What is the function of a Post Indicator Valve (PIV) in fire protection systems?

• A. A type of valve used to control underground water mains that provides a visual means for indicating 'open' or 'shut' position; found on the supply main of installed fire protection systems.
• B. A device that premixes foam concentrate with water in a container.
• C. A pressure relief valve used to vent excess pressure.
• D. A fog nozzle used to create low-pressure sprays.

Answer: (A)

The function of a Post Indicator Valve is to control the water supply to a fire protection system while providing a visible indication of whether the supply main is open or shut. It’s installed on the main supply line, usually above ground, so firefighters and maintenance personnel can quickly see the valve’s status and confirm or change water flow into the system as needed. This clear visual indicator helps isolate the system when required and ensures the correct status is known at a glance.

The other devices serve different purposes: a foam concentrate mixer combines foam with water; a pressure relief valve vents excess pressure; a fog nozzle creates low-pressure spray patterns. None of these describe the valve’s role in signaling and controlling the fire-protection water supply.