Gear Operator vs Handwheel on Gate and Butterfly Valves
Technical guide · Supreme Valves India · Updated 2026-10-28
Direct answer: Add a gear operator when handwheel or lever rim pull is too high for safe operation — typically larger gates (often ≥8") and most medium/large butterflies. Write GEAR OPERATED and any limit switches (LS) on the BOQ; do not assume the factory will add them.
Rules of thumb (always verify torque)
| Valve | Often handwheel / lever | Often gear |
|---|---|---|
| Gate Class 150 | ≤6" typical | ≥8" common |
| Gate Class 600 | Small sizes | Gears earlier due to torque |
| Butterfly PN16 / CL150 | Small DN with lever | DN200+ frequently geared |
These are plant practice heuristics, not code. Use published torque at design ΔP and the operator’s maximum rim pull.
BOQ language
GEAR OPERATED/GOLS— limit switches- Actuator + gearbox for automated tags (fail position stated separately)
RFQ checklist
- Handwheel, gear or actuator
- Open/close switches yes/no
- ISO 5211 mounting if actuated
- ΔP for torque check
Tools: butterfly torque estimator. RFQs: WCB butterfly, WCB gate.
Frequently asked questions
At what gate size should I add a gear?
As a practical rule of thumb, many plants gear NPS 8 and larger Class 150/300 gates, and smaller sizes at higher classes or where handwheel rim pull exceeds safe limits. Confirm with torque data for the trim and ΔP.
Do butterflies need gears earlier than gates?
Often yes — resilient and high-performance butterflies develop seating torque that exceeds comfortable lever operation above roughly DN150–DN200 depending on ΔP and seat. Large water butterflies are almost always geared.
What does LS mean on a butterfly BOQ?
Limit switch (open/close feedback). Specify switch type and quantity with the gear or actuator package.