Okay Power Rangers, let's talk "intent" of the standard. NFPA 13, 2022 edition, specifically boring into 19.3.1.3 (3) regarding "rooms or compartments" that are ≤800 sq. ft. in area. That subsection empowers the designer to use the average coverage per sprinkler in the subject design area to establish minimum end sprinkler flow rate. So if I have a "room or compartment" that's 756 sq. ft., the average is 189 sq. ft. or 18.8 gpm starting flow rate but I have to verify that the flow rate is at least equal to or greater than the listed flow rate, which is going to be at .05 density for a residential sprinkler. So if I wanted the flexibility of installing a sprinkler up to 10' from a wall, the minimum flow rate for most residential pendents will be 20 gpm, which means I have to raise the end sprinkler flow rate in my hydraulic model. But otherwise, I can bounce back and forth between the average and the listing so long as I satisfy both 19.3.1.3 (1) and 19.3.1.3 (3).
But what's the "compartment in question here and what's a room? And how does a room differ from a compartment and if it's different why isn't it defined and if it's not different, why is the term "room" even used in this context? (Mr. Fetter, you sure do ask a lot of stupid questions.) Let's say I have an APARTMENT that's composed of 5 sprinklered "rooms" - combined entry/kitchen/living/dining; bedroom; bathroom; walk-in closet; mechanical closet - all of them divided by non-rated partitions within a one-hour capsule that's required around every dwelling unit. And the gross area within this apartment is 756 sq. ft. Is that dwelling unit the compartment in question or is it the bedroom? Am I limited to four sprinklers in a single "room" in order to use 19.3.1.3 (3) or is it four sprinklers withing the rated apartment/compartment? In a perfect world, when I'm protecting small dwelling units in a multi-family building, I would like to average the four most demanding sprinklers in the most demanding dwelling unit (apartment), raise the flow rate to satisfy 10' max spacing off walls and obstructions, and buy the installer ultimate flexibility to avoid fan motors and detector clusters and whatever else they stumble across that's not on the approved building plans. But we have a SoCal AHJ that sees it differently, and with mad respect for them and the collective brainpower at that particular bureau, I think this is worthy of a shout-out TC members - what's the significance of room vs. compartment? Is there a difference and if not, please either define or remove the word room from the standard. Your pal, Steve [cid:[email protected]] Steve Leyton, President T | 619.255.8964 x 102 | www.protectiondesign.com<http://www.protectiondesign.com/> 2851 Camino Del Rio South | Suite 210 | San Diego, CA 92108 Fire Protection System Design | Consulting | Planning | Training
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