ball valve

Ball valve model editing instructions are mainly from the increase of additional conditions of the ball valve, the selection of the drive mode, the difference of the connection form, the change of the structure form, the type of sealing material, the level of valve pressure and the material of the valve body, etc. to facilitate the explanation, hope It is helpful to the majority of users.
Ball valve model representation method:
Ball valve additional code: V means the valve core has a V-shaped structure, D means low temperature, B means heat preservation, P means eccentric structure, U, S and DY mostly mean top-mounted type;
Ball valve name code: Q means ball valve; Ball valve drive code: 2 means electro-hydraulic, 3 means turbine, 6 means pneumatic, 7 means hydraulic, 9 means electric, manual without code;
Code of connection method: 1 means internal thread, 4 means flange type, 6 means welding, 7 means wafer type;
Structural type code: Floating type: 1 means straight-through runner, 2 means Y-type tee, 4 means L-type tee, 5 means T-type tee; Fixed type: 0 means hemispherical through, 6 means four-way runner, 7 Means straight-through flow to, 8 means L-type tee, 9 means Y-type tee;

fixed ball valve

Sealing material code: B babbitt alloy, F fluorine rubber, F46 lining fluorine, H stainless steel, J rubber lining, M Monel alloy, N nylon plastic, Monel P, Y cemented carbide, W valve body directly processed;
Pressure rating code: 16 means the pressure is 16 kg (1.6Mpa) and the maximum can reach 64Mpa; 150LB means the American standard pound pressure, and the maximum pressure rating can reach 2500LB (150LB=1.6MPA/300LB=2.5-4.0mpa/400LB=6.4 mpa/600LB=10mpa); 5K means Japanese pressure, maximum pressure is 63K; Valve body material code: A titanium and titanium alloy, C carbon steel, I chromium molybdenum steel, P18-8 series stainless steel, RMo2Ti series stainless steel, S plastic.
ball valve model editing instructions:
Q645F-16P Stainless steel pneumatic flange three-way ball valve
1. Q: represents the ball valve;
2. 6: It means that the transmission mode is pneumatic;
3. 4: The connection method is flange connection;
4. 5: The structure is a floating T-type tee;
5. F: The sealing material is fluorine rubber;
6. 16: Indicates that the nominal pressure is 1.6MPa;
7. P: indicates that the valve body is made of stainless steel.

Editing instructions for electric ball valve model:
VQ947F-16P Stainless steel electric flange V-shaped ball valve
1. V: indicates that the spool has a V-shaped structure
2. Q: represents the ball valve;
3. 9: indicates that the transmission mode is electric;
4. 4: The connection method is flange connection;
5. 7: The structure is a fixed straight flow channel;
6. F: The sealing material is fluorine rubber;
7. 16: Indicates that the nominal pressure is 1.6MPa;
8. P: indicates that the valve body is made of stainless steel.

More details for valve model establishment, you can visit another article: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

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

Pneumatic ball valve-with high platform vs with bracket

June 9, 2021

The difference between pneumatic high platform ball valve and pneumatic ball valve with bracket
Pneumatic ball valve is one of the most widely used valve types in recent years. It is not only convenient in operation, but also very fast in execution. It is used in a variety of fields, such as petroleum, chemical, power generation, paper, food, and pharmaceutical industries. And in people’s daily lives. By connecting the air source, solenoid valve control, and related accessories, the pipeline can be quickly opened or closed, and it can also be intelligently controlled to achieve the adjustment of various process parameters such as pipeline media!

Schematic diagram of high platform ball valve

There are many types of pneumatic ball valves, which can be divided into various models according to pressure, material, connection form, applied medium, including control form. Today we will analyze the difference and choice between the pneumatic high platform ball valve and the ordinary pneumatic ball valve with bracket!
Description and advantages and disadvantages of pneumatic high platform ball valve:
Pneumatic high platform ball valve, as the name implies, is that the ball valve adopts a high platform design. The ISO standard is commonly used. The purpose of this is to facilitate the installation of the drive device. The connecting plate can be directly installed and connected with the (electric/pneumatic) actuator without a bracket. And connecting shaft. It can save costs by avoiding the bracket, improve production efficiency, and greatly improve the stability between the valve and the actuator, and the performance is very stable in use, so the application of the overall valve will not be affected by the looseness of the bracket or the large coupling gap. To
The advantage of pneumatic high platform ball valve is that its shape is more beautiful than ordinary ball valve, more refined, beautiful and generous, it takes up less space, and the structure is more compact. The disadvantage is that it is not resistant to high temperature, and the temperature is transmitted to the cylinder. The rubber ring in the cylinder is easy to age, and it is generally applicable. In the pipeline where the medium temperature is below 80 degrees. To
Description and advantages and disadvantages of pneumatic ball valve with bracket:
The use and function of the pneumatic bracket ball valve and the high platform ball valve are the same. The difference is that between the pneumatic bracket ball valve actuator and the ball valve body, there is a bracket supported, usually high medium temperature needs to be equipped with a bracket , This can avoid damage to the actuator due to high temperature. In layman’s terms, the ultimate purpose of the bracket is to extend the service life of the valve. The advantage of the pneumatic ball valve with bracket is that the heat dissipation function is relatively strong. For example, the medium temperature of the pipeline is above 300 degrees. At this time, it is recommended that the valve stem of the pneumatic ball valve should be correspondingly lengthened and the bracket should be attached at the same time. The reason for the extension of the valve stem with the bracket is to separate the valve body of the ball valve from the actuator, so as to prevent the medium temperature of the ball valve body from being too high, thereby affecting the service life of the actuator. For example, when the valve body of a ball valve is immersed in a liquid medium, and the liquid medium is strongly corrosive, the operator cannot approach it, and the actuator is outside the liquid surface, and the actuator needs to be operated by the staff. In this case It is necessary to choose a ball valve with a longer stem and a bracket, and if the liquid is strongly corrosive, the material of the ball valve must also be standard stainless steel, so as to ensure the normal operation of the pneumatic ball 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

The difference between internally and externally threaded valves

June 1, 2021

Threaded valve (also called internal threaded valve) generally refers to a valve with internal or external thread on the valve body. It is mainly divided into internal threaded valve and external threaded valve. Corresponding to the pipeline. Usually threaded valves can only be manufactured with small diameters and are used for normal pressure or low pressure projects. If they are not available for high pressure work, they need to be used with welded link valves or flanged valves.

internally threaded valve and externally threaded valve

Common threaded valves are: threaded gate valve, threaded ball valve, threaded globe valve, threaded check valve.
The difference between internal threaded valve and external threaded valve:
From the point of use: Due to price and working flow requirements, most of the valves on the market use internal threaded valves. From the channel: Taking into account the thread connection, the passage of the external thread of the same caliber is smaller than the internal thread, the flow rate is faster, and the flow rate is small.
From the appearance: Most of the internal threads are pipe threads, the external threads are mostly taper threads, and the bite-type external threads are pipe threads.
In terms of pressure resistance: The wall of the valve with external thread of the same material is usually thicker than that of the internal thread (the smaller the passage, the thicker the wall), and the pressure resistance is greater. This is the reason why valves with high pressure ratings are all external threads. To
Sealing form of threaded valve:
1. Direct sealing: internal and external threads directly play a sealing role. In order to ensure that the joints are not leaking, they are often filled with lead oil, thread hemp and PTFE raw material tape; among them, PTFE raw material tape is widely used every day; this material has good corrosion resistance and extremely sealing effect. Good, it is convenient to use and store. When disassembling, it can be completely removed, because it is a non-sticky film, which is much better than lead oil and hemp.
2. Indirect sealing: the tightening force of the thread is transmitted to the gasket between the two planes, so that the gasket plays a sealing role.
Thread standard of threaded valve:
1. International standards ISO228/1, DIN259, are internal and external parallel threads, code G or PF (BSP.F);
2. German standard ISO7/1, DIN2999, BS21, taper external thread, parallel internal thread;
3. British standard ISO7/1, BS21, internal and external tapered thread, code PT or BSP.Tr or Rc;
4. American standard ANSIB21, internal and external tapered thread, code name NPT.

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

Properties of Fixed ball valve

May 31, 2021

The fixed ball valve is a new generation of high-performance ball valve, suitable for long-distance pipelines and general industrial pipelines. Its strength, safety, and harsh environment resistance have been specially considered in the design, and it is suitable for various corrosive and non-corrosive media. . Compared with the floating ball valve, when working, the force generated by the fluid pressure in front of the valve on the ball is all transmitted to the bearing, and the ball will not move to the valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions. The fixed ball valve has two-piece and three-piece valve body structures. The middle flange is connected by bolts, and the seal adopts reinforced PTFE embedded in the stainless steel ring. The rear of the steel ring is equipped with a spring to ensure that the valve seat is tightly attached to the ball. Keep it sealed.

fixed ball valve

The fixed ball valve is a new generation of high-performance ball valve, suitable for long-distance pipelines and general industrial pipelines. Its strength, safety, and harsh environment resistance have been specially considered in the design, and it is suitable for various corrosive and non-corrosive media. . Compared with the floating ball valve, when working, the force generated by the fluid pressure in front of the valve on the ball is all transmitted to the bearing, and the ball will not move to the valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions. The advanced spring pre-valve seat assembly has self-tightening characteristics to achieve upstream sealing. Each valve has two valve seats, which can be sealed in each direction, so the installation has no flow direction restriction and is two-way. This valve is generally installed horizontally.

The fixed ball valve has two-piece and three-piece valve body structures. The middle flange is connected by bolts, and the seal adopts reinforced PTFE embedded in the stainless steel ring. The rear of the steel ring is equipped with a spring to ensure that the valve seat is tightly attached to the ball. Keep it sealed. Both the upper and lower valve stems are equipped with PTFE bearings to reduce friction and save labor. The bottom of the small shaft is equipped with an adjustment plate to ensure the joint position of the ball and the sealing ring. Full bore diameter: The flow aperture of the valve is the same as the inner diameter of the pipeline to facilitate the pipeline cleaning.

Product features of fixed ball valve:

Operational reliability

The relative linkage (seat and stem bearing) of the large-diameter ball valve adopts Teflon with a small friction coefficient, so the operating torque is small. In addition, the long-term lubrication of the sealing grease makes the operation more flexible.

Valve seat structure

There are two types of valve seat structures: single-seal and double-seal structures. Generally, the one with self-relief function is single-seal, and double-seal is the additional safety relief on the valve body.

Lengthened stem

The extension of the valve stem is suitable for buried and low-temperature use. The length of the extension is determined according to the needs. The operation modes include manual, pneumatic, electric, gas-liquid linkage, etc.

Security of external forces

The wall thickness of the valve body is designed in accordance with the safety regulations of the high-pressure vessel, and meets the requirements of API6D for withstanding external force and bending resistance, and has sufficient strength.

As shown in the figure, the sealing of the gland part adopts four O-rings and a sealing grease injection device.

Performance advantages of fixed ball valves

Labor-saving operation: The ball is supported by the upper and lower bearings to reduce friction and eliminate the excessive torque caused by the huge sealing load formed by the imported pressure pushing the ball and the sealing seat.
Reliable sealing performance: PTFE material sealing ring is embedded in the stainless steel valve seat, and the end of the metal valve seat is equipped with a spring to ensure sufficient pre-tightening force of the sealing ring. When the sealing surface of the valve wears during use, it will be under the action of the spring. The valve continues to ensure good sealing performance.
Fireproof structure: In order to prevent the PTFE seal ring from being burnt due to sudden heat or fire, and large leakage occurs, which encourages the fire, a fireproof seal ring is set between the ball and the valve seat. When the seal ring is burned, Under the action of the spring force, the valve seat sealing ring is quickly pushed to the ball to form a metal-to-metal seal, which has a certain degree of sealing effect. The fire resistance test meets the requirements of AP16FA and API607 standards.
Automatic pressure relief function: When the pressure of the stagnant medium in the valve cavity rises abnormally and exceeds the pre-load of the spring, the valve seat retreats from the sphere to achieve the effect of automatic pressure relief. The valve seat automatically recovers after pressure relief.
Drainage pipeline: Drain holes are set up and down the valve body to check whether the valve seat is leaking. During work, when the valve is fully open or fully closed, the pressure in the middle cavity can be removed, and the packing can be directly replaced; the middle cavity can be discharged. Retentate, reduce the pollution of the medium to the valve.

Main features of fixed ball valve:

advantages of fixed ball valve:

Double blocking and discharge function: the fixed ball valve adopts spring pre-tensioned floating seat, no matter the valve is in the fully open or fully closed state, the upstream and downstream valve seats block the fluid, and the retentate in the valve body is discharged through the discharge valve. .
Automatic pressure relief function: When the temperature of the medium in the valve body cavity increases and causes abnormal pressure rise, it does not need to pass through the safety valve, but the valve seat function can automatically relieve the pressure, which is to ensure the safety of the valve when transporting liquid media. Sex is very important.
Fire safety structure: All valves have fire safety functions, and their design and manufacturing follow the requirements of API 607 and API 6FA.

Disadvantage of fixed ball valve:

Sealing emergency grease injection rescue: due to foreign matter in the medium or fire causing the valve seat seal to fail unexpectedly, the grease injection valve provides a quick connection with the grease injection gun, and the imported pump can easily and quickly inject the sealing grease into the valve seat sealing part. Mitigating leakage.
Reliable valve stem sealing and low operating torque: In addition to the standard sealing ring, an O-ring seal is also set on the packing gland. The double seal ensures the reliability of the valve stem seal; additional graphite packing and sealing grease Injection minimizes valve stem leakage after a fire. The valve stem sliding bearing and thrust bearing make the valve easy to operate.
Full diameter or reduced diameter: Full diameter or reduced diameter structure can be selected according to needs. The flow aperture of the full-bore valve is the same as the inner diameter of the pipeline, which is convenient for pipeline cleaning.
The valve stem can be lengthened: According to the needs of installation or operation, the valve stem can be lengthened. The extended stem ball valve is especially suitable for occasions where pipelines need to be buried in the ground, such as city gas. The size of the lengthened stem is determined according to customer needs.
Flexible operation: The valve seat and stem bearing with small friction coefficient and good self-lubricating property are adopted, which greatly reduces the operating torque of the valve. Therefore, even in the absence of sealing grease, the valve can be operated flexibly for a long time.

Application range of fixed ball valve:

The fixed ball valve is suitable for various pipelines of Class150～Class1500, PN16～PN100, JIS 10K～JIS 20K, applicable temperature: -196～350℃, used to cut off or connect the medium in the pipeline. Different materials can be selected. They are suitable for transporting water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, etc., and are widely used in petroleum refining, long-distance pipelines, chemical industry, papermaking, pharmaceuticals, water conservancy, electric power, municipal administration, steel and other fields. The driving mode of the fixed ball valve is worm gear drive, manual, pneumatic or electric. The fixed ball valve generally adopts flange connection, but also can adopt butt welding connection.

Related types of valves:

We can also produce gate valve, check valve, globe valve, knife gate 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,

The difference between fixed ball valve and floating ball valve

May 28, 2021

There are many types of ball valves, such as hard-sealed ball valves, soft-sealed ball valves, welded half-ball valves, V-shaped ball valves, flanged ball valves, wafer ball valves, fixed ball valves, and floating ball valves. These classifications are based on the actual use of the manufacturer and the actual situation of the customer. Need, it is slowly researched and developed, but no matter how it develops, it is inseparable from the design principle of the ball valve. The so-called new product of the ball valve, no matter what kind of ball valve is developed, the principle and design plan are designed around the main body of the ball valve. The principles and standards come.
Here, we mainly talk about fixed ball valves and floating ball valves.

14 ball-valve-6

The more intuitive difference between the fixed ball valve and the floating ball valve is that the fixed ball valve is located at the lower end of the valve, and there is a stem supporting hole corresponding to the upper stem. The upper and lower stems firmly fix the spool of the ball valve to make the spool of this valve. Can not roll at will. The sealing principle is that the valve seats on both sides are pressed against the fixed ball core in the middle, so that the valve has a sealing function.
The soft sealing ball valve is round at the lower end of the valve without opening. The ball core is only fixed unilaterally by the upper stem. The ball core can move freely inside the valve cavity. When sealing, the valve seats on both sides of the ball valve are fixed. The valve seat is pressed by the valve core to produce a sealing effect.
Generally speaking, fixed ball valves are suitable for large diameters and high pressure ball valves when the pressure is relatively high. The soft-sealed ball valve is suitable for small caliber, and is suitable for low-pressure sealing ball valve when the pressure is relatively low.
The main feature of the floating ball valve is that the ball has no supporting shaft. The ball is supported by the valve seats at the inlet and outlet ends of the valve. The valve stem and the ball are movably connected. The ball of this ball valve is held in a “floating state” by two valve seats.

The ball can freely rotate between the two valve seats through the valve stem by means of a handle or other driving device.

When the flow channel hole of the ball is aligned with the valve channel hole, the ball valve is in an open state, the fluid is unblocked, and the fluid resistance of the valve is small. When the ball is rotated by 90°C, the flow channel hole of the ball is perpendicular to the valve channel hole, and the ball valve is in a closed state. Under the action of fluid pressure, the ball is pushed to the valve seat at the outlet end of the valve (referred to as the back of the valve) to make it press Tighten and ensure sealing.

Features of floating ball valve:
Under the action of the pressure difference, the ball will move slightly downstream of the valve;
The sealing performance of the ball valve mainly depends on its downstream valve seat;
The valve seat cannot move between the ball and the valve body.

Features of fixed ball valve:

The ball of the fixed ball valve is connected with the upper and lower stems as a whole, or made into an integral connecting ball, that is, the ball is forged (welded) with the upper and lower stems and mounted on the bearing. The ball can be aligned with the valve channel. The vertical axis rotates freely, but cannot move along the channel axis.

Therefore, when the fixed ball valve is working, all the force generated by the fluid pressure in front of the valve on the ball is transmitted to the bearing, and the ball will not move to the rear valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions.
Function of fixed ball valve
The function of preventing the valve stem from blowing out
Double cut and bleed (DBB) function
Safety function (fire protection function)
The function of injecting sealing grease when the valve leaks
Piston effect of ball valve seat (two-way piston effect of G series ball valve)
The purpose of the two-way piston effect: automatically release the pressure in the cavity of the valve body.
The use of the one-way piston effect: After the upstream valve seat is damaged, the fluid flows into the middle cavity, and the pressure in the middle cavity is higher than the pressure downstream of the valve.
Floating ball valve design should focus on the medium load to be considered in the material of the sealing ring. Excessive medium pressure will affect the life of the valve seat, and the ball can only have a slight offset. Therefore, the floating ball valve is generally suitable for DN200 or below DN200. The ball of the fixed ball valve whose nominal pressure does not exceed CLASS600Lb (10.0MPa) is fixed in the middle of the valve body by the upper and lower stems, and will not move after being pressed. The sealing of the fixed ball valve is to ensure the sealing by providing sufficient pre-tightening force through the leaf spring or cylindrical compression spring on the sealing valve seat, which is a double-sided forced sealing. The ball is supported by the upper and lower bearings, reducing friction, eliminating the excessive torque caused by the huge sealing load formed by the imported pressure pushing the ball and the sealing seat, and the operation is labor-saving. The fixed ball valve is double-sided and sealed on both sides, which will form a sealed cavity between the two sealed valve seats. To avoid danger, the fixed ball valve must be designed with an automatic pressure relief function, that is, when the pressure of the stagnant medium in the valve cavity increases abnormally and exceeds the spring At the time of pre-force, the valve seat retreats away from the sphere to achieve the effect of automatic pressure relief. After pressure relief, the valve seat automatically recovers. The fixed ball valve is widely applicable to various process pipelines with large diameter and high pressure due to its structural characteristics. Due to the need to assemble the upper and lower stems, only ball valves with a nominal diameter of DN50 or above can be produced. The nominal diameter is too small to be assembled.

Structure of fixed ball valve
1). Sphere
After introducing the various structural forms of the seal seat, I came to observe the ball structure of the same ball valve. The most important feature of the Tongding ball valve is that the ball does not deviate from the center of the sphere during the process of storing and opening. The ball I: the design of the pivot has three structural forms:
① the upper part of the sphere has a shaft, and the lower part is a shaft hole for a fixed shaft to insert. The structure of the sphere is a shaft and a hole structure.
② there are two upper and lower shaft holes on the sphere, which are inserted by the upper shaft and the lower shaft respectively. The structure is suitable for small diameters. The insertion depth of the hole is short, and it can only bear a small medium force. The structure is suitable for large diameters, can bear a large medium force, and the supporting journal is separated from the drive shaft. The drive shaft only bears the effect of torque.
③ there are two extending shafts on the sphere, two supporting plates vertically up and down. The medium force is transmitted to the valve body through the journal and the supporting plate. Similarly, the drive shaft only bears a single rotation. The moment action separates the medium force and the operating moment.

2). the valve body

Since the valve body is a forged cylinder, there is no usual valve neck. The valve neck is replaced by a stuffing box. The stuffing box is fixed on the platform of the valve body by bolts. The shaft seal is made of O-shaped rubber ring. The connecting support plate of the valve is also fixed on the valve body through the through hole on the stuffing box. It can be seen that the strength of the valve body in the journal part of this cylindrical structure is greatly weakened.

As for the structure of the valve body, like the floating ball valve, there are two types: side-mounted and top-mounted.

The side-mounted type can be divided into two sections, a main valve body and a secondary valve body structure, or a three-section type, a main valve body and two secondary valve body structures.

The top-mounted valve body is an integral structure. The upper valve cover uses bolts to form a complete pressure boundary with the valve body. The ball is a ball with upper and lower support shafts. The lower support bearing is embedded in the valve body, and the upper support bearing is placed in the valve cover. , The upper shaft end is machined with a groove connected to the flange of the shaft head to transmit torque. The medium force acts on the bearing. The drive shaft only transmits torque. It is designed as a blow-out prevention structure. The design of the valve seat The difficulty of assembly or disassembly is that the valve seat must move to both sides when the ball is installed in the valve cavity. In this way, a slidable back valve seat is designed. The valve seat is retracted into the left and right channels in advance. After the ball is installed, pass the back The flange on the valve pushes the valve seat to the center of the ball, and then uses a snap ring to snap into the groove of the back valve seat. When disassembling, first take out the snap ring, and then push the valve seat into the left and right sides of the valve cavity. In the right channel, the sphere can be taken out from the upper part. Therefore, the top-mounted structural ball has the advantage of being able to be repaired online.

Related types of valves:

We can also produce gate valve, check valve, globe valve, knife gate 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,

Valve selection basis and selection guide

September 18, 2020

How to select the righty type of valve? the following article will give you an idea how to choose the right structure/type valve.

Nowadays, there are more and more valves on the market, the types of valves are particularly complex, and the

ball valve working diagram-3D GIF animated presentation

structures and materials are all different. The selection of valves is very important for the long-term operation of the device in working conditions. Improper selection of valves and users’ ignorance of valves are the source of accidents and safety threats. Nowadays, the demand for valve products in the social industry is becoming more and more extensive, and users should have a further understanding and cognition of knowledge about valves and other aspects.

There are generally two types of valve characteristics, use characteristics and structural characteristics.

Use characteristics of the valve: It determines the main use performance and use range of the valve. The

butterfly valve working diagram-3D GIF animated presentation

characteristics of the valve use include: valve category (closed circuit valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve) Etc.); the materials of the main parts of the valve (valve body, bonnet, valve stem, valve disc, sealing surface); valve transmission mode, etc.

The structural characteristics of the valve: it determines the structural characteristics of the valve installation, repair, maintenance and other methods. The structural characteristics include: the structural length and overall height of the valve, the connection form with the pipeline (flange connection, threaded connection, clamp Connection, external thread connection, welding end connection, etc.); the form of the sealing surface (inlaid ring, threaded ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting

gate valve working diagram-3D GIF animated presentation

rod), etc.

Valve selection steps:
1. Clarify the purpose of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
2. Determine the nominal diameter and connection method of the pipe connected to the valve: flange, thread, welding, ferrule, quick installation, etc.
3. Determine the method of operating the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electrohydraulic linkage, etc.
4. Determine the material of the valve housing and internal parts according to the medium, working pressure and

globe cut-off valve working diagram-3D GIF animated presentation

working temperature conveyed by the pipeline: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
5 Select the type of valve: closed circuit valve, regulating valve, safety valve, etc.
6. Determine the valve type: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.
7. Determine the parameters of the valve: For automatic valves, first determine the allowable flow resistance, discharge capacity, back pressure, etc., according to different needs, and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole.
8. Determine the geometric parameters of the selected valve: structural length, flange connection form and size, valve height dimension after opening and closing, connecting bolt hole size and number, overall valve outline size,

tilting disc swing check valve working diagram-3D GIF animated presentation

etc.
9. Use existing information: valve product catalog, valve product sample, etc. to select appropriate valve products.

Basis for valve selection:
1. The purpose, operating conditions and operation control mode of the selected valve.
2. The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable or explosive medium, the viscosity of the medium, etc.
3. Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level, etc.
4. Requirements for installation dimensions and external dimensions: nominal diameter, connection to the pipeline and connection dimensions, external dimensions or weight restrictions, etc.
5. Additional requirements for the reliability and service life of valve products and the explosion-proof performance of electric devices. (Note when selecting parameters: If the valve is to be used for control purposes, the following additional parameters must be determined: operation method, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop when closed, maximum and minimum inlets of the valve Pressure.)

According to the above-mentioned basis and steps for selecting valves, the internal structure of various types of valves must be understood in detail when selecting valves reasonably and correctly, so that the correct choice can be made on the preferred valve. The ultimate control of the pipeline is the valve. The valve opening and closing parts control the flow mode of the medium in the pipeline. The shape of the valve flow channel makes the valve have a certain flow characteristic. This must be considered when selecting the most suitable valve for the pipeline system.

Valve flow characteristic curve and classification

September 18, 2020

The flow characteristic of the valve is the relationship between the relative flow of the medium flowing through the regulating valve and its opening under the condition that the pressure difference between the two ends of the valve remains constant. Flow characteristic is an important technical index and parameter of regulating valve. It is very important to make the correct selection in the application process of the control valve.

Flow characteristics of regulating valve

Valve flow characteristics can be defined as: the relative flow of the controlled medium flowing through the valve, and the relationship between the relative opening (relative displacement) of the valve is called the flow characteristics of the regulating valve. Generally speaking, it is divided into four types: straight line, equal percentage (logarithm), parabola and quick opening! The specific description and advantages are as follows:

1. The linear characteristic refers to the linear relationship between the relative flow of the valve and the relative opening, that is, the time constant of the flow change caused by the change of unit opening. The relative stroke of the linear characteristic is linear with the relative flow. The flow change caused by the change of unit stroke is constant. When the flow is large, the relative value of the flow changes little, and when the flow is small, the relative value of the flow changes greatly.

2. the equal percentage characteristic (logarithm) means that the relative flow change caused by the change of the unit opening is proportional to the relative flow at that point, that is, the amplification factor of the regulating valve changes, and it increases with the increase of the relative flow. The relative stroke and relative flow of equal percentage characteristics are not in a linear relationship. The change in flow caused by the change of unit stroke at each point of the stroke is proportional to the flow at this point, and the percentage of flow change is equal. Therefore, its advantage is that when the flow rate is small, the flow rate changes small, and when the flow rate is large, the flow rate changes greatly, that is, it has the same adjustment accuracy at different opening degrees.

3. the parabolic characteristic means that the relative flow change caused by the change of the relative opening of the unit is proportional to the square root of the relative flow value at this point. The flow rate changes in proportion to the two sides of the stroke, and generally has an intermediate characteristic between linear and equal percentage characteristics.

4. the quick opening flow characteristic means that there is a larger flow when the opening is small. With the increase of the opening, the flow can reach the maximum quickly, and then the opening is increased, and the flow change is small, so it is called For quick opening characteristics.

The flow characteristic of the diaphragm valve is close to the quick opening characteristic, the flow characteristic of the butterfly valve is close to the equal percentage characteristic, the flow characteristic of the gate valve is the linear characteristic, the flow characteristic of the ball valve is linear in the middle opening and closing stage, and the equal percentage characteristic in the middle opening.

Globe valve (9)

Under normal circumstances, ball valves and butterfly valves are usually not used for adjustment. If they are used for adjustment, they are only used for adjustment when the opening is small. Generally, they can be classified as quick-opening, and they are really used for adjustment. Most of them are basically cut-off valves (globe valve). The valve head is processed into a parabolic cone, spherical shape, etc., and different curve characteristics are used. Generally speaking, as an adjustment, the basic percentage characteristic is used more.

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

Types and selection of electric valves

September 16, 2020

Types of electric valves:
Electric valves are valves driven by electric energy, mainly composed of electric actuators and various types of valves.

double eccentric butterfly valve (2)

Because the electric valve is easy to use and can be operated when the power is turned on, it is the longest-used type of automatic control valve. There are many types of electric valves. Commonly used are electric control valves, electric ball valves, electric butterfly valves, electric gate valves, and electric globe valves. Different types of electric valves have different applications.

1. The electric control valve can choose different valve structures and spool types according to the working conditions of the medium. It is mainly suitable for high, medium and low pressure pipelines with various media to adjust pipeline parameters. With the increasing requirements in the field of modern industrial automation, electric control valves are becoming more and more widely used. Different materials can be used to use various liquid and gas media pipelines.

2. Electric ball valve and electric butterfly valve are the most widely used electric valve models, equipped with different actuators, which can not only realize the two-position cut-off of the pipeline, but also can be used for occasions where the linearity requirements are not too strict. Electric butterfly valves There are two connection methods: wafer type and flange type. Normal pressure and large diameter pipes are mostly used. Electric ball valves and electric butterfly valves are similar in use, but they use more pressure than electric butterfly valves.

3. Both the electric gate valve and the electric shut-off valve have a blocking function in the pipeline, but it should be noted that these two types of valves cannot be used for adjustment. It is suitable for all kinds of large diameter, high, medium and low pressure medium working conditions.

Electric valve selection:
Electric valves are usually valves that are driven by a motor. Because the motor needs to be decelerated to drive the valve to open and close, it is generally not recommended to use electric if it is required to close and open the valve quickly. Basically, you can choose electromagnetic quick-closing valve, pneumatic or hydraulic quick-closing valve. Close the valve. But if necessary, you must choose an electric type of quick-closing valve, then you should choose an electric butterfly valve or an electric ball valve, because this type of valve has a short switching stroke.

Posts

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Electric ball valve principle | Electric ball valve working principle

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Properties of Fixed ball valve

The difference between fixed ball valve and floating ball valve

Valve selection basis and selection guide

Valve flow characteristic curve and classification

Types and selection of electric valves

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