subject: Solenoid Valves [print this page] Factory automation makes frequent use of solenoid valves. A computer device running a factory automation program to fill a container with some liquid can send a signal to the solenoid valve to open, allowing the container to fill, and then remove the signal to close the solenoid valve and stop the flow of liquid until the next container is in place. A gripper for grasping items on a robot is frequently an air-controlled device. A solenoid valve can be used to allow air pressure to close the gripper, and a second solenoid valve can be used to open the gripper.