working principle Archives

Working principle and characteristics of triple eccentric butterfly valve

August 9, 2021

Triple eccentric butterfly valve, also named triple offset butterfly valve.

Nowadays, butterfly valves have been used in many industries. In the beginning, the butterfly valve was only used for the interception and communication of water media. The triple eccentric design enhances the function of the butterfly valve and has become one of the valves with excellent performance in industrial industrial pipeline equipment. The triple eccentric butterfly valve, as the name implies, is that three independent offsets are designed as valves. In reality, many people do not know which one is a triple-eccentric butterfly valve because of insufficient cognition. In this article, let’s talk about the working principle and characteristics of the triple-eccentric butterfly valve.

triple offset butterfly valve-double flange- (5)

The working principle of the triple eccentric butterfly valve is that the valve body of the butterfly valve has a horizontal valve port connected to the pipeline in structure, and the valve port has a valve plate. The shaft is perpendicular to the valve port and penetrates the valve body and the valve plate. The edge of the valve plate is provided with an outer spherical surface, and the valve port is provided with a sealing surface that can be matched with the outer spherical surface. When the sealing surface and the outer spherical surface are matched and sealed, there is an eccentric distance a between the sealing line and the axis of the shaft, which is in the transverse center of the valve plate. The line is the eccentricity b between the center line of the valve port and the center line of the shaft, and there is an angle β between the connection line of the outer spherical surface and the center line of the valve port. This is the principle of the triple eccentric butterfly valve.
The triple eccentric butterfly valve cleverly puts the triple eccentricity on the valve plate, and adopts a partial outer spherical structure on the outer edge of the valve plate. This structure needs to be completed on a CNC machine with a self-designed simple fixture. The outer eccentric spherical surface is polished to reach a roughness of Ra0.4, the spherical surface is chrome-plated or made of Stellite alloy, and the hardness reaches HRC45-60.
Put the eccentric angle on the valve plate, and press the valve seat on the valve body with a pressing ring, which solves the difficulties encountered in the processing of ordinary triple eccentric butterfly valves. The valve body, valve plate and valve seat cannot be exchanged for pairing. Repair after damage A series of problems such as high cost, all parts are modularized, warehouse management is simple, processing is simple, maintenance is convenient, and the cost of spare parts is reduced.
The butterfly valve is suitable for making large-diameter valves. It can be widely used in the cutting of petroleum transportation pipelines, metallurgical steel plants, gas main pipeline adjustment and cutting, chemical smelting equipment medium adjustment and cutting, water treatment equipment inlet and outlet adjustment and shutdown, and cooling water in thermal power stations. System, natural gas, lye, sea water, acid and other industries.

The characteristics of the triple eccentric butterfly valve are as follows:
1. Simple structure, light weight, composed of only a few parts. easy to use.
2. After the valve plate is fully opened, the thickness of the butterfly plate is the only resistance for the medium to pass through the valve body. The pressure is small and the flow can be better controlled.
3. When the valve plate is closed, the specific pressure between the outer spherical surface of the valve plate and the sealing surface of the valve seat is generated by the driving torque applied to the shaft. Coupled with the elastic compensation of the M-type elastic valve seat, the sealing performance of the valve can be enhanced, and the service life is greatly improved.
Understand the working principle and characteristics of triple eccentric butterfly valve, then where can I buy high-quality triple eccentric butterfly valve products? of course, Tanghai valve.

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

Principle of Globe Valve (Figure)

July 21, 2021

Globe Valve is also called stop valve, shut-off valve. The opening and closing part of the globe valve is a plug-shaped valve disc, the sealing surface is flat or cone, and the valve disc moves linearly along the centerline of the fluid. The movement form of the valve stem includes a lifting rod type (the valve stem is raised and lowered, the hand wheel does not lift), and there is a lifting rotating rod type (the hand wheel and the valve stem rotate and lift together, and the nut is set on the valve body). The stop valve is only suitable for fully open and fully closed, adjustment and throttling are not allowed.
Brief introduction to the principle of the globe valve:

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

To put it simply, the principle of the globe valve is to use the torsion of the valve stem to give a downward pressure on the sealing surface, and rely on the pressure of the valve stem to make the disc sealing surface and the valve seat sealing surface closely fit to prevent the inflow of the medium or adjust the flow rate of the medium. . The opening and closing part of the stop valve is a cylindrical valve disc, the sealing surface is flat or conical, and the valve disc moves linearly along the center line of the fluid. The movement mode of the valve stem includes a lifting rod type (the valve stem is raised and lowered, and the hand wheel does not lift), and there is also a lifting rotating rod type

Schematic diagram of shut-off valve (closed state)

(the hand wheel and the valve stem rotate and lift together, and the nut is set on the valve body). The globe 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.

The working principle of the stop valve:
We assume that there is a pipe with a lid. Water flows in from the bottom of the pipe and flows out toward the nozzle. The lid of the outlet pipe is equivalent to the closing part of the shut-off valve. If the pipe lid is lifted up by hand, the water will flow out. When the cap is closed, the water stops flowing, which is equivalent to the working principle of a shut-off valve.

The shut-off valve relies on rotating the hand wheel to make the valve stem rise and fall, and drive the valve disc to make a linear displacement parallel to the flow direction of the medium to achieve the purpose of opening and closing. The handwheel rotates in a clockwise direction, and the working medium enters from the channel under the valve disc. At this time, the applied sealing force must be equal to or greater than the sum of the required specific pressure generated on the sealing surface and the upward force of the medium.

Schematic diagram of shut-off valve (open state)

When the shut-off valve is opened, when the opening height of the disc is 25% to 30% of the nominal diameter, the flow has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the shut-off valve should be determined by the stroke of the valve disc.
Note:
1. The shut-off valve only allows the medium to flow in one direction, and has directionality when installed. ,
2. The function of the shut-off valve is either 0 or 1, either through or not through. In other words, the shut-off valve is only suitable for fully open and fully closed, and adjustment and throttling are not recommended.

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 of electric globe valve

July 12, 2021

The principle of electric globe valve; The working principle of electric globe valve
Overview of electric shut-off valve:
The electric shut-off valve is equipped with an electric actuator on the basis of the shut-off valve, and the opening

electric globe valve

and closing of the valve is controlled by an electric device. The connection between the valve and the actuator adopts a direct connection method. The electric actuator has a built-in servo system, no need to be equipped with a servo amplifier, input 4-20mA signal and 220VAC power supply to control the operation. It has the advantages of simple connection, compact structure, small size, light weight, low resistance, stable and reliable action, etc. It can also be operated manually on site according to requirements, with the actuator with hands and electric switching mechanism. In addition to local operations, remote operations can also be performed.
Working principle of electric shut-off valve:
The closing principle of the electric shut-off valve is to rely on the electric thrust to rotate the valve stem, so that the sealing surface of the disc and the sealing surface of the valve seat are closely attached to prevent the medium from flowing. The electric shut-off valve only allows the medium to flow in one direction and is directional when installed. The structural length of the shut-off 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.
1 In the closed position, the valve body is mechanically pressed by the valve stem, and the sealing surface of the valve clack is tightly pressed on the valve seat.
2 When turning the handwheel counterclockwise, the valve stem moves in the opposite direction, and the bottom angle plane makes the valve body separate from the valve seat.
3 The valve stem continues to lift, and interacts with the guide pin in the spiral groove of the valve stem, so that the valve flap starts to rotate without friction.
4 Until it reaches the fully open position, the valve stem is raised to the limit position and rotated to the fully open position.
Parameters of electric shut-off valve:
Valve material: cast iron, cast steel, stainless steel, forged steel, forged stainless steel, chromium molybdenum steel, low temperature steel.
Working pressure: 1.6-32MPa
Working temperature: -196°C-550°C
Valve diameter: DN15-DN800 Connection method: flange, wire or welding
Drive mode: electric
Applicable medium: water, oil, gas, steam, etc.
Application areas: mechanical equipment, chemical equipment, general parts, industrial equipment, water supply and drainage equipment, papermaking equipment, pharmaceutical equipment, general equipment, petrochemical equipment, power equipment, metallurgical powder equipment, mining equipment, municipal, electronic industry, etc.

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

Working Principle of Pneumatic Globe Valve

July 7, 2021

Principle of Pneumatic Globe Valve, Working Principle of Pneumatic Globe Valve
Working principle of pneumatic stop valve:
Pneumatic shut-off valve is a valve that uses compressed air as the power source. It adopts remote control. The main control room manually or automatically triggers the action command to activate the inlet and exhaust solenoid

pneumatic globe valve

valves to supply and discharge compressed air into the actuator. Compressed air acts on the piston or diaphragm to overcome the frictional force of the valve action and the spring force on the valve stem, thereby depressing (for the loss of air to open the valve) or lifting (for the loss of air to close the valve) the valve stem, driving the valve core to move up and down , Make the valve open or close. When the valve loses air and there is no compressed air in the drive head, the valve will be in a safe position of fully open or fully closed according to the requirements of the system. Compressed air for power plant instruments, the supply pressure is generally 4-9bar. Before entering the valve, the compressed air is first filtered and purified through the filter, and then reduced by the pressure reducing valve. The reading of the inlet pressure gauge does not exceed 4bar. Pressure adjustment can be achieved by adjusting the adjustment screw installed on the top of the pressure reducing valve, and the protective cover must be loosened before adjustment.
Pneumatic globe valve installation instructions:
Pneumatic shut-off valve is usually used in fully closed and fully open gas and liquid unidirectional flow pipelines. It has a longer structure and shorter length than gate valves. When the medium is highly corrosive, a low-inlet and high-outlet stop valve should be used. When the medium pressure is high or the valve stem is frequently opened and closed, the valve stem should be thickened to avoid bending of the valve stem caused by the thrust of the medium. Compared with other valves, the flow resistance of the pneumatic shut-off valve is larger. Pay attention to the problems of the air source pressure and the pressure and corrosion resistance of the valve stem during use. Pneumatic shut-off valve is not suitable for media with particles, high viscosity and easy to coke.

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

V-type regulating ball valve

July 1, 2021

Working principle of pneumatic V-type regulating ball valve
The ball core of the pneumatic V-shaped regulating ball valve is designed with a special V-shaped notch, which has a shearing effect on the valve seat. It is especially suitable for media containing fibers, small solid particles, slurry and other media. According to different structural methods, it can generally be divided into flange and Wafer type; Pneumatic V-type ball valve is a fixed ball valve and also a single-seat sealed ball valve. It has the best adjustment performance among ball valves and can achieve flow adjustment. At the same time, since the valve core and seat are rotated without gaps, they can be wiped by themselves. The fouling on the ball and valve seat keeps a good seal between the ball and the valve seat.

electric V type ball valve

Working principle of pneumatic V-shaped regulating ball valve:
Pneumatic V-shaped regulating ball valve realizes different degrees of proportionality according to the V-shaped angle of the V-shaped sphere. It is generally used in conjunction with a valve positioner to achieve proportional adjustment. The V-shaped spool is most suitable for various adjustment occasions and has a large rated flow coefficient. ,, The pressure loss is small, the use flow capacity is large, and it has accurate shut-off characteristics and control functions. The flow characteristics are approximately equal percentages. The opening and closing parts adopt the V-shaped ball structure, which completely solves the problem of easy deposition of medium in the valve cavity.
Features of pneumatic V-shaped regulating ball valve:
1. Pneumatic V-shaped ball valve V-shaped gap and valve seat produce a strong shear force to cut off impurities such as fibers, and has a self-cleaning function to avoid valve jamming.
2. The pneumatic V-type regulating ball valve has an inherent flow characteristic of approximately equal percentage and an adjustable ratio of up to 300:1, so it can provide precise control in a wide range of changes.

Note: Because the pneumatic V-type regulating ball valve is generally a single-seat sealed ball valve, it is not suitable for two-way use. Due to its streamlined shape and full right-angle rotation control, the maximum volume is extremely high, the flow capacity is particularly large, and the flow resistance is small.

pneumatic V type ball valve

Pneumatic V-type regulating ball valve principle dynamic diagram
The valve core of the pneumatic V-shaped regulating ball valve is designed as a V-shaped gap with a special switch. The V-shaped gap and the valve seat generate a strong shear force, which can cut off high-viscosity media containing fibers or small solid particles, and has a self-cleaning function , To avoid the phenomenon of valve jamming. Pneumatic V-shaped ball valve is suitable for regulation and control, with high stability. Even in the case of small flow or high-viscosity medium, it can also ensure the accuracy of control within the entire range; while O-shaped ball valve is suitable for cutting off, relatively It is economical.
There is a V-shaped opening on the sphere of the pneumatic V-shaped regulating ball valve. As the ball rotates, the opening area changes, but the shape of the opening surface is always triangular. The flow characteristics are approximately equal percentages, the adjustable ratio is large, and the pressure loss is small. The flow capacity is large, and it has accurate interception characteristics and control functions. The opening and closing parts adopt a V-shaped spherical structure, which completely solves the problem of easy deposition of medium in the valve cavity. It is suitable for fibrous and slurry fluids!
The angle of the V-shaped port of the pneumatic V-shaped ball valve can be customized to meet more precise shut-off characteristics and control functions. Generally, more V-shaped valves are used in slurry media. They are similar to cam flex valves and are much better than O-shaped valves. V-shaped ball valves are used as regulating valves. For example, if the medium is not clean, the flow coefficient is low, and the leakage level is high, etc. occasion.

Working principle of electric V-type regulating ball valve

V type ball valve drawing

The electric V-shaped regulating ball valve has a special-shaped V-shaped incision. When the valve is closed, the V-shaped incision and the valve seat form a wedge shape, which has a shearing effect. The electric V-shaped ball valve is suitable for the control of fibrous slurry, sewage and viscous particle media. It can prevent the seizure of dirt between the ball and the valve seat. It has a self-cleaning function and is a wide-ranging regulating valve.
When the electric V-shaped ball valve rotates, the V-shaped blade of the ball is tangent to the valve seat, thereby cutting off the fiber and solid matter in the fluid. However, the general ball valve does not have this function, so it is easy to cause the fiber impurities to get stuck when closed. , Bring great inconvenience to repair and maintenance. The valve core of the electric V-shaped ball valve will not be jammed by the fiber, and the flow rate of the pipeline medium is adjusted and controlled according to the change of the opening area of the V-shaped gap.
Note: Since the electric V-type regulating ball valve is generally a single-seat sealing ball valve, it is not suitable for two-way use. The integral valve body structure is adopted, and there is no potential for leakage.
Features of electric V-shaped ball valve:
1. It has the advantages of compact structure, small volume, vertical and horizontal installation, etc., adopts movable metal valve seat, self-compensation function, and has superior sealing performance and long service life.
2. The electric V-shaped ball valve adopts a double-bearing structure, which has high mechanical stability and low starting torque, which ensures that the valve has excellent sensitivity and induction speed.
3. Maximum reliability (safety): The valve body is a whole, sturdy and durable, operation is not affected by pipeline pressure, and leakage of the valve body can be avoided.
4. The V-shaped gap and valve seat of the electric V-shaped regulating ball valve produce a strong shearing force to cut off impurities such as fibers, and has a self-cleaning function to avoid valve jamming.
5. Maximum flow volume: Due to the streamlined shape of the electric V-shaped ball valve and the full right-angle rotation control, the maximum volume is particularly high, the flow capacity is particularly large, and the flow resistance is small.

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 of electric gate valve

June 30, 2021

Principle of electric gate valve, Working principle of electric gate valve
Principle of electric gate valve:
Electric gate valve, as the name suggests, is to control the gate valve with an electric actuator, which is mainly

electric stainless steel gate valve

divided into an upper part and a lower part. The upper part is an electric actuator, and the lower part is a gate valve. Connect the actuator and the gate valve, and the electric actuator controls the opening and closing of the gate valve to work to achieve the on-off of the pipeline medium. Gate valves are generally suitable for on-off occasions and are normally open and normally closed valves. If you need to adjust the working conditions, generally choose electric control valve, electric ball valve, electric butterfly valve, electric shut-off valve, etc.
Working principle of electric gate valve:
The electric gate valve is powered by electric energy to turn on the electric actuator to drive the valve, and the valve stem is connected to drive the valve plate to move up and down or open and close, so that the valve can control the switch of the pipeline medium. It can be remotely controlled when it is added into the control box and other accessories, which is convenient and trouble-free.
Classification of electric gate valve actuators:
There are two common types of rotary electric actuators and linear electric actuators. Angular-stroke electric actuator: the angular-stroke electric actuator is used in conjunction with the angular-stroke valve to realize the internal rotation of the valve within 90 degrees to control the flow of the pipeline.
Straight-stroke electric actuator: a straight-stroke electric actuator is used in conjunction with a straight-stroke valve to realize the up and down movement of the valve plate to control the on-off of the pipeline fluid. It is usually used in conjunction with equipment with a higher degree of automation.

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 of Pneumatic Gate Valve

June 29, 2021

Brief introduction of pneumatic gate valve:
The pneumatic gate valve is equipped with a pneumatic actuator, which is driven by compressed air to control the gate valve. The valve core is composed of a wedge-shaped structure and a parallel structure, which is suitable for the emergency cut-off and discharge of gas and liquid pipelines.

pneumatic gate valve (3)

Working principle of pneumatic gate valve:
When using the air source to operate the gate valve, the small handle of the manual device must be turned to the pneumatic position to open and close the nut and the screw rod. When the compressed air enters from the upper pipeline of the cylinder, the piston and the piston rod in the cylinder are pushed straight When the compressed air enters from the lower pipe, the gas pushes the piston and piston rod in the cylinder to move upwards, and at the same time drives the valve stem to move upwards to open the valve. When there is no air source, the screw rod and the opening and closing nut can be used to open and close the valve. First, the upper and lower intake pipes of the cylinder are in the exhaust state, and the small handle of the manual part is in the manual position, so that the opening and closing nut and the screw are in the manual position. In the normal meshing state, turn the large handwheel at the manual part at this time. When the handwheel is turned clockwise, the valve is closed, and when the handwheel is turned counterclockwise, the valve is opened. When the air source is introduced from the upper air inlet, the valve stem drives the valve plate to move downward, and the valve is closed.
When the air source is introduced from the lower air inlet, the valve stem drives the valve plate to move upward, and the valve opens.
Pneumatic gate valve parameters:
Actuator: cylinder piston structure;
Optional accessories: manual device, filter, solenoid valve, echo device, control box;
Main material: ductile iron, cast steel, stainless steel; Caliber: DN50-500;
Pressure: PN1.6-6.4mpa;
Temperature: Q-29～350℃, C-29～450℃, P-30～540℃;
Medium range: water, steam, petroleum, gas, fluid, medium containing hard particles and impurities.

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, API6

Characteristics and working principle of electric globe valve

August 12, 2020

Features of electric globe valve:

The fluid resistance is small, and its resistance coefficient is equal to that of a pipe section of the same length.
Globe valve (9)
Simple structure, small size and light weight. Electric globe valve
It is tight and reliable. The sealing surface material of the gate valve is widely used plastic, and it has good sealing performance. It has also been widely used in vacuum systems.
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.
The maintenance is convenient, the gate valve has a simple structure, the sealing ring is generally movable, and it is convenient to disassemble and replace.
When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when the medium passes.
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.

Electric globe valve classification:

According to its channel position, it can be divided into straight-through type and right-angle type.

Working principle of electric globe valve:

The working principle of the electric shut-off valve is to make the valve unblocked or blocked by rotating the valve. The gate valve switch is light, small in size, can be made into a large diameter, reliable in sealing, simple in structure, convenient in maintenance, the sealing surface and the spherical surface are often closed, and it is not easy to be eroded by the medium. It is widely used in various industries.

A. Opening process of globe check valve:

In the closed position, the valve body is pressed against the valve seat by the mechanical pressure of the valve stem.
When the hand wheel is turned counterclockwise, the valve stem moves in the opposite direction, and the angular plane at the bottom causes the ball to separate from the valve seat.
The valve stem continues to lift and interacts with the guide pin in the spiral groove of the valve stem, so that the ball begins to rotate without friction.
Until it reaches the fully open position, the valve stem is raised to the limit position, and the ball rotates to the fully open position.

B. Closing process of electric globe valve:

When closing, turn the handwheel clockwise, the valve stem begins to drop and the ball leaves the valve seat to start rotating.
Continue to rotate the hand wheel, and the valve stem will be acted on by the guide pin embedded in the upper spiral groove to make the valve stem and the gate rotate 90° at the same time.
When it is about to close, the gate body has rotated 90° without contact with the valve seat.
In the last few turns of the handwheel, the angular plane at the bottom of the valve stem mechanically wedges and presses the sphere to make it tightly press on the valve seat to achieve a complete seal.

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

The working principle and characteristics of the globe valve

August 12, 2020

The globe valve is a tool that relies 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 flow of the medium. It is a forced sealing valve and is one of the most widely used valves.

According to the direction of the passage, the globe valve is divided into four types: straight-through globe valve, direct-flow globe valve, angle globe valve and plunger globe valve.
1. Working principle of globe valve:

Globe valve (9)

The stop valve, also called the cut-off valve, is one of the most widely used valves. The reason why it is popular is that the friction between the sealing surfaces is small during the opening and closing process, which is relatively durable, has a small 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 shut-off 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 closely fit, preventing the flow of the medium. 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 shut-off 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.

As one of the most important cut-off valves, the globe valve plays an important role in the aerospace field. As an important component of aerospace equipment, the shut-off valve realizes the functions of medium transportation, cut-off, and adjustment, and its sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and influencing rules of the sealing characteristics of typical globe valves has guiding significance for the structural design of the valve sealing pair, thereby improving the sealing performance and reliability of the valve.

2. Globe valve characteristics:

The valve plays an important role in cutting off and throttling the medium in the pipeline. As an extremely important cut-off valve, the valve is sealed by applying a torque to the valve stem, and the valve stem is in the axial direction. The valve clack applies pressure to make the sealing surface of the valve clack closely fit the sealing surface of the valve seat, and prevent the medium from leaking along the gap between the sealing surfaces.

The sealing pair of the globe valve is composed of a valve flap sealing surface and a valve seat sealing surface, and the valve stem drives the valve flap to move vertically along the center line of the valve seat. During the opening and closing process of the globe valve, the opening height is small, the flow is easy to adjust, and the manufacturing and maintenance are convenient, and the pressure application range is wide.

Compared with another commonly used shut-off valve in industrial production, an alarm valve, the shut-off valve is simpler than the former in terms of structure, and is easy to manufacture and maintain. In terms of service life, the sealing surface of the globe valve is not easy to wear and scratch. During the opening and closing process of the valve, there is no relative sliding between the valve disc and the sealing surface of the seat, so the wear and abrasion of the sealing surface are small, so the sealing is improved. During the full closing process of the auxiliary service life stop valve, the disc stroke is small, and its height is relatively small compared to the alarm valve. The shortcoming of the globe valve is that the opening and closing torque is large and it is difficult to achieve rapid opening and closing. Because the flow passage in the valve body is relatively tortuous, the fluid flow resistance is large, and the fluid power is lost in the pipeline.

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

Check valve and its working principle

July 30, 2020

What is check valve?

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, also called check valve, one-way valve, return valve or isolation valve. The movement of the disc is divided into lift check valve and swing check valve. The lift check valve is similar in structure to the stop valve, but lacks the valve stem to drive the valve disc. The medium flows in from the inlet end (lower side) and flows out from the outlet end (upper side). When the inlet pressure is greater than the sum of the weight of the disc and its flow resistance, the valve is opened. On the contrary, the valve is closed when the medium flows back. The swing check valve has a disc that is incline

tilting disc check valve body (2)

d and can rotate around the axis, and its working principle is similar to that of the lift check valve. The check valve is often used as the bottom valve of the pumping device to prevent the backflow of water. The combination of check valve and stop valve can play a role of safety isolation. The disadvantage is that the resistance is large and the sealing performance is poor when closed.

Working principle of check valve:
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 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.

Among them, check valves belong to this type of valve, which includes swing check valves and lift check valves. The swing check valve has a hinge mechanism and a valve flap like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve clack can reach the proper position of the valve seat surface every time, the valve clack is designed in a hinge mechanism so that the valve clack has enough space for rotation and makes the valve clack truly and comprehensively contact the valve seat. The valve clack can be made of metal, or inlaid with leather, rubber, or synthetic covering, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall back to the seat and cut off the flow. According to the conditions of use, the valve disc can be an all-metal structure, or it can be in the form of a rubber pad or a rubber ring inlaid on the disc holder. Like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve, and the flow rate of the swing check valve is restricted.

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