Our high-rise facility consists of apartments, condominiums, retail on the bottom floor, restaurant tenants on the top floor, and (3) levels of underground parking. We are 9 stories tall out of the ground.
They have great water pressure at the site with 140 static and 118 residual, flowing about 1,900 GPM, but with our floor-to-floor distances, I cannot get 100 PSI at the top of my standpipes. The building footprint is spread out, so I will need (8) standpipes to cover the hose lay inside the building (fully sprinklered). I'm assuming one 1,000 gpm pump will cover all the standpipe demand. To complicate matters, this is in a seismic area D classification, and with it being a high rise, I am required to have a secondary on-site water supply. The intent was to install an underground tank to supply the fire pump or pumps, if necessary. My thought was to supply water directly from the city main to the tank, and if there is ever a break in the city supply line, the pump would be served from water in the tank, which would have enough capacity to serve the facility for 30 minutes. Is 30 minutes the duration I need? What do you think about how I plan to serve the building? Would that meet the requirement for a secondary water supply? Do I consider the standpipe demand when sizing the underground tank, or just the most demanding area of my sprinklers? Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
4 Comments
Dan Wilder
8/1/2024 09:02:23 am
The secondary water supply will need to be able to meet the sprinkler demand + hose stream per 914.3.2...it does not state the need to be sized to meet standpipe demands....this would also correspond to the duration (based on hazard classification). With the OH areas of the restaurants on the upper floor, this may trigger the 60 minute duration vs the 30 min.
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Anthony
8/1/2024 09:44:44 am
Dan, IBC 403.3.3 does require a secondary supply as this building is in a class D seismic design category. the 420'-0 designation is only referenced in 403.3.1 and 403.3.2.
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Dan Wilder
8/1/2024 11:39:29 am
Yes, I was referring to the 2 water main connections on different streets for 403.3.2, 403.3 is just a secondary water onsite water supply (i.e. the tank).
Jack G
8/2/2024 11:31:21 am
914.3.2 Secondary water Supply:
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