10 Factors to Consider When Choosing Butterfly Valves

A butterfly quarter is a quarter-turn valve, allowing for a quick shut off making it cost-efficient. The “butterfly” is a metal disc positioned in the center of the pipe with a rod passing through the disc to an actuator on the outside of the valve. It is in the shape of a gear, which is usually referred to as a gearbox, while the handwheel is connected to the stem. Rotating the actuator turns the disc either parallel or perpendicular to the flow.  The valve is fully opened or closed when the disc is rotated a quarter turn, to stop, regulate, or start the flow. They are suited for handling large flows of liquid and gas at low pressures.

Read on for more information on how to choose a butterfly valve.

 

Pressure Drop

Energy costs go up with excessive pressure drop. The valve or valves are but one factor in a piping system that contributes to pressure drop. Of equal concern are these factors:

 

• The flow area of piping.

• Friction loss against pipe walls.

• Change of flow direction via fittings

• Butterfly valves have flow characteristics three times better than globe valves and approximately 75% of an equivalent size gate valve.

 

Operating Life

Butterfly valves can provide many maintenance-free cycles and still accommodate "bubble tight" shut-off.

 

Weight

Installation dollars saved with lightweight butterfly valves as compared to heavyweight cast iron valves; i.e. a 10" butterfly may weight 55 pounds, whereas a 10" iron gate may weigh 490 pounds. This can be an important saving when it is calculated over an entire system. The heavier the system, the stronger the pipe hangers, and the more expensive they become. So, by considering the weight of a valve one can also reduce piping system costs.

 

Versatility

Butterfly valves can be used for on/off service and throttling/balancing. They are superior in "versatility" as compared to a gate or globe valve. Butterfly valves have a wider range of chemical resistance due to the trim options and choice of elastomeric liners.

 

Bubble Tight Shut-Off

Gate and globe (metal to metal) seats cannot provide bubble-tight shut-off. Resilient seated butterfly valves are bubble-tight by design.

 

Physical Size

Butterfly valves take up approximately 1/6 the space of a gate valve. Every cubic foot of a building costs money.

I.E.: 10" butterfly is about 21" high and a 10" iron gate is about 43" high.

 

Cost

A butterfly valve is generally 40% the cost of an iron gate valve, not only in low initial costs but in low installation costs as well.

 

Maintenance

Properly installed butterfly valves are virtually self cleaning and are less susceptible to failure due to trash material in the line.

 

Ease of Operation

Butterfly valves offer 1/4" turn (90 degrees) open to close. Gates and globes require multiple turns to open and close. Ease of opening or closing means that butterfly valves can employ less expensive operators.

 

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The Evolution of Butterfly Valves

 

The prototype of a butterfly valve

The original butterfly valve was a simple, poorly closed flap valve. It is usually used as a flow regulator and damper valve in water piping systems. With the application of chemically resistant synthetic rubber on the butterfly valve, the performance of the butterfly valve has been improved. Synthetic rubber has the characteristics of corrosion resistance, erosion resistance, dimensional stability, good resilience, ease to form, low cost, etc., and can be selected according to different requirements for the use of different properties of synthetic rubber to meet the working conditions of the butterfly valve. Therefore, it is widely used to manufacture the lining and resilient seat of a butterfly valve.

 

The development of butterfly valve

 

PTFE

Polytetrafluoroethylene (PTFE) has strong corrosion resistance, stable performance, not easy to aging, low coefficient of friction, easy to shape, dimensional stability, and other characteristics. And it can also be filled and added with appropriate materials to improve its comprehensive performance, to get better strength, the lower friction coefficient of the butterfly valve sealing material, to overcome some of the limitations of synthetic rubber. Therefore, the polymeric materials represented by PTFE and its filler-modified materials are widely used in butterfly valves. Thus, the performance of butterfly valves has been further improved. There are butterfly valves with a wider temperature and pressure range, sealing performance, and longer service life.

 

Metal Sealed Butterfly Valves

To meet the use requirements of industrial applications such as high and low temperature, strong erosion, and long life, metal sealed butterfly valves have been developed greatly in the last decade or so. With the application of high-temperature resistance, low-temperature resistance, strong corrosion-resistance, strong erosion resistance, and high strength alloy materials in butterfly valves, metal sealed butterfly valves have been widely used in industrial fields such as high and low temperature, strong erosion, and long life. The butterfly valve with a large diameter (9750mm), high pressure (2.2kN/cm2), and wide temperature range (-102～606℃) has emerged, thus bringing the technology of the butterfly valve to a whole new level.

 

CAD&CAM

Due to the application of computer-aided design (CAD) and computer-aided manufacturing (CAM) and flexible manufacturing system (FMS) in the valve industry, the design and manufacture of butterfly valves have reached a whole new level. The comprehensive innovation of the valve design calculation method reduces the heavy and repetitive routine design work of professional and technical personnel. So that technical personnel has more energy to improve the technical performance of the product and the research and development of new products. Shorten the cycle, improve labor productivity. Especially in the field of metal sealed butterfly valves, due to the application of CAD/CAM, there is a three-dimensional seal designed by CAD and manufactured by cAM CNC machining. It makes the sealing surface of the valve free from any extrusion, abrasion, and wears during the opening and closing process, thus increasing the sealing and service life of the butterfly valve by orders of magnitude.

 

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Ball Valve vs Gate Valve

Choosing the right valve can determine the success or failure of the system. In today's market, with so many types of valves, it may be difficult to find the most ideal valve for your application.

The Main Difference Between The Ball Valve And Gate Valve

Ball valves are also called "shut-off valves." Ball valves are the only way to immediately shut off the flow of water. The gate valve cannot be turned immediately. Except for three-way ball valves, machined stops can prevent most ball valves from moving more than 90 degrees.

Cast iron high-temperature ball valve

Gate valves usually have a round knob, which you can turn to control the flow of water. This raises or lowers an internal gate to stop or start the water. The gate valve provides control over the flow pressure, rather than simply closing or opening it. Gate valves provide users with greater flow and pressure control than ball valves, but they do not provide users with the option to stop the flow immediately. For those who wish to use gate valves but are concerned about corrosion, stainless steel gate valves are incredibly flexible and are not more susceptible to corrosion than ball valves.

DIN cast iron resilient bolted stem gate valve

Before asking the question "Is a ball valve better than a gate valve", we need to determine the key difference between the two. The first thing to remember is that they all have essentially the same function, which is why they are so similar.

The main difference between ball valves and gate valves lies in the quality of their structure and the way they are marked. When the gate valve is opened, the circular or rectangular gate is lifted from the fluid passage, while the ball valve has a rod and a horizontally rotating ball. This is why ball valves are often called rotary valves.

The gate valve has a sealing surface that separates the gate plate and the valve seat. Therefore, they are usually used when a straight-line flow of fluid and minimal restriction are required. Because the ball valve is a form of the quarter-turn valve, their functions are different. They use hollow balls, both perforated and rotated to control the flow. When the ball hole is consistent with the flow, the valve opens. When the valve handle rotates 90 degrees, it closes, and the handle lies flat. It is horizontal to the flow when it is opened, and perpendicular to the flow when it is closed. This makes it easy to visually confirm the state of the valve.

Are Better Ball Valves Than Gate Valves?

The advantage of ball valves is that their seals are tighter, so they are better at avoiding leakage than gate valves. This is due to its 100% shut-off characteristics. In addition, they are easier to use than gate valves, and have a lower failure rate and a longer service life.

The durability of the ball valve makes it ideal for closed applications. They always perform well after multiple cycles, are reliable, and can be safely shut down even if they are not used for a long time. For these reasons, they are generally preferred over gate valves and globe valves.

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How To Operate And Actuate a Butterfly Valve

Butterfly valves are one of the most useful valves in piping systems. They enable the operator to start, stop, or restrict fluid flow in the system. This method is especially useful if you need to repair, clean, or modify the system, and you want to make sure that no liquid passes through the pipeline.

Despite this name, the butterfly valve does not look like a butterfly. Butterfly valves are quarter-turn valves, which means they go from fully open to fully closed at a 90-degree angle. A butterfly is called a "butterfly" because its wings move around a central axis, just like the body of a butterfly. But for a butterfly valve, there is much more to it than the central disc.

Butterfly valve components

At the most basic level, a butterfly valve consists of a disc, a valve seat, a valve body, and an actuator. Most butterfly valves have more parts, but they are an essential part of a butterfly valve.

Actuator: This part is also called a handle or manipulator. It controls the opening or closing distance of the butterfly valve. It is usually a handle that can move 90 degrees, but it can also be a faucet-like rotating handle. On the valve above, you can squeeze the handle to operate the actuator.

Seat: The seat of a butterfly valve is usually made of some kind of rubber. It ensures that when the valve is in the closed position, there will be a tight and safe seal. If the butterfly valve stops working properly, it is likely that the valve seat has been damaged in some way.

Disc: The disc is what gives a butterfly valve its name. When the disc rotates, the valve opens, giving the disc a butterfly-like appearance. The disc is moved by the actuator and can be completely closed, completely opened, or somewhere in between.

Body: The body of a butterfly valve enables it to be connected to pipes and fittings. It is everything around the valve seat and constitutes a large part of the valve structure.

What is actuation and why is it important?

Actuate literally means "to put into action." Therefore, when you activate the butterfly valve, you are putting it into action. The default state of the butterfly valve is closed; this does not allow liquid to pass through. If you want the fluid to flow through without any drop inflow pressure, you can turn the handle 90 degrees to fully activate the butterfly valve.

When people usually talk about actuation in butterfly valves, they are actually talking about automation. When a butterfly valve must be opened to a very specific degree, you can choose an electrically actuated butterfly valve. These are also useful if your butterfly valve needs to be opened and closed frequently.

What makes these valves so valuable and different from other valves is that they have more than two positions. It can be opened anywhere from 0 degrees to 90 degrees. The more open the blood vessels, the more fluid will pass through. Although some piping systems do not require local flow, many other systems do.

Gas: When adjusting the flow of compressed air or other gases, it is often extremely important to control how much gas flows. The butterfly valve works equally well for gas and liquid. When used correctly, these valves can act as dampers to control the flow so that only the specified amount passes.

Liquid: The obvious application of butterfly valves is liquid conveying. In agriculture and manufacturing, regulating the flow of water and other liquids is crucial. If you allow too much water in the irrigation system, you may over-irrigate your crops and destroy your crops. The butterfly valve allows you to select the amount of liquid to pass through the system.

We are a butterfly valve supplier. If you are interested in our products, please feel free to contact us!

Butterfly Valves: The Ultimate Guide

 

What is a Butterfly valve?

A butterfly valve is a quarter-turn valve that starts throttling as well as circulation control of fluids. Given its name, you can quickly picture a slim steel disc that "flutters" about a dealt axis (stem assembly). The opening and closing device permits and limits the flow of a medium between an upstream and also downstream pipeline.

What type of valve is a butterfly valve?

In a much more technological tone, a butterfly valve is a regulated rotating valve that includes a turning disk that directs the flow of fluid in a system. Basically, the disk is operable as much as 90 degrees and that's why it is called a quarter-turn valve. A butterfly valve regulates the flow linearly and also can be bi-directional. The setup, as well as the procedure of the valve, is similar to a ball valve, but it is lighter and less expensive.
For strangling services, you can make use of a high-performance butterfly valve, which is a greater sector criterion for bigger applications. Normally, this kind of valve is made to process huge capacities and often, viscous and seawater tools. We will certainly obtain much more right into high-performance butterfly valves later.
You can locate butterfly valves usually in piping systems supplying big volumes of liquids. These valves are fragile and also not recommended to take care of completely dry mass solids as they can choke or break the butterfly valve.
The procedure can be through 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.
1. Lightweight and compact
2. Easy to install
3. Low-pressure loss
4. Low maintenance
5. Simple, rapid operation

Disadvantages

The disc can interrupt flow even when it is open
Not recommended for high differential pressures

What are Butterfly Valves used for?

Butterfly valves are used in many industrial applications such as:

ㆍHVAC

ㆍVacuum service

ㆍHigh-temperature applications

ㆍRefrigeration and Air Conditioning systems

ㆍIrrigation and agricultural needs

ㆍCorrosive processing

ㆍLubrication

ㆍPetroleum Industries

ㆍWastewater treatment

ㆍSlurries

ㆍSanitary valve applications

ㆍSprinkler and fire protection systems

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 are easily done by just turning the valve handle. As it is a regulating valve, it controls the flow rate of the system with 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 that 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 their 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.

Installation

Here are a few installation tips, as well as a checklist to take note of:
1. In order to check parts of the butterfly valve, you can be able to disassemble it in order to further inspect its parts.
2. Before anything, see to it that the flange and pipeline are clean from foreign materials. These can damage the seat or disc and can also cause the disc to move restrictions.
3. Since resilient seated valves extend to both faces, gaskets are not needed.
4. In order to easily insert the valve body spread the flanges and align the pipe-work. With this, the valve body is inserted even with no contact with pipe flanges.
5. Partially open the valve disc to prevent the valve from jamming.
6. Insert the valve between the flanges, taking care not to damage the seat faces.
7. When you lift the valve, hold it by the locating holes. Also, you can tie up a nylon sling around the body or the neck. Make sure you do not lift the valve at the actuator or its operator.
8. Once the valve is placed and aligned in between the flanges, insert all the bolts before hand-tightening them.
9. Slowly open the disc. This will test if it has the right clearance from the inside of the pipes.
10. After which, a gradual closure of the valve should also be done to verify enough clearance from the disc to the pipe flanges.
11. Fully open the valve and start to tighten all of the bolts.
12. To test proper clearances after fastening the valve in the pipeline, repeatedly fully open and close the valve. This ensures the valve functions well during operation.

The Advantages and Selection Principles of Ball Valve

The ball valve is the evolution of the plug. It's opening and closing member as a ball, the use of the ball around the axis of the stem rotation of 90 degrees to achieve open and close. The ball valve in the pipeline is mainly used to cut off, distribute and change the direction of media flow, designed V-shaped opening of the ball valve also has a good flow regulation function.

 

The advantages of ball valve

1. Simple structure. Small volume. Lightweight.

2. Small fluid resistance. The resistance coefficient is equal to the same length of the pipe section.

3. Tight and reliable. At present, the sealing surface material of the ball valve is widely used plastic, good sealing, and has been widely used in vacuum systems.

4. In fully open or fully closed, the ball and seat sealing surface and media isolation. When the medium passes, it will not cause erosion of the sealing surface of the valve.

5. Easy to operate. Open and close quickly. Just rotate 90° from fully open to fully closed, easy to control from a distance.

6. Easy maintenance. The ball valve is simple in structure. Seals are generally movable, disassembly and replacement are relatively convenient.

7. Wide range of applications. Small diameter to a few millimeters, large to several meters. High vacuum to high pressure can be applied.

 

The main principles of ball valve selection

1. The transmission pipeline and storage equipment of refined oil products, the choice of flange connection ball valve.

2. Oil, natural gas transmission lines, the need to clean the pipeline, and need to be buried underground, the choice of full diameter, full welded structure of the ball valve; buried in the ground, choose full diameter welded connection or flange connection of the ball valve; branch pipe, choose flange connection, welded connection, full diameter or reduced ball valve.

3. City gas and natural gas pipeline, choose flange connection and internal thread connection of the floating ball valve.

4. In low-temperature media pipeline systems and devices, it is appropriate to use the low-temperature ball valves with valve cover.

5. Metallurgical system in the oxygen pipeline system, it is appropriate to use a strict degreasing treatment, flange connection of the fixed ball valve.

6. On the piping system of the catalytic cracking unit of the oil refinery, the lift rod ball valve can be used.

7. Metallurgical systems, electric power systems, petrochemical devices, urban heating systems, high-temperature media in the piping system or device, you can choose metal-to-metal sealed ball valves.

8. Chemical systems, such as acid and alkali corrosive media devices and piping systems, it is appropriate to use austenitic stainless steel manufacturing, polytetrafluoroethylene for the seat seal of the full stainless steel ball valve.

We are a ball valve supplier, please feel free to contact us if you need them.