Zedd may disagree since it's not referenced any more, but I use the old 
definition for small room (pre 2016). Later it seemed to be split in to small 
room and compartment.

11.3.1 went through some changes in 2016 to add the "room or compartment". In 
2013 it referenced small room (8.6.2.1.2)

This was new in 2002 (11.2.3.5.2). Read the substantiation.

Golinveaux had a white paper in the early aughts that explained this in detail, 
I don't have it handy, but I bet someone could chime in with it. (Chuck)


Taylor Schumacher

From: Steve Leyton <[email protected]>
Sent: Wednesday, May 22, 2024 2:33 PM
To: [email protected]
Subject: [Sprinklerforum] Room, compartment, residential sprinkler design areas


Caution: This email originated from outside your organization. Please take care 
when clicking links or opening attachments.


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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