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What Is a Butterfly Valve?
A butterfly valve is a quarter-turn rotary valve widely used for on-off and throttling applications in industrial systems. Its compact design, lightweight structure, and fast operation make it one of the most preferred valve types in HVAC, water treatment, steam, compressed air, and process industries.
Unlike gate or globe valves, butterfly valves regulate flow using a rotating disc positioned in the center of the pipe. This design provides quick shut-off, reduced pressure loss, and lower installation costs.
Key Advantages of Butterfly Valves
Butterfly valves offer several advantages compared to other valve types:
- Compact & Lightweight Design – Requires less space and support
- Quick Operation – 90-degree turn from fully open to fully closed
- Cost-Effective – Lower material and installation costs
- Wide Size Range – Available from small DN sizes to large diameters
- Automation Ready – Easy integration with pneumatic and electric actuators
These benefits make butterfly valves ideal for both manual and automated systems.
Types of Butterfly Valves
1. Wafer Type Butterfly Valve
Wafer type butterfly valves are designed to fit between two flanges. They are commonly used in HVAC, water distribution, and general industrial services due to their compact form and easy installation.
2. Lug Type Butterfly Valve
Lug type butterfly valves feature threaded inserts that allow dead-end service. This makes them suitable for systems requiring maintenance without shutting down the entire line.
3. Double Flanged & High Performance Butterfly Valves
These valves are used in higher pressure and temperature applications, offering enhanced sealing and longer service life.
| Feature | Wafer Type | Lug Type |
|---|---|---|
| Installation | Between flanges | Bolted to flanges |
| Dead-End Service | No | Yes |
| Cost | Lower | Medium |
| Typical Applications | HVAC, Water | Process Lines |
Materials & Seat Options
Selecting the right material is critical for long-term performance:
- Body Materials: Ductile Iron, Carbon Steel, Stainless Steel (AISI 304 / AISI 316)
- Disc Materials: Stainless Steel, Ductile Iron, Nickel Coated
- Seat Materials: EPDM, NBR, PTFE (Teflon)
Each combination is selected based on fluid type, temperature, and pressure conditions.
Actuated Butterfly Valves
Butterfly valves can be automated using:
- Pneumatic Actuators (Double Acting / Spring Return)
- Electric Actuators (On-Off or Modulating)
- Accessories:
- Limit Switch Box
- NAMUR Solenoid Valves
- Positioners
Automated butterfly valves improve process control, safety, and operational efficiency in modern industrial facilities.
Common Industrial Applications
Butterfly valves are widely used in:
- Water & Wastewater Treatment Plants
- HVAC Systems
- Steam & Hot Oil Lines
- Chemical & Petrochemical Plants
- Food & Beverage Processing
- Compressed Air Systems
Their versatility makes them suitable for both low and medium pressure systems.
Why Choose UNOX Butterfly Valves?
At UNOX, we design and supply butterfly valves that meet international standards such as ANSI, DIN, PN, and ISO. Our products are engineered for durability, precise flow control, and seamless automation compatibility.
👉 Explore our full butterfly valve range on unoxus.com and contact our technical team for selection support.
Frequently Asked Questions (FAQ)
What is a butterfly valve?
A butterfly valve is a quarter-turn rotary valve used to start, stop, or regulate flow in industrial piping systems. It is compact, lightweight, and suitable for automation.
What are butterfly valves used for?
Butterfly valves are used in water treatment, HVAC systems, steam lines, compressed air, chemical processing, and general industrial flow control applications.
Can butterfly valves be used for steam applications?
Yes, butterfly valves can be used for steam when designed as high-performance or metal-seated valves and selected according to pressure and temperature requirements.
What is the difference between a butterfly valve and a ball valve?
Butterfly valves are lighter and more cost-effective for large diameters, while ball valves offer tighter shut-off and are preferred for high-pressure applications.
Are butterfly valves suitable for automation?
Yes, butterfly valves are highly compatible with pneumatic and electric actuators, making them ideal for automated and remote-controlled systems.
What materials are butterfly valves made of?
Butterfly valves are commonly manufactured from ductile iron, carbon steel, and stainless steel, with EPDM, NBR, or PTFE seat options.
What is the difference between wafer type and lug type butterfly valves?
Wafer type butterfly valves are installed between flanges, while lug type butterfly valves allow dead-end service and easier maintenance.
Can butterfly valves be used for throttling?
Yes, butterfly valves can be used for throttling flow, although precise control depends on disc design and application conditions.
What pressure ratings are available for butterfly valves?
Butterfly valves are available in PN10, PN16, PN25, Class 150, and higher pressure ratings, depending on design and material.
How do I choose the right butterfly valve?
Choosing the right butterfly valve depends on fluid type, pressure, temperature, connection standard, and whether manual or automated operation is required.