Classification of solenoid valve electricity A solenoid valve is an electromagnetically controlled industrial equipment, which is the basic element of automation for controlling fluids. It belongs to the actuator. It is used to adjust the direction, flow, speed, and other parameters of the medium in the industrial control system. Solenoid valves can be matched with different circuits to achieve the required control and ensure the accuracy and flexibility of the control. Solenoid valves can be divided into three principal categories: direct-acting solenoid valves, step-by-step direct-acting solenoid valves, and pilot-operated solenoid valves.