Dead Weight Butterfly Valve

A Dead Weight Butterfly Valve operates as a critical flow control component engineered for applications where fail‑safe closure and backflow prevention are paramount. Unlike spring‑return mechanisms that fatigue over time, this design uses a weighted lever arm to deliver consistent, maintenance‑free performance. In municipal water networks, cooling water intakes, and stormwater discharge systems, operators rely on variants like the Weighted Counterbalance Butterfly Valve for its predictable disc closure under zero‑energy conditions. Where space constraints exist or a compact footprint is needed, the Counterbalanced Butterfly Valve offers an optimized weight‑arm geometry without sacrificing closing torque. In submerged or high‑vibration environments, the Gravity Counterweight Butterfly Valve ensures bubble‑tight shutoff by harnessing gravitational force alone, eliminating the risk of external power failure completely. Each variant shares a core principle: precise balance of the disc and counterweight mass to achieve the desired open‑close profile while maintaining minimal head loss in the fully open position.

The Dead Weight Butterfly Valve is designed around a robust ductile iron body with an epoxy‑coated interior and exterior, providing excellent corrosion resistance in both potable water and wastewater services. An adjustable cast‑iron counterweight attaches to the extended shaft via a keyed connection, allowing field adjustment of closing speed and seating torque without disassembly. The disc is typically stainless steel or duplex stainless steel for aggressive media, equipped with a replaceable EPDM or NBR seat that eliminates leakage at both low and high differential pressures. Integral mechanical stops prevent over‑travel in either direction, while an optional hydraulic dashpot can further dampen closure to mitigate water hammer. The valve can be supplied in wafer, lug, or double‑flanged configurations to match any piping standard, and the top mounting flange accepts manual gearboxes, electric actuators, or pneumatic cylinders for remote operation when needed. Maintenance remains straightforward thanks to the self‑lubricating bushings and a split‑body design that permits in‑line seat replacement.

Key Technical Parameters

• Size Range: DN 150 – DN 1800 (6″ – 72″)
• Pressure Rating: PN 10, PN 16, PN 25 (Class 150 / 300)
• Body Material: Ductile iron GJS-400-15, carbon steel (optional)
• Disc Material: Stainless steel 304/316, duplex 2205, aluminium bronze
• Shaft Material: Stainless steel 420, 17-4PH, Monel K500
• Seat Material: EPDM, NBR, Viton, metal‑seated option
• Counterweight: Cast iron, multiple segments, position lockable
• Leakage Rate: Zero leakage (EN 12266-1 Rate A)
• Face‑to‑Face: ISO 5752 series 20, API 609 short/long pattern
• Flange Drilling: EN 1092-2, ASME B16.5/B16.47, JIS B2220
• Operating Modes: Gravity closure (fail‑safe), manual override, actuated
• Temperature Range: -20°C to +120°C (standard seat), up to 250°C (metal seat)
• Coating: Fusion bonded epoxy min. 250 µm, RAL 5005 blue

Material Combinations by Service

Counterweight Selection Chart (Typical)

*Close time measured from fully open to fully closed in still water, without dashpot. Adjustable via segment removal or position shift.