Butterfly Disc Valve

1. Basic Structure of Butterfly Valve
Butterfly valve is mainly composed of the following parts:

(1) Valve Body
● It adopts disc design, does not have a self-contained flange, and is fixed by pipe flange clamping.

● The material is usually cast iron (HT200), cast steel (WCB), stainless steel (CF8/CF8M) or plastic (UPVC/CPVC).

(2) Disc Plate
● Disc-shaped design, which can be turned on and off by rotating 90°.

● The material can be stainless steel, aluminum bronze, or plastic cladding (EPDM, PTFE).

● Structure Shape:

● Concentric type (central symmetry): suitable for low pressure and normal temperature environment.

● Double eccentric (valve stem off-center): Reduces friction and improves tightness.

● Triple eccentric (valve stem and sealing surface are both eccentric): suitable for high temperature and high pressure environments.

(3) Valve stem
● Connects the butterfly plate and the actuator (handle, worm gear or electric actuator).

● The material is usually stainless steel (SS304/SS316).

(4) O-ring
● Common Materials:

● Rubber (EPDM, NBR): Suitable for water, air and other media.

● PTFE (Polytetrafluoroethylene): Corrosion resistant, suitable for acidic and alkaline environments.

● Metal Solid Seal (Stainless Steel Graphite): Suitable for high temperature and high pressure environment.

2. Working Principle of Butterfly Wafer Valve
● Open state: The butterfly plate rotates parallel to the pipeline, and the liquid passes through it with little to no resistance.

● Closed state: The butterfly valve rotates 90° to be perpendicular to the pipeline, and sealing is achieved by pressing the O-ring.

● Flow adjustment: control the flow rate by partial opening (such as 30°, 60°) (but the adjustment accuracy is low).

3. Main characteristics of wafer choke
✅ Benefits
● Compact Structure: Small size, light weight, suitable for pipelines with limited space.

● Easy to install: No extra flange is required, it can be directly clamped between the pipeline flanges to save costs.

● Low Flow Resistance: Small flow resistance when fully opened, good energy saving effect.

● Low cost: More cost-effective than flanged butterfly valve.

● Easy Maintenance: Easy to disassemble, and the O-ring can be replaced.