Maximum Length from Hydrant to Water Main?

5/3/2024

Hi all, what is the maximum length of the connection from the hydrant to the fire water main?

NFPA 24 mentions that the minimum size is 6" but couldn't find anything related to the pipe length. Thanks

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7 Comments

Franck

5/3/2024 08:17:13 am

No limitation as long as the friction losses are not too important because of the length...
But with a 6 in. pipe and a demand flow of 500 gpm, friction losses are only 1 psi per 100 ft...

Chuck

5/10/2024 07:27:50 am

Nice job !

Fred Walker

5/3/2024 08:18:30 am

There is no code or standard driven maximum length for a lateral between the water service main and a fire hydrant. There are the practical limits of hydraulics to obtain the desired flow at the hydrant.

Jesse

5/3/2024 08:19:36 am

There is no max length.

Todd E Wyatt

5/3/2024 08:37:05 am

IFC-2021 Appendix C Table C102.1 REQUIRED NUMBER AND SPACING OF FIRE HYDRANTS identifies the minimum number of hydrants based on the Fire-Flow Requirements (gpm), the average spacing between hydrants (feet), and the maximum distance from any point on street or road frontage to a hydrant (feet).

Keynote C references “new water mains” : “Where new water mains are extended along streets where hydrants are not needed for protection of structures or similar fire problems, fire hydrants shall be provided at spacing not to exceed 1000 feet to provide for transportation hazards.”

Lastly, Keynote H states “The fire code official is authorized to modify the location, number and distribution of fire hydrants based on site-specific constraints and hazards.”

Anthony

5/3/2024 08:38:46 am

As all have said, no there isn't a limit. However, consider the application, if this hydrant is going to feed a manual standpipe you may want to use 8'' instead of 6''. Those friction losses can add up with a tight curve.

Jack G

5/3/2024 09:39:48 am

Check out the ibc and Nfpa 1 also for guidance.
From memory, you must first calculate the fire flow.
It is common to need more than one hydrant to satisfy the fire flow. A hydrant must be within 1000 feet to count as fire flow hydrant
1 and 2 story res buildings need a minimum 500 gpm calculated fire flow.
The hydrant must be within 600 feet and spaced to a maximum of 800 ft between hydrants.
For commercial buildings the hydrant must be within 400 ft and a max of 500 ft apart.
IBC and municipalities for high rise and commercial buildings the hydrant must be within 100 feet of the fdc.
Always check with the ahj and fire department for thread type, and what they require for minimum flow as it might be more than the calculated fire flow.
With no city water and facility has a tank, and vertical pump, ( for the pumper truck) the local ahj has had me install a hydrant near the building connected to an fdc out by the road, and the underground line supervised with water connected to the buildings fire pump. ( check valve pit near the fire hydrant) was a strange request. But they had kitchen fires every couple months. The buildings fire system, tank refill from a high capacity well, worked flawlessly.

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Maximum Length from Hydrant to Water Main?

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