NFPA 13 HDBK
Automatic Sprinkler Systems Handbook
|Publication Date:||1 January 2019|
This standard provides a range of sprinkler system approaches, design development alternatives, and component options that are all acceptable. Building owners and their designated representatives are advised to carefully evaluate proposed selections for appropriateness and preference.
This standard shall provide the minimum requirements for the design and installation of automatic fire sprinkler systems and exposure protection sprinkler systems covered within this standard.
The scope of NFPA 13 states that the standard includes the minimum requirements for design and installation of sprinkler systems employing automatic or open sprinklers that discharge water to suppress or control a fire. The phrase "minimum requirements" does not mean that the criteria are marginally acceptable, but rather it defines what is required for a reasonable level of protection.
This standard shall not provide requirements for the design or installation of water mist fire protection systems.
The definition of sprinkler system in 3.3.206 could be misconstrued to include a water mist system. Subsection 1.1.2 clarifies that NFPA 13 does not address other water-based systems, such as a water mist system installed in accordance with NFPA 750, Standard on Water Mist Fire Protection Systems.
Various codes and standards allow exceptions and reductions in building fire protection and other construction features where fire sprinkler systems are installed in accordance with NFPA standards. Only after appropriate analysis and evaluation of a tested mist system has been performed for the intended installation, and taking into consideration criteria other than solely fire-fighting performance (visibility, pressure ratings of backup systems, etc.) should exceptions and reductions in building fire protection and other construction features be allowed by the authority having jurisdiction. These systems are adequately described in NFPA 750.
Water mist fire protection systems shall not be considered fire sprinkler systems.
The design and installation of water mist fire protection systems shall comply with NFPA 750.
This standard is written with the assumption that the sprinkler system shall be designed to protect against a single fire originating within the building.
In recent years, there have been incidents where fires have started on or near the building exterior that have impacted the building, including fires started by discarded smoking materials in landscaped areas or fires originating at exterior utility equipment. NFPA 13 does not require an exterior exposure protection system to address those types of fires.
This standard also provides guidance for the installation of systems for exterior protection and specific hazards. Where these systems are installed, they are also designed for protection of a fire from a single ignition source.
Prior to the 2010 edition, this standard was silent on the issue of multiple ignition sources because a single ignition scenario was assumed but not stated. The lack of such a statement led to increasing discussion and varying interpretation of the standard with regard to multiple ignition sources. One side of the discussion maintains that multiple ignition source fires, if not accounted for in the system design, could overwhelm the sprinkler system water supply. However, adding such a statement within the standard would still leave unresolved the determination of how many ignition sources should be considered and their appropriate location within the building. Attempting to resolve such wide-ranging variables would result in an overdesign of the system at considerable expense, with little technical justification.