One project question I very commonly receive from civil engineers is whether a post-indicator valve (PIV) is required.
In short, there are options. I'm exploring PIVs in more detail in this week's article. If you want to get more like this, subscribe for free here.
Purpose of Post-Indicator Valves
Post-indicator valves have long been used to stop the flow of water into a building during developed stages of a fire. Exterior wall collapse of a burning building poses a threat to break water supply mains as well as create many openings to the water supply. Without a valve to stop supply to these areas, firefighters and their efforts could be compromised by the loss of pressure and outflow of water to areas of a site that don't need water.
With the recognized effectiveness of sprinkler systems and cost pressures, the requirement for post-indicating valves have become more relaxed in the last decade. Code references to account for building collapse, for instance, now appear only indirectly in location requirements for hydrants and post-indicator valves to be sufficiently away from a building.
Components of Post-Indicator Valves
The post-indicator valve has several important features - first is the ability to quickly shut the valve with use of the post indicator valve handle. The second is to quickly see whether the system is in the 'open' or 'shut' condition in a protected enclosure. It can sometimes be difficult to see after years of dirt on the glass, but not impossible.
The valve itself is along the water main below frost depth such that only the stem is subject to freezing conditions. It's a simple concept that's carefully crafted to protect the valve and stem in a reliable fashion.
One example of a post-indicating valve - a Mueller Company Vertical Adjustable Post Indicator Valve (see https://www.muellercompany.com/fire-protection/ulfm-indicator-posts/)
History of the PIV Requirement
So is a post-indicator valve required or not? This used to be an easier question to answer.
While not a referenced standard from the International Building Code, the International Fire Code requires that all private fire service mains be installed in accordance with NFPA 24 (IFC 2000-06 Section 508.2.1, 2009-18 507.2.1). NFPA 24, the Standard for the Installation of Private Fire Service Mains and Their Appurtenances, governs system requirements between a water supply main and a building's service entry.
Up until the 2010 Edition, NFPA 24 required a listed post indicator valve on every connection from a private fire service main to a building unless special criteria were met (NFPA 24 Section 6.3). The special criteria included the use of a non-indicating underground gate valve with a roadway box and T-wrench or locating an inciating valve in a pit. Either special case required approval of the AHJ.
Current Valve Options within NFPA 24
Since the 2010 Edition, NFPA 24 gives a series of options for isolating a building's system and does not mandate that a post-indicator valve be used. These options (from 2010-13 6.2.11, 2016-19 6.2.9) include:
While still considered an "indicating" type valve, wall indicating valves are generally less preferred than post-indicating valves as they are more susceptible to a building collapse than post-indicating valves.
Post-Indicator Requirements of NFPA 14
NFPA 14, the Standard for the Installation of Standpipe and Hose Systems, also weighs in on post-indicator valve requirements.
NFPA 14 requires that each water supply (except for an FDC) shall be provided with a listed indicating valve in an approved location (NFPA 14 2000 4-2.6.1, 2003-07 18.104.22.168, 2010-19 22.214.171.124.1).
The prescriptive way to accomplish this is through the use of a post-indicating valve. Annex material within NFPA 14 goes further, stating a list of preferences for outside control valves:
NFPA 14 does give exceptions (as is almost always the case in fire protection), but they require AHJ-approval. Wall-point-indicating valves, or underground valve with roadway box and T-wrench, are alternative options that require AHJ approval (NFPA 14 2000 4-2.6, 2003-07 6.2.6, 2010-19 6.3.6).
Post-Indicator Requirements of NFPA 13
So where does NPFA 13 stand on post-indicator valves? In short, it doesn't. NFPA 13 only states that where post-indicator valves are used, they top of the post must be 32-40 inches above grade, and they must be protected against mechanical damage (NFPA 13 2002 126.96.36.199, 2007-16 188.8.131.52, 2019 16.9.9).
AHJ & Insurer Inputs
Authorities Having Jurisdiction may also want to weigh in on requirements for post-indicating valves. Some municipalities write code amendments to require PIVs, while others may request PIVs be installed for certain building types.
Insurers, such as FM Global, may also want input. FM Global for instance, recommends that each system has a control valve a minimum of 40 feet from the building (with less preferred options also recommended in Data Sheet 2-0 2.6.2).
What's the best course of action for your project? First, check for local or state code amendments that may affect post-indicating valves. If you have a standpipe system within the building, plan to provide a PIV. Last, check with your AHJ for any nuanced requirements you may be missing or to coordinate a location with the AHJ.
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Joseph Meyer, PE, owns/operates his own Fire Protection Engineering practice in St. Louis, Missouri. See bio on About page.