Butterfly Valve

Butterfly valves are widely used in water supply, wastewater treatment, HVAC, chemical processing, and food industries to control or isolate fluid flow. They are specified by nominal diameter, pressure rating, body material, disc material, seat material, and actuator type. Grades vary from economy versions for low-pressure water to high-performance triple-offset designs for high-temperature and high-pressure applications, with differences in sealing materials, trim, and manufacturing tolerances. This directory entry covers general parameters and standards for butterfly valves as a product category. The nominal diameter range is DN50 to DN1200 per ISO 5752, with pressure ratings from PN10 to PN25 per EN 593. Working temperature typically ranges from -20°C to +120°C, depending on seat material; PTFE seats allow up to 200°C. Leakage rate for soft-seated valves is Class VI per ISO 5208, while metal-seated versions may achieve Class IV. Flow coefficient (Kv) ranges from 50 to 12000 m³/h. Face-to-face dimensions follow ISO 5752 for short and long patterns. Disc thickness varies from 5 to 50 mm, and shaft diameter from 12 to 100 mm. Body surface finish is ≤6.3 μm Ra, with epoxy coating thickness of 150–300 μm per ISO 12944. Actuator mounting flanges comply with ISO 5211. Shell and seat test pressures are 1.5×PN and 1.1×PN respectively per EN 12266-1. Operating torque ranges from 10 to 5000 N·m, and life cycle from 10,000 to 50,000 cycles. Materials on file include WCB (ASTM A216), CF8 (SS304), CF8M (SS316), ductile iron (ASTM A536), and seats in EPDM, PTFE, or NBR. Relevant standards include ISO 5752, EN 593, API 609, GB/T 12238, and AWWA C504. Always verify model-specific values and standards with the legal manufacturer or supplier before procurement.

The valve consists of a circular disc mounted on a rotating shaft. When the handle or actuator turns the shaft, the disc rotates 90 degrees to open or close the flow path. In the open position, the disc is parallel to the flow, minimizing pressure drop; in the closed position, it is perpendicular, sealing against a seat. The disc's rotation allows for precise throttling and quick shut-off.