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# Ball Valve Actuator Torque Calculations

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## Ball Valve Actuator Torque Calculations

(OP)
I have a Double Acting Actuator originally sized for a 4" 900# Full Port Ball Valve.  I need to know if this Actuator could be used for a 3" 1500# Full Port Ball Valve.  I need to use this 3" 1500# Ball Valve in a max 2000 psig/100F application.  There will be a By-Pass in the line to balance upstream and downstream pressure when the Valve is actuated.  Does anyone know how to make this type of calculation?  Or do I need more information?

J. Alton Cox
President
DeLuca Test Equipment
www.delucatest,com

Replies continue below

### RE: Ball Valve Actuator Torque Calculations

You need to establish the manufacturer and model number of the actuator and then contact them for the torque details relative to the input pressure.  Once you know the torque output of your actuator you can compare this to the torque requirement for your new valve.  Bear in mind that you need to add at least 25% to the valve torque to cover for performance degradation over its operating life relative to the torque output of the actuator.

### RE: Ball Valve Actuator Torque Calculations

(OP)
Thank you for the explanation of the 25% factor.
The actuator rep told me I needed a 25% additional torque, but did not explain why.  The actuator has approx 10% more torque than the ball valve requires.  However, my question remains, if I have a Ball Valve in a balanced upstream/downstream pressure situation, do I still need the same torque value?

J. Alton Cox
President
DeLuca Test Equipment
www.delucatest,com

### RE: Ball Valve Actuator Torque Calculations

The answer to your question lies with the 3" ball valve maufacturer.  You need to explain the duty to them and they need to tell you the torques necessary to operate their valve.  Once you know this information you can compare the torque output from your actuator with the torque requirements for your valve and determine if your existing actuator can perform the duty.

### RE: Ball Valve Actuator Torque Calculations

(OP)
Thank you for your prompt reply and good advice.
I will contact the actuator vendor as you suggest.

J. Alton Cox
President
DeLuca Test Equipment
www.delucatest,com

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