NFPA 13 Chapter 19 indicates that for sloped ceilings over 16.7 percent or 9.5 degrees, the system area shall be increased by 30 percent.
My understanding is that the test facility used had this limitation.
We further do recognize that highly sloped ceilings will cause heat to move fast towards the apex and will result in a delayed response of sprinklers, or worse, heads operate over areas not affected by fire.
With a ceiling of 10 degrees which is 0.5 degrees over the limit, will the affect on sprinkler operation really be affected to the extent where the 30% corrective is considered essential?
Without running a full CFD model, the three means of calculating response times of sprinklers we have do not consider ceiling pitch adequately. Looking at calculated results it simply would be more effective to just have lower sprinkler temperature ratings and use quick-response.
Would use of quick response sprinklers be enough to mitigate the concern in CMSA design instead of high temperature sprinklers (K11.2 or more)?
Thinking a little outside the box here, thanks in advance for the advice/input.
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6/20/2022 06:16:38 am
6/20/2022 08:08:06 am
Lots of items contained within this question:
6/20/2022 08:19:16 am
If you can provide and substantiate alternative means and methods proving either equivalency/superior performance AND the AHJ accepts the alternative, then there is no issue. This is one of the first things in NFPA 13 described - "Section 1.5 Equivalency".
6/20/2022 09:31:32 am
I can see some risk in using QR sprinklers in this scenario, and doing so won't absolve you of the need to modify the design area due to slope. QR reductions aren't permitted for anything beyond OH2. And of course, not all K=11.2 sprinklers are created equal. Many aren't listed for storage protection at all.
6/20/2022 11:06:10 am
Back to the basic...
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