Sprinkler Age A Publication of the American Fire Sprinkler Association
The gears of the standard development process have been churning the last two months and elevating requirements in several standards of interest to the fire sprinkler industry. In October, the technical committee for NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, had their first draft meeting to review public inputs for the 2028 edition of the standard and, in November, the technical committee for NFPA 88A, Standard for Parking Structures, had their second draft meeting to review public comments. For NFPA 20, the committee has tentatively addressed the required horsepower rating for fire pumps, and NFPA 88A has developed robust prescriptive requirements and performance-based guidance for the protection of parking structures, car stackers, and parking systems.
Fire Pump Driver Selection
While the requirements for the power to operate a fire pump have not changed over the years, the interpretation has. Based on that interpretation, testing laboratories have been requiring pumps to run through their maximum break horsepower at any flow condition, even if it was beyond the usable capacity of the fire pump. This testing procedure disincentivized efficient curves and pushed manufacturers to develop steep curves to limit the power draw. In order to maintain a reasonable degree of protection, NFPA 20—a minimum standard—has proposed a first revision to limit the power of the driver to only supply the pump up to 220% of rated flow. Unlike some committee numbers, this was not just pulled out of the air. In the committee’s statement, they explain how the number was derived from the model curve already in NFPA 20.
This revision provides a maximum flow condition for maximum HP for fire pump drivers. The flow criteria was determined to be the variable most directly related to horsepower. Extrapolating the steepest head capacity curve shape permissible using a second order polynomial in Figure A.6.2 results in 0 percent of rated pressure being produced at the 220% flow condition. Beyond this condition, the pump would be of no material value to the systems supplied downstream. Additionally, if the pump is run beyond 220% on the steepest head capacity curve, the pump would become an impediment and begin to restrict the flow.
While this significant change still must pass ballot and survive the public comment stage, we keep inching towards an ultimate solution that has been a topic of discussion for the last three revision cycles.
Protecting Parking Structures
If you asked me a couple of months ago what I thought about the proposed sprinkler requirements for protecting parking structures and car stackers, I would have told you that you would be better off getting your discharge criteria from a fortune cookie. Since then, the Fire Protection Research Foundation (FPRF) is in the process of completing another phase of its project and some preliminary data obtained from testing has been used to justify the NFPA 88A changes. The proposed language in the second draft of NFPA 88A should fill the knowledge gaps and provide one source of truth for the protection of parking structures so that local jurisdictions can stop making up their own requirements. Within the changes, there is an expansion of the Chapter 6 requirements for typical parking structures with car stackers up to two vehicles in height. These requirements affirm the recommendations of NFPA 13 and the preliminarydata provided by the FPRF by specifying Ordinary Hazard (Group 2) for parking structures and car stackers with supplemental sprinklers above each vehicle and Extra Hazard (Group 2) when supplemental sprinklers are not provided. Chapter 9 now addresses parking systems for stackers with more than two vehicles in height and mirrors a rack storage approach with requirements for in-rack sprinklers at every level in the flues. If all else fails, NFPA 88A also created a new Chapter 10 to address the design goals and objectives for a performance-based design where the prescriptive requirements cannot be met.
Next Steps
It should be noted that the proposed changes discussed have only been accepted preliminarily in the NFPA standard development process. These changes still require a two-thirds affirmative vote from the committee to become a First or Second Revision.
ABOUT THE AUTHOR: Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE, is the Director of Engineering for the American Fire Sprinkler Association (AFSA). He is a member of several National Fire Protection Association (NFPA) technical committees responsible for developing the model codes and standards, including, NFPA 1 Fire Code, NFPA 13/13R/13D Installation of Sprinkler Systems, NFPA 20 Installation of Stationary Fire Pumps for Fire Protection, NFPA 25 Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, and NFPA 200 Hanging, Bracing, and Anchorage of Water-Based Fire Protection Systems. He also represents AFSA on numerous UL technical committees responsible for revising and maintaining the product standards used in the sprinkler industry. He is a registered professional engineer in Delaware and Maryland, NICET III certified in water-based system layout, a certified water-based system professional through NFPA, and a professional member of the Society of Fire Protection Engineers (SFPE). He earned his Bachelor of Science and Master of Engineering degrees from the University of Maryland College Park in fire protection engineering. In 2021, he was recognized as one of SFPE’s “5 Under 35” award recipients. Prior to his association and committee work, he worked for Reliance Fire Protection in Baltimore, Maryland as a project manager overseeing projects of various sizes and complexity.