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Strainer valve introduction and its features

August 17, 2020

STRAINER VALVE, also known as filter: a device for filtering pretreatment. The filter valve is the filter equipment necessary for the use of hydraulic control valves and precise and easy-to-clog mechanical products.

Strainer valve Introduction:
STRAINER VALVE, also known as filter: a device for filtering pretreatment. The filter valve is the filter equipment necessary for the use of hydraulic control valves and precise and easy-to-clog

15 Y-type-strainer-filter-valve-7

Y type strainer filter valve (11)

mechanical products. It is an indispensable device in the pipeline series that transports the medium. It is usually installed at the inlet of hydraulic control valves, pressure relief valves, pressure relief valves, fixed water level valves and other equipment to eliminate impurities in the medium and prevent particulate impurities from entering The channel causes wall plugs to protect the fittings on the equipment pipeline from wear and blockage. When cleaning is needed, just take out the detachable filter cartridge and reinstall it after treatment. Therefore, the use and maintenance are extremely convenient.

Features of filter valve:
The filter valve mesh adopts a stainless steel double-layer mesh structure, which is sturdy and durable. It has the characteristics of advanced structure, low flow resistance, and convenient sewage discharge. It can be used for water, steam, oil, nitric acid, urea, oxidizing media and other media. The mesh number of the filter screen should be set according to the user’s needs. Generally, the water network is 18-30 mesh, the ventilation network is 40-100 mesh, and the oil network is 100-480 mesh. The Y-type filter can also be combined with the telescopic joint to form a Y-type pull rod telescopic filter with adjustable installation length. The filter screen can be made according to user requirements.

Filter valve performance parameters:
Connection method: flange, butt welding, thread
Nominal pressure/MPa: 1.0-2.5
Pressure test pressure/MPa: 1.1-2.75
Working pressure/MPa 1.0 -2.5
Shell material: gray cast iron. ductile iron. carbon steel. stainless steel
Filter material: stainless steel
Total mesh area: 3～4DN

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

Daily maintenance and precautions of ball valves

August 14, 2020

Daily maintenance of ball valve:
Long service life and maintenance-free period will depend on the following factors: normal working conditions, maintaining a harmonious temperature/pressure ratio, and reasonable corrosion data.

14 ball-valve-6

When the ball valve is closed, there is still pressurized fluid inside the valve body.

Before maintenance: relieve the pipeline pressure and leave the valve in the open position; disconnect the power or air source; separate the actuator from the bracket.

It is necessary to find out that the upstream and downstream pipelines of the ball valve have indeed been relieved of pressure before disassembling.

Care must be taken to prevent damage to the sealing surface of parts, especially non-metal parts, when disassembling and reassembling. Special tools should be used when removing O-rings.

The bolts on the flange must be tightened symmetrically, gradually and evenly during assembly.

The cleaning agent should be compatible with the rubber parts, plastic parts, metal parts and working medium (such as gas) in the ball valve. When the working medium is gas, gasoline (GB484-89) can be used to clean metal parts. Clean non-metal parts with pure water or alcohol.

Non-metal parts should be taken out of the cleaning agent immediately after cleaning, and should not be soaked for a long time.

After cleaning, it needs to be assembled after the cleaning agent of the wall surface to be washed evaporates (can be wiped with silk cloth not soaked in cleaning agent), but it should not be left for a long time, otherwise it will rust and be contaminated by dust.

New parts also need to be cleaned before assembly.

When assembling, it should not be allowed to have metal chips, fibers, grease (except those specified for use), dust, other impurities, foreign objects, etc., to contaminate, adhere or stay on the surface of the parts or enter the cavity. Then tighten the stem nut.

Note: Don’t lock it too tightly, usually lock 1/4 turn to 1 turn, the leakage will stop.

A), disassembly

Keep the valve in a half-open position to flush and remove dangerous substances that may exist inside and outside the valve.

Close the ball valve, remove the connecting bolts and nuts on both flanges, and then completely remove the valve from the pipeline.

Disassemble the drive device-actuator, connecting bracket, lock washer, stem nut, butterfly shrapnel, glam, wear-resistant piece, stem packing in order.

Remove the body cover connecting bolts and nuts, separate the valve cover from the valve body, and remove the valve cover gasket.

Make sure that the valve ball is in the “off” position. This will make it easier to take it out of the valve body, and then take out the valve seat.

Gently push the stem down from the hole in the valve body until it is completely taken out, and then take out the O-ring and the lower packing of the stem.

Note: Please operate carefully to avoid scratching the surface of the valve stem and the sealing part of the valve body stuffing box.

B), reassembly

Clean and inspect the removed parts. It is strongly recommended to replace the valve seat and valve cover gasket with spare parts kit.

Assemble in the reverse order of disassembly.

Use the specified torque to tighten the flange connecting bolts crosswise.

Tighten the stem nut with the specified torque.

After installing the actuator, input the corresponding signal to drive the valve core to rotate by rotating the valve stem to make the valve open and close.

If possible, please perform pressure seal test and performance test on the valve according to relevant standards before reinstalling the pipeline.

Applicable occasions and operation method of ball valve

August 14, 2020

Applicable occasions of ball valve:
Since the ball valve usually uses rubber, nylon and polytetrafluoroethylene as the seat sealing ring material, its use temperature is limited by the seat sealing ring material. The cut-off effect of the ball valve is accomplished by

14 ball-valve-6

pressing the metal ball against each other between the plastic valve seats under the action of the medium (floating ball valve). Under the action of certain contact pressure, the seat sealing ring has elastic-plastic deformation in some areas. This deformation can compensate the manufacturing accuracy and surface roughness of the ball, and ensure the sealing performance of the ball valve.

In addition, since the seat sealing ring of the ball valve is usually made of plastic, when selecting the structure and performance of the ball valve, the fire resistance and fire resistance of the ball valve must be considered, especially in the petroleum, chemical, metallurgical and other sectors, in the flammable and explosive media Ball valves are used in the equipment and piping systems, and more attention should be paid to fire and fire resistance.

Generally, in two-position adjustment, strict sealing performance, mud, wear, necking channel, rapid opening and closing action (1/4 turn opening and closing), high pressure cut-off (large pressure difference), low noise, cavitation and vaporization, In piping systems with a small amount of leakage to the atmosphere, small operating torque and low fluid resistance, ball valves are recommended.

Ball valves are also suitable for piping systems with light structure, low pressure cut-off (small pressure difference), and corrosive media. Ball valves can also be used in cryogenic (cryogenic) devices and pipeline systems. In the oxygen pipeline system of the metallurgical industry, ball valves that have undergone strict degreasing treatment are required. When the main line in the oil pipeline and gas pipeline needs to be buried underground, full-diameter welded ball valves are required. When the adjustment performance is required, a ball valve with a special structure with a V-shaped opening should be selected. In petroleum, petrochemical, chemical, electric power, and urban construction, metal-to-metal sealed ball valves can be used for pipeline systems with operating temperatures above 200 degrees.

Operation method of ball valve:
1) Before operation, make sure that the pipeline and valve have been flushed.

2) The operation of the valve drives the valve stem to complete rotation according to the size of the input signal of the actuator: when it rotates 1/4 turn (90°) in the forward direction, the valve is closed. When reverse rotation is 1/4 turn (90°), the valve opens.

3) When the actuator direction indicator arrow is parallel to the pipeline, the valve is open; when the indicator arrow is perpendicular to the pipeline, the valve is closed.

Hard seal installation method of ball valve

August 14, 2020

Hard seal installation method of ball valve:

1) Remove the protective covers on both sides of the flange, and rinse and clean with the valve fully opened.

ball valve (6)

2) Before installation, the whole machine should be tested according to the specified signal (electrical or pneumatic) (to prevent vibration caused by transportation from affecting the performance), and then it can be installed online (wiring according to the electric actuator circuit diagram).
3) Before preparing to connect with the pipeline, flush and remove the remaining impurities in the pipeline (these substances may damage the valve seat and ball).
4) During installation, please do not use the actuator part of the valve as a lifting point to avoid damage to the actuator and accessories.
5) This type of valve should be installed in the horizontal or vertical direction of the pipeline.
6) The pipeline near the installation point should not be drooping or bear external force. Pipe supports or supports can be used to eliminate pipeline deviation.
7) After connecting with the pipeline, please cross-tighten the flange connecting bolts with the specified torque.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest ball valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Installation instructions for ball valves

August 14, 2020

Installation instructions for ball valves:

1. Indoor devices or outdoor applications with protective methods;

ball valve (7)

2. Outdoor installations are corroded by wind, sand, rain, dew, and sunlight;
3. Have flammable, explosive gas or dust environment;
4. Humid tropical and dry tropical environment;
5. The temperature of the pipeline medium is as high as 450℃;
6. The ambient temperature is lower than -20℃;
7. Easy to be flooded or immersed in water;
8. Possess a radioactive material (nuclear power plant and radioactive material test device) environment;
9.The environment on the ship or dock (with salt spray, mold, humidity);
10.Occasions with severe vibration; occasions prone to fire;

For the electric ball valve in the above environment, the electric device structure, material and protection method are different. Therefore, the corresponding valve electric device should be selected according to the above-mentioned obligation environment. According to engineering control requirements, for electric ball valves, their control functions are completed by electric devices. The purpose of applying electric ball valves is to complete non-manual electrical control or computer control of valve opening, closing and adjustment linkage. The application of electric devices is not just for diligence and labor saving. Since the functions and quality of products from different manufacturers are quite different, the selection of electric devices and the selection of valves are equally important to the project. As the requirements of industrial automation level are constantly improving, on the one hand, the application of electric valves is increasing, and on the other hand, the control requirements for electric valves are getting higher and higher and more complicated. Therefore, the design of electric valves in electrical control is always updated. With the continuous improvement of use requirements and the popularization and application of computers, new and diverse electrical control methods will always appear. Regarding the overall control of the electric valve, attention should be paid to the selection of the control method of the electric valve. For example, depending on the needs of the project, whether to use a centralized control method or a single control method, whether to link with other equipment, sequence control or application computer sequence control, etc., the control principles are different. The sample of valve electric device manufacturers only gives standard electric control principles, so the application department should make technical clarifications with the electric device consumer to understand the technical requirements.

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

Classification and characteristics of ball valve

August 14, 2020

There are different ways of classification of ball valves.

Function classification:
1. Bypass valve: The ball valve is generally opened by static water, so the bypass valve is set to be pressed first, that is, both sides are filled with water;

ball valve (6)

2. Air valve: when filling with water, the buoy will automatically close the valve when the air is removed; when draining, the buoy will drop by itself when it is used for replenishing air;

3. Pressure relief valve: When opening and closing the valve, remove the pressure water between the valve and the sealing cover to avoid wearing the sealing cover;

4. Drain valve: drain the sewage in the lower part of the ball shell.

Transmission classification:
1. Pneumatic ball valve

2. Electric ball valve

3. Hydraulic ball valve

4. Pneumatic hydraulic ball valve

5. Electro-hydraulic ball valve

6. Turbine drive ball valve

Classification characteristics of ball valve:

Ball valves are divided into: floating ball valve, fixed ball valve, orbital ball valve, V-shaped ball valve, three-way ball valve, stainless steel ball valve, cast steel ball valve, forged steel ball valve, ash unloading ball valve, anti-sulfur ball valve, pneumatic ball valve, electric ball valve, card sleeve Ball valves, welded ball valves.

Classified by shell/body material, ball valves can be divided into:

1. 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, aluminum alloy valves, lead alloy valves, etc.

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

3. Valves of non-metallic materials: such as ceramic valves, glass valves, and plastic valves.

There are many domestic manufacturers of ball valves, and most of the connection sizes are not uniform. Mainly divided into the following categories:

The ball of the ball valve is floating. Under the action of the medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure that the outlet end is sealed.

Structural features of ball valve:
The sealing performance is good, but all the load of the sphere bearing the working medium is transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the sphere medium. When subjected to higher pressure impact, the sphere may deviate . This structure is generally used for medium and low pressure ball valves.

The ball of the ball valve is fixed and does not move when pressed. The fixed ball valve is equipped with a floating valve seat. After receiving the pressure of the medium, the valve seat will move, so that the sealing ring is pressed tightly on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, and the operating torque is small, which is suitable for high pressure and large diameter valves.

In order to reduce the operating torque of the ball valve and increase the reliability of the seal, an oil-sealed ball valve has appeared, which not only injects a special lubricant between the sealing surfaces to form a layer of oil film, which enhances the sealing performance and reduces the operating torque. Suitable for high pressure and large diameter ball valves.

Flexible features of ball valve:

The ball of the ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials, and the sealing specific pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and external force must be applied. This valve is suitable for high temperature and high pressure media.

The elastic sphere is made by opening an elastic groove on the lower end of the inner wall of the sphere to obtain elasticity. When closing the passage, use the wedge-shaped head of the valve stem to expand the ball and press the valve seat to seal. Loosen the wedge-shaped head before rotating the sphere, and the sphere will return to its original shape, so that there is a small gap between the sphere and the valve seat, which can reduce the friction and operating torque of the sealing surface.

Qv347, Qv647, Qv947 V-type regulating ball valve

The Qv347, Qv647, and Qv947 V-type regulating ball valves have a shearing effect on the valve seat because the ball core has a V-shaped structure. Therefore, it is suitable for the control of relevant process parameters in the suspension medium containing fibers or small solid particles in papermaking, chemical, metallurgical and other industrial enterprises. It is especially suitable for the pulp, white water, black liquor and white water in the pulp and paper production process. Automatic adjustment of the fluid of suspended particles such as liquid and thick and turbid slurry fluid medium.

This V-shaped ball valve is a fixed ball valve and also a single-seat sealed ball valve. The adjustment performance is the best among ball valves, the flow characteristics are equal percentages, and the adjustable ratio is 100:1. It has a shearing effect between the V-shaped incision and the metal valve seat, which is especially suitable for media containing fibers, small solid particles, slurry, etc.

Three-way ball valve has T type and L type. The T type can connect three orthogonal pipelines with each other and cut off the third channel, which can split and merge. The L-shape can only connect two orthogonal pipelines, and cannot maintain the third pipeline to communicate with each other at the same time. It only plays a role of distribution.

Characteristics of ball valve

August 14, 2020

Features of ball valve:
1. Wear resistance; because the valve core of the hard-sealed ball valve is spray-welded alloy steel,

ball valve (2)

The sealing ring is made of alloy steel surfacing, so the hard sealing ball valve will not produce too much wear when opening and closing. (Its hardness coefficient is 65-70):

Second, the sealing performance is good; because the sealing of the hard-seal ball valve is manually ground, it can be used until the valve core and the sealing ring are completely matched. So his sealing performance is reliable.

3. The switch is light; since the bottom of the sealing ring of the hard-sealed ball valve adopts a spring to make the sealing ring and the valve core tightly hug together, the switch is very light when the external force exceeds the preload of the spring.

4. Long service life: It has been widely used in petroleum, chemical industry, power generation, papermaking, atomic energy, aviation, rockets and other departments, as well as people’s daily life.

The pneumatic ball valve has a simple and compact structure, reliable sealing, and convenient maintenance. The sealing surface and the spherical surface are always in a closed state, which is not easy to be eroded by the medium. It is easy to operate and maintain. It is suitable for general working media such as water, solvent, acid and natural gas. It is mainly used for cutting off. Or connect the medium in the pipeline, and can also be used for fluid adjustment and control.

Compared with other types of valves, pneumatic ball valves have angular stroke output torque, quick opening, stable and reliable, wide application, and the following advantages:

1. The thrust bearing reduces the friction torque of the valve stem, which can make the valve stem operate smoothly and flexibly for a long time.

2. Anti-static function: a spring is set between the ball, valve stem and valve body, which can lead out the static electricity generated during the switching process.

3. Since materials such as polytetrafluoroethylene have good self-lubricating properties and small friction loss with the ball, the pneumatic ball valve has a long service life.

4. Small fluid resistance: Pneumatic ball valves have the smallest fluid resistance among all valve categories. Even the reduced diameter pneumatic ball valves have relatively small fluid resistance.

5. Reliable valve stem sealing: Since the valve stem only rotates and does not move up and down, the packing seal of the valve stem is not easy to be damaged, and the sealing ability increases with the increase of the medium pressure.

6. Good sealing performance of the valve seat: The sealing ring made of elastic materials such as polytetrafluoroethylene is easy to seal in structure, and the valve sealing capacity of the pneumatic ball valve increases with the increase of the medium pressure.

7. The fluid resistance is small, and the full-bore ball valve basically has no flow resistance.

8. Simple structure, small size and light weight.

9. Close and reliable. It has two sealing surfaces, and the sealing surface materials of the ball valve are widely used in various plastics, which have good sealing performance and can achieve complete sealing. It has also been widely used in vacuum systems.

10. Convenient operation, rapid opening and closing, only need to rotate 90° from fully open to fully closed, which is convenient for remote control.

11. Convenient maintenance, simple structure of the ball valve, generally movable sealing ring, easy to disassemble and replace.

12. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium. When the medium passes, it will not cause erosion of the valve sealing surface.

13. It has a wide range of applications, with a diameter ranging from a few millimeters to a few meters, and can be applied from high vacuum to high pressure.

14. Because the ball valve has wiping properties during opening and closing, it can be used in media with suspended solid particles.

15. The processing precision is high, the cost is expensive, and it is not suitable for use in high temperature. If there are impurities in the pipeline, it is easy to be blocked by the impurities, causing the valve to fail to open.

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

Knife gate valve introduction and its characteristics

August 14, 2020

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)

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-

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 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

Working principle and movement mode of gate valve

August 13, 2020

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

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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.

The difference between globe valve and check valve

August 13, 2020

With the development of high-tech industry, various valves are often used in daily life. Today we will understand the difference between globe valves and check valves.

The difference between globe valve and check valve:
1. Check valve and stop valve are not the same thing, the difference between the two is mainly that the structure is

Globe valve (6)

very different.

2. The check valve is a one-way valve, which automatically prevents the fluid from flowing in the reverse direction, without a knob, and cannot artificially block the forward flow.

3. The stop valve has a knob, which can artificially control the forward flow. Due to its special structure, even if there is no artificial pipe valve, the fluid cannot flow in the reverse direction.

Globe valve:

The globe valve, also known as the shut-off valve, is a forced sealing valve, so when the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve from below the valve

lift-swing-check-valve-2

disc, the resistance that the operating force needs to overcome is the friction force of the valve stem and the packing and the thrust generated by the pressure of the medium. The force of closing the valve is greater than the force of opening the valve, so the valve stem The diameter of the valve must be large, otherwise the valve stem will bend failure.
working principle of globe valve:
The globe valve, also called the cut-off valve, is one of the most widely used valves. The reason why it is so popular is that the friction between the sealing surfaces is small during the opening and closing process, which is relatively durable, has a low opening height, and is easy to manufacture. , Easy maintenance, not only suitable for medium and low pressure, but also suitable for high pressure. The closing principle of the globe valve is to rely on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat tightly fit to prevent the medium from flowing. Our country’s valve “Sanhua” once stipulated that the flow direction of the stop valve should be from top to bottom, so there is directionality when installing. The structural length of the stop valve is longer than that of the gate valve, and the fluid resistance is large, and the sealing reliability is not strong during long-term operation.

Check valve:

Check valve refers to the valve that automatically opens and closes the disc depending on the flow of the medium itself to prevent the medium from flowing back, also known as check valve, one-way valve, reverse flow valve, and back pressure valve. Check valve is a kind of automatic valve, its main function is to prevent the back flow of the medium, prevent the pump and drive motor from reversing, and the discharge of the container medium.

working principle of check valve:
Check valve refers to the valve that automatically opens and closes the disc depending on the flow of the medium itself to prevent the medium from flowing back. It is also called check valve, one-way valve, reverse flow valve and back pressure valve. Check valve is a kind of automatic valve, its main function is to prevent the back flow of the medium, prevent the pump and drive motor from reversing, and the discharge of the container medium. The check valve can also be used to supply the auxiliary system whose pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

Valve manufacturers recommend:
Tanghai Valve Factory is a technological enterprise that produces globe valves and check valves. It designs and produces according to your needs, and provides you with professional, high-quality, low-priced valve products. Welcome to call us for quotations.

Posts

Strainer valve introduction and its features

Daily maintenance and precautions of ball valves

Applicable occasions and operation method of ball valve

Hard seal installation method of ball valve

Installation instructions for ball valves

Classification and characteristics of ball valve

Characteristics of ball valve

Knife gate valve introduction and its characteristics

Working principle and movement mode of gate valve

The difference between globe valve and check valve

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