Daily Maintenance And Maintenance Of Ball Valves

In this comprehensive guide, we will delve into the world of ball valves and discuss the daily maintenance and maintenance practices that ensure their optimal performance. Ball valves are essential components in various industries, providing efficient control and regulation of fluid flow. By following these best practices, you can extend the lifespan of your ball valves and prevent potential issues that may arise from neglect or improper handling.

1. Regular Inspection and Cleaning

To maintain the functionality of your ball valves, it is crucial to perform regular inspections and cleaning. Start by visually inspecting the valve for any signs of leaks, corrosion, or damage. If any issues are identified, it is essential to address them promptly to prevent further complications.

To clean the ball valve, use a soft cloth or brush to remove any debris or contaminants that may have accumulated. Ensure that the valve is completely free from dirt and grime, as these can impede its smooth operation. Consider using mild detergent or specialized cleaning solutions recommended by the valve manufacturer for a thorough cleaning.    

2. Lubrication

Proper lubrication is vital to maintain the smooth movement of ball valves. Apply a suitable lubricant to the valve's moving parts, such as the stem and ball, according to the manufacturer's instructions. This helps reduce friction, prevents seizing, and ensures the valve operates seamlessly.

Remember to use lubricants specifically designed for valve applications, as using the wrong type can compromise the valve's performance and integrity. Avoid excessive lubrication, as it can attract dirt and contaminants, leading to potential issues. 

3. Testing and Calibration

Regular testing and calibration are crucial to verify the accuracy and reliability of ball valves. Conduct pressure and flow tests periodically to ensure the valve operates within the specified parameters. This helps identify any deviations or abnormalities and allows for timely adjustments or repairs.

Calibration should be performed using precision instruments to guarantee accurate measurements. Consult the valve manufacturer's guidelines or seek professional assistance to ensure proper testing and calibration procedures.

4. Preventive Maintenance

In addition to regular inspections, cleaning, lubrication, and testing, implementing a preventive maintenance plan can significantly enhance the lifespan and performance of ball valves. Consider the following practices:

a. Schedule Maintenance Tasks

Create a maintenance schedule that outlines specific tasks and intervals. This includes inspections, cleaning, lubrication, testing, and calibration. Adhering to a predetermined schedule helps ensure that essential maintenance activities are not overlooked or delayed.

b. Keep Detailed Records

Maintain a comprehensive record of all maintenance activities performed on the ball valves. This record should include dates, tasks performed, observations, and any necessary repairs or replacements. Having a documented history allows for better tracking of maintenance efforts and facilitates troubleshooting if issues arise in the future.

c. Train Personnel

Properly train personnel who handle ball valves to ensure they understand the maintenance procedures and adhere to best practices. This helps prevent mishandling, reduces the risk of accidents, and promotes the overall longevity of the valves.    

Conclusion

By implementing a comprehensive maintenance routine, you can optimize the performance and longevity of ball valves. Regular inspection, cleaning, lubrication, testing, and calibration are essential practices that help identify and address issues before they escalate. Additionally, preventive maintenance ensures that potential problems are proactively managed, reducing downtime and improving overall efficiency.

Remember, taking care of your ball valves not only extends their lifespan but also contributes to the smooth operation of your industrial processes. Prioritize maintenance, and you'll reap the rewards of reliable and efficient valve performance. We are ball valve suppliers. If you are interested in our products, please feel free to contact us.

Butterfly Valve Introduction Guide

The invention of the butterfly valve has improved the processes and applications of various industries.

What is a butterfly valve?

The butterfly valve is a mechanism that regulates the flow of materials in a large pipe diameter through a quarter-turn rotation of the disc.

A rod passes through the center of the disc, and this rod is connected to a drive that controls the movement of the disc. The position of the disc is parallel or perpendicular to the flow of the medium. The butterfly valve is different from other valves because the butterfly plate is always in the fluid, resulting in pressure changes at any position of the valve.

Double eccentric flange butterfly valve

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Why is it called a butterfly valve?

Some valves are named after their shapes, such as ball valves, globe valves, needle valves, etc. Other valves are named after their movement and function: gate valve, plug valve, pinch valve, life valve, slide valve, etc. The butterfly control valve is also named for its movement.

The butterfly valve gets its name because its movement is similar to that of wings in flight. The rod is similar to the body of a butterfly, and the disc moves like a butterfly's wings. The movement of a butterfly valve is similar to that when a butterfly descends, its wings move up and down in a 90-degree motion.

What is the purpose of the butterfly valve?

The butterfly valve regulates the flow by starting, decelerating, or stopping the medium. The disc opens and closes with a low torque of 90 degrees, which is suitable for any compatible application. Because of their low cost and lightweight, butterfly valves are generally more popular than other types of valves.

For some processes, extreme temperatures and corrosion are factors that can easily damage the valve seal. Butterfly valves can withstand extreme cold or extreme heat. This means that the integrity of the sealing device is critical for high-risk applications such as energy production and oil processing (because a leak may threaten public safety or the environment).

Where is the butterfly valve located?

There are some standard guidelines for the positioning of butterfly valve components. The butterfly valve needs to have a certain distance from other parts, such as pumps, elbows, and another valves-6 pipe diameter separation is ideal.

Generally, the valve stem of a butterfly valve is installed vertically with the actuator directly above it, but in some cases, the valve stem is installed horizontally. When connected to a pump or check valve, the disc must have a gap to avoid interference with other nearby components.

Butterfly Valve

3 Main Butterfly Valve Types 

While these valves all do essentially the same function, there are variations of butterfly valve design to suit different operations. Below are the three main butterfly valve types.

• Zero-offset Butterfly Valve

  “Concentric” or “rubber seated” are other names for the zero-offset design. Zero-offset means there is no offset by the stem of the valve. The valve seals via interference along the disc edge at the stem between the disc and the rubber seat. The rubber seated valve has the lowest pressure rating (up to 250 PSI) and withstands heat up to 400°F. Its rubber seat encases the body to prevent contact with the material which maintains the purity of the media.

• High-Performance Double Offset Butterfly Valve

  This butterfly valve is referred to as a double offset because the offset is in two places: at the line of the disc seat /body seal, and at the bore. Off-center positioning increases durability for the seal. High-performance valves tolerate pressure up to 1440 PSI and temps up to 1200°F. A cam-action occurs from the stem being behind the disc as it rubs against the during rotation at 90° for the first 10 degrees of opening, but also for the 10 degrees of closing.

• Triple Offset Butterfly Valve

  The best type of butterfly valve for high-pressure systems is the triple offset butterfly valve. Of the three types, the triple offset is the most advanced with lower emissions and is designed to work with various environments. Its heat tolerance is 1200°F as it can withstand 1,480 PSI of pressure. Like the double offset valve, the triple offset valve consists of two offsets situated in the center, but with a third offset having cam action with right-angled conical sealing. It is frictionless and long-wearing by the metal seal components not making contact until their final point.

Common Butterfly Valve Applications

Cast steel Butterfly valve

Some processes need more tolerant and wear-resistant valves with special features. Below are some common applications that rely on the unique mechanisms of a butterfly control valve.

ㆍFood Processing

Simple design, high durability, and low maintenance are the features needed to regulate fluid flow in any piping system. Certified Food Grade Seat is best for the Food Processing sector, so a White seat is preferred. 

While standard resilient seated valves are not 3A approved, there are many on the market that maintain sanitary connections inside and outside. The body material for the valve can range from Epoxy coated iron to Nylon 11 coated iron to Bronze, 304SS, and 316SS.

ㆍRefineries

The butterfly valve is commonly found in refineries. These would typically use the more “high end” High-Performance valve with Steel Bodies, or the Triple Offset design that is “Fire Safe” and bubble tight. Many applications involving water use the resiliently seated version.

Fire signal butterfly valve

ㆍShut Off Valves

A butterfly valve is often the best choice as a general shut-off valve above 1.5”-148”. Their simple design allows them to take up less space and less weight than other types of valves. These valves provide a tighter seal than a gate of globe valve and are usually bubble tight. This is most useful when trying to stop the fluid flow as it prevents any fluid from passing through the pipe when closed.

ㆍShip Building

Because of their high durability in saltwater, butterfly valves are commonly used in ships where ABS-approved materials are selected. This type of valve effectively creates a water-tight shutoff in the piping system of a ship to prevent any flow in the pipe. Their small size also allows them to be used in those tight spaces that are common aboard the ship.

They can be used for “jack up” rigs, ballast systems, ship side, and many other applications. Fire Safe approved valves are also necessary for many applications. Additional capabilities are automation and pneumatic function (“closed-loop” pneumatic underwater, electric, and hydraulic).

Be sure to use valves with an ISO-5211 mounting pad and stem. This way it’s easier to get a drop-in replacement at any port. Also, be wary of valves that just have an ISO-5211 mounting pad as the stems are often manufacturer’s “special.”

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How To Apply Ball Valves?

With the technological progress of ball valves, there will be wider applications in the foreseeable short time, especially on oil and gas pipelines, cracking units for oil refining, and in the nuclear industry. In addition, ball valves will become one of the dominant valve types in other industries in large and medium diameter, low and medium pressure areas.

Application of ball valves

The many unique features of ball valves determine the relatively wide range of occasions for the use of ball valves, usually, in the two-position adjustment, strict sealing performance, mud, wear, indentation channel, rapid opening and closing action (1/4 turn opening and closing), high-pressure shut-off (large differential pressure), low noise, cavitation and cavitation phenomenon, a small amount of leakage to the atmosphere, small operating torque, low fluid resistance piping system, the recommended use of ball valves.

Ball valves are also suitable for light structure, low-pressure cut-off (small differential pressure), and corrosive media piping systems. In the low-temperature (deep cooling) devices and piping systems can also be selected ball valves. In the metallurgical industry, the oxygen pipeline system, the need to use the ball valve after strict degreasing treatment. In the oil pipeline and gas pipeline in the mainline to be buried in the ground, you need to use the full diameter welded ball valve. In the requirement of regulating performance, need to use a special structure with a V-shaped opening of the ball valve. In petroleum, petrochemical, chemical, electric power, and urban construction, a working temperature above 200 degrees in the pipeline system can be selected metal to metal sealed ball valve.

 

Ball valve application principles

ㆍNeed to clean the pipeline and need to be buried in the underground oil, and natural gas transmission mainline, choose the full passage through, the all-welded structure of the ball valve.

ㆍBuried in the ground, choose the full passage through the welding connection or flange connection of the ball valve; branch pipe, choose flange connection, welding connection, full passage through, or reduction of the ball valve.

ㆍFinished oil transmission pipeline and storage equipment, choose flange connection of the ball valve.

ㆍCity gas and natural gas pipeline, the choice of flange connection, and internal thread connection of the floating ball valve.

ㆍIn the oxygen pipeline system of the metallurgical system, it is appropriate to use the fixed ball valve with strict degreasing treatment and flange connection.

ㆍLow-temperature media piping systems and devices, it is appropriate to use the low-temperature ball valve with the valve cover.

ㆍThe piping system of the catalytic cracking unit of the oil refinery can be used to lift the lever ball valve.

ㆍChemical system of acid and alkali and other corrosive media devices and piping systems, it is appropriate to use austenitic stainless steel, PTFE for the seat seal of the full stainless steel ball valve.

ㆍMetallurgical systems, electric power systems, petrochemical devices, urban heating systems, high-temperature media piping systems or devices, and metal-to-metal sealed ball valves can be used.

ㆍWhen flow adjustment is required, the worm gear drive, pneumatic or electric with a V-shaped opening adjustment ball valve can be used.

 

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General Service VS High Performance Butterfly Valves

When selecting a butterfly valve for your application, there are a number of things to take into consideration. What materials should be selected? What is the highest or lowest temperature that the valve needs to endure? What type of process fluid is the butterfly valve going to control?

These are just a few of the questions that you need to answer. The answers to these questions will help you determine if you need a general service or high-performance butterfly valve.

 

What Is A General Service Butterfly Valve

General service butterfly valves are designed for operation in—surprise, general purpose applications. The valves are supplied standard with a 10-position handle or can be automated with an air or electric actuator, providing consistent and long-lasting on/off, throttling, and isolation control.

General service butterfly valves are ideal for use in numerous industrial and commercial applications, including the control of air, water, steam, and other inert gases. The valve’s seat design allows for operation in vacuum applications. The seat covers the body, allowing for the selection of a metal body to hold the seat. The resilient seat isolates the process from the body. Different types of seat elastomers can be selected, so as to not blow the budget on an expensive metal body.

The shaft typically is one piece, goes through the disc, and is pinned. The shaft usually has bushings to act as the bearing for the shaft. These types of valves are offered in the lugged or wafer design to match piping process applications.

Torques are generally high than the high-performance butterfly valve, and the seat material limits the upper-temperature range of the valve. Generally speaking, this type of valve accepts pressures up to 285 PSI, and is found in sizes up to 30”.

 

What is A High-performance Butterfly Valve

High-performance butterfly valves can be used for shutoff and throttling control. They are designed to handle everything from general applications to viscous and corrosive liquids; corrosive gases and steam.

A wide variety of seat types are available including:

Fire-safe seats - designed for fire-safe applications  

PTFE seat  - providing bubble-tight shutoff in both directions),

Seats for dirty, viscous services

Soft seats are offered in several materials along with metal seats for the high-temperature applications. Stem seal options for fugitive emissions control, pressurized neck extensions for cryogenic applications, plus many other options are available.

High-performance butterfly valves come in sizes up to 60”, with body materials ranging from carbon steel to stainless steel. Their temperature ranges are from -20 to 900F depending on the seat design.

They also include a packing gland that allows for adjustment of the load to the packing to prevent external leakage.  Seats are typically replaceable and the body has a stop to prevent over-travel. Generally, they also include a solid shaft, bodies up to class 600 ratings, and wafer or lugged manual or actuated.

 

To select the butterfly valve that's right for your application, make sure you take viscosity, temperature and the application itself into consideration. Still not sure which butterfly valve will work for you? Ask us about it! We'll help find just the right valve for your application.

What Is Butterfly Valve?

The butterfly valve is also called butterfly valve, as the name suggests, its essential components like a butterfly against the wind, and free turning. The butterfly valve disc is the disc, around the seat of a shaft rotation, the dimension of the angle of turning is the valve open and also close.

Stainless steel butterfly valve

Butterfly valve introduction

Butterfly valves have been in use since the end of the 18th century. James Watt made use of a butterfly valve in his steam engine prototype. With advances in materials and modern technology, butterfly valves can be made smaller as well as can hold up against higher temperatures. After the Second World War, synthetic rubber was used for seals, enabling butterfly valves to be made use of in more sectors. In 1969, James E. Hemphill patented an improvement in the butterfly valve that lowered the hydrodynamic torque required to transform the valve's outcome.

The butterfly valve is a quarter-turn rotating movement valve used to quit, change as well as start the flow.

The butterfly valve can be opened up easily as well as promptly. The 90 ° rotation of the handle supplies complete the closing or opening of the valve. Large butterfly valves are usually equipped with a supposed transmission, where the handwheel is linked to the valve stem by equipment. This simplifies the operation of the valve but at the expense of speed.
As a result of their small dimension, easy framework, as well as light-weight, butterfly valves are increasingly used in piping systems such as cool and hot air, water as well as electrical power, environmental protection, structure supply of water as well as water drainage, as well as community engineering. Used as a tool for intercepting or intermediary flow. On several events, due to the benefits of the butterfly valve itself, it has been possible to change gate valves, globe valves, ball valves, and various other valves in industrial pipeline applications.
The structure of the butterfly valve is very straightforward, with just a few basic parts such as the valve body, valve stem, valve disc, valve seat, and transmission. Although the framework is basic, the feature of the butterfly valve can not be ignored. The little framework has terrific practical value.
The butterfly valve can be used to readjust the flow. When the flow adjustment butterfly valve requires to be under special working conditions, or in a closed environment, the performance needs are stringent, or the operating problems of the butterfly valve are seriously worn, low-temperature level, and other harsh work.

Butterfly valve parts

Below are the major butterfly valve components:

Valve Body

The valve body fits between the pipe flanges - the most common end connection types being flanged, double lug, and wafer types.

 

Disc

Attached to the valve body is the disc that functions as a gate that stops or throttles fluid flow; it can be considered equivalent to a gate in a gate valve, or a ball in a ball valve. The disc is typically bored to receive the stem, or shaft. There are many variations in disc design, orientation, and material in order to improve flow, sealing, and/or operating torque. For example, Hawle’s 9881k double eccentric disc is designed to reduce seal wear and “scuffing” as well as operating torque requirements.

Cast iron rubber lined butterfly valve

Seat

Lining the internal valve body is a strong elastomer or metal anti-leak seal that secures the disc in place in the closed position in order to achieve complete shutoff. The 9881k series’ stainless steel weld filled and microfinished integral body seat ensures a corrosion and erosion resistant seat face. With this special type of seat design, it is possible to manufacture the valve drop tight according to EN12266 –A requirements.

 

Stem

The valve shaft, often also referred to as the stem, is the component that connects the disc to the actuation mechanism and transmits the torque through itself.

 

Seals

Seals are present at multiple interfaces within the valve to either ensure a tight seal during operation or to isolate the process media from the valve’s internal components for a more flexible and cost-efficient design.

Sealing on seat face is ensured by a continuous T-profile resilient sealing ring which is held on the periphery of the disc by a retaining ring, preventing the sealing ring from rolling out. In the closed position, the sealing ring is pressed against the seat face, providing a tight seal on both the upstream and downstream ends. In the open position, the sealing ring is completely unstressed due to the double eccentric disc design.

By eliminating interaction between the process media and the stem/shaft, the multiple O-ring shaft sealing system ensures a maintenance-free sealing for the entire life span of the valve. Besides, there are smaller more common components such as the bushings, bearings, and fasteners that are part of most other valve constructions as well. Details on some of the components on the actuation end, such as the handle, lever, gearbox, and handwheel will be covered in the actuation section.

Butterfly valve: working principle

The construction of a butterfly valve is relatively simple, with the rotation of the valve disc controlling the fluid flow. In the closed position, the disc blocks the valve bore while in the open position, the disc is oriented perpendicular to the flow direction to allow flow. Butterfly valves generally provide bi-directional flow and shutoff capability. However, they are not full-bore, which renders them unsuitable for pigging or swabbing. The body material is ductile iron with an epoxy powder coat on both internal and external surfaces. The valves are typically operated by handwheels, gears, or actuators, or a combination thereof, according to the specific application requirement and technical specifications. We will be discussing the actuation methods later in the article.

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Where Is the Check Valve Installed?

Today we will discuss the installation location of the check valve:

ㆍHow do determine the installation position of the check valve? 

ㆍWhat is the difference between the installation of the check valve before and after the pump? 

ㆍWhen used in conjunction with other valves?

ㆍWhere should the check valves be installed?

Cast Steel Check Valve

Check Valve

The check valve, also called a check valve, is an automatic valve. It relies on the pressure of the flowing medium in the pipeline to push the valve flap to close and open the valve. When the medium stops flowing, the check valve flap closes, it can be effective to prevent the medium in the pipeline from flowing back, which plays a great role in ensuring the safety of the pipeline.

ANSI Swing Check Valve China is divided into three types: lift check valve, swing check valve, and butterfly check valve. 

Lift check valves can be divided into two types: vertical and straight-through. 

Swing check valves are divided into three types: single valve, double valve and multi-valve. 

Butterfly check valves are divided into butterfly double flaps and butterfly single flaps. 

The above types of check valves can be divided into four types in connection form: threaded connection, flange connection, welding, and wafer connection.

Installation Position

The check valve is installed to ensure the flow direction of the water flow inside the pump, so as to ensure the normal operation of the pump. Therefore, regarding the installation position of the check valve, whether it is installed before or after the water pump, there are two situations:

ㆍOne is installed at the end of the vertical suction pipe in front of the pump, also called a bottom valve. The purpose is to fill the pump without pumping water once, because when there is no water in the pump and the suction pipe in front of the pump, the pump can only be idling and cannot pump water, so the pump must be filled with water to pump out water. The installation of this kind of water pump is a method when it is above the liquid level, also called the negative pressure method.

ㆍThe other is installed behind the pump. This installation method is that when the liquid level is higher than the water pump, it is convenient to start and stop the water pump without closing the water pump outlet valve, especially for the main control water pump system to prevent backflow.

DIN Cast Iron Check Valve

Discussion on The Installation Sequence

The cast steel check valve must be installed at the outlet of the pump and before the outlet control valve in order to check the check valve. Generally, the first outlet of the pump is the soft connection (shock absorber), the next is the check valve, and then the isolation valve (such as butterfly valve, gate valve, stop valve, etc.)

1. Install the check valve first and then the gate valve or butterfly valve

Advantages: It can protect check valves, especially in parallel pumps. When one pump does not start, its outlet door is closed, and when the other pump starts, the impact force is borne by the gate valve or butterfly valve. After the check valve fails, the inlet and outlet valve isolation system can be closed for repair.

Disadvantages: Who will protect the gate valve or butterfly valve? There has been a case where the valve plate of a butterfly valve was broken.

2. Install gate valve or butterfly valve first and then check the valve

Advantages: It can protect the butterfly valve or gate valve, and the impact force is borne by the check valve.

Disadvantages: Who will protect the check valve? The check valve is switched on and off by the pressure difference. If the pressure of the main pipe is high, it will be closed, and the pressure of the pump will be opened. If the flow rate used is unstable, the check valve will switch repeatedly. Affect the life of the check valve. And the check valve is broken, especially the mother control system, which can be repaired after shutting down the system.

Generally speaking, due to the frequent opening and closing actions of the check valve, the internal connecting parts, and the sealing parts are prone to damage. In order to facilitate repairs and prevent the entire system from shutting down due to the failure of the check valve, from this perspective. The check valve will be installed in front of the outlet gate valve or butterfly valve. We are a check valve supplier. If you are interested in our products, please contact us now!

Butterfly Valve : Working Conditions,Sealing Principle and Applicable Mediums

At present, the butterfly valve has become the most widely used valve in the application field. Many people are not very familiar with the applicable occasions of butterfly valves. This article will take you to understand working conditions, sealing principle and applicable mediums of butterfly valves, so that you have a better understanding of butterfly valves.

Butterfly Valve Working Conditions

Butterfly valves are mainly used for liquid and gas low-pressure large diameter pipelines. It is suitable for occasions where the pressure loss is not high, flow adjustment is required, and the opening and closing requirements are fast; usually, the temperature is below 300 ℃ and the pressure is below 40 kg (butterfly valves generally use low pressure, like domestic ones. It is rare to achieve CL600). The medium is generally used for water and gas, and the medium is not demanding. The granular medium can also be used.

 

As a sealed butterfly valve, it brought rapid development after the emergence of synthetic rubber, so it is a new type of shut-off valve. In our country-China until the 1980s, butterfly valves were mainly used for low-pressure valves, and the valve seat was made of synthetic rubber. By the 1990s, due to increased exchanges with foreign countries, hard-seal (metal-seal) butterfly valves developed rapidly. At present, there are many valve factories that can produce medium-pressure metal-sealed butterfly valves stably, which makes the application field of butterfly valves wider.

Cast steel butterfly valve

Butterfly Valve Sealing Principle

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1. The sealing principle of a single eccentric sealing butterfly valve

Since the center of rotation of the butterfly plate (that is, the center of the valve shaft) is offset from the centerline of the valve body on the basis of the single eccentric butterfly valve, the sealing surface of the butterfly plate will be faster than the single eccentric sealing butterfly valve during the opening process. When the valve seat is separated from the sealing surface and the butterfly plate rotates to 8°~12°, the butterfly plate sealing surface is completely separated from the seat seal. When fully opened, a larger gap is formed between the two sealing surfaces. The design of this type of butterfly valve greatly The mechanical wear and extrusion deformation between the two sealing surfaces are reduced, and the sealing performance of the butterfly valve is improved.

 

2. The sealing principle of a double eccentric sealing butterfly valve

Since the centerline of the valve seat and the centerline of the valve body form a β angle offset on the basis of the double eccentric butterfly valve, the sealing surface of the butterfly plate immediately leaves the sealing surface of the valve seat at the moment of opening during the valve opening process. Only at the moment of closing does it contact and compress the seat sealing surface. When fully opened, a gap same as the double eccentric sealing butterfly valve is formed between the two sealing surfaces. The design of this type of butterfly valve completely eliminates the mechanical abrasion and abrasion between the two sealing surfaces, so that the sealing performance and service life of the butterfly valve are improved. Have been greatly improved.

 

3. The sealing principle of a variable eccentric sealing butterfly valve

The uniqueness of the variable eccentric butterfly valve is that the valve stem shaft where the butterfly plate is installed is a three-segment shaft structure. The three-segment shaft type valve stem has two shaft sections concentric, and the centerline of the central shaft is deviated from the two ends of the axis by a center distance, The butterfly plate is installed on the intermediate shaft section. Such an eccentric structure makes the butterfly plate a double eccentric shape when in the fully open position, and a single eccentric shape when the butterfly plate rotates to the closed position. Due to the effect of the eccentric shaft, when it is close to closing, the butterfly plate moves a distance into the sealing cone surface of the valve seat, and the butterfly plate matches the sealing surface of the valve seat to achieve reliable sealing performance.

 

Since the rotation center of the butterfly plate (that is, the center of the valve shaft) and the sealing section of the butterfly plate are set eccentrically, the butterfly plate sealing surface gradually separates from the valve seat sealing surface during the opening process of the butterfly valve. When the butterfly plate rotates to 20°~25°, The sealing surface of the butterfly plate is completely separated from the sealing surface of the valve seat. When fully opened, a gap is formed between the two sealing surfaces, so that the relative mechanical wear and extrusion between the two sealing surfaces of the butterfly valve is greatly reduced during the opening and closing process, thereby ensuring sealing of butterfly valves.

Cast iron rubber lined butterfly valve

Butterfly Valve Applicable Mediums

The media that the butterfly valve can transport and control are water, condensate, circulating water, sewage, seawater, air, gas, liquid natural gas, dry powder, mud, fruit pulp, and mixtures with suspended solids.

 

Butterfly valves are suitable for flow regulation. Since the pressure loss of the butterfly valve in the pipeline is relatively large, about three times that of the gate valve when selecting the butterfly valve, the influence of the pressure loss of the pipeline system should be fully considered, and the strength of the butterfly plate to withstand the pressure of the pipeline medium should also be considered. In addition, it is necessary to consider the limitation of the working temperature of the elastic valve seat material at high temperatures. The structural length and overall height of the butterfly valve are small, the opening and closing speed is fast, and it has good fluid control characteristics. The structural principle of the butterfly valve is most suitable for making large-diameter valves. When the butterfly valve is required to control the flow, the most important thing is to correctly select the size and type of the butterfly valve so that it can work properly and effectively.

1. Generally, in throttling, regulating control and mud medium, the structure length is short and the opening and closing speed is fast (1/4 revolution). Low pressure cut-off (small pressure difference), butterfly valve is recommended.

2. The butterfly valve can be used when two-position adjustment, narrow passage, low noise, cavitation and vaporization phenomenon, a small amount of leakage into the atmosphere, and abrasive media.

3. When the butterfly valve is used under special conditions, such as throttling adjustment, or strict sealing requirements, or severe wear, low temperature (cryogenic) and other operating conditions, it is necessary to use a specially designed metal seal with a triple eccentric or double eccentric adjustment device Special butterfly valve for ground.

4. The centerline butterfly valve is suitable for fresh water, sewage, sea water, salt water, steam, natural gas, food, medicine, and oil that require complete sealing, zero gas test leakage, high life requirements, and working temperature of -10℃~150℃ And various acid and alkali and other pipelines.

5. The soft-sealed eccentric butterfly valve is suitable for two-way opening and closing and adjustment of ventilation and dust removal pipelines. It is widely used in gas pipelines and waterways in metallurgy, light industry, electric power, and petrochemical systems.

6. The metal-to-metal wire sealing double eccentric butterfly valve is suitable for urban heating, gas, water supply and other gas, oil, acid and alkali pipelines, as a regulating and throttling device.

7. In addition to being used as a large-scale pressure swing adsorption (PSA) gas separation device program control valve, the metal-to-metal surface sealing triple eccentric butterfly valve can also be widely used in petroleum, petrochemical, chemical, metallurgical, electric power and other fields. It is a gate valve and a stop valve. A good alternative product.

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