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Applicable occasions and operation method of ball valve

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

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.

The parameter and troubleshooting of the ball valve

The parameter level of the ball valve:

1. Nominal pressure or pressure level: PN1.0-32.0MPa, ANSI CLASS 150-900, JIS10-20K;

14 ball-valve-6

14 ball-valve-6

2. Nominal diameter or caliber: DN6~900, NPS 1/4 ~36;

3. Connection method: flange, butt welding, thread, socket welding, etc.;

4. Applicable temperature: -196℃~540℃;

5. Drive mode: manual, worm gear drive, pneumatic, electric, hydraulic, gas-liquid linkage, electro-hydraulic linkage;

6. Valve body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M (316), CF3M (316L), Ti. Different materials are used, which can be applied to various media such as water, steam, oil, nitric acid, acetic acid, oxidizing medium, urea, etc.

Pressure limit of ball valve:
The nameplate shows the maximum allowable operating pressure of the ball valve at the maximum and minimum operating temperatures.

Seats and seals made of PTFE or RTFE are used. The operating temperature of other types of seat and seals should be checked by the KI factory.

The nominal pressure rating (PN) of the valve can indicate the maximum working pressure of the valve under normal temperature conditions. (For example: PN4.0, indicating that the maximum working pressure is 40 Bar (4.0MPa) when the operating temperature is between -190C and 380C).

For the precautions of electric or pneumatic actuators, refer to their corresponding instructions.

Troubleshooting of the ball valve:
The ball valve has been scoured by the material for a long time, causing friction, causing severe impact and abrasion, which cannot meet the normal production, and at the same time, the equipment life is shortened. At present, wear-resistant materials, such as ceramic materials and polymer composite materials, are mostly used for the wear of ball valves, and there are more technical systems used. The polymer material has superior adhesion performance, super wear resistance, and safely solves the disadvantages of frequent metal wear and ensures the normal production of enterprise equipment. Moreover, the unique ceramic material and special surface strengthening agent in the material make it better than any steel or even ceramic tile in wear resistance and physical impact resistance in the harshest dry grinding environment. The incompatibility of the product with coal is to prevent Ideal material for coal deposits.

Product features and advantages of ball valve

Product features of ball valve:
1. The three-way ball valve adopts an integrated structure in structure, with a four-sided valve seat sealing type, fewer flange connections, high reliability, and a lightweight design.

ball valve (8)

ball valve (8)

2. The three-way ball core is divided into T type and L type, with long service life, large circulation capacity and low resistance.

3. The ball valve is divided into two types: single-acting and double-acting according to the action type. The single-acting type is characterized in that once the power source fails, the ball valve will be in the state required by the control system.

Advantages of ball valve:

1. The fluid resistance is small, and its resistance coefficient is equal to that of a pipe section of the same length.

2. Simple structure, small size and light weight.

3. It is tight and reliable, and the sealing surface material of the ball valve is widely used in plastics and has good sealing performance. It has also been widely used in vacuum systems.

4. It is easy to operate and open and close quickly. It only needs to rotate 90° from fully open to fully closed, which is convenient for remote control.

5. The maintenance is convenient, the structure of the ball valve is simple, the sealing ring is generally movable, and it is convenient to disassemble and replace.

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

This type of valve is a high-pressure ball valve commonly used in existing mines. It bears high pressure and adopts a U-shaped card quick connection method. It can be quickly installed and disassembled in the daily production and use of the mine, and is convenient to use.

The ash unloading ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. The ash unloading ball valve can be divided into floating ball type, fixed ball type, and elastic ball type. The ash unloading ball valve is mainly used to cut off or connect the medium in the pipeline. It can also be used for fluid adjustment and control. The ash unloading ball valve Compared with other valve types, it has angular stroke output torque, opens quickly, is stable and reliable, and is widely applicable. The working principle of the ash unloading ball valve is to make the valve unblocked or blocked by rotating the valve.

Electric ball valve structure is composed of only a few parts, saving data; small size, light weight, small installation size, electric ball valve structure diagram, small driving torque, pressure regulating valve, easy and agile operation, only need to rotate 90° Fast opening and closing; and also has a good flow regulation effect and sealing characteristics at the same time, in the application of large and medium caliber, medium and low pressure, electric ball valve is the dominant valve form. When the electric ball valve is in the fully open position, the thickness of the butterfly plate is the resistance when the medium flows through the valve body, so the pressure drop that occurs through the valve is small, so it has better flow control characteristics. Electric ball valves have two sealing types: elastic seal and metal seal. Elastic sealing valve, the sealing ring can be embedded in the valve body or attached to the periphery of the butterfly plate. Valves with metal seals generally have a longer life than valves with elastic seals, but it is difficult to achieve a complete seal. Metal seals can adapt to higher operating temperatures, while elastic seals have the disadvantage of being limited by temperature. If the electric ball valve is requested to be used as a flow control, it is important to accurately select the size and type of the valve. The construction principle of the electric ball valve is particularly suitable for manufacturing large diameter valves. Electric ball valves are not only widely used in general industries such as petroleum, gas, chemical, and water disposal, but also used in cooling water systems of thermal power stations. Commonly used electric ball valves include wafer type electric ball valves and flange type electric ball valves. Wafer type electric ball valve uses double-head bolts to connect the valve between two pipe flanges. Flange type electric ball valve is equipped with flanges on the valve. The two flanges on the valve are connected to the pipe flanges with bolts. The strength performance of the valve refers to the ability of the valve to withstand medium pressure. The valve is a mechanical product that is subjected to internal pressure, so it must have sufficient strength and rigidity to ensure long-term use without cracking or deformation. Pneumatic ball valve is composed of ball valve and pneumatic actuator. Pneumatic actuator is divided into double-acting pneumatic actuator and single-acting pneumatic actuator. Through solenoid valve control, ball valve switching action is realized. The pneumatic ball valve can realize intelligent control, quickly open or close the pipeline, and can effectively control and manage the pipe network.

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:
What is a ball valve?;
Electric ball valve principle | Electric ball valve working principle;
Classification and advantages of gate valve;
Advantages and disadvantages of butterfly valve and structure diagram;

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.

The difference between globe valve and check valve

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)

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

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.

Y type ball check valves’ work theory, construction feature, advantage

1. Overview of ball check valve:
Ball type check valve is widely used in petroleum, chemical and electric heating boilers and other devices. It is

fig.01-ball check valve drawing

fig.01-ball check valve drawing

mainly used to prevent the reverse flow of the medium in the pipeline and protect the safe operation of the equipment. It is an ideal non-return device for pipelines. However, the current common check valve structures include swing type and lift type. Because these common check valves have problems such as easy sticking, poor sealing, difficult to repair, and may cause serious shutdown when they close by themselves. The valve water hammer phenomenon, and the water hammer pressure far exceeds the system working pressure, so the system safety may be endangered. Therefore, in addition to meeting the basic requirements of flow, the design of the check valve is the most important thing is the size of the flow resistance, whether there is leakage or vortex, which is related to energy consumption, and at the same time affects the level of production cost and product competitiveness. This new ball check valve is designed based on the theory of reducing flow resistance and eliminating water hammer.
2. Working principle of ball check valve:
The ball check valve shown in Figure 1 includes a valve body, a valve seat 2, a valve cover 7, and a valve disc. The valve body is composed of a left valve body 5 and a right valve body 1. The right valve body is the medium inlet end, and the left valve body The body is the outlet end of the medium. The valve seat 2 is installed between the left valve body 5 and the right valve body 1. The valve disc is a ball 3, and the sealing surface of the valve seat 2 is a spherical surface that cooperates with the surface of the ball 3. The left valve body is composed of a fluid channel and a ball track. The centerline of the sphere track forms an acute angle with the centerline of the fluid channel, and the angle design of the acute angle is determined according to the flexible rise and fall of the valve flap 3 in the sphere track. An arc-shaped filter screen 6 is arranged at the intersecting line of the fluid channel and the sphere orbit. The arc-shaped filter screen 6 has the same curvature as the inner circular wall of the sphere orbit, so that the inner arc of the arc-shaped filter screen 6 and the inner circular wall of the sphere orbit are formed The integral inner cylindrical surface constitutes a smooth rolling passage for the valve flap 3, which does not affect the flow of the medium, and enables the valve flap 3 to roll flexibly. This valve uses media thrust and disc gravity to automatically control the rolling position of the ball in the ball track. When the medium flows in the forward direction, the media thrust pushes the disc to the upper end of the ball track. When the positive thrust of the medium disappears, the disc moves from the ball track. The upper end rolls off and fits the valve seat sealingly, which has the advantages of simple structure, the ball is not easy to be stuck in the ball track, the sealing reliability is good, and the water hammer is small.
3. Structural features of ball check valve:

fig.2-ball check valve 3D schematic

fig.2-ball check valve 3D schematic

The ball check valve has no transmission parts in structure and has a free opening and closing structure, so there is no wear of the shaft and sleeve. The valve flap automatically rotates in the ball orbit, and the sealing surface is always updated, and there is no fixed wear point. The ball surface wears evenly during the working process, and always maintains a high shape accuracy. The use performance will not decrease with the passage of time, which improves the service life of the seal. The surface of the valve disc is lined with rubber, and the dimensional accuracy and surface roughness of the ball can be controlled by the rubber lined mold. The processing accuracy of the ball is reduced, and it can be reused, which reduces the cost of the disc. The surface rubber of the steel ball will elastically deform, can absorb and dampen vibration, and play a certain buffering effect. The low density of rubber makes the inertia of the disc movement small and the movement is sensitive. The sphere adopts a hollow structure and is light in weight, which reduces the impact force of the valve disc on the valve seat when it is closed. The inner diameter of the sphere track is designed to be larger than the pipe diameter of the corresponding flange, which increases the flow cross section, reduces the medium resistance and reduces the pressure. When the sealing structure is designed according to the corresponding flange, the working pressure is from vacuum to medium pressure. Under the premise of not being restricted by installation conditions, the ball check valve can be installed horizontally or vertically. Moreover, the valve is easy to maintain in the pipeline, and only needs to replace the lower disc.
4. Conclusion of ball check valve:
In accordance with DIN EN 12266 “Pressure Test of Valves” and corporate standards, the series of ball check valves have been inspected and tested. As a result of the test, the technical performance parameters fully meet the design requirements. The application of this valve improves the safety factor of other equipment on the pipeline, with low flow resistance, flexible opening and closing, and good sealing performance, which is welcomed by users. This valve is also equipped with a curved filter screen to purify the medium. One valve has multiple functions, meeting customers’ multi-functional requirements, and greatly reducing customer costs.

Related news /knowledge:
Classification and characteristics of ball valve;
Types and classifications of ball valves;
What is a ball valve?;

The principles and difference between one-way valve and check valve

One-way valve is sometimes called a check valve. One-way valve is a device in which fluid can only flow along the

double-wing-check-valve-3

double-wing-check-valve-3

water inlet, but the medium at the outlet cannot flow back. The function of the check valve is to prevent the medium in the pipeline from flowing back. So what is the difference between the two? What is their working principle? Now, Mr. Harry Li from Tanghai Valve will give you a detailed introduction.

The difference between one-way valve and check valve:

One-way valve is a control type One-way valve, and check valve is a non-control type One-way valve. That is: One-way valve is used to provide pressure, and its main function is to maintain pipeline pressure. Although the check valve can also provide this function, it is mainly used to control the return of the medium and does not require pressure. That is: One-way valve has a tendency to control, and check valve is purely natural.

One-way valve means that the fluid can only flow along the water inlet, but the medium at the outlet cannot flow back, commonly known as the One-way valve. One-way valve is a check valve. The installation position of a swing check valve is not restricted. It is usually installed in a horizontal pipeline, but it can also be installed in a vertical pipeline or a dumping pipeline. When installing a check valve, pay special attention to the flow direction of the medium. The normal flow direction of the medium should be consistent with the arrow direction indicated on the valve body, otherwise the normal flow of the medium will be blocked. The bottom valve should be installed at the bottom of the pump suction line. When the check valve is closed, water hammer pressure will be generated in the pipeline. In severe cases, it will cause damage to the valve, pipeline or equipment, especially for large-mouth pipelines or high-pressure pipelines. Therefore, it should cause high attention of the check valve selection. . The check valve is only a one-way opening and closing valve that prevents the backflow of fluid media on various pipelines or equipment.

all types of check valve and structures -code names-photos

all types of check valve and structures -code names-photos

1. One-way valve: It is a typical seat valve, One-way valve, also known as check valve or check valve. Used in hydraulic systems to prevent reverse flow of oil flow.

One-way valve has two types: straight type and right angle type. The straight-through One-way valve is installed on the pipeline with a threaded connection. Right-angle One-way valve has three forms: thread connection, plate connection and flange connection. The hydraulically controlled One-way valve is also called a lock valve or a pressure holding valve. It is the same as the One-way valve to prevent the reverse flow of oil. However, when the oil flow is required to flow in the reverse direction in the hydraulic circuit, the oil pressure can be controlled and the One-way valve can be opened so that the oil flow can flow in both directions. The hydraulically controlled One-way valve uses a tapered valve core, so the sealing performance is good. When the oil circuit is required to be closed, this valve can be used as a one-way locking of the oil circuit to maintain pressure. There are two types of hydraulically controlled One-way valve to control oil leakage: internal leakage and external leakage. The internal drain type can be used in the oil circuit with no back pressure at the oil flow reverse outlet; otherwise, the external drain type is required to reduce the control oil pressure.

2. Check valve is only one type of valve, it can be said that One-way valve is a kind of check valve. The check valve is only a one-way opening and closing valve that prevents the backflow of fluid media on various pipelines or equipment.

There are many types of check valves:

(1) Spring type: the liquid is from bottom to top, relying on the pressure to push up the valve flap controlled by the spring. After the pressure disappears, the spring force will press down the valve flap to seal the liquid back flow. Often used for check valves with small diameters.

(2) Gravity type: similar to the spring type, it relies on the self-gravity of the valve flap to close it to prevent backflow.

(3) Swing type: The liquid flows directly through the valve body, and the rotating disc on one side is opened by the pressure. After the pressure is lost, the disc relies on its own weight to return to the position, and the reverse liquid pressure closes the disc.

(4) Other One-way valve (check valve), such as sewage check valve.

The working principle of one-way valve:

The one-way valve only allows airflow to pass in one direction, and is completely closed in the opposite direction. After the air pressure is added to the left side, the air pressure acting on the valve core overcomes the spring force and friction force to open the valve core, and the air inlet and outlet are connected. The flow of airflow from left to right is called forward flow. In order to ensure a stable flow of air from the air inlet to the air outlet, a certain pressure difference should be maintained between the air inlet and outlet to keep the valve in the open position. If air pressure is added to the air outlet, the air cannot flow in and out, that is, the air flow cannot flow in the reverse direction.

The working principle of the check valve;

Check valve refers to the valve that automatically opens and closes the valve flap 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 discharge the container medium. Check valves can also be used to supply pipelines for auxiliary systems whose pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

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

Related news /products:
The difference between one-way valve and check valve;
The difference between globe valve and check valve
Introduction of cast steel lift swing check valve(;

The difference between one-way valve and check valve

One-way valve means that the fluid can only flow along the water inlet, and the medium at the water outlet

double-wing-check-valve-3

double-wing-check-valve-3

cannot return. Used in hydraulic systems to prevent reverse flow of oil or pneumatic systems to prevent reverse flow of air. Check valve refers to a valve whose opening and closing parts are circular discs and rely on its own weight and medium pressure to generate actions to block the back flow of the medium. It is an automatic valve.

There are two types of check valves: straight-through and right-angle. The straight-through check valve is installed on the pipeline with a threaded connection. Right-angle check valves have three forms: threaded connection, plate connection and flange connection. Hydraulic control check valve is also called lock valve or pressure maintaining valve. It is the same as check valve to prevent reverse flow of oil. However, when the oil flow is required to flow in the reverse direction in the hydraulic circuit, the oil pressure can be controlled to open the one-way valve so that the oil flow can flow in both directions. The hydraulic control check valve adopts a conical valve core, so the sealing performance is good. When the oil circuit is required to be closed, this valve can be used as a one-way locking of the oil circuit to maintain pressure. There are two types of hydraulically controlled check valve to control oil leakage: internal leakage and external leakage. The internal drain type can be used in the oil circuit where the oil flow reverse outlet has no back pressure; otherwise, the external drain type is required to reduce the control oil pressure.

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

One-way valve is a directional control valve in which air flow can only flow in one direction but not in the reverse direction. Its working principle is the same as the hydraulic one-way valve. Compressed air enters from port P, overcomes the spring force and friction force to open the one-way valve port, and the compressed air flows from P to A; when there is no compressed air at port P, it will be under the action of spring force and remaining force of port A (cavity) ; The valve port is in the closed state, so that the air flow from A to P is blocked. The one-way valve is used in occasions where the air flow is not allowed to flow in the opposite direction. For example, when the air compressor is inflating the air tank, a one-way valve is set between the air compressor and the air tank to prevent the air tank when the air compressor stops working. The compressed air in the air flow is returned to the air compressor. One-way valves are often combined with throttle valves and sequence valves to form one-way throttle valves and one-way sequence valves.

Check valves have a wide range of uses, and there are many types. The following are the check valves commonly used in water supply and heating:

1. Spring type: the liquid is from bottom to top, and the valve clack controlled by the spring is pushed up by the pressure. After the pressure disappears, the spring force pushes down the valve clack to seal the liquid back flow. Often used for check valves with small diameters.

2. Gravity type: Similar to spring type, it is closed by the gravity of the valve disc to prevent backflow.

3. Swing type: The liquid flows directly through the valve body, and the rotating disc on one side is opened by the pressure. After the pressure is lost, the disc relies on its own weight to return to the position, and the reverse liquid pressure closes the disc.

4. Plastic diaphragm type: Both the shell and the diaphragm are plastic. The general shell is ABS, PE, PP, NYLON, PC. The diaphragm includes silicone resin, fluororesin, etc.

In general, the check valve and the check valve are basically the same thing, but there are some differences. The check valve is a controlled check valve, and the check valve is a non-controlled check valve. That is to say, the one-way valve is used to provide pressure, and its main function is to maintain pipeline pressure. Although the check valve can also provide this function, it is mainly used to control the return of the medium and does not require pressure.

The above is about the difference between check valve and check valve. In fact, a check valve is only one type of valve, and a oneway valve is only a type of check valve. It is only a one-way open-close valve that prevents backflow of fluid in various pipelines or equipment. Check valves have a wide range of uses.

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The principles and difference between one-way valve and check valve;
The difference between globe valve and check valve;
Working principle diagram of three-way valve;
Valve actuator / actuation -(3)-classifications;

Installation instructions of double eccentric butterfly valve

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

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

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

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

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

TH Valve is a professional manufacturer of butterfly 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:
Description of valve pressure& installation direction requirements;
The sealing characteristics and principle of eccentric butterfly valve;
What is double plate swing check valve;
Selection and application of eccentric butterfly valve

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