Generally speaking, we have five main principles for valve electric actuator selection.

1. Operation torque is one of the most critical parameters in selecting actuator. We should bear in mind that the electric actuator’s output torque should be 1.2~1.5 times larger than the maximum valve operation torque.

2. We should control the opening and closing speed of valve by regulating the output speed of actuator in a proper range, otherwise it will appear water hammer easily.

3. There are two kinds of master structures to operate the trust of electric actuator: one is not configured with trust plate but outputting the torque directly, while the other one is outputting the switched torque by stem nut.

4. The rotation numbers of output shaft is related to nominal diameter, stem pitch and number of starts. And the formula is M=H/ZS. (M is the total number of rotation number, H is the operation height of the valve, S is the stem pitch and Z is the number of starts)

5. Valve electric actuator has its own special requirements and it must be able to limit the torque and axial force. Normally, electric actuator is equipped with coupling to limit the torque. After the standard of an electric actuator is determined, the torque is also determined.