Capacities of Fire Department Connections?

4/5/2019

Where can I find information on how much flow each type of fire department connection can handle (siamese, 4" Storz, or 5" Storz)? Is this provided in a standard, or manufacturers data?

Also, does just about every fire department have the ability to connect to Storz? I've heard from many departments that the FDC type depends on the flow of the building, which leads me to believe that many departments can connect to any type of FDC.

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4 Comments

Scott

4/5/2019 11:05:32 am

NFPA did a study through Exponent on the flow capacities of various FDCs (although I don't think Storz connections were tested). See: https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/Suppression/RFFireDepartmentConnectionInletFlowAssessment.ashx?la=en

Not every fire department carries hose with Storz connections. Usually larger cities do not have a need for such large hose diameters. Also, be careful of using a Storz on an FDC. I believe those connections are only rated for 175psi.

Robert Bennett

5/20/2021 09:26:32 am

In reading the report it leads you to believe that single FDC is more hydraulically efficient. However a MAJOR shortcoming of the study was they did not include the loss in the supply hose. By example a single 2.5 inch hose flowing 500 GPM has a friction loss of 50 PSI/100ft. When the total system pressure demand is 150 PSI or higher the required pump pressure could reach 225 PSI very easily. This is the practical limits of the hose, so although single FDC is definitely more efficient the whole system must be considered when designing systems.

Richard Mercer

4/5/2019 12:01:48 pm

It's not the fittings by themselves s that determine the flow capacity of the FDC piping arrangement, the size and arrangement of the piping to the system, determines the flow capabilities. The friction loss of the LD Storz connections is minimal. (4 or 5" Storz x 4" PT)

The standard takes piping arrangement into account by requiring a minimum 4 inch piping or no smaller than system riser, which should meet most system demands or exceeds the output of a Class A engine (1000GPM @ 150 psi)

Dean Melanson

4/5/2019 12:38:55 pm

An additional issue with the number and size of the inlets lies with the local FD responding and the location of the nearest hydrant.
NFPA 13 does not require a hydrant to FDC distance for sprinklers while NFPA 14 does. So on the sprinkler system support issue hose friction loss can become an issue and the 250 gpm per 2.5 in. inlet is often very reasonable.
LDH hose can be bought in various pressure capabilities meeting either the supply hose or attack hose code. If attack hose certified hose is used greater than 200 psi discharge pressures can be attained.

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Capacities of Fire Department Connections?

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