Which statement about 3-way solenoid valves is true?

• A. They are the only valves used in chemical plants
• B. They cannot be operated electrically
• C. They are a type of control valve that can direct flow to two different paths or a bypass
• D. They are used only for gas handling

Answer: (C)

Three-way solenoid valves are designed to control routing of a single flow path to two different destinations (or to provide a bypass) by using an electrically actuated mechanism. They have three ports and the internal passage can be shifted so the common port connects to one of the two other ports. This lets you divert a process stream, bypass something in the line, or implement a simple mixing/diverting control without manual intervention. That ability to select between two downstream paths under electrical control makes them a form of control valve optimized for routing flow, rather than a valve with a single fixed path. They are not the only valves used in chemical plants, they are not limited to electrical actuation, and they are used for many fluids beyond gas, so those statements are not accurate.