Quick Answer
ISO 5211 standardizes the mounting interface between industrial valves and actuators: flange pattern, drive (stem) dimensions, and mounting bolt holes. It lets you pair a valve with a pneumatic or electric actuator from any manufacturer as long as both comply. Knowing the ISO 5211 flange size (F03, F05, F07, F10, F12, F14, F16, F25, F30…) is essential for actuator selection.
What ISO 5211 Defines
ISO 5211 (Industrial valves — Part-turn actuator attachments) specifies:
- Top flange dimensions: bolt circle, hole size, and number of bolts
- Drive details: stem or coupling shape, size, and height
- Torque classes: flange sizes correlate with torque capacity
Common flange sizes and approximate torque classes:
| Flange Size | Bolt Circle (mm) | Approx. Torque Class (Nm) |
|---|---|---|
| F03 | 36 | up to 60 |
| F05 | 50 | up to 250 |
| F07 | 70 | up to 1000 |
| F10 | 102 | up to 4000 |
| F12 | 125 | up to 8000 |
| F14 | 140 | up to 16000 |
| F16 | 165 | up to 32000 |
How to Select an Actuator Using ISO 5211
- Determine the valve’s operating torque (breakaway torque at max differential pressure)
- Add a safety margin (typically 1.25–1.5x for pneumatic, 1.5–2x for electric)
- Select the flange size whose torque class covers the total
- Check the drive type: square drive, female keyed drive, or coupling
- Verify bolt pattern matches between valve top flange and actuator base
Why Standardization Matters
ISO 5211 makes actuators and valves interchangeable: you can replace an actuator from one brand with another without machining adapters, and mounting plates are universally compatible. It simplifies procurement, spares management, and retrofits.
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Frequently Asked Questions
What does ISO 5211 F10 mean?
F10 is a top flange size with a 102 mm bolt circle (4 bolts, M12 typically), rated for torques up to about 4000 Nm. The exact class depends on the material and bolt size.
Is ISO 5211 only for quarter-turn valves?
ISO 5211 covers part-turn (quarter-turn) actuators. Linear multi-turn actuators use ISO 5210.
Can I mount any actuator on any valve?
Only if both follow ISO 5211 and the flange size, drive dimensions, and torque class match. Otherwise you need an adapter kit.
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Disclaimer: This article is provided for general educational and informational purposes only and does not constitute professional engineering advice. Valve applications vary with pressure, temperature, media, and applicable codes. Always verify specifications against the manufacturer’s data sheet and consult a qualified engineer before selecting, installing, or repairing any valve. Valve Knowledge Hub makes no warranties about the accuracy or completeness of the information on this site and assumes no liability for any use of it.