A post indicator valve (PIV) is a valve assembly used to open or close the water supply to fire protection systems in large buildings. It consists of a conventional gate or butterfly valve located on the fire system water main with a raised post that protrudes above ground level or from a wall. The valve actuator and a visual indicator of the valve status are housed at the top of the post. This arrangement allows the valve to be opened and closed easily and for its position to be clearly seen. The three main types — ground, pedestal, and wall — are installed in different configurations and orientations.
The fire protection systems in large buildings and factories are generally fed by underground or wall cavity water mains. These systems include sprinklers, sprays, deluge, foam, and stand pipe installations, and all include at least one main isolation valve, usually of the post indicator type. This valve is typically placed at the ingress point of any fire system or subsystem, and the actual gate or butterfly mechanisms are more often than not underground or in wall cavities. To ensure that they can be easily seen and accessed, the controls and a valve status indicator are placed on a prominent post that protrudes above the ground or wall surface.
The three most common types of post indicator valves are ground, pedestal, and wall. Each type is suitable for different types of water main installations although all function in the same way and have many common features. The ground post type is typically used where the valve is situated outside a building. It features a tall, vertical post with its lower portion buried in the ground and typically has a locking, wrench type of operating handle at the top. The open/closed indicator or target plate is located below the top of the post behind a window and gives a clear visual indication of the valve status.
The pedestal indicator valve is used inside buildings with underground water mains. This variant is similar in most respects to the ground post type with the exception of the post mounting method. This valve features a post fitted with a flange that is bolted onto a concrete plinth or pedestal. The rest of the valve post mechanisms remain the same as the ground post valve.
The wall post indicator valve is used where the water main passes through a wall cavity. This valve type features a short post that protrudes horizontally from the wall. This type generally has a hand-wheel type of actuator and a similar status indicator to the other types.