According to recent research from the National Fire Protection Association (NFPA), sprinklers are a highly reliable and effective component of a comprehensive fire protection system. The most recent NFPA report, U.S. Experience with Sprinklers, offers the following findings:
- Between 2010-2014, fires in properties without sprinkler systems killed an average of 2,660 people per year — more than 60 times the average annual number of people killed in structural fires where sprinklers were present.
- During this time, the death rate due to fires was 87 percent lower in properties with sprinklers than in properties without, and the injury rates were 27 percent lower.
- Dollar loss per fire varied significantly based on the occupancy type, but the average overall loss was 30 percent lower in occupancies where sprinklers were present.
Based on these statistics, it stands to reason that increased usage of sprinklers will further reduce the loss of life and property from fire. With that said, the statistics on sprinkler operation and effectiveness illustrate that there is still a need to understand and address the issues that can affect sprinkler system operation and performance reliability.
For example, the report shows that the sprinklers in buildings with fires large enough to activate them operated and were effective 88 percent of the time; while in the other 12 percent, the sprinklers either did not operate effectively or failed to operate at all. This post will examine the most common reasons for sprinkler system failures identified in the NFPA report and other research, and identify some things we might do to prevent them.
Defining Sprinkler System Performance
In 2013, Fire Science published one of the most comprehensive reviews of sprinkler system effectiveness ever conducted. The authors reviewed more than 50 studies and found that sprinkler performance in fires can be affected by a number of factors, including:
- Characteristics of the sprinkler system as well as its age and deterioration
- Standards and technology available at the time the system was designed
- The inspection, testing, and maintenance of the system
- Changes in the type of occupancy or hazard being protected
- Building design and other building systems, such as heating and ventilation
- Modification of the system or changes in its water supply
In this study, “effectiveness” describes the overall performance of a sprinkler system, which includes both its “reliability” — the probability that the sprinklers will activate and supply water to a fire — and its “efficacy”, which is the probability that if the sprinklers function, they will function properly in accordance with the system’s design.
Why do Fire Sprinkler Systems Fail?
The distinction between reliability and efficacy is illustrated in the results presented in the NFPA report. While the sprinklers were found to be reliable in 92 percent of the fires large enough to activate them, in 4 percent of those fires, they failed to operate effectively. In more than half of these fires (51 percent), the reason for their ineffectiveness was that the water did not reach the fire. Of those systems that failed to operate at all, three out of every five (59 percent) were found to have been shut off.
The authors of the Fire Science report found similar results in the studies they reviewed. The most frequent reason for sprinkler system failure was human error — in 33-100 percent of fires in which the sprinklers failed to operate, the system had been shut off. And, in 19-55 percent of the fires in which the sprinklers were activated but failed to operate effectively, the most common reason was that the water did not reach the fire. The report also provides insights into the reasons for sprinkler system failure and ineffectiveness:
- Inappropriate systems, lack of maintenance, and manual intervention were reported in 5-33 percent of the fires reported.
- Damaged components and frozen systems account for only a small number, around 2 percent of the failures.
- Inappropriate systems were the second most commonly reported reason for sprinkler ineffectiveness, followed by not enough water released.
The authors of this report suggest that while the highest probability of sprinkler effectiveness appears to be between 90-95 percent, achieving a range of sprinkler system effectiveness up to 99.5 percent may be possible.
Our Thoughts on Improving Fire Sprinkler Reliability and Effectiveness
Given the results in both the NFPA report and the Fire Science study, any discussion of how to make sprinkler systems more reliable must begin with how to address human error. Both sources show that the vast majority of sprinkler failures occur because the equipment has been shut off. This can occur when a building is vacant or under construction, or when there are problems with the system, such as leaks or other impairments, that require it to be shut down while it is being repaired.
Chapter 15 of the NFPA 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems establishes the length of time a system may be out of service and provides procedures to ensure they are properly returned to service whenever inspection, testing, or maintenance activities are completed. Closer adherence to these standards will help to minimize the sprinkler system failures. To facilitate that, we provide below a summary of the NFPA 25 requirements regarding shutting down a sprinkler system and restoring it to service.
Preplanned Impairments
All preplanned impairments must be authorized by the impairment coordinator who is responsible for:
- Verifying that the extent and expected duration of the impairment have been determined and the areas involved have been inspected to determine the risks.
- Providing recommendations for mitigating any increased risks to management or the property owner or designated representative.
When a fire protection system is out of service for more than 10 hours in a 24-hour period, the impairment coordinator must arrange for one of the following:
- Evacuation of the entire building or the areas affected by the impairment
- An approved fire watch
- A temporary water supply
- An approved program to eliminate potential ignition sources and limit the amount of available fuel
All of the following must be notified prior to shutting the system down:
- Any supervisors in the area of the building in which the impairment will occur
- The local fire department
- The property owner or designated representative
- The insurance carrier for the building
- The alarm company
- Any other authorities having jurisdiction
Additional requirements include installing an impairment tag and assembling all the necessary tools and materials at the impairment site. The latter helps to minimize the time necessary to complete inspections, maintenance and/or repairs, which in turn minimizes the amount of time the system must remain shut off.
Emergency Impairments
For emergency impairments, such as an interruption of water supply, frozen or ruptured piping, and equipment failure, prior to restoring the system to service, the supervisor must check to ensure that any and all necessary inspections and tests, which are also outlined in NFPA 25, have been conducted to verify that affected systems are operational. Then, once the system is restored, the impairment tag must be removed and the following people notified:
- The Supervisor
- The local fire department
- The property owner or designated representative
- The insurance carrier for the building
- The alarm company
- Any other authorities having jurisdiction
According to the NFPA report and the Fire Science study, the most common reason for sprinklers activating yet failing to operate effectively is that the water did not reach the fire. There can be a number of reasons for this including:
- Obstructions installed after the sprinkler system has already been installed that prevents the water from reaching the fire or the sprinkler discharge pattern from developing properly.
- The occupancy and/or hazard classification of a building has changed and the sprinkler system design is no longer suitable.
- Inadequate or improper inspection, repair, and maintenance of the sprinkler system.
- Manual intervention in which either facility staff or firefighters shut off a system after the fire starts but before the sprinklers have discharged any water. This can happen when the fire is not immediately visible or is assumed to have already been extinguished.
- Explosions or collapse of a ceiling or roof that damage one or more of the sprinkler system components.
While not all of these problems can be prevented, many can. Particularly those relating to inspection, repair, and maintenance of the sprinkler system and changes that occur after it has been installed. Again, closer adherence to the NFPA standards would help to ensure sprinkler system effectiveness.
For example, whenever there is a change in the ownership of a building, the NFPA 1 Fire Code requires the owner or occupant to evaluate the design of the installed system to determine its suitability for the current occupancy and hazards. Likewise, adhering to NFPA 25 requirements for inspection, testing, and maintenance can help to ensure that when the sprinklers are needed, they will not only activate but operate effectively.
Koorsen Can Help
Are you 100 percent confident that your sprinkler system will function properly in the event of a fire? If not, Koorsen can help. Our certified fire safety experts can answer any questions you may have and provide the necessary inspections and testing, along with any repairs, your fire sprinkler system might need to keep it compliant, reliable, and effective. Contact Koorsen today so you can enjoy the utmost confidence in your fire sprinkler system.
