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Bulletin Fire Sprinkler Calculations Residential Systems

Permit Sonoma Fire Prevention

The Purpose of this bulletin is to assist designers, contractors and property owners in the plan review process.

Codes Referenced:

  • California Residential Code
  • National Fire Protection Association (NFPA) 13D

Fire sprinkler plans and calculations submitted for review must show referenced location of water supply known as the source and the length of pipe to the associated structure or building. This is important to all parties to provide the necessary pressure and volume (gallons per minute.)

Fire sprinklers are designed by hydraulic method to provide a preset pressure and volume to the most remote 2 sprinklers. If the sprinkler contractor is not provided this data it can lead to costly resubmittals and design changes late into the project. Sonoma County Fire Prevention and HazMat Division will not accept electronic submittals of plans missing the referenced underground.

Underground details shall provide the following.

  • Source location
  • Elevation of source and sprinkler riser
  • Pump required pressure and volume
  • Size of underground pipe from source to structure
  • Length of underground pipe from source to structure

This can be referenced in any way on the submitted plan, but must be shown for reference and shall be included in the required calculations.

Domestic demand referenced in the California Residential Code and NFPA 13D shall be a minimum of 5 gallons per minute. Systems shall be designed to utilize the same supply for the domestic and fire sprinklers as amended by California Office of the State Fire Marshal.

Per NFPA 13D, a warning sign, with minimum ¼ inch (6 mm) letters, shall be affixed adjacent to the main shutoff valve.

The main shutoff valve shall be labeled.