In order to make the regulating valve work properly, the actuators should be able to produce enough output force to 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, so the key to selecting the actuator is to know the maximum output force and the rotation torque of the motor. For the single action of the pneumatic actuator, the output force and the opening of the valve, the regulating valve on the emergence of the force will also affect the movement characteristics, so the requirements in the opening range of the entire regulating valve to establish a force balance.
After the output force of the actuator is determined, the corresponding actuator is selected according to the requirements of the process environment. For on-site explosion-proof requirements, pneumatic actuator should be selected. From the aspect of energy saving, electric actuator should be selected as far as possible. If the adjustment precision is high, hydraulic actuator can be selected. For example, the speed regulation of the transparent machine in power plant, the temperature regulation control of the catalytic unit reactor in oil refinery, etc.
The mode of action of the regulating valve is only available when the pneumatic actuator is selected. The mode of action is formed by the combination of positive and negative effects of the actuator and the valve. There are 4 combination forms that are positive (gas type), positive and negative (gas type), anyway (gas type), anti (gas type), through the formation of the four combination of regulating valve mode of action has two kinds of gas and gas off.
The choice of the mode of action of the regulating valve is mainly considered from three aspects: a) process production safety; B) properties of the medium; C) Ensure product quality and minimize economic loss.
