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ISO5211 is an important standard set by the International Organization for Standardization (ISO) for connecting valve actuators to industrial valves. Its main goal is to make sure that part-turn valves (like butterfly valves and ball valves) and actuators are compatible and can be easily interchanged worldwide. The standard clearly defines the dimensions of flange connections, torque requirements, hole patterns, and drive structures. It also specifies the maximum torque values (ranging from 32 to 10,000 Nm) for different flange types (from F03 to F25)..Through unified interface design, ISO5211 significantly simplifies the matching process between valves and actuators, reduces installation complexity, and improves system reliability and maintenance efficiency.
In terms of structural design, ISO5211 emphasizes the standardization of high-platform flanges (top mounting platforms), allowing actuators to be installed directly, eliminating traditional brackets and connecting shafts, thereby reducing the number of components and enhancing stability. For example, butterfly valves that meet this standard can be directly adapted to pneumatic or electric actuators for fast installation and precise control.
So it also applied in our butterfly valve, we can provide various standard, if you need round stem, we also can provide, it was usually can applied in some country like Vietnam and Russia ect.
Square shaft is the drive shaft form recommended by ISO5211 standard. Its core advantages are:
1.High torque transmission efficiency: Square shaft transmits torque through flat contact, which has greater friction than round shaft, and can effectively reduce the risk of slipping, especially suitable for high-pressure and high-frequency operation scenarios.
2.Precise positioning: The keyway matching of square shaft and actuator interface (such as right-angle square key or diagonal square key) can ensure the strict alignment of drive and valve axis, avoiding seal failure caused by angle deviation.
3.Standardization and compatibility: ISO5211 specifies square shaft size and flange hole position, so that actuators and valves of different brands can be seamlessly connected, significantly improving supply chain flexibility.
4.Wide application in international market: Square shaft design has become mainstream in European, American and international high-end markets. For example, the imported pneumatic flange ball valve of AMISCO in the United States adopts ISO5211 square shaft high platform, directly installs the actuator without additional adjustment, and supports anti-slip valve stem and anti-static settings, which are suitable for harsh working conditions. Similar designs are also found in industrial valve products from Germany, Japan and other countries, reflecting their technological maturity and reliability.
So that’s the reason why square stem and Iso5211 usually show up together, our Bare Stem and Square Stem Butterfly Valve also follow this, some our customer also ask why the top flange have some other drilling, it was multi-standard (ISO 5211/GB standard.), some dimension we have wide range customer, some Russia customer think the round stem is fine, cause usually have lower cost, so in some dimensions in our Bare Stem and Square Stem Butterfly Valve, we provide not only one standard.
