How do you calculate valve torque?

Valve torque depends on valve type, size, pressure, and seat material. For quarter-turn valves (ball, butterfly): Total torque = Breakaway torque + Seat torque + Packing torque + Dynamic torque. Breakaway torque is typically 1.5-2x running torque. For gate valves (linear): Thrust = Stem factor × Pressure × Area + Packing friction. Actuator must provide torque/thrust exceeding the maximum required with a safety factor of 1.25-1.5.

What is breakaway torque vs running torque?

Breakaway torque is the torque needed to start moving the valve from its seated (closed) position. It is the highest torque point and typically 1.5-2x the running torque due to static friction and seat compression. Running torque is the torque needed to keep the valve moving through mid-stroke. End torque is the torque at the fully open or closed position.

How do I size a pneumatic actuator for a valve?

1. Determine the maximum valve torque (breakaway). 2. Apply a safety factor of 1.25-1.5. 3. Select an actuator whose output torque at minimum air supply pressure exceeds the required torque. For spring-return (fail-safe): the spring must provide enough torque at end of stroke. For double-acting: both air-open and air-close torques must exceed requirements.

What safety factor should I use for actuator sizing?

Standard safety factor: 1.25 (25% margin). For critical service (safety valves, ESD): 1.5 or higher. For high-cycle applications: 1.5. For corrosive or dirty service: 1.5-2.0 (torque increases over time due to corrosion/buildup). Always verify with the valve manufacturer's torque data.

Valve Torque & Actuator Sizing Calculator

Calculate the operating torque for ball valves, butterfly valves, and gate valves. Determine the actuator output required with appropriate safety factors.

Quarter-Turn Valve Torque (Ball & Butterfly)

For ball valves and butterfly valves. Uses empirical torque coefficients based on valve size, pressure class, and seat type.

Valve Type

Valve Size

Operating Pressure

bar (gauge)

Safety Factor

Torque Calculation Result

Seat Torque–

Packing Torque–

Dynamic (Bearing) Torque–

Running Torque–

Breakaway Torque (BTO)–

Required Actuator Output–

Gate Valve Thrust (Linear Motion)

For gate valves and globe valves. Calculates stem thrust required for seating and unseating.

Valve Size

Design Pressure

bar (gauge)

Stem Diameter

mm (leave blank for auto)

Safety Factor

Thrust Calculation Result

Seat Area–

Seating Thrust–

Packing Friction–

Total Stem Thrust–

Required Actuator Thrust–

Handwheel Rim Force (est.)–

Typical Torque Values (Nm) – Quick Reference

Size	Ball Valve (PN16)	Ball Valve (CL150)	Butterfly (Rubber, PN16)	Butterfly (Metal, CL150)
DN50 (2")	15	20	10	25
DN80 (3")	35	50	25	55
DN100 (4")	60	85	40	95
DN150 (6")	140	200	80	220
DN200 (8")	250	350	140	400
DN250 (10")	400	560	220	650
DN300 (12")	580	810	320	950
DN400 (16")	1050	1470	580	1700
DN500 (20")	1650	2300	900	2700
DN600 (24")	2400	3350	1300	3900

Note: These are typical breakaway torque values at rated pressure. Actual torque varies by manufacturer, seat material, temperature, and service conditions. Always verify with the valve manufacturer's certified torque data.

Actuator Type Selection Guide

Criteria	Pneumatic (Double Acting)	Pneumatic (Spring Return)	Electric	Hydraulic
Speed	Fast (1-5 sec)	Fast (1-5 sec)	Slow (15-60 sec)	Medium (5-15 sec)
Fail-Safe	No (needs solenoid)	Yes (spring return)	Optional (battery)	Optional (accumulator)
Torque Range	Up to 10,000 Nm	Up to 5,000 Nm	Up to 100,000 Nm	Up to 500,000 Nm
Modulating Control	With positioner	With positioner	Built-in	With servo
Cost	Low	Medium	Medium-High	High
Best For	On/off, fast cycling	ESD, safety valves	Remote, modulating	Very high torque
Air Supply Needed	Yes (4-7 bar)	Yes (4-7 bar)	No (power supply)	Yes (hydraulic unit)

Need Actuated Valve Packages?

Supreme Valves India supplies complete valve + actuator packages with AUMA, Rotork, and pneumatic actuators. We handle sizing, selection, and testing.

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