(1) Consideration of output force
Regardless of the type of actuator, its output force is effective in overcoming loads (mainly referring to the effects of unbalanced forces and moments combined with frictional forces, sealing forces, gravity, and other related forces). Therefore, in order to ensure the normal operation of the diaphragm pump, the actuator used should be able to generate sufficient output force to overcome various resistances, ensure high sealing and valve opening. For double acting pneumatic, hydraulic, and electric actuators, there is generally no return spring. The magnitude of the force is independent of its direction of operation, therefore, the key to selecting an actuator is to determine the maximum output force and the rotational torque of the motor. For single acting pneumatic actuators, the output force is related to the opening of the valve, and the force acting on the diaphragm pump will also affect the motion characteristics. Therefore, it is required to establish force balance throughout the entire opening range of the diaphragm pump.
(2) Determination of the type of executing agency
After determining the output force of the actuator, select the corresponding actuator according to the requirements of the process usage environment. When there are explosion-proof requirements on site, pneumatic actuators should be selected, and the junction box should be explosion-proof, and electric actuators cannot be selected. If there are no explosion-proof requirements, both pneumatic and electric actuators can be selected, but from the perspective of energy conservation, electric actuators should be selected as much as possible. For hydraulic actuators, their use is not as extensive as pneumatic and electric actuators, but they have the characteristics of high adjustment accuracy, fast action speed, and stability. Therefore, in some cases, in order to achieve better adjustment effects, hydraulic actuators must be selected, such as speed regulation of transparent machines in power plants, temperature regulation control of catalytic reactors in refineries, etc.