Actuation & AutomationFull Glossary

ETO (End-to-Open Torque)

The torque required to unseat a valve from its fully open position when initiating a closing stroke. Usually lower than BTO for ball valves but can be the critical value for butterfly valves depending on disc geometry.

What is ETO (End-to-Open Torque)?

The torque required to unseat a valve from its fully open position when initiating a closing stroke. Usually lower than BTO for ball valves but can be the critical value for butterfly valves depending on disc geometry.

Vajra Industrial Solutions is an engineering-driven industrial valve manufacturer and supplier. Concepts such as eto (end-to-open torque) inform how we select, manufacture, and document valves for industrial service.

Related Terms

ActuatorBTORTO

Frequently Asked Questions

What is a ETO (End-to-Open Torque)?

The torque required to unseat a valve from its fully open position when initiating a closing stroke. Usually lower than BTO for ball valves but can be the critical value for butterfly valves depending on disc geometry.

How is a ETO (End-to-Open Torque) sized for a valve?

Actuator sizing requires the valve's breakaway torque (BTO), running torque (RTO), and end-to-close torque (ETO) at the maximum differential pressure and operating temperature. The actuator output torque at minimum supply pressure must exceed the valve BTO by a safety factor (typically 1.25x minimum). For pneumatic actuators, the supply pressure range, fail-safe direction (spring return FC or FO), and speed requirements must also be specified.

When is a ETO (End-to-Open Torque) required versus manual operation?

Automation is required when: (1) the valve is in a remote or hazardous location, (2) rapid opening/closing is needed for emergency shutdown (ESD), (3) the valve must respond to a control signal (4–20 mA, HART, or fieldbus), (4) the operating torque is too high for manual operation, or (5) the valve is part of a Safety Instrumented System (SIS) requiring SIL certification. Contact Vajra Industrial Solutions for fully automated valve packages including actuator, limit switch, solenoid, and positioner.

Reviewed by Engineering Applications Team, Vajra Industrial SolutionsDiscipline: Industrial Valve TerminologyLast reviewed: 20 June 2026

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