General service process solenoid valves use a solenoid to control the flow of gases and liquids. Solenoids are coiled components that respond to electromagnetic currents to control the valve’s actuation. When the valve actuates, it either opens to allow gas or liquid to flow through the valve or closes to shut off flow. General service process solenoid valves are designed to handle fluid control applications. They come in two-, three-, and four-way designs.