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Wet Chemical Fire Suppression

Pre-Engineered Fire Suppression Systems

Wet-Chemical fire suppression systems are important systems that have prevented countless kitchen fires.  The systems are typically installed at the requirements of the International Building Code or National Fire Protection Assocation (NFPA) 1, The Uniform Fire Code.

Systems are installed due to code requirements adopted in a community.  Many contractors refer to the the term “grease ladden vapors” as the minimum requirement for the system to be installed.  Over the years the basis for installation has been tweaked and modified.  You can see in the most recent IBC the language from section 904.2.1 truly refers to the type of exhaust hood.  Similar language can be found in NFPA 1 or NFPA 101.

The systems are typically pre-engineered by the manufacture.  The system go under very specific testing and scrutiny.   This means the system is has limitations on what and how it protects appliances, plenum spaces, and exhaust ducts.  The qualified contractor (attended training by the manufacture) would provide working shop drawings that show the system complying with the manufacture requirements.

These manufacture requirements are documents which indicate how nozzles protect an appliance, which type of nozzle, mounting height, piping limitations, and how many flow points can be achieved from a specific size bottle.  It is critical that the system is designed by certified personnel, properly installed, and maintained.  It is important to realize that NFPA 17a is critical for the installation, maintenance, and testing of each system.  This can include location of manual activation, installation of signage, and other minimum requirements.

When conducting a plan review the submittal package must contain (at a minimum):

  • Drawings which are legible, contain basic plan information, and all equipment to be installed
  • Description of equipment and mechanical equipment to be protected
  • Code and standard for basis of installation
  • Date of Manufacture installation manual
  • General notes and requirements
  • Site plan indicating location of installation
  • Sufficient technical data sheets from the manufacture
  • Technical calculations to show the system meets the manufacture requirements
  • Type of acceptance testing to be completed

Although this is a basic list, the documents must include all information which demonstrates the system meets the manufacture requirements and NFPA 17a.

Resources:

Checklists

UL 300

These systems require continued maintenance and inspection.  What information do you require on shop drawings or to be provided at time of inspection?

    { 4 comments… add one }

    • Tim Knisely December 8, 2010, 11:11 am

      Have a question with extinguishers. Do other AHJ’s allow the ABC fire extinguisher in the kitchen with the Class K? I’ve heard recommendations to remove the ABC so the employee doesn’t use the wrong extinguisher. If an ABC is within the travel distance of the kitchen but not in the immediate area it could still be compliant.

      Thanks….

      • Frank Herrick January 26, 2011, 3:04 pm

        My answer would be no, NFPA 10: Standard for Portable Fire Extinguishers, 2010 Edition, requires that the extinguisher be slected for the fire most likly to occur, per
        5.1 General Requirements.

        The selection of fire extinguishers for a given situation shall be determined by the applicable requirements of Sections 5.2 through 5.6 and the following factors:
        (1)Type of fire most likely to occur
        (2)Size of fire most likely to occur
        (3)Hazards in the area where the fire is most likely to occur
        (4)Energized electrical equipment in the vicinity of the fire
        (5)Ambient temperature conditions
        (6)Other factors (See Section H.2.)

        The use of a ABC extinguisher in a kitchen would not be indicated if a wet chemical system is installed.

        FRANK J. HERRICK
        City Of Leawood Fire Department
        Office of the Fire Marshal
        14801 Mission Road
        Leawood, Ks. 66224-9560
        Office: 913.681.6788 x 26
        Fax: 913.681.2399
        Fire Sprinklers Save Lives, Property, the Environment, and Water – Protect what you value most!

    • Grant Mogford December 8, 2010, 2:18 pm

      “ABC”‘s should NOT be in commercial kitchen enviornments as the chemical is not compatible with the chemicals in the automatic supression systems. “BC”‘s are what was acceptable until “K” class extinguishers were introduced. I have found some AHJ’s allowing the “BC”‘s to stay but now most are requiring the removal of all except “K” class.

      NFPA 10 (1998 edition) ” 2-3.2 Fire extinguishers provided for the protection of cooking appliances that use combustable cooking media (vegetable or animal oils and fats) shall be listed and labeled for Class K fires.”

      The arguement then becomes what about non cooking media combustibles in the same area.

    • Earl Gregory December 30, 2010, 1:12 pm

      I agree with the above statements and code requirements to a point. A commercial kitchen environment has not only the hood and cooking appliances, but many other areas of concern such as microwave ovens, mixers, coolers, and trash recepticals to name a few. You will note that a class “K” fire extinguisher is only to be used after a suppression system discharges and only on cooking media. An ABC extinguisher inside the kitchen is a reasonable addition to use on the areas not covered by the hood system. Place the ABC extinguisher close to an exit, or away from the hood for use on other fires.

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