An air actuated butterfly valve is a type of actuated butterfly valve that is power-driven. The actuator is “air-driven” so it can open or close the disc. These valves are also known as pneumatic actuators.
Not all actuated butterfly valves are pneumatic or air-actuated. Understanding the different types helps you choose the right power actuator.
This guide explores how actuated valves work, the different types, and how they work. It also discusses the different applications and the advantages of using actuated valves.
What Is an Actuated Butterfly Valve?
A butterfly valve controls flow through a disc that rotates 90 degrees inside the pipe bore. To open or close the disc, an operator turns a lever or gear to stop or allow flow. The actuated version does that automatically. The power source can be pneumatic, electric, or hydraulic.
The quarter-turn design is what makes butterfly valves ideal for industrial use. Compared to gate or globe valves, they open and close faster, weigh less, and occupy a fraction of the space.
What are the DIfferent Types of Actuated Butterfly Valves?
To understand how air-actuation works, you must understand the different actuating valves and how they are powered:
- A pneumatic or air-actuated valve is powered by air or air compression.
- An electric or motor-driven valve is powered by electricity.
- A hydraulic valve is powered by hydraulics.
What are the Components of an Actuated Butterfly Valve?
An actuated butterfly valve is composed of a valve body, disc, stem, and sealing. The components are similar to a manual valve, the only difference is the actuator that powers it.
The image below shows the components of a pneumatic valve to help you understand how it works.
How Does an Air Actuated Butterfly Valve Work?
An air actuated butterfly valve works by using compressed air, typically at 6 to 8 bar. The compressed air drive internal pistons that rotate the valve stem. This results in an open-closed cycle time of 2seconds or less for rapid process isolation.
An air actuated valve is also called a pneumatic actuator. When you select this type, you also choose between two core configurations:
- Double Acting: The compressed air drives the disc open and closed. This configuration cycles faster and suits high-frequency applications. In this case speed matters more than a fail-safe position.
- Spring Return or Single Acting: The air opens the valve and a mechanical spring closes it when the air supply is lost. This is ideal for safety-critical systems. If the air supply fails, the valve automatically closes and prevents uncontrolled flow.
Pneumatic vs Electric: Which One Should You Choose?
In hazardous or explosive environments, classified as ATEX zones, pneumatic actuation is the only compliant choice.
Electric motors generate heat and sparks that pose a risk. Compressed air is safer in oil and gas, chemical, and pharmaceutical facilities.
Pneumatic actuators also cycle faster than electric alternatives. This makes them ideal for high-frequency automated sequences. They are easier to operate and do not require complex motor controls. They can also tolerate wash-down environments with the right IP rating.
How Do You Select an Air Actuated Butterfly Valve?
To select an air‑actuated butterfly valve, you need to match the valve and pneumatic actuator to your process conditions, piping, and control needs.
Here are the steps on how to choose a pneumatic valve in case you need to undergo an air actuated butterfly valve replacement:
Step 1: Define your process conditions.
Check the fluid type such as water, air or chemicals. Evaluate the conditions if they are slurry, corrosive, flammable, etc. This helps you choose the right materials such as cast iron, ductile iron, stainless steel, or lined bodies.
Evaluate the temperature and pressure. Make sure that the valve and seat ratings cover your max operating temperature and pressure, including surges.
Evaluate flow control needs. Do you need a simple on/off vs partial-opening service? This affects whether you need a positioner and actuator type.
Step 2: Choose the right valve size and type.
Match the pipe size to the valve bore (DN/NPS) and required flow/velocity. This avoids oversizing for precise control.
Choose the body style whether wafer, lug, or flanged. This depends on pipe mounting and whether you need to support the weight or allow line disassembly.
Make sure the disc and seat material are compatible. Choose rubber-lined (NR, EPDM, NBR) for water or air. PTFE, or metal-seated, is ideal for higher temperature, abrasion, or chemicals.
Step 3: Select the pneumatic actuator.
When selecting the actuator type, there are two processes you need to consider. First, the spring-return (fail-safe) closes or opens when air is lost. This is ideal for safety-critical lines. Next is double-acting where it needs air to open and close. This is required for large valves where more force is necessary.
Evaluate the air supply for available air pressure (usually 4 to 8 bar0. Ensure that the actuator torque matches the valve’s breakout torque at working pressure. Check the manufacturer’s air actuated butterfly valve manual for torque/pressure charts.
Consider accessories such as solenoid valves, limit switches, positioners, and filters/regulators. These are necessary for control and monitoring.
Step 4: Check installation and environment.
Evaluate the space and orientation. Make sure that there is enough room for the actuator, limit switches, and manual override. Check also if vertical or horizontal mounting is necessary.
Check for temperature, humidity, and whether the area is hazardous. This is critical in ATEX/IECEx-rated actuators that may pose a risk in explosive atmospheres.
Always verify the certifications if they meet standards for water, HVAC, oil & gas, or chemical industries. Examples of certifications are API, ISO, ANSI, and PN/DN pressure rating.
Step 5: Decide on control mode and accessories.
Evaluate whether you need a simple 2-way solenoid (on/off only) with spring-return. This is common for ventilation, water lines, or emergency isolation.
If you need a modulating control, add a positioner and 4 to 20 mA/Pulse signal. This helps to proportionally control disc angle for flow regulation.
If you need to monitor the control room, include limit switches or smart positioners.
When Do You Need to Schedule an Air Actuated Butterfly Valve Replacement?
Immediately replace the valve assembly when you notice visible external leakage at the seat or body. Other signs are sluggish response time that persists after actuator maintenance and stem wear or scoring that causes misaligned disc or corrosion.
In high-cycle applications, repeated repairs are more costly than an air actuated butterfly valve replacement.
Conclusion
An air actuated butterfly valve is ideal for flow applications that require automation. Choosing the right valves help reduce labor costs, improve process consistency, and enhance safety. This is important especially in hazardous environments where electric actuation is not recommended.
Routine maintenance and inspection will show you signs of wear and leakage. Once you see these signs, schedule an air actuated butterfly valve replacement right away. Check the included air actuated butterfly valve manual for specifications before ordering a replacement.
TG Valve manufactures pneumatic butterfly valves that comply with API 609, ASME, and ISO standards. Our technical team will help you calculate specifications to align with the right actuator requirements for your project.
