ISO 5211 Mounting & Dimensions Guide
Overview
ISO 5211 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 | d1 | d2 | d3 | d4 | h1 max | h2 min | Bolts / Studs | 
|---|---|---|---|---|---|---|---|
| F03 | 46 | 25 | 36 | M5 | 3 | 8 | 4 | 
| F04 | 54 | 30 | 42 | M5 | 3 | 8 | 4 | 
| F05 | 65 | 35 | 50 | M6 | 3 | 9 | 4 | 
| F07 | 90 | 55 | 70 | M8 | 3 | 12 | 4 | 
| F10 | 125 | 70 | 102 | M10 | 3 | 15 | 4 | 
| F12 | 150 | 85 | 125 | M12 | 3 | 18 | 4 | 
| F14 | 175 | 100 | 140 | M16 | 4 | 24 | 4 | 
| F16 | 210 | 130 | 165 | M20 | 5 | 30 | 4 | 
| F25 | 300 | 200 | 254 | M16 | 5 | 24 | 8 | 
| F30 | 350 | 230 | 298 | M20 | 5 | 30 | 8 | 
| F35 | 415 | 260 | 356 | M30 | 5 | 45 | 8 | 
| F40 | 475 | 300 | 406 | M36 | 8 | 54 | 8 | 
| F48 | 560 | 370 | 483 | M36 | 8 | 54 | 12 | 
| F60 | 686 | 470 | 603 | M36 | 8 | 54 | 20 | 
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.
Need Assistance?
Q: How do I work out which ISO5211 mount I have?
A: Measure across the mounting holes and compare to the dimensions table, example below is F05/F07, inside bolt holes measure as F05, and the outer holes are F07
Concentrate on the F05, as this is where the bolts are located in this instance.
Drive Types
| Drive Type | Description | Typical Use | 
|---|---|---|
| Square | Most common (across-flats drive). Allows precise torque transfer. | Ball and butterfly valves | 
| Double-D | Stem has two parallel flats; used for compact couplers. | Compact electric actuators | 
| Keyed Round | Stem with keyway for high-torque couplings. | Heavy-duty valves | 
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 (usually 1.3–1.5).
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

ISO5211 Torque Chart
| ISO5211 type | Maximum torque (Nm) | 
| F03 | 32 | 
| F04 | 63 | 
| F05 | 125 | 
| F07 | 250 | 
| F10 | 500 | 
| F12 | 1000 | 
| F14 | 2000 | 
| F16 | 4000 | 
| F25 | 8000 | 
| F30 | 16000 | 
| F35 | 32000 | 
| F40 | 63000 | 
| F48 | 125000 | 
| F60 | 250000 | 
| F80 | 500000 | 
| F100 | 1000000 | 
View our range of ISO5211 Valves & Actuators
Need Assistance?
Our engineering team can confirm actuator-valve compatibility across all ISO 5211 flange sizes (F03–F30) for all Pneumatic and electric actuators


