What You Need to Know: Meeting Specialty Fire Hydrant Flow Requirements

Every jurisdiction has fire protection codes and requirements for new construction and remodels.  Many require only that you follow the International Fire Code and have signed sealed hydraulic calculations, but others have their own requirements. 

Alternatives in Engineering can help you with signed sealed hydraulic calculations and any unique requirements a jurisdiction can throw at us.

Here are some examples of unique requirements around the country:

City of Austin Fire Protection Rule requires the following:

For hydrant flow calculations, follow Appendix B of 2012 IFC but limit reduction of fire flow to 50% for certain building types

Accepted “C” values for calculations are 110 for PVC & Copper 80 otherwise

Austin Water also requires General Construction Notes and project information on drawings.

Port St. Lucie, FL requires the following in stamped sealed calculations:

Maximum day domestic requirements plus fire flow at residual pressures of not less than 20 psi

Domestic flows shall be based on 250 gallons per single-family dwelling unit, which equates to one Equivalent Residential Connection (ERC); the ERC factors for residential, commercial and institutional establishments.

The velocity shall be less than 6 feet per second (fps) at peak hour.

ISO to determine fire flow

The Orlando area gives you a form (see below) to use to determine ISO required hydrant flow and has some extra requirements for hydrants. 

No individual fire hydrant delivers more than 1,250 gallons per minute (gpm) of the required fire flow.

The required fire flow for commercial structures shall be determined as specified in the standard: Determination of Required Fire Flow as published by the Insurance Services Office (ISO). The fire flow for a building when sprinkler protected in accordance with NFPA 13 will be calculated at 50% of a non sprinkler protected building, but shall not be less than 1000 gpm. Calculations and a water supply analysis shall be provided to demonstrate delivering of fire flow.

No fire hydrant will be acceptable as meeting any requirement of this Code unless it will deliver at least 1,000 gpm.

Concord North Carolina Water Distribution engineering calculations must be signed and sealed. 

Pasco County FL requires signed sealed Hydraulic Calculations showing that the site meets Florida Fire Prevention Code 18.4 “Fire flow Requirements for Buildings”

As you can see a wide variety of methods are utilized by different jurisdictions to determine a project’s required fire hydrant flow.

While determining the required fire hydrant flow is critical, it is only the first step.  Once the required flow is known, AIE’s engineers can work closely with the projects civil engineer to determine the best method of meeting the hydrant flows requirements.  Using sophisticated modeling programs, our experienced engineers can ensure the jurisdictions requirements are met with the most cost-effective design.

For more information on the requirements of specific jurisdictions and for help in meeting those requirements, contact us today at 636-398-5288 or engineering@aiefirestl.com.

Contributed by Nancy Epstein; October 4, 2018.

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