ISO 5211 Mounting & Dimensions Guide
Overview
ISO5211 is the international standard defining the interface between quarter-turn actuators and valves.
It standardises:
The flange size designation (F03 – F30)
Bolt circle diameter (PCD) and hole size/thread
Drive type (square or double-D) and stem dimensions
This ensures interchangeability, faster assembly, and simplified selection for actuated ball, butterfly, and plug valves.
Why ISO 5211 Matters
Universal fitment — mix and match actuator and valve brands easily
Consistent torque transfer — precision square or double-D stem drives
No custom brackets — standard bolt circles and coupler interfaces
Reduced downtime — simplified replacement or upgrade process
ISO 5211 Mounting Dimensions
| ISO 5211 | d2 | d3 | d4 | h1 max | h2 min | Bolts / Studs | Max Torque (NM) |
|---|---|---|---|---|---|---|---|
| F03 | 25 | 36 | M5 | 3 | 8 | 4 | 32 |
| F04 | 30 | 42 | M5 | 3 | 8 | 4 | 63 |
| F05 | 35 | 50 | M6 | 3 | 9 | 4 | 125 |
| F07 | 55 | 70 | M8 | 3 | 12 | 4 | 250 |
| F10 | 70 | 102 | M10 | 3 | 15 | 4 | 500 |
| F12 | 85 | 125 | M12 | 3 | 18 | 4 | 1000 |
| F14 | 100 | 140 | M16 | 4 | 24 | 4 | 2000 |
| F16 | 130 | 165 | M20 | 5 | 30 | 4 | 4000 |
| F25 | 200 | 254 | M16 | 5 | 24 | 8 | 8000 |
| F30 | 230 | 298 | M20 | 5 | 30 | 8 | 16000 |
| F35 | 260 | 356 | M30 | 5 | 45 | 8 | 32000 |
| F40 | 300 | 406 | M36 | 8 | 54 | 8 | 63000 |
| F48 | 370 | 483 | M36 | 8 | 54 | 12 | 125000 |
| F60 | 470 | 603 | M36 | 8 | 54 | 20 | 250000 |
Note: The ISO 5211 standard allows for both tapped or through holes. Always check the actuator drawing to confirm whether bolts are inserted from above (through-holes) or into tapped threads.
Selecting the Correct ISO Mount
Measure valve stem (square AF or flat-to-flat on double-D).
Measure bolt circle (PCD) and hole type (threaded / clearance).
Match to actuator data sheet for correct F-size.
Confirm torque – actuator output must exceed valve break torque × safety factor (Ball Valves usually 1.3–1.5 / butterfly valves x2).
Typical Pairings
| ISO Size | Common Valve DN Range | Typical Actuator Type |
|---|---|---|
| F03 – F04 | DN8 – DN25 (¼″ – 1″) | Compact electric or rack & pinion pneumatic |
| F05 – F07 | DN25 – DN65 (1″ – 2½″) | Standard pneumatic / electric |
| F10 – F12 | DN80 – DN150 (3″ – 6″) | Medium torque pneumatic |
| F14 – F16 | DN200 – DN300 (8″ – 12″) | Heavy-duty actuators |
| F25 – F30 | DN350 – DN600 (14″ – 24″) | High-torque electric / hydraulic |
FAQs
Q: Does ISO 5211 specify torque or pressure?
A: No – it standardises only the mechanical interface. However torque values are limited by ISO sizing. See below table of torque values.
Q: Can I use F05 actuator on F07 valve?
A: Not directly. You’ll need an adapter bracket or ISO conversion plate. But check the actuator has the required torque for the valve plus 30-50% safety margin.
Q: Are stainless actuator mounts standardised?
A: Yes – as long as dimensions match ISO 5211, the material is optional (aluminium, steel, stainless, or reinforced polymer).
Q: Will I need a drive adaptor?
A: possibly if the valve stem is smaller than the actuator drive socket. See below ISO5211 drive adaptors
How to measure a hex drive adaptor.
When measuring an iso5211 drive torque adaptor you measure the distance between the opposing vertical sides.
Which technically is the diameter of the square shaft it is being fitted too.
ISO5211 Motor Actuators → View Range
ISO 5211 Spacing / Mounting Brackets → Here
Need Assistance? → Contact Us
Our engineering team can confirm actuator-valve compatibility across all ISO 5211 flange sizes (F03–F30) for all Pneumatic and electric actuators