Fire Flows For Fire Hydrants 6

[Norm01]

I am involved in a project for a correctional facility located outside the city limits. The facility has a fire pump to provide water for their sprinkler system and a separate diesel fire pump taking water from the river to supply only fire hydrants. The exisiting hydrant pump was installed in the 1970's. Their are approx. 12 hydrants on the fire loop around the property. There are numerous buildings spaced out across the propery. The client is looking at replacing the the existing diesel fire pump with a new one. The existing diesel pump is rated at 6000 gpm. This seems quite large to me, but I have never desinged a hyrant system before (usually civil engineers take care of the under ground water distribution systems).
Does anyone know which code would provide you with the information regarding designing for fire hydrants? NFPA? Other (i.e. fire flow calculations)?

Thanks

 

[FFP1]

I wonder why the original designer used a 6,000 gpm rated fire pump? You might want to dig a little deeper and make sure the underground mains (which feed the fire hydrants) does not feed something else which requires a much higher volume than the fire hydrants.

NFPA 24 provides information for fire hydrants. You will need to determine the occupancy and hazard for each individual building to determine the actual flow requirements for the various yard hydrants. Using a combination of NFPA 13 & NFPA 24 will more than likely provide the guidance you need. I would suggest some serious questions before I replaced a 6,000 gpm fire pump with a 500-1,000 gpm fire pump.

 

[firepe]

I would suggest that the 6000 gpm pump may have been stipulated based on the old ISO water supply rating/ fire flow charts and formulas, which are now mostly replaced with the Fire Flow requirements provided in the IFC codes.

If this is a large multi building facility and just this one pump provides the fireflow, then 6000-gpm may not be out of line.

Just my 2 cents

 

[SprinklerDesigner2]

Unless it has changed recently I think the largest UL fire pump you could get was 5,000 gpm. They may want to look at two 3,000 gpm pumps maybe one diesel and one electric.

 

[TravisMack]

Look at appendix B in the IFC. That will give you site fire flows based on area and construction type. You can also apply a reduction if you have fully sprinklered facility.

Just check the table and follow the notes. That should get you going in the right direction.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[stookeyfpe]

Be careful on the sprinkler exception in IFC Appendix B. Your original post said multiple buildings. The fire flow should be based on a comparison of the largest unsprinklered building and the largest building of Type VB construction.

 

[DavidCR]

Check NFPA 1, (I have the 2003 Ed.). On appendix H, it has something like what you are looking for. It has a table (H.5.1). There you have have hydrant fire flows and durations with respect to building independent fire areas and construction type per NFPA 220. There you can find info on hydrant quantity and distances. Check your AHJ if that may apply to your case.