Gear Operator Selection Rules of Thumb
Technical reference · Supreme Valves India · Updated 2026-10-28
Direct answer: Specify a gear operator when manual rim pull exceeds safe limits — commonly gates NPS 8+ and butterflies from roughly DN200 upward depending on ΔP. Add limit switches when the control system needs position feedback.
| Situation | Operator |
|---|---|
| Small gate Class 150, low ΔP | Handwheel |
| Gate ≥8" or high class | Gear (verify torque) |
| Butterfly lever size exceeded | Gear + optional LS |
| Automated on/off | Actuator on ISO 5211 mount |
Use published breakaway torque at design differential pressure. Rules of thumb are starting points only.
Gear vs handwheel blog · Butterfly torque estimator · Valve torque calculator
Frequently asked questions
What is ISO 5211?
A mounting interface standard between valves and actuators/gearboxes. State flange type (F07, F10, etc.) when actuating.
Does LS mean limit switch?
Yes on many butterfly BOQs — open and/or close end switches.
Can I add a gear later?
Sometimes via ISO mount adapters — but stem design and torque must allow it. Better to specify at RFQ.
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Confirm governing values against the current standard edition and the approved datasheet for each order.