A three-way valve has how many ports and what is its purpose?

• A. Two ports; to allow bidirectional flow
• B. Three ports; to divert flow direction
• C. Four ports; to merge two flows
• D. One port; to isolate flow

Answer: (B)

Three-way valves are built to route water between two different paths. They have three ports—one inlet and two outlets (or two inlets and one outlet, depending on the design). The valve’s internal element shifts so that flow from the source is directed to only one of the two outputs at a time. This lets you switch which line receives the water, which is especially useful in irrigation for selecting between zones, redirecting to a purge line, or isolating parts of the system for maintenance. In irrigation practice you’ll often see this as a valve that can divert flow left or right (or up or down) via its internal alignment, such as in L-port or T-port configurations. The other options don’t fit because a two-port device can only be on/off or pass through, a four-port device handles more complex crossovers or mixing, and a single-port device can’t direct flow at all.