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Concentric Butterfly Valve (Zero Offset) – Resilient Seated
The concentric butterfly valve features a centrally positioned stem and disc, providing economical quarter-turn operation for isolation and throttling. Resilient rubber seat ensures bubble-tight shutoff. Available in wafer, lug, and flanged configurations.
What is Zero Offset?
In a zero offset (concentric) design, the stem passes through the exact center of the disc. The disc rotates symmetrically around the pipe centerline. This is the simplest and most cost-effective butterfly valve design.
Key Standards
Size Range: DN50 to DN1200 (2" to 48")
Technical Specifications
Valve Type
Concentric (Zero Offset)
Design Standard
API 609, BS EN 593, MSS SP-67
Face to Face
API 609, EN 558-1
Testing Standard
API 598, BS EN 12266
Pressure Rating
PN10, PN16, Class 150
Size Range
DN50 - DN1200 (2" - 48")
End Connection
Wafer, Lug, Flanged
Flange Standard
ASME B16.5, EN 1092-1, BS 4504
Operation
Lever, Gear, Pneumatic, Electric
Seat Type
Resilient (Rubber) Seated
Temperature Range
-20°C to +120°C (EPDM)
Leakage Class
Zero Leakage (Bi-directional)
Material of Construction Options
Seat Material Selection Guide
Dimension Table (Wafer Type)
Applications
Water Treatment
Municipal water, wastewater, irrigation
HVAC Systems
Chilled water, cooling towers, AHU
Fire Protection
Fire fighting, sprinkler systems
Food & Beverage
Dairy, brewing, food processing
Frequently Asked Questions
What is a concentric butterfly valve?
A concentric butterfly valve (also called zero offset or centric butterfly valve) has the stem passing through the center of the disc and the disc center aligned with the pipe center. The disc rotates around its own center axis. This is the most common and economical type of butterfly valve, ideal for low-pressure applications.
What is the difference between concentric and eccentric butterfly valve?
In a concentric butterfly valve, the stem is centered in the disc and pipe. In an eccentric (offset) butterfly valve, the stem is offset from the disc center, reducing seat wear. Concentric valves are more economical but have higher seat friction, while eccentric valves offer longer service life and better sealing.
What seat materials are used in concentric butterfly valves?
Common seat materials include EPDM (for water, air, weak acids), NBR/Buna-N (for oil, petroleum, hydrocarbons), Viton/FKM (for high temperature, chemicals), PTFE (for corrosive chemicals), and Silicone (for food grade applications).
What is the maximum temperature for a rubber seated butterfly valve?
Maximum temperature depends on the seat material: EPDM up to 120°C (248°F), NBR up to 82°C (180°F), Viton/FKM up to 200°C (392°F), PTFE up to 200°C (392°F). For higher temperatures, metal seated butterfly valves are recommended.
What is the pressure rating of concentric butterfly valves?
Concentric butterfly valves are typically rated for PN10 (10 bar/145 PSI), PN16 (16 bar/232 PSI), or ANSI Class 150 (20 bar/290 PSI). They are designed for low to medium pressure applications. For higher pressures, double or triple offset butterfly valves are recommended.
Compare Butterfly Valve Types
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