Overview of NFPA 13: The Standard for Fire Sprinkler Systems

Shubham More
Author : Shubham More
March 24, 2021
5 Minutes Read
  
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    NFPA 13 is the industry standard on all matters related with sprinkler systems in the USA, and the first version was published over a century ago in 1896. It is important to note, however, that state and municipal authorities often introduce additional requirements. For example, fire sprinkler systems in NYC must also meet local amendments to NFPA 13, along with additional requirements set forth in the NYC Building Code and NYC Fire Code.

    The NFPA 13 standard is nearly 500 pages long, and very detailed in requirements and specifications. This article will provide an overview of the main points covered, but is by no means a substitute for the whole document. Also keep in mind that automatic fire sprinkler installations in NYC can only be approved if a Registered Design Professional (RDP) submits construction documents, and the work permit is only issued to a qualified and licensed contractor - either a Licensed Master Plumber (LMP) or Licensed Fire Suppression Contractor (LFSC).


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    Local Law 26 of 2004 makes fire sprinklers mandatory for all business occupancies where the building is at least 100 feet tall. If an NYC property is covered by LL26/04, the deadline to install an automatic sprinkler system is July 1, 2019. Since these projects can be time-consuming and capital-intensive in large buildings, the best advice we can give you is to start as soon as possible and with the assistance of qualified engineering consultants.

    Newer editions of the NFPA 13 are not retroactive in most cases, which means you are not required to upgrade existing installations that were compliant at the time of installation. If any specific requirement is retroactive, it is state clearly in the current version of NFPA 13.

    General Definitions and Requirements

    Since fire sprinkler design involves plenty of technical concepts, the NFPA 13 dedicates its Chapter 3 to defining key terms that are used throughout the document. An automatic sprinkler is defined as a “a fire suppression or control device that operates automatically when its heat-activated element is heated to its thermal rating or above, allowing water to discharge over a specified area.” There is a common misconception that automatic sprinklers are activated by smoke, but actually they respond to heat.

    General requirements apply for all sprinkler systems regardless of the type of building or specific configuration, unless there is a direct exception in the code. If a building uses fire sprinklers, NFPA 13 demands full coverage for the entire property unless the standard indicates clearly that a specific building area is optional.

    NFPA 13 Occupancy Classification

    The NFPA 13 standard classifies occupancies by hazard level. It is important to note that this only applies for fire sprinkler systems, and is not a general classification. The general classification for occupancy groups is in the NYC Building Code.

    OCCUPANCY CLASSIFICATION

    DESCRIPTION

    Light Hazard

    Low combustibility of contents and low heat release expected from a fire.

    Ordinary Hazard

    Group 1: Low combustibility, moderate amount of combustible materials, stockpiles are not taller than 8 feet, and moderate heat release is expected from a fire.

    Group 2: The combustibility and amount of contents ranges from moderate to high. Contents with a moderate heat release are not stacked taller than 12 feet, and contents with a high heat release are not stacked taller than 8 feet.

    Extra Hazard

    Group 1: The combustibility and amount of contents is very high, and there are compounds like dust or lint present, which can accelerate a fire if it occurs. The rate of heat release from a fire is high, but combustible and flammable liquids are only present in small amounts or not present at all.

    Group 2: Moderate to large amounts of flammable or combustible liquids. Also includes occupancies with ample shielding of combustibles.

    In addition to classifying the occupancy, NFPA 13 has a classification for materials stored, called “commodities” in the standard. There are four classes, I through IV, where Class I is the least vulnerable to fire and Class IV is the most vulnerable. The classification is determined based on both the materials stored and the containers used (boxes, pallets, crates, etc.).

    Fire Sprinkler System Components and Installation

    The core content of NFPA 13 is a description of all components used in automatic sprinkler systems, and a description of their correct installation procedure and mechanical support requirements. The standard establishes the requirements for all system components depending on their material and type. NFPA 13 provides both general requirements and application-specific requirements.

    The NFPA 13 standard provides detailed requirements for each sprinkler system type.

    SPRINKLER SYSTEM TYPE

    DESCRIPTION

    Wet pipe

    Permanently filled with water.

    Dry pipe

    Filled with pressurized gas, allows water into the system when one sprinkler activates.

    Preaction

    Fills with water with an alarm signal from an independent heat or smoke sensor, and water is released when sprinklers activate individually.

    Deluge

    All sprinklers are open and controlled by sensors. When fire is detected, all sprinklers shower water at once.

    Combined dry pipe and preaction

    Filled with pressurized air but activates just like a preaction system.

    Multi-cycle

    Can activate many times consecutively.

    Antifreeze

    A wet pipe system where water is mixed with an antifreeze compound.

    Circulating Closed-Loop

    A wet pipe system that can be used to circulate water for heating and cooling purposes.

    Gridded

    Sprinkler system with parallel connections between cross mains, so that each sprinkler receives water from both sides of the pipe when active.

    Looped

    Sprinkler system where many cross mains are connected together to provide multiple paths for water.

    Pipe schedule

    Sprinkler system where pipe size is determined by the occupancy classification.

    Note that a sprinkler system can be of more than one type. For example, a wet pipe system can be configured as an antifreeze or circulating closed-loop system.

    Conclusion

    The NFPA 13 standard is demanding in its requirements, but this is necessary considering the important role of automatic sprinkler systems in fire protection. Keep in mind that NYC codes establish additional requirements for fire sprinkler systems, while amending the NFPA 13 standard. The best way to ensure compliance is working with qualified fire protection engineers.

    Tags new york | Sprinkler design | Fire sprinkler system | Fire protection engineering | sprinkler system installation | local law 26 | Fire protection

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