What Are the Three Main Actuators of a Butterfly Valve?

In this blog, you will read:Actuators have a vital role in correctly functioning your industry's valve system since they control the movements of the valves present in your system. This is why getting the appropriate actuator for your wafer butterfly valve is essential.

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Actuators have a vital role in correctly functioning your industry’s valve system since they control the movements of the valves present in your system. This is why getting the appropriate actuator for your wafer butterfly valve is essential.

What are the three primary actuators of a wafer butterfly valve? The manual wafer butterfly actuators include lever-based actuators and gear-box-based actuators. Furthermore, pneumatic actuators include spring-return actuators and double-acting actuators. Lastly, an electric actuator is also a viable option.

All the various options of actuators for a wafer butterfly valve may be overwhelming to confront when deciding which actuator is most suitable for your butterfly valve. Lucky for you- this blog post covers all you need to know about them to make the right choice, so continue reading!

What Is a Butterfly Valve?

A commonly used name for butterfly valves is ‘Quarter-turn’ valves. This is because when the metal disc attached to the valve is turned at 90 degrees, it either fully closes or opens.

This metal disc is the ‘butterfly’ of the valve- it is attached to a rod and is used to control fluid flow through the system. This flow can be completely unrestricted, slightly controlled, or entirely restricted.

When the butterfly disc opens slowly, the fluid flow is reduced. Moreover, when the butterfly valve is completely opened, it is a quarter turn- leading to an utterly unrestricted fluid flow within the system. On the other hand, when the valve is completely closed, the passage is blocked, hence not allowing any fluid flow.

These situations are possible because the disc is always perpendicular to or aligned with the fluid flow, automatically decreasing the pressure regardless of its position.

What Is a Valve Actuator?

A valve actuator is a tool required to open or close a valve.

As previously discussed, your wafer butterfly valve will either be manual or automatic, and each case will require a tool to open or close the valve.

This tool might be someone in attendance rotating the valve by hand manually, or the device may be automatic- an ‘actuator’ which is a machine that will use electricity, hydraulic pressure, or gas pressure to rotate the valve.

An actuator will use ‘torque’ to automate your industrial valves and can be found in varying power plants.

The Three Different Actuators of a Wafer Butterfly Valve

A wafer butterfly valve can be equipped with different actuators, and knowing which actuator to choose for your wafer butterfly valve is of utmost importance.

Our blog post will highlight the significance of each actuator, and by the end, you are bound to be aware of the actuator to pick for your wafer butterfly valve.

Manual Operators for Your Wafer Butterfly Valve

The manually operated wafer butterfly valve has two variations- the lever-operated butterfly valve and the ‘gear’ operated butterfly valve.

Many assume that both are generally the same; however, the lever and the gear-operated butterfly valves have some stark differences that highlight which valve is correct for a particular valve system.

Lever-Operated Butterfly Valve

Di Hand Lever
Di Hand Lever

The lever-based manual actuators are the most basic form of actuator controlled by man.

Lever-based manual actuators are inexpensive and easy to operate, making them most suitable for remote pipelines that are cut off from power systems and hence cannot be equipped with electric actuators.

Since lever-based manual operators provide minimal torque, they are suitable for small wafer butterfly valves.

Gear- Operated Butterfly Valve

Gear Box

The gearbox actuator is an advanced version of the manual actuators. This means it also surpasses the lever-based actuator regarding torque power since it rotates the disc and stem of the butterfly valve with a gearbox’s help.

Furthermore, the gearbox-based manual actuator has analog features which remain consistent with the exact position of the valve’s discs hence allowing for the flawless operation of the system.

Like the lever-based manual actuator, the gear-based actuators are suitable for small butterfly valves.

Lever-Operated Butterfly Valve vs. Gear Operated Butterfly Valve

So you’ve understood the difference between the two manually operated actuators but still can’t decide which is ideal for your industry’s requirements?

Not to worry, we’ll address some key differences between the two actuators to help you determine the perfect match!

Speed of Operation and Labour Required

The speed at which each variation closes the disc varies.

The lever-operated wafer butterfly valve controls the disc independently, because of which the disc opens and shuts very quickly; however, it is tiresome.

On the contrary, the gear-operated butterfly valve controls the disc using a ‘worm gear,’ which leads to the disc opening and closing slowly, however, with little effort.

If your industry has high-pressure fluid flow in the pipelines, it will be extremely laborious to use the lever-operated wafer butterfly valve. In this situation, choosing a gear-operated butterfly valve for your industry’s system would be best.

Sealing Service

A gear-operated butterfly valve has various other advantages, such as having excellent sealing service, which is lacking in a lever-operated butterfly valve.

Therefore, if the frequency at which valves are opened and closed in your industry is high, it would be recommended to instill a gear-operated butterfly valve in your industry as it will last longer than a lever-operated butterfly valve.

Diameter That Can Be Supported

The diameters of valves directly affect the amount of torque that would be required to rotate that valve.

A valve with a small diameter- of up to DN200 can be supported by a lever-operated butterfly valve. This is because valves with smaller diameters require less torque to rotate the disc.

On the other hand, if the diameter of a valve is more significant than DN200 and requires a torque of 300N.M- a gear-operated butterfly valve would be more appropriate as it would save labor effort.

This is because a gear-operated butterfly valve would not control the disc directly but would instead use a gearbox.

Electric Actuators for Your Wafer Butterfly Valve

Electric Actuator
Electric Actuator

As indicated by its name, an electric actuator is ‘automated.’

This automated electric motor comes with a two-way engine, making using these actuators in a remote system possible.

Because the electric actuator is automated, it can quickly identify when the disc is shut to allow fluid flow. Furthermore, the electric actuator comes attached to a gearbox and slows down the motor speed to amplify the torque power.

An electric actuator is designed to rework electrical energy into mechanical energy. This mechanical energy is the ‘torque’ used to open or close the wafer butterfly valve.

Therefore, these electric actuators will be perfectly functional for your wafer butterfly valve system if they are present near and can easily be connected to electricity.

These electric actuators are perfect for your wafer butterfly valves if they operate in minor and lightweight modulation activities.

Ultimately, the electric actuator’s benefits surpass those of the manual actuator because of its tremendous torque since it does not require manual labor to open or close the wafer butterfly valves.

Expenses and Maintenance of an Electric Actuator

These ‘Electric actuators’ are more expensive than manually operated actuators. Moreover, their repair and replacement are more costly than manually operated actuators because they involve more advanced components, such as an electric motor.

However, this is not usually an issue for electric actuator owners because electric actuators are easy-to-install devices that have a long service life and therefore do not require regular maintenance.

Pneumatic Actuators for Your Wafer Butterfly Valve

Pneumatic Actuator
Pneumatic Actuator

The ‘Pneumatic’ actuator has two main versions- the Spring-return pneumatic actuator and the double-acting pneumatic actuator.

The Spring-Return Pneumatic Actuator

The spring-return actuator, also known as the ‘single-acting’ actuator, is controlled by the air output of the control valve positioner found only on one side of the valve. In contrast, a membrane or spring controls the other side of the valve.

The single-acting actuator only requires force on a single side of the valve to operate.

Moreover, it will use the spring force attached to the actuator to pull the valve into an open or closed position.

The Double Acting Pneumatic Actuator

The double-acting pneumatic actuator is controlled by the air output of the control valve positioner found on both sides.

This double-acting actuator will force both sides of the valve to open or close it.

Therefore, this actuator is highly dependent on its piston to operate the valve.

The Spring-Return Pneumatic Actuator Vs. The Double Acting Pneumatic Actuator

The question that fazes most industrialists is which pneumatic actuator is most appropriate for their system. Hence, we have rounded up the most common differentials between the two variations.

Torque or Thrust Power

The spring-return and double-acting actuators have nearly the same torque power; however, to be specific, the double-acting pneumatic actuator has a low to very high thrust power, whereas the spring-return pneumatic actuator has a low to high thrust power.

Switching To the Last Position

Some systems are prone to malfunctions, such as when the signal or supply of fluid is lost or disrupted. An example of such a situation is when the production valve becomes choked.

In such situations, specific industries automatically require valves to switch to the last position.

It is important to note that this function is only available in the double-acting pneumatic actuator because the pressure from both sides of the valve will cause it to switch to and remain in its last position.

Processing Application Requirements

Process control applications that use control valves to regulate their valves and systems have specific actuator diaphragm requirements.

In the case of an 8-inch valve, the process control application would require a spring return diaphragm.

Whereas, if the valve is more extensive than 8-inches, the process control application would require a double-acting diaphragm as it will create a higher torque power to keep the valves functioning.

In some rare circumstances where valves of less than 8 inches require greater torque than usual, a double-acting pneumatic actuator is used.

Furthermore, a double-acting pneumatic actuator’s strong and sturdy build makes it more suitable than a spring pneumatic actuator when processing applications that face constant changes or higher pressure ranges are being considered.

Safety Integrated System Application

Specific process applications have certain safety feature requisites. An example of such applications can be a shut-down valve system (SDV) or a blow-down valve (BDV).

These applications require the vale to automatically switch to a fully opened or closed position when the supply, power, or signal is disrupted.

For this scenario, the appropriate actuator would be a spring-return actuator since it will be simple to navigate and perform this function.

A double-acting pneumatic actuator would also be able to perform this job; however, it would be much more complicated and challenging to set up the panel. Therefore, we do not recommend it for this role.