NFPA 13 is the most important standard for the design of automatic sprinkler systems. Fire protection engineers use this detailed standard to determine the design of an automatic sprinkler system. There are many factors that need to be determined in the prescriptive analysis of the adequacy of an automatic sprinkler system. Some of these factors include but are not limited to a recent water supply analysis, storage variables such as type, configuration, height and lastly the design of the automatic sprinkler system.
NFPA documents are updated on a three year basis. The 2010 version which has been recently released includes some changes to the 2007 version. The changes are as follows:
- New definitions for the following terms:
- Carton records storage
- Back to back shelf storage
- Shelf storage (revised)
- Ceiling pockets
- New fire test data added new section on high bay storage and compact storage.
- Compact storage can be protected as a light hazard occupancy if the following criteria are met:
- Storage up to 8 ft. in height
- A Class III commodity classification or less
- A minimum of 18 in. clearance between the top of storage and the ceiling sprinklers
- Sprinklers must be ordinary temperature, quick response
- A storage area of 2,500 sq. ft. or less
- The term large drop sprinkler was removed and a new section on Control Mode Specific Application (CMSA) was added.
- A section on excessive clearances was added as follows:
- For solid pile storage that exceeds 20 ft. between the top of storage and underside of the roof deck, the protection scheme should be based upon the storage height that would result in an exact 20 ft. clearance
- For rack storage less than or equal to 25 ft. for Class I – IV commodities where clearance between the top of storage and underside of the roof deck exceeds 20 ft., the protection scheme should be based upon the storage height that would result in an exact 20 ft. clearance or insert one level of quick response in-rack automatic sprinklers (IRAS) located directly below the top tier of storage and at every flue space intersection
- For rack storage greater than or equal to 25 ft. for Class I – IV commodities and all heights of plastics where clearance between the top of storage and underside of the roof deck exceeds 10 ft., the protection scheme should be based upon the storage height that would result in an exact 10 ft. clearance or insert one level of quick response in-rack automatic sprinklers (IRAS) located directly below the top tier of storage and at every flue space intersection
- Storage designs must be based on 3,000 sq. ft. remote area size.
- Fire test date from both NFPA and FM Global have never been able to provide a proven advantage to installing roof vents and draft curtains in storage areas; NFPA has clarified the following:
- Roof vents can only be installed if they are manual in operation
- A less desirable installation would be an automatic vent but only if the operating element on the roof vent is a higher temperature than the element on the sprinklers operating in the area
- Draft curtains should not be allowed with Early Suppression Fast Response (ESFR) systems unless they are separating ESFR systems under different occupancies or separating a suppression mode system from a control mode system
- Full scale fire testing has been conducted for high volume low speed fans or they are sometimes referred to as "Big Ass Fans" but the testing has not provided conclusive evidence to provide a prescriptive design approach in NFPA 13.
- The obstruction rules for sprinklers now include a paragraph about ceiling fans and indicate if fans blades are less than 60 in. and the plan view of the fan is at least 50% open sprinklers can be spaced without regard to the blades
- These provisions may conflict with jurisdictions enforcing the International Fire / Building Code or NFPA 1 Fire Code so designers may need to resolve any conflicts with the AHJ's
- All wet pipe sprinkler systems are required to be provided with a minimum 1/2-inch relief valve to relieve any pressures exceeding maximum system working pressure. Previously this requirement on1y applied to gridded sprinkler systems.
- The use of heat collectors (e.g., pie pans) to assist activation of sprinklers, in lieu of locating the sprinkler properly with respect to the ceiling, will no longer be permitted.
- Sprinklers must be provided at the top and bottom of elevator shafts that use polyurethane-coated steel belts or other similar combustible belt material.
- With respect to bracing for earthquake protection the Zone of Influence tables were updated and the method for calculating loads in the Zone of Influence was revised to be in conformance with Chapter 13 of SEI/ASCE-7 Minimum Design Loads for Buildings and Other Structures.
- Sprinkler Protection of Carton Records Storage with Catwalk Access includes a section with criteria for ceiling sprinkler protection and requirements/criteria for sprinkler protection below each catwalk level.
- A requirement that where a water hydrant flow test is used for the system design the test must be completed within 12 months of plan submittal.
- If treatment of the water is needed to prevent corrosion in piping this information must be included on the working Plans.
- The scope statement of NFPA 13 (paragraph 1.1) clarifies that the requirements of the standard assume sprinkler systems are designed to protect against a single fire only, not an incident involving several points of fire origin.
NOTE: Based on fire test data submitted to the Technical Committee that show unacceptable results, the Storage Density/Area Curves have been truncated at 3,000 ft2 for remote area size. Previously, the Storage Density/Area Curves stopped at 6,000 ft2 for remote area size. No longer will a designer be able to slide up the curve to select a lower density over a larger remote area over 3,000 ft2.
NFPA 13 is a very detailed and complex automatic sprinkler fire protection standard. A well trained fire protection engineer can help provide engineering consulting services with regard to NFPA 13 and the recent changes. We at Risk Logic are licensed Fire Protection Engineers and are well trained with regard to NFPA 13 and can provide these services for you.