Quick Guide to Butterfly Valve: Parts, Working Principle, and Applications

Unlike bulky gate or globe valve, butterfly valves save space, reduce weight, and offer quick operation. Whether you need a manual butterfly valve, an electric butterfly valve, or a pneumatic butterfly valve, the basic design stays the same.

1. What Are the Key Parts of a Butterfly Valve?

·Valve Body:

The body holds everything together and connects the valve to the pipeline. Common connection types include wafer butterfly valves, lug butterfly valves, and flanged butterfly valves, each fitting different installation standards.

·Valve Disc – The "Butterfly Wings":

The disc is the rotating element that opens and closes the flow. Made from ductile iron, stainless steel, or special alloys, it is selected according to the medium - from clean water to corrosive chemicals.

·Valve Seat:

Think of the seat as the "cushion" that seals against the disc. Soft seats (EPDM, NBR, PTFE) are ideal for water and general service, while metal seats are designed for high-temperature or abrasive conditions.

·Valve Stem (Shaft):

The stem connects the disc to the operator, transmitting torque. It is usually made of corrosion-resistant materials to ensure durability even under harsh service.

✔ The most common butterfly valve material configuration is: body Ductile Iron (FCD), disc stainless steel 304, seat EPDM, stem 410 stainless steel.

2. How Does a Butterfly Valve Control Flow?

The principle couldn't be simpler:

· Disc parallel to flow → fully open.

· Disc perpendicular to flow → fully closed.

· Anything in between → throttling or flow regulation.

Because the disc rotates only 90 degrees, butterfly valves provide quick shut-off with minimal effort.

3. Manual, Electric, or Pneumatic: Which Butterfly Valve Do You Need?

· Manual Butterfly Valve – Lever or gearbox operated, low cost, easy to use.

· Electric Butterfly Valve – With an electric actuator, ideal for remote control and automation in HVAC and water systems.

· Pneumatic Butterfly Valve – With a pneumatic actuator, driven by compressed air for fast and frequent operation in industrial plants.

4. Where Are Butterfly Valves Used – and How to Choose the Right One

· Municipal Water & Wastewater → Wafer type or lug type manual butterfly valves.

· HVAC Systems → Electric butterfly valve for automated building management.

· Chemical Plants & Power Stations → Pneumatic butterfly valve for quick shut-off.

· High-Temperature or Abrasive Media → Metal-seated or eccentric butterfly valve.

✔ Buyer Tip: Butterfly valves are most efficient for large-diameter, low-to-medium pressure pipelines. For higher pressure, consider double or triple eccentric designs.

Butterfly valves may look simple, but every part - body, disc, seat, and stem - plays a critical role. By understanding their components, working principle, and operation methods, buyers can make smarter decisions.

At SLVCN, we supply a full range of manual, electric, and pneumatic butterfly valves, including wafer, lug, and flanged types. All products are ISO, CE, and TUV certified, trusted in industries worldwide.