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Which valves are used for wastewater and sewage treatment

Which valves are used for wastewater and sewage treatment? The continuous increase of water pollution in my country has made the sewage treatment and regeneration industry receive unprecedented attention. In the sewage treatment pipeline system, the valve plays a very important role.

marine valve; butterfly valve; check valve; gate valve; manufacturer in China

marine valve; butterfly valve; check valve; gate valve; manufacturer in China

Definition of sewage treatment
Sewage treatment: The process of purifying sewage in order to make it meet the water quality requirements for discharge into a body of water or for reuse. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical treatment, catering and other fields, and is increasingly entering the daily life of ordinary people.

Sewage treatment classification
According to the classification of sewage sources, sewage treatment is generally divided into production sewage treatment and domestic sewage treatment. Production sewage includes industrial sewage, agricultural sewage and medical sewage, etc., while domestic sewage is sewage generated in daily life, which refers to the complex mixture of various forms of inorganic and organic substances, including: ① floating and suspended solid particles; ② glue shape and gel-like diffusion; ③ pure solution.
According to the quality of water pollution, there are two types of water pollution: one is natural pollution; the other is man-made pollution. At present, man-made pollution is the most harmful to water bodies. Water pollution can be divided into three categories: chemical pollution, physical pollution and biological pollution according to the different pollution impurities. The main pollutants are: (1) industrial wastewater discharged without treatment; (2) domestic sewage discharged without treatment; (3) farmland sewage with extensive use of chemical fertilizers, pesticides, and herbicides; (4) industrial waste and domestic garbage piled up by the river ; ⑸ soil erosion; ⑹ mine sewage.

Sewage treatment valve
Modern sewage treatment technology can be divided into primary, secondary and tertiary treatment according to the degree of treatment. Generally, the degree of sewage treatment is determined according to the water quality and the destination of the treated water. The valves used at each level are also different.
primary treatment
It mainly removes suspended solid pollutants in sewage, and most of the physical treatment methods can only complete the requirements of primary treatment. After primary treatment of sewage, BOD can generally be removed by about 30%, which does not meet the discharge standard. The primary treatment belongs to the preprocessing of the secondary treatment. Valves and their pipeline accessories are used: knife gate valve, triple eccentric butterfly valve, filter, etc.
secondary processing
It mainly removes colloidal and dissolved organic pollutants (BOD, COD substances) in the sewage, and the removal rate can reach more than 90%, so that the organic pollutants can meet the discharge standard, and the suspended solids removal rate can reach 95%, and the effluent effect is good. The valves used are soft-sealed butterfly valves, gate valves, ball valves, check valves, etc.
tertiary treatment
Further treatment of refractory organic matter, nitrogen and phosphorus and other soluble inorganic matter that can lead to eutrophication of water bodies. The main methods are biological denitrification and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. The valves used are wafer butterfly valve, gate valve, ball valve, check valve, rubber soft joint, etc.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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
Video of triple eccentric butterfly valve: https://youtu.be/AkRwg2X1Wh0
Video of dual plate wafer check valve: https://youtu.be/XqRRI7o-LFI
Video of knife gate valve: https://youtu.be/vFSbTF_FGXM
Video of resilient seated gate valve: https://youtu.be/AI-LT1dy2sU

Related news/knowledge:
Application of Soft Seal Wafer Butterfly Valve in Sewage treatment
Gate valve has a broad market in the field of sewage treatment
Knife gate valve introduction and its characteristics

How many types of gate valves? gate valve classification

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)

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)

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 valvegate valvecheck valveglobe valveknife 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:

Related news/knowledge:
Pneumatic gate valve model preparation method
The difference between knife gate valve and ordinary gate valve
Valve body and material classification

The difference between knife gate valve and ordinary gate valve

There are many types of gate valves. Knife gate valve is one of them, also called knife gate valve. According to different structure types, gate valves can be divided into flat gate valves and knife gate valves. According to the different connection methods, knife gate valves can be divided into flange type; lug type and wafer type.

DIN-F5-BB-NRS-soft seated-wedge gate valve (10)

DIN-F5-BB-NRS-soft seated-wedge gate valve (10)

Compared with ordinary gate valves, the structure of the knife gate valve is simple, the opening and closing part is a gate, and the movement direction of the gate is perpendicular to the direction of the fluid. It is small in size, flexible in operation, and easy to install. It is more suitable for media with higher consistency and solid particles. As we can see from the name, the knife gate valve mainly relies on the knife-edge gate to cut off the medium. The gate has two sealing surfaces, forming a wedge shape. The gate can be made into an integral rigid gate; it can also be made into an elastic gate that can produce slight deformation and improve the sealing performance from the process. To sum up, compared with ordinary gate valves, knife gate valves mainly highlight the following product advantages:

1. The U-shaped gasket has a good sealing effect.
2. The full-diameter design makes the medium passability strong. At the same time, it can be easily installed, easily disassembled, and maintained under the working conditions of dirty media. The valve seal can be replaced without removing the valve, making the valve maintenance easier.
3. The gate with the function of the guillotine knife has good sluicing effect, can effectively squeeze off all kinds of debris in the medium, and solve the leakage phenomenon of the medium containing lumps, particles and fibers after the sluice is broken.
4. The knife gate valve has an ultra-short structure length, small size, small flow resistance, light weight, material saving, and small effective space.
Although the price of knife gate valve is about 20% higher than that of ordinary gate valve, its better performance has been generally recognized by the market, and it has quietly boarded the list of the most popular product series of Tanghai Valve. Through more than 20 years of research and production of valve technology, Tanghai Valve has senior production experience and advanced technical level, has a formal and modern production base, and has stably provided a large number of products for the knife gate valve market with a good reputation. If you need a knife gate valve, choose Tanghai Valve.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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

Related news/knowledge:
Pneumatic gate valve model preparation method
Knife gate valve introduction and its characteristics
Comparison of bellows globe valve and ordinary globe valve

Maintenance Methods of Common Valves

Common valve failures include leakage, opening and closing parts damage and failure, etc. One of the most important reasons for the valve failure problem is that the valve is not well maintained. The valve is an important part of the pipeline transportation system. Maintenance and maintenance can make the valve better serve us. At the same time, it can also prevent valve failure from the source and reduce production accidents caused by valve failure. Therefore, this article will talk about the maintenance methods of commonly used valves.

marine valve; butterfly valve; check valve; gate valve; manufacturer in China

marine valve; butterfly valve; check valve; gate valve; manufacturer in China

1. For valves that are not in use for a long time, they must be cleaned regularly to remove dirt and dust on the exposed surface of the valve, and at the same time, they must be sealed to ensure that the inside of the valve is clean and dry. Store the valve neatly in a ventilated and dry place indoors, and it is strictly forbidden to stack it or store it in the open air. When storing, the butterfly valve is the easiest to store, just keep the butterfly plate in the closed state. For gate valves, globe valves and check valves, both ends of the passage should be blocked during storage, and the valve plate should be closed. The storage of the ball valve requires that both ends are blocked and in an open state.
2. Before installing the valve, you need to check the pressure and diameter of the valve again, and clean up the dirt on the valve during transportation.
3. When installing the valve, install the valve correctly according to the connection method of the valve. Generally, the commonly used valves can be installed at any position in the pipeline, but it is necessary to consider whether the operation of the operator is convenient after installation and whether it is convenient for future valve maintenance .
4. When the gate valve and ball valve are working, they are only used for fully open and fully closed. They cannot be used for flow adjustment, otherwise the sealing surface will be severely washed and corroded, and the opening and closing parts of the valve will be greatly worn.
5. When the handle valve and handwheel valve are opened or closed, levers, wrenches or other tools cannot be used to avoid damage to the valves.
6. Tighten the bolts on the valve packing gland evenly. Don’t beat the gland to make the gland tilt, which will damage or hinder the movement of the valve stem and cause valve leakage.
7. During use, the valve should be maintained regularly to keep the valve clean, and the transmission part should be regularly lubricated. Once the valve is found to be malfunctioning, it must be stopped immediately to find out the cause of the malfunction and clean up the malfunction.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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

Related news/knowledge:
Common failures of butterfly valves and the characteristics of installation
Installation and Maintenance of Butterfly Valve
Installation and maintenance of electric ball valve
Valve cleaning steps and assembly requirements

Commonly used valves for Water Supply and Drainage System

Valves often used in water supply and drainage piping systems include butterfly valvegate valvecheck valve.
This article introduces common water supply and drainage system valves one by one.
1. Butterfly valve: a simple regulating valve, generally used in low-pressure medium pipelines for cutting off and intercepting. It is also one of the common valves in water supply and drainage piping systems. It regulates and intercepts the flow of water on the water supply and drainage pipeline. The butterfly valve is small in size, light in weight, easy to install and operate, but the opening and closing torque is relatively large.

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

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

The butterfly valve can be divided into wafer butterfly valve and flange butterfly valve according to the connection mode; according to the different driving mode, it can be divided into handle butterfly valve, turbine butterfly valve, electric butterfly valve, pneumatic butterfly valve, etc.
2. Gate valve: It can only be a kind of valve that can cut off the flow of the pipeline medium. The structure of the gate valve is more complicated. It can only be fully opened and fully closed. The opening and closing torque is small, the fluid resistance in the pipeline is small, and it can flow in both directions. The gate valve is most suitable for media that does not contain particles, such as water, because the sealing surface of the gate is easy to wear with impurities or particles in the medium. In addition, impurities precipitate to the bottom of the valve body, which will affect the sealing performance of the gate valve. Causes the defect that the valve is not closed tightly.

dual plate wafer type check valve (1)

dual plate wafer type check valve (1)

The gate valve is only suitable for use in pipelines that need to be normally open or normally closed, because if the gate valve is frequently opened and closed, it may cause the valve plate to fall off and make the system lose its control ability.
The gate valve can be divided into parallel plate gate valve and wedge plate gate valve according to the difference of the gate. According to the difference of valve stem, it can be divided into open stem gate valve and dark stem gate valve.
3. Shut-off valve: similar to gate valve, the functions of the two are similar when the medium in the pipeline is cut off. But the difference between the globe valve and the gate valve is that the globe valve has a simpler structure and is more convenient to maintain, but the force used to switch the valve is greater than that of the gate valve. In addition, the globe valve is a one-way valve. When installing, pay attention to the valve body. The instructions on the operation must not be reversed.
4. Check valve: It is also a list valve and check valve, which has strict directio

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

nality and stipulates that the medium is only allowed to flow in one direction. The check valve is used in pipelines where the medium is water, and is mainly used to prevent backflow of water.
Commonly used check valves include butterfly check valves, muffler check valves, swing check valves and so on. When installing, according to the type of valve, determine whether to install on a vertical pipeline or a horizontal pipeline, and install it strictly in the direction marked by the arrow on the valve body, and the installation cannot be reversed.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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

Related news/knowledge:
Wafer type butterfly valve (TH-BTV-AW)
Features and working principle of silent check valve
Characteristics and working principle of electric globe valve

Gate valve model meaning and representation method

Gate valve model representation method | Gate valve model meaning
Explanation of the meaning of the gate valve model:

pneumatic gate valve (3)

pneumatic gate valve (3)

Gate valve is one of the more common types of shut-off valves. It is generally suitable for full-open or full-close two-position operation control. It is mainly used to close the medium in the pipeline. It is usually called a cut-off valve or a blocking valve. With the increase in demand for valves and the expansion of demand in the machinery industry, gate valves have become an indispensable part of modern industrial control systems. For more and more complex working conditions and harsh use requirements, the correct selection of gate valve models is related to the adaptability of the pipeline medium and an important guarantee for the safety of the working conditions. The user should have a detailed understanding of the method of preparing the gate valve model to avoid problems such as selecting the wrong model, placing the wrong order, and unclear technical parameters resulting in replacement and return.
This compilation method is the representation method of the standard gate valve model in my country. It mainly explains in detail the additional conditions of the gate valve, drive mode, connection form, structural feature, sealing material, pressure level and valve body material. Other customized or special product models are not applicable to this method and need to be explained separately.
The method of formulating and expressing gate valve model:
Additional code for gate valve: WZ means bellows gate valve, DZ cryogenic gate valve, NKZ vacuum gate valve, PZ knife gate valve;
Type of gate valve: Z;
Drive mode: manual without code (usually omitted according to regulations), 2 electro-hydraulic, 3 worm gear, 5-bevel gear transmission, 6 pneumatic, 9-electric;
Connection mode: 4 flange connection, 6 welding, 7 pair clip type;
Structural form: 0 elastic gate, 1 open-rod wedge-type single gate, 2-open-rod wedge-type double gate, 3-open-pole parallel single gate, 4-open-pole parallel double gate, 5 concealed Rod wedge single gate, 6 concealed rod wedge double ram, 7 concealed rod parallel single ram, 9 concealed rod parallel double ram;
Sealing material: W valve body is directly processed, T alloy, X rubber, F fluoroplastic, H-Cr stainless steel, Y cemented carbide, M Monel alloy;
Pressure rating: PN1.0-32Mpa, 16=1.6MPA means the pressure is 16 kg, 150LB-1500LB means the American standard pound pressure, 5-63K means the Japanese pressure;
Valve body material: Z-gray cast iron, Q ductile iron, T alloy, C carbon steel, P stainless steel 304, R stainless steel 316, V chromium molybdenum vanadium steel.

Knife-gate-valve-1-

Knife-gate-valve-1-

Example of preparing gate valve model:
PZ973H-16C Electric Wafer Type Knife Gate Valve

1. PZ: stands for knife gate valve;
2. 9: indicates that the transmission mode is electric;
3. 7: The connection method is a clip-on connection;
4. 3: The structure is an open pole parallel single gate;
5. H: The sealing material is stainless steel;
6. 16: Indicates that the nominal pressure is 1.6MPa;
7. C: Indicates that the valve body material is carbon steel.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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

related news /knowledge:
Representation method of butterfly valve model;
Representation method of electric gate valve model;
Pneumatic gate valve model preparation method;

The difference between internally and externally threaded valves

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

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 valvegate valvecheck valveglobe valveknife 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

Knife gate valve introduction and its characteristics

Knife gate valve entered China in the 1980s. In less than two decades, its use has expanded from ordinary fields to a

Knife gate valve (1)

Knife gate valve (1)

wider range of industries, from coal preparation, gangue discharge, and slag discharge in mines and power plants to Urban sewage treatment has evolved from general industrial pipelines to specialized pipeline systems for food, sanitation, and medicine.

What is a knife gate valve:
Knife gate valve-also known as knife door valve, knife-type slurry valve, entered my country in the 1980s. In less than two decades, its scope of use has expanded from the general field to a wider range of industries. Coal preparation, gangue discharge and slag discharge from mines and power plants. It has developed into urban sewage treatment, from general industrial pipelines to professional pipeline systems such as food, sanitation, and medicine. The ultra-thin knife gate valve completely solves the large flow resistance of ordinary gate valves, flat gate valves, ball valves, globe valves, regulating valves, butterfly valves and other valves with its advantages of small size, small flow resistance, light weight, easy installation, and easy disassembly. , Heavy weight, difficult installation, large area and other difficult problems. After the emergence of knife gate valves, a large number of general shut-off valves and regulating valves have been replaced. To date, the world’s largest consumption of knife gate valves is the United States and Japan.

Characteristics of knife gate valve:

Knife gate valve-

Knife gate valve-

1. Valve control can be used for local and remote control, and can also realize remote position display and remote centralized control according to user requirements.

2. Light weight: The body is made of carbon steel, and the weight is about 20%-30% lighter than the traditional gate valve. It is easy to install and maintain.

3. The use of this valve can improve the closing and sealing performance of the conveying pipeline system, prevent leakage to the maximum extent, and play a positive role in improving production efficiency and protecting the environment.

4. The sealing surface is made of highly wear-resistant and corrosion-resistant ceramic materials, and the use of inlay technology has high corrosion resistance and good wear resistance, so that the valve has a long life and the cost performance is 10 times higher than that of ordinary valves.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife 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

Related news/knowledge:
Pneumatic gate valve model preparation method;
Gate valve model meaning and representation method;
Gate valve structure diagram and working principle;

Classification and advantages of gate valve

Gate valve types:

There are many domestic manufacturers of gate valves, and most of the connection dimensions are not uniform.

gate valve (3)

gate valve (3)

Mainly divided into the following categories: 1. According to JB/T2203-1999 “Structural Length of Gate Valve”, the standard valve of the Ministry of Machinery; 2. According to GB/T12221-2005 “Metal Valve Structure Length”, the national standard valve; 3. According to American standard valves produced by ASME B16.10-2009 “Face-to-face and End-to-End Dimensions of Valves”.

Gate valves are divided into wedge type and parallel type according to the structure of the gate. There are 3 types of wedge gates: single gate, double gate and elastic gate.

Gate valves are divided into flat gate valves and knife gate valves according to their structure types.

The working principle of manual gate valve: Turn the hand wheel, and the valve plate connected with the valve stem can be lifted or lowered by the thread of the hand wheel and the valve stem to open and close.

According to the classification of shell/body material, gate valves can be divided into:

Metal material valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, lead alloy valves, etc.

Metal valve body lining valves: such as rubber-lined valves, fluorine-lined valves, lead-lined valves, plastic-lined valves, and enamel-lined valves.

Non-metallic materials valves: such as ceramic valves, glass valves, plastic valves.

Advantages of gate valve:
1. Small flow resistance. The medium channel inside the valve body is straight, the medium flows in a straight line, and the flow resistance is small.
2. Less effort when opening and closing. It is compared with the shut-off valve, because whether it is open or closed, the direction of movement of the gate is perpendicular to the direction of medium flow.
3. Large height and long opening and closing time. The opening and closing stroke of the gate is large, and the lifting is carried out by the screw.
4. Water hammer is not easy to produce. The reason is the long closing time.
5. The medium can flow in any direction on both sides, easy to install. Both sides of the gate valve channel are symmetrical.
6. The structural length (the distance between the two connecting end faces of the shell) is small.
7. Simple shape, short structure length, good manufacturing technology and wide application range.
8. Compact structure, good valve rigidity, smooth passage, small flow resistance, stainless steel and hard alloy sealing surface, long service life, PTFE packing, reliable sealing, light and flexible operation.

Disadvantages of gate valve:

It is easy to cause erosion and scratches between the sealing surfaces, and maintenance is difficult. The overall size is large, opening requires a certain amount of space, and the opening and closing time is long. The structure is more complicated.

Working principle and movement mode of gate valve

The gate valve is a gate for opening and closing. The movement direction of the gate is perpendicular to the direction

13 gate-valve-5

13 gate-valve-5

of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate valve is sealed through the contact between the valve seat and the gate plate. Usually, the sealing surface will be welded with metal materials to increase wear resistance, such as 1Cr13, STL6, stainless steel, etc. The gate has a rigid gate and an elastic gate. According to the difference of the gate, the gate valve is divided into a rigid gate valve and an elastic gate valve.

Working principle of gate valve:
The opening and closing part of the gate valve is a 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 has two sealing surfaces. The two sealing surfaces of the most commonly used model gate valve form a wedge. The wedge angle varies with valve parameters, usually 5°, and 2°52′ when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce slight deformation to improve its manufacturability and compensate for the deviation of the sealing surface angle during the processing. The plate is called an elastic gate. When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, relying on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the seat by external force to ensure the sealing performance of the sealing surface. The gate valve of the gate valve moves linearly with the valve stem, which is called the lifting stem gate valve, also called the rising stem gate valve. Usually there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is turned into operating thrust. When the valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid channel is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as the mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the locking phenomenon of temperature changes, it is usually opened to the top position, and then back 1/2-1 circle, as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate, that is, the stroke. In some gate valves, the stem nut is set on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve is called a rotating stem gate valve, or a dark stem gate valve.

Movement mode of gate valve:
When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, only rely on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the seat by external force to ensure the sealing performance of the sealing surface.

Movement mode: The gate of the gate valve moves linearly with the valve stem, which is also called the rising stem gate valve. Usually there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed into operating thrust. When the valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid channel is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as the mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the locking phenomenon due to temperature changes, it is usually opened to the top position, and then rewind 1/2-1 turn, as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (i.e. stroke). Some gate valve stem nuts are set on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve is called Rotating stem gate valve or dark stem gate valve.