Improving on 95% Reliability
Why sprinkler system reliability can, and should, be improved.
NFPA Journal®, May/June 2009
A recent NFPA report, U.S. Experience with Sprinklers and Other Automatic Fire Extinguishing Equipment, contains a solid endorsement of fire sprinklers as "highly effective and reliable elements of total system designs for fire protection in buildings."
The study, based on reported fires for 2003–2006 and using details captured by the National Fire Incident Reporting System (NFIRS), states that sprinklers operate in 95 percent of all reported structure fires large enough to activate sprinklers, and are effective 96 percent of the time. These separate considerations of operational and performance reliability result in a combined reliability of 91 percent, or 92 percent for the most common wet-pipe systems. Although some suspect that many successful sprinkler performances continue to go unreported, these figures deserve analysis.
The 95 percent figure for operational reliability can easily be improved, especially since the reason most often given for failure to operate is that the system was shut off (63 percent of failures). A December 2008 report from the Danish Institute of Fire and Security Technology states that its survey of hundreds of sprinkler systems in Denmark during 2007 showed that, had those systems been called upon to operate in the event of fire, 98 percent would have operated correctly, the same percentage as found in a 2001 survey.
Perhaps the best way to increase operational reliability is to provide periodic system inspections in accordance with NFPA 25, Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems. These inspections are intended to ensure that all equipment will operate when needed in a fire. NFPA 25 is widely adopted, but it is not always effectively enforced.
One proposal in NFPA’s current code-development cycle leading to the 2011 edition of NFPA 25 was to establish three conditions for a system following an inspection. The system would be classified as either in "operating condition," in a "condition that needs attention," or in an "impaired condition." This approach would change the current pass/fail system that does not appear to differentiate between a problem that renders the system inoperable and a minor shortcoming that would not interfere with system operation. This proposal was rejected, but a task group has been assigned to address the underlying issue. The NFPA 25 Committee is looking for jurisdictions that have successfully implemented NFPA 25 enforcement programs, so it can develop an enforcement model for other communities.
Some aspects of NFPA 25 enforcement can also be expected to improve system performance reliability, but there is always the possibility that the hazard has increased beyond the sprinkler system’s capability. Although NFPA 25 contains a schedule for periodic inspection of various system components, it does not contain a schedule for reevaluating occupancy hazard versus system design capability. Usually, this type of analysis only takes place as part of an insurance carrier’s review or as part of a building and fire code review triggered by a change in use or occupancy.
The committee also proposes to address this issue by including a form for fire sprinkler hazard evaluation in the annex material of NFPA 25. While there would still be no specific trigger to mandate the use of such a form, it will serve to highlight the difference between a system inspection and a system hazard evaluation. If such an evaluation is considered appropriate, the owner or authority having jurisdiction can ask an individual qualified to address system design issues to use the form when performing the system hazard evaluation.
Russ Fleming P.E. is the executive vice-president for the National Fire Sprinkler Association and a member of the NFPA Technical Correlating Committee on Automatic Sprinklers.