Butterfly valves have applications in various areas such as vacuum services, compressed air or gas operations, suspended solid services and many others. Whether functioning as control or shut-off valves, they play a major role in most industrial operations.
If you are looking for more details, kindly visit our website.
Butterfly valves have replaced the ball valves in industries (especially petroleum) and are preferred to gate valves because of their throttling function, simple operation, and ease of maintenance.
The selection of a butterfly valve requires adequate knowledge of its types and their functions in different conditions and various other factors that influence the selection of the suitable valve.
This post discusses all you need to know about a butterfly valve, including its definition, parts, functions, and types.
A butterfly valve is a machine that rotates its disk by a quarter-turn to allow or restrict the flow of media within the diameters of large pipes. The butterfly valve has a rod and a disc. The rod passes through the disc into an actuator which regulates the movement of the disc, rotating the disc either parallel or perpendicular to the flow of media.
The butterfly valve, as the name implies, operates like the butterfly. With the rod of the machine representing the body of a butterfly and the disc representing the wings, the movement of the valve mirrors the movement of a butterfly, with each wing making a 90-degree rotation.
Originally, the butterfly valves were installed where tight seals are not necessary; however, the production of the valves with tight seals made of rubber or elastic materials enabled the butterfly valve to function as a shut-off valve.
While throttling valves, most butterfly valves function as only block valves. They are functional for various media, and due to their lightweight and low cost, they are found in several modulation devices. The main components of a butterfly valve are the disk, stem, seat, and body.
The symbol of the butterfly valve is composed of two vertical parallel lines, with a diagonal line extending from the top of the first line to the bottom of the second line (P&ID symbol).
The two solid horizontal lines by the sides of the vertical lines indicate that butterfly valves are two-way inline valves used for flow control, either on/off or throttling. In the centre of the two vertical lines and the middle of the diagonal line is a solid circle.
Similar to a globe valve symbol with two diagonal lines crossing themselves, the butterfly valve symbol is the only symbol where a full triangle is not used. Isometric symbols are used in isometric drawings.
Butterfly valve types vary based on their different classifications. They are classified here based on their valve actuators, connection design, and disc closure design.
Based on their valve actuation method, butterfly valves can be separated into manually operated valves that use manual handles or gears and automatically operated valves that function using electric, pneumatic or hydraulic actuators.
Manual operation of the butterfly valve involves using a hand lever or a gear. This operation is not expensive and is easy to perform.
Manual butterfly valve operations work without the use of power. But they work low speed and cannot be used for critical pipe systems.
Automatically Operated butterfly valves can be controlled from remote locations. The valve actuators allow for control of larger valves. With an ability to remain open or stay closed if the actuator fails, the actuated valves provide a safe and dependable option. The actuated valves include:
Various methods are employed to connect a butterfly valve to a piping system. Common types of butterfly valves based on their connection design are:
This type of valve offers the most economical option. While placed between two pipe flanges, the wafer-type butterfly valve is designed to seal against the two-directional flow differential pressure of the guild. It restricts any backward flow in the system designed for any unidirectional flow.
Bolts are passed through holes on the body of the two sides of the valves to connect the two pipe flanges. The space between the pipe flanges and the valves is closed using gaskets or o-rings on the two sides of the valve.
With threads on the outer sides of the valve body, the Lug-type butterfly valve allows a joining of the valve and the pipe flanges with two bolts on each side of the valve.
This setup permits a disconnection of one side of the system without affecting the other side for dead-end service. The lug-type butterfly valve installation for dead-end service usually occurs at lower pressures (75 psi). Still, the installation occurs at a higher pressure (150 psi) when the valve is placed between two pipe flanges.
These valves are insusceptible to solvents and chemicals, and they can withstand a temperature of up to 200-degree Celsius.
These have flanges at end connections, which makes it easier to be connected directly with pipe flanges. The Flanged-Type butterfly valves are better used in high and low temperatures. Eight bolts join the valve body to the pipe flanges.
Here, butterfly valves are differentiated based on the position of the stem to the disc and the design of the butterfly valve seat. Based on their disc closure design, the types of butterfly valves are:
In this type of butterfly valve, the stem goes through the middle line of the disc, and the seat is designed into the valve body. They are called &#;zero offset butterfly valves because the disc does not offset from the stem.
This butterfly valve design depends on how flexible the rubber seat is to seal the valve effectively. This valve design has a low-pressure work rating (reaching 250psi) and can handle temperatures between 0 and 400F.
In this butterfly valve, the stem passes behind the disc and not through its centre. A single offset butterfly valve occurs when the stem is positioned behind the middle of the disc.
There are two offsets in a double offset butterfly valve (also double eccentric butterfly valve), with one behind the middle of the disc and another additional offset. Likewise, In a triple offset butterfly valve, there are three offsets, where the last offset is the contact axis of the seat.
Eccentric valve designs (double offset) are also high-performance butterfly valve designs. The valve seals are resilient and do not jam from closing action. They operate at high pressures and do not get destroyed easily.
A butterfly valve is a common machine in factories, workshops, or places requiring pipe operations. In these places and for its users, the butterfly valve has various advantages over other valves of similar function and disadvantages that make them less effective than other valves. Some of these advantages are:
Mechanical workers and the pipe operators in the workshops go for butterfly valves because of their high efficiency. The valves require little or no effort from workers because of their actuation options. They are easy to control or adjust. Because they are lightweight with uncomplicated components, the butterfly valves allow for simple maintenance.
The butterfly valve sizes vary in function and application, making them a versatile option in the industry. The availability of different valve sizes makes them suitable for many pipes, regardless of the pipeline size.
For compact or large size requirements, a butterfly valve easily presents an option for a pipeline operator.
Butterfly valves provide excellent sealing operations in low-pressure conditions. With lightweight disks, butterfly valves seal effectively at low pressures.
Other advantages of butterfly valves include:
Butterfly valves have very few disadvantages, some of which are:
The small size and simple construction of the Butterfly valve allow it to be applied in different systems, sometimes functioning as a replacement for another valve.
Butterfly valves function in flow regulation (throttling) as control valves and on-off operations.
In on-off operations, the butterfly valve disc is either fully open or closed. In the open position, the valve requires a low-pressure condition. Also, there is a small flow resistance when the valve is opened completely.
In the open position, sensitive flow control can be done, resulting in butterfly valves in large diameter regulation.
For proper handling of fluids, control valves are essential. Adequate research should be done before choosing a valve for this function from an industrial valve manufacturer.
The butterfly valve has a large pressure drop in the pipes, so the effect of the pressure loss should be taken into account&#;the strength of the valve disc when shut should also be considered. The flow requirements consisting of the design flow and max pressure drop should be identified.
The valve stem, the disc, the valve seat, and the valve body make up the components of the butterfly valve. With only a few parts, the butterfly valve has a simple design and construction.
The valve&#;s body houses the parts of the valve and can be set between pipe flanges because of its construction. Valve bodies are of two types: wafer type and lug type.
The difference between the two body types is that the lug-type valve body has threads on the outer part of the valve, which allow for attachment with the pipe flanges, while the water-type body type does not have attachments. Instead, bolts are passed through the water-type valve body to allow for joining with the pipe flanges.
Elastomeric seats are found in many butterfly valves. The valve disc closes into the seat. Proper shutoff of the valve is accomplished because of the interference fit between the disc&#;s edge and the seat. When the disc closes into the seat, the flow is restricted.
In valves that are not expensive, the butterfly valve seat is usually designed into the body and, if damaged, has to be replaced. But in precision valves, the seats are repairable.
The valve&#;s stem is composed of a one-piece or two-piece shaft design. It can be joined to the valve disc in two ways. The first method involves securing the stem to the disc by the bolts which pass through the disc.
In the second method, the stem is shaped by the disc by floating to locate the middle of the seat.
The disc regulates the flow of media through the valve. The Butterfly valve disc can be designed to fit specific operations, improve flow or enhance sealing operations.
The valve shaft is connected to the valve disc to ensure transmission of torque from a remote location. The shaft and disc are joined together by a hub which is created on top of the disc. The shaft end is inserted into the hub and forms a connection between the disc and shaft.
Butterfly valves have different working principles because of their different classifications and types. The manual butterfly valves comprising the hand lever and gear valves operate in a way that is usually suitable for small valves. In contrast, the actuated butterfly valves are usually suitable for larger valves.
Butterfly valves operated by hand levers function with a locking mechanism which controls the stem to allow and restrict flow through the disc. The hand lever operation is easy but unsuitable for larger valves.
Gear-operated butterfly valves operate through a hand-operated wheel that controls the stem to allow and restrict flow through the disc. The gear wheel operation is good for valves larger than the hand lever-operated valves. The gear and hand lever operations are the most common ways of operating butterfly valves.
The actuation methods (Electric, Pneumatic, and Hydraulic) use power in their operations. Large diameter butterfly valves require automated operations to control media flow through the disc. Specific valves are designed to meet the mounting requirements of actuators to ensure the proper functioning of the actuated butterfly valves.
Butterfly valves that function as modulators can be constructed in linear or equal percentage forms.
Below are some practices that should be considered before installing butterfly valves.
Below are some essential practices to ensure the butterfly valve works effectively and lasts longer.
Before selecting a valve to buy, various factors should be considered. Butterfly valves are available in different sizes, material types, pressure ratings, standards, and designs. Therefore selecting the butterfly valve suitable for an operation should be based on these factors.
Below, we explain how some of these factors influence butterfly valve selection.
Made from Iron, Nickel, and Chromium, stainless steel is insusceptible to rust. Scrapings and scratches are prevented from damaging the valve body because the chromium element in stainless steel prevents rust by forming a preventive layer with oxygen.
Most butterfly valves are made with PVC. Butterfly valves made with PVC material are not used in high-pressure conditions. These valves, while lightweight, have solid and durable constructions.
The cast iron material is also commonly used in making butterfly valves. With solid construction and tested durability, these valves function effectively in different conditions. Within the metal family, iron is an economical option for use in making butterfly valves.
For petrochemical industries and piping applications, the following specifications cover the dimensions and tolerances of butterfly valves:
Other industrial butterfly valves are designed with these specifications:
The butterfly valve designs have been explained above but will be listed here:
Valve size is an important factor to consider in selecting a butterfly valve. In selecting a valve size, here are some areas to look at:
Operational conditions of butterfly valves are measured in two ways: Body Pressure Rating and Close-off Pressure Rating.
This explains how pressure the butterfly valve stem and body can withstand without breakage. The ratings vary depending on the manufacturer. Some common ratings are:
This is the maximum differential through the disc that the valve can withstand against the rated seat breakage.
This post discusses all you need to know about the butterfly valve, including its function, parts, installation and maintenance requirements, and what you need to consider before buying an industrial butterfly valve.
Dombor valve is an industrial butterfly valve manufacturer that provides high-quality valve solutions to fit market requirements. With our 20 years of manufacturing experience, we specialise in creating valve types that function in any environment. So contact us today!
If you are looking for an easy installation and low-cost valve for fluid flow control and throttle with a tight shut-off, then look no further. You&#;re probably looking for a butterfly valve.
We don&#;t exactly know what and where you will be using it for, but in this guide, you will find plenty of things insightful about Butterfly Valves. First, you will learn the basics on butterfly valves, its operation, installation and maintenance. Then, we will show you how a designer, engineer and investor thinks and does before actually buying high-performance butterfly valves.
Beware that this IS an actionable guide. You might want to take down notes which can help you decide on how to choose and purchase butterfly valves.
Contents of this Guide:
A butterfly valve is a quarter-turn valve that initiates throttling and flow control of fluids. Given its name, you can easily visualize a thin metal disc that &#;flutters&#; about a fixed axis (stem assembly). The opening and closing mechanism allows and restricts the flow of a medium between an upstream and downstream pipe.
In a more technical tone, a butterfly valve is a regulated rotary valve that consists of a rotating disk which directs the flow of fluid in a system. Basically, the disk is operable up to 90 degrees and that&#;s why it is called a quarter-turn valve. A butterfly valve controls the flow linearly and can be bi-directional. The configuration and operation of the valve is similar to a ball valve, but it is lighter and less costly.
For throttling services, you can use a high performance butterfly valve, which is a higher industry standard for larger applications. Generally, this type of valve is manufactured to process large capacities and oftentimes, viscous and seawater medium. We will get more into high performance butterfly valves later.
You can find butterfly valves typically in piping systems delivering large volumes of fluids. These valves are delicate and not recommended to handle dry bulk solids as they can choke or break the butterfly valve.
The operation can be through a packing from a pneumatic actuator, an electric motor, a solenoid or a hydraulic piston and cylinder. Either way, this type of valve is the most economical and the easiest to handle. Butterfly Valves are also more affordable than other types of valves.
Advantages
Here are some of the advantages of butterfly valves compared with other valve types.
Disadvantages
Butterfly valves are used in many industrial applications such as:
When it comes to choosing a butterfly valve type for a specific application, one can look into a pile of different valve classifications. Seat, body and disc materials are varied depending on the service they will be used.
Regulating Fluid Flow
In butterfly valves, fluid flow constriction and control is easily done by just turning the valve handle. As it is a regulating valve, it controls the flow rate of system through the help of actuators. Basically, when a flow monitor senses that a set parameter (differential pressure) has been reached, it will signal the valve actuator to close or open the valve.
To control a regulating valve remotely, it must have a flow controller which automatically communicates with the valve mechanism based on the flow rate.
Flow Isolation
Butterfly valves are used typically in low pressure and low-temperature applications. They are lightweight and easy to manipulate and its quarter-turn action can also be used for flow isolation.
Backflow Prevention
In food industries where there are aggressive washdown processes, butterfly valves can be used for backflow prevention. This is necessary, from standard regulations, as it is aimed in food processing to deliver procedures in sanitary conditions.
General Butterfly Valves for Smaller Processing Units
For example, lightweight and AWWA butterfly valves are meant for water lines and potable water control applications. Other light duty valves can be used for aquariums and sprinkler systems. Some valves are also meant for fuel flow control.
High-Performance Valves for Heavy-duty industry applications
For large and heavy-duty applications such as in oil and gas industries or high-pressure controls, high-quality and high performance butterfly valves are needed. These high-grade valves are certified and quality tested to meet quality demands and international standards.
Constant Load Applications
With competitive price and timely delivery, Yaxing Valve sincerely hope to be your supplier and partner.
It should be noted that even though butterfly valves can handle large volumes of liquids, care is needed when controlling its load. This type of valve has a limited capacity in handling small load changes as only allowing a few millimeters opening is equivalent to a large volume difference. However, designs can be enhanced to diversify its control range, especially in larger applications where pressure is intricately regulated.
Parts of a Butterfly Valve
Generally, there are four main parts: the stem, disc, seat and valve body.
Valve Body
The valve body fits between the pipe flanges. It holds the other valve component into place. The valve body can be lug-type or wafer type.
It can also be made of different materials depending on the application. For example, Carbon steel is a general type of valve body used in common applications that do not require corrosion resistant properties. Stainless Steel, Nickel Alloy and Titanium Alloy, on the other hand, can be used for corrosive environments.
Disc
Attached to the valve body is the disc that functions as a gate that stops fluid flow. Again, it can be made from different materials depending on application.
Seat
Lining the internal valve body is a strong elastomer or metal anti-leak seal that secures the disc in place. It main function is This can be soft seated or metal seated. Soft seats (PFTE/RTFE) can be made of O-rings or rubber rings, while metal seals can be inconel or stainless steel.
Stem
The stem is valve component that usually lies protected inside the disc in resilient valves. However, in high-performance valves, it is typically in contact with the fluid.
The stem connects the disc to the actuator, like a shaft connecting a propeller to a motor. Similarly, the rotary action of the stem initiated from the power of the actuator is transmitted to the disc, allowing the close and open position of the valve.
Types of Butterfly Valves
How many types are there?
Butterfly valves can be categorized in many types. The most known classification is by end-connection type (lug or wafer). But it can also be classified according to seat design, body material and offset design. Some even classify these valves according to their mode of operation.
But each classification can also be intertwining. For example, you need a specific design for severe, heavy-duty applications where vibration is high and the substance is corrosive. In this type of scenario you can use a lug-style (end-connection type), titanium alloy (body material type) butterfly valve &#; two different valve classification in a row.
What are the two body styles of butterfly valves? Classification by end-connection
Seat Material
Offset Design
Body Material
For a more detailed discussion of butterfly valve types, you can refer here.
Valve Actuation
There are many ways to operate a butterfly valve. It can be manual, semi-manual or automatic.
Electric-Operated Valve &#; use an electric actuator for operating the valve in an open and close position.
Pneumatically-operated valves &#; Pneumatic actuators are used to operate these types of valves for shut-off pipelines. Pneumatic Butterfly valves are typically used for transferring compressed and pressurized air.
Hydraulic Piston &#; These types of valves are used for applications requiring huge impacts or force for opening and closing the valve.
Manual or handwheel operation &#; These types of valves are manually operated through a hand-wheel or crank. Hence, they are not automatic.
Check out this video to see how this type of valve work.
Installation
Here are few installation tips, as well as a checklist to take note of:
Valves, as having constant contact with fluids, are prone to rusting and corrosion. The applied grease on the butterfly valves should also be monitored.
What to Consider When Choosing Butterfly Valves?
When choosing butterfly valves for your operation, you would need to determine a few things before jumping in with the technical specifications of the valve. These basic information are the valve application, type of fluid, mode of operation and mode of installation, which are expounded below.
Valve Specific Application
The first thing you have to determine when choosing a butterfly valve type is to know what you will use it for. Do you need it for flow control applications such as regulating or stopping fluid flow?
Type of Fluid
Next is to know what type of fluid or substance will be circulating your system. Butterfly valves can generally accommodate liquids and gases, but not bulk solids. Also find out the properties of your media. It could be corrosive which requires stainless steel valve body and disc. However, for general fluids such as water, you can use carbon steel or cheaper alloys.
Mode of Operation
After knowing the type of fluid, you can choose the mode of operation of the butterfly valve. Manufacturers and suppliers usually have a range of choices for this. They would have manually operated, semi-automatic or automatically-operated valves. This would depend on the location of your valve, application, cost and on how often you need to turn on and off the valve.
Mode of Installation
Lastly, you should be able to see to it if you would need to flange the valve at both ends, weld it or screw it in between the pipes.
Upon determining these necessary information, you can now determine the technical specifications regarding your butterfly valve installation as coordinated with the manufacturer or supplier.
Capacity
The capacity includes the flow rate or the rate at which the material will pass through. This parameter also accounts for the safe internal pressure capacity of the valve. Make sure to check the butterfly valve specifications to ensure that you buy a valve sufficient to what your system needs.
Level of Precision
Each valve from a supplier specifies valve specifications which states the leakage volume or amount, if there is. It also indicates the shut-off position specs, the width of the passage and the volume of fluid that it can accommodate when fully opened.
Operating Life
Typically, you can find the operating life of the valve in the specifications sheet. Overall, butterfly valves promise less maintenance activities and can still give bubble-tight shut-off.
Pressure Drop
Pressure drop is an important parameter when sizing the valve for your specific application. It describes the difference in pressure which occurs between the outlet and inlet of the butterfly valve.
It is recommended that &#;If the pressure drop across the fully opened valve is not a large enough percentage of the total system drop, there will be little change in the fluid flow until the valve closes. In this case, a fast acting valve would be appropriate.&#;
Consider that 25% to 50% of the total system pressure drop of the butterfly valve should be absorbed by the valve.How to Choose the Best Butterfly Valve Manufacturer
If you are planning to search for the most reliable butterfly valve manufacturer, there are a few things you should look for to know that you have chosen the right one. There are a pool of valve manufacturers to select from but how do you know you have fished out the right one?
Let us guide you with the following questions to help you choose the best butterfly valve manufacturer:
How to inspect butterfly valves?
First is inspection. You can&#;t buy a product you haven&#;t even inspected. Here are some of the things you should check in the butterfly valve:
Do they have the proper certification?
A butterfly valve supplier should have an ISO certification. Some valve manufacturers place this on their websites. Having this certification ensures that the facility meets the valve standards and quality in their manufacturing process and end products. It also notes that the manufacturer takes full responsibility for their product quality. You need to see their ISO certification first before you make any purchase for your own safety.
What is the cost?
Cost is actually one of the first things clients look for. For this, you can either see butterfly valve prices online or you can contact specific valve suppliers. If it&#;s a physical conversation, chances are, you can readily negotiate. However, you might want to see first the cost of China butterfly valve manufacturers as they offer huge savings on valve price. Again, to make sure that you are getting a high quality valve, you should look for proper company certifications.
Is there an After Sales Service?
The best manufacturers provide after sales service. This is one of the most crucial aspects in choosing a valve provider. When you see a lot of good testimonials about the company, it must mean they provide good quality service and perhaps they are true to their word. Also, valve suppliers who have professional staff ready and willing to solve your product problems are the best companies. So you should carefully choose who among the valve suppliers actually care.
How about repair services?
It is not uncommon that a few problems may arise upon installation of the butterfly valve. Although this can barely happen if you install it right, there may be times that it is not your fault why it does not work well. Manufacturers who provide clients with the best repairing services are top-notch.
These services may range from repairing to replacing your valve part and accessories.
Since Huamei is a butterfly valve manufacturer, we provide professional repair service along with our after sales service. Repair service may include repair, replacement, overhaul or instrumentation if necessary.
Do they have Warranties?
Warranties are protectional tools which ensures that you are protected from defective products over the span of the warranty period. Be sure to look for a valve manufacturer that promise product warranty.
Huamei offers 18 months warranty, complete with customer support, repair services and aftersales service to ensure that you get the best experience with your purchased high performance butterfly valves.
Do they have a good company reputation?
It also matters that the supplier/manufacturer has a good reputation which reflects the quality of the product they deliver, the services they provide, and the response time on queries. You can verify this by simply checking their testimonials, history and ratings from other customers.
Frequently Asked Questions
Have some confusion? Here, we have gathered some of the most famous FAQ about butterfly valves that may answer your question in mind. However, if you did not find the solution here, just contact us for more information.
1. Are butterfly valves good for throttling?
They are mainly used for regulating large fluid flows, including viscous slurries, but it should be noted that they are not meant for precision throttling.
2. Do butterfly valves require gaskets?
Butterfly valves are available with built-in elastomer seal that rests on flanges to prevent leaks. So most of them do not require additional gaskets.
3. Can Bi-directional high-performance butterfly valve supply for dead-end services?
Bidirectional high-performance butterfly valves can be used for dead-end service. But it should be noted that for such service, you cannot subject it in high-pressure applications.
A valve used for a normal service with KPA can be used on a dead-end service but with only 500KPA. The high pressure may tend to cause the seat retainer to unload. The seat retainer may be bolted to prevent this, but the easiest way is to install it with a bolted flange. This flange can support the seat retainer.
4. Can a butterfly valve be used for flow control?
Yes. Butterfly valves, like needle valves, have good control capacities.
5. What is the difference between the ball valve and butterfly valve?
The butterfly valve with the same specification as the ball valve is usually cheaper in price and easier to install. Easier maintenance may go in recognition to ball valves as butterfly valves have a disc that can block some impurities that got stuck. Furthermore, ball valves are used in most high-pressure applications because they are more suitable for high differential pressures as compared to butterfly valves.
Butterfly valves are simpler in design, having lesser moving parts. Ball valves material and torque use is only low for narrower pipe diameters. For butterfly valves, it may start from DN 50mm and above.
6. How to Avoid Problems with Butterfly Valves?
Most of the major problems with butterfly valves are a result of poor installation and not the device itself. Therefore, it should be noted that in order to reduce maintenance work, butterfly valves should be properly installed during the commissioning stage.
Conclusion
So there. We have finally reached the end of this guide. We hope that it has given you a better understanding of a butterfly valve; its operation, maintenance and installation. Most importantly, we hope that it gave you an idea on how you can choose and buy butterfly valves from manufacturers/suppliers.
Huamei is a high-performance butterfly valve manufacturer and supplier for many years. We are dedicated to helping you deliver the best performance butterfly valves in the market. Please do contact us for more details if you have any queries.