Good morning all.
So I'm looking at an Extra Hazard Group 1 (EH1) dry system under NFPA 13 (2016 edition). I want to apply multiple adjustments per 11.2.3.2.7 because I want to use high temperature sprinklers to get me a 25% reduction under 11.2.3.2.6. This can result in the following math: 2,500 * 1.3 for dry system = 3,250 sqft. 3,250 * 0.75 (for 25% reduction) = 2,437.5 sqft. And this always stays above the 2,000 sqft requirement of 11.2.3.2.6 and everyone is happy. But it can also result in the following math happening: 2,500 * 0.75 = 1,875 sqft. 1,875 gets forced into 2,000 sqft because I'm not ever supposed to go below a 2,000 sqft design area under 11.2.3.2.6. So then 2,000 * 1.3 (for dry system) = 2,600 sqft. So would the system have a 2,437.5 sqft design area or a 2,600 sqft design area? Yeah, it's only two sprinklers, but at these densities that can change a system. I can see an argument for either conclusion. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
6 Comments
danefre
10/17/2023 07:06:46 am
Your first calculation is the correct one. Step 1: make all the area adjustments. Step 2. Check if you are below 2000 sqft.
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Anthony
10/17/2023 07:33:19 am
I don't think either is wrong and this falls under good (or bad, depending on your point of view) "code lawyering." I'd take the smaller area if it was convent and would be compliant and happy with that.
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Dan Wilder
10/17/2023 10:55:43 am
As it looks like you are referencing 2016, my approach would be:
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Jack G
10/17/2023 12:28:45 pm
I would do all required increases to the dry system (bigger number) Then I would apply the discounts.
Reply
Pete H
10/17/2023 12:31:26 pm
Unfortunately the code doesn't spell it out... but I think the correct math is:
Reply
Pete H
10/17/2023 12:47:41 pm
A dry extra hazard occupancy. I forgot to point out dry in that last paragraph.
Reply
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