Important data required for multi-turn electric actuator sizing

[muidrees]

For sizing a multi-turn electric actuator for a Knife Gate Valve:

1.Should we consider both Torque (Torque required to open & close valve i.e. seat/unseat) and Thrust (Force required to open and close the gate) or anyone of these could be enough?
2.Why do we need to know the valve stem number of Turns?

 

[btrueblood]

You probably only need to specify torque, but knowing both would be good - I have seen some undersized thrust bearings on actuators before.
There are actuators with a limited number of rotations, so knowing how many turns are required can be important.

 

[LittleInch]

I agree with bt - the actuator only really needs to see the torque and let the valve cope with the thrust. You need to know the number of turns to work out the required rotational speed - either the actuator is specified in how long it takes to open / close or it is something the buyer wants to know. One turn to close versus 10 turns to close at the same closure time needs a different speed motor or different gearing.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[MNValveGuy]

The thrust base plates on multi-turn electric actuators have an upper limit. Where the thrust force is taken is another matter. If there is a thrust plate on the valve that takes that thrust force, your actuator will only see torque. If the actuator drive bushing is taking the thrust, then the thrust of the valve is required to ensure your actuator can handle the force, in which case, you must consider both thrust and torque.

Number of stem turns is typically related to the speed in which you open or close the valve. If you have a 1/4" pitch 1/4" lead valve stem, and you need 12 full stem turns to open the valve, you need 48 revolutions. If your actuator has 96 RPM, you can open the valve in 30 seconds.

 

[muidrees]

Gentlemen thanks for sharing the knowledge. Actually I am trying to size a multi turn actuator and I do not have these two parameters available with me. I do have thrust value but do not have enough stem data. Could we get a screw made to operate the valve with multi turn actuator? I have experienced in the past that by measuring/counting the number of stem threads wont be that much useful (in case you do not have valve data sheets).

 

[MNValveGuy]

What is the valve thrust? Do you have any of the valve data? Size, manufacturer, rising stem or non-rising stem, etc.? You really should have stem dimensions to determine the stem factor - this will allow you to more accurately predict the torque required.

 

[muidrees]

Finally ,I got some info. regarding valve. Its 24" FCC. I downloaded the data sheet from internet but it does not shows much of stem data.