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Introduction
NAMUR (Normenarbeitsgemeinschaft für Mess- und Regeltechnik) is a standardized interface specification that ensures compatibility between pneumatic rotary actuators and quarter-turn valves (typically ball and butterfly valves). This guide provides detailed information about NAMUR standard dimensions, mounting specifications, and selection criteria for pneumatic rotary actuators.
1. What is the NAMUR Standard?
The NAMUR standard (VDI/VDE 3845) defines:
✔ Mounting interface dimensions for direct actuator-to-valve connection
✔ Bolt hole patterns (4-bolt or 8-bolt configurations)
✔ Drive shaft specifications (square or flat)
✔ Compatibility with ISO 5211 and VDI/VDE 3845 standards
This standardization allows for quick installation and interchangeability between different manufacturers.
2. Key NAMUR Standard Dimensions
A. Mounting Flange Specifications
B. NAMUR vs. ISO 5211 Comparison
3. Benefits of NAMUR-Compliant Actuators
✅ Plug-and-play installation – No adapters needed for NAMUR valves
✅ Compact design – Saves space compared to ISO 5211 flanges
✅ Interchangeability – Works with multiple valve brands (e.g., Fisher, Samson, Bray)
✅ Reduced maintenance – Fewer components mean fewer failure points
4. How to Select a NAMUR Standard Actuator
Step 1: Verify Valve Compatibility
- Check if the valve has a NAMUR interface (54mm bolt pattern).
- Ensure the drive shaft matches (11mm square or 14mm flat).
Step 2: Choose Actuation Type
- Double-acting (air-to-air, bidirectional control)
- Spring-return (failsafe in power loss)
Step 3: Consider Torque & Size
Step 4: Check Environmental Ratings
- IP65/IP67 for dust/water resistance
- ATEX/IECEx for hazardous areas
- Stainless steel housing for corrosive environments
5. Installation Guide
- Align actuator shaft with valve stem.
- Secure with 4 or 8 bolts (M6/M8, torque to manufacturer specs).
- Connect pneumatic lines (Port A = open, Port B = close).
- Test operation before full system pressure.
Pro Tip: Use anti-seize compound on bolts in corrosive environments.
6. Common Applications
✔ Process Control Valves (chemical, oil & gas)
✔ Water Treatment Plants (butterfly valve automation)
✔ Pharmaceutical & Food Industry (sanitary NAMUR actuators)
✔ Power Generation (steam and gas valve control)
7. Troubleshooting NAMUR Actuators
Conclusion
NAMUR standard pneumatic rotary actuators provide a compact, reliable, and standardized solution for quarter-turn valve automation. By following the correct dimensions, torque ratings, and installation procedures, you can ensure optimal performance and longevity.
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