Function of a Post Indicator Valve (PIV) in Fire Safety Systems

Function of a Post Indicator Valve (PIV)
Known for its usage of process and domestic water supply, post indicator valves are also an important part of fire protection systems in large buildings. In this article, we will study how this mechanism works, and also the various purposes it can be used for.
Did You Know?
Post indicator valves were created and patented by inventors Crookham and Lee in 1972 for Clow Corp., a pipe manufacturing company, and were publicly installed for the first time in 1974.

Also known as PIV, indicator post, I post, IP, post indicator, or wall post, a post indicator valve is a valve assembly used for the purpose of underground piping for water supply to fire protection systems such as sprinklers, sprays, foams, deluges, etc. These systems usually have a lockable actuator which looks like a red metal steering wheel or a wrench/handle on top of a post. It also has a glass or plastic window, which indicates whether the valve is open or shut. These valve mechanisms can be recognized by the post indicator valve symbol, which displays the acronym PIV inside a circle. One can commonly see these devices on the interior walls of buildings.
Types of Post Indicator Valves
PIVs can be broadly divided into 3 types:
  • Ground Post: This is an indicator post which has its base buried in the ground, and generally has a lockable handle or wrench. It is used when the valve is located out of the building.
  • Wall Post: This is a short indicator post, usually bolted horizontally to the wall of the building through a flange. This post is operated through a handwheel. This is used when the water mains pass through a wall cavity.
  • Pedestal Post: This indicator post looks similar to a ground post. However, instead of being buried in the ground, it is bolted through a flange to a horizontal surface, usually a platform of concrete. It is also operated through a lockable handle or wrench. It is used when the valve is located inside a building, and the water mains are underground.

All these are available in a variety of sizes, which range from 3 - 10 inches in width. Nowadays, electronic PIVs are also available, which communicate with the fire alarm system whenever the valve is opened or closed.
Post indicator valves and fire department connections are usually located close to each other, so that the water can be supplied to the system even in case of PIV failures. The fire department connections can be found in 2 distinct styles.:
  • Wall Mounts: These setups have two nozzles that are mounted on a round plate of brass, horizontally on a wall.
  • Free Standing: This setup also usually comes with two nozzles. However, they are mounted on a vertical pipe instead of a wall.

The fire department connections are not controlled by PIVs, but instead use fire department pumpers. Let's now look at what a post indicator valve does while operating the mechanism.
How Do Post Indicator Valves Work?
A PIV consists of 4 parts, i.e., a gate or butterfly valve, the post/body, the handle or wrench actuator, and the visual indicator. The gate or butterfly valve connects to a shut off valve in the underground fire line, while the post protrudes out from the ground or the wall. The actuator and the visual indicator are on the post, which allows the valve to be opened and closed easily by moving the actuator, and checking its position through the 'OPEN ' or 'SHUT' notification in the indicator.
Functioning
A post indicator valve functions to control the water flow to control fire systems such as hydrants and sprinklers that are located in or near public or private buildings, factories, and warehouses, to protect the structures from fires. It is used to cut off water supply to the systems in case of emergencies or for maintenance reasons, and may or may not be required depending on the fire department requirements for the area.
PIVs are also used to transport process water, i.e., water which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, byproduct, or waste product. While red post indicator valves are designated for stopping fires, the yellow, green, and blue ones are used for domestic purposes and for controlling water used for industrial purposes.
It is important that all PIVs are maintained periodically so that problems such as leaks or failures in operation are tackled promptly. This will save a lot of money by avoiding replacement of parts, and fines for negligence. But most importantly, these valves, when working as a part of a fire suppression system, will save lives.