Sprinkler Supervision: What Does it Mean?
Automatic Sprinklers have proven to be highly effective over the years. Recent statistics show that sprinklers operated 92% of the time in fires that were considered large enough to activate sprinklers. The leading cause of sprinklers failing to operate is because the sprinkler system had been shut off. In fact, that is the reason cited in three out of every five incidents where sprinklers failed to operate according to the U.S. Experience with Sprinklers Report. One way to prevent shut-off of sprinkler systems is through sprinkler supervision. What is sprinkler supervision and why is it necessary? A sprinkler system has a number of control and isolation valves which allow portions of the system to be shut down for things like maintenance, testing, or rehabilitation work. These valves allow for the rest of the system to remain operational while the necessary work is completed in a specific area. It isn’t uncommon to see a main control valve which controls water to the entire system as well as a floor control valve on every floor. This way, if rehabilitation work is happening on the second floor, the isolation valve on the second floor can be closed and that portion of the system can be worked on. The system would remain operational on the remaining floors. While the benefit of being able to isolate certain parts of the system is obvious, there can be risks associated with it. Valves can remain shut after the work is complete, or, valves can be accidentally, or intentionally, shut thus rendering portions of the system useless. This is where sprinkler supervision is important. Sprinkler supervision is intended to ensure the overall integrity of the piping system by providing a method to verify all control and isolation valves are fully open. What does supervision mean in NFPA 13, Standard for the Installation of Sprinkler Systems? NFPA 13 provides the designer with options of how to monitor the isolation and control valves. The options are: Electrical supervision that reports to either Central station, proprietary, or remote station signaling service Local signaling service that will cause the sounding of an audible signal at a constantly attended point Valves locked in the correct position Valves located within fenced enclosures under the control of the owner, sealed in the open position, and inspected weekly as part of an approved procedure If you want to learn more about NFPA 13 and sprinkler supervision, check out this article. Any of the above means of supervision is acceptable per NFPA 13 for all valves except floor control valves in high-rise buildings and valves controlling flow to sprinklers in circulating closed loop systems. In those two special cases, NFPA 13 requires that those valves be electrically supervised. What does supervision mean in NFPA 101, Life Safety Code and NFPA 1, Fire Code? The Life Safety Code does not provide the designer the same options for supervision that NFPA 13 does. Instead, the Life Safety Code requires that all supervised sprinkler systems be electrically supervised. The supervisory signal must be reported either at a location within the protected building that is constantly attended by qualified personnel or at an approved, remotely located receiving facility. It is important to note, that there are instances where the Life Safety Code does not require electrical supervision and instead permits supervision in accordance with NFPA 13. In these cases, such as what is seen in the extinguishment requirements for existing mercantile occupancies, the Life Safety Code requires an “approved automatic sprinkler system” in specified locations. Since the word “supervised” is not included, the electrical supervision requirements specific to the Life Safety Code do not apply, and the sprinkler system is permitted to be supervised in accordance with NFPA 13. Since the Fire Code extracts the automatic sprinkler system provisions from the Life Safety Code, the same requirements for electrical supervision apply to any sprinkler system that is required to be supervised by the Fire Code. Why is there a difference? Not all Codes require electrical supervision like the Life Safety Code and Fire Code do. For instance, NFPA 5000, Building Construction and Safety Code, only requires electrical supervision when specifically called for, otherwise any form of supervision permitted by NFPA 13 is acceptable. The electrical supervision required by the Life Safety Code is a vital component. In many cases, by providing a supervised automatic sprinkler system, other modifications to building design are permitted. For example, in most occupancies, a sprinklered building is permitted to have a longer travel distance and a longer common path of travel when electrically supervised. Other trade-offs include different allowable construction types or reduced fire resistance rating of fire barriers. NFPA 13 also recognizes the improved reliability of electrically supervised sprinkler systems through trade-offs like the Life Safety Code does. One example is that, when determining the water supply duration requirements for hydraulically calculated systems, the lower duration values are permitted to be used where the waterflow alarm devices and supervisory devices are electrically supervised. This means that for an ordinary hazard occupancy, the water supply duration for an electrically supervised system would be permitted to be 60 minutes instead of 90 minutes. These types of allowances found in NFPA 13 and the Life Safety Code, are based on the assumption that the automatic sprinkler system is going to perform as expected. To increase the probability of this occurring, electrical supervision is required so that any time a valve is closed, somebody, either a qualified person on site or an approved remotely located receiving facility is made aware of the system impairment.