We were sent the attachment as part of an assessment - it is supposed to be based on NFPA 13, Ch. 12 & 13. I cannot determine where he got the highlighted figure from. Can anyone help explain it to me?
Any idea which year. 13???
he said it was 2016
Still think it is doodling
Found in NFPA 30 220.127.116.11
Mentions 12 @ 50
Number of sprinklers @ stated pressure.
Not sure you are looking at something from 13 ???
Seems to be a CMSA criteria from one of the storage chapters (14 to 17) of NFPA 13. Without knowing the type of storage and commodities involved it will be difficult to know from which table the pulled the numbers.
Looks like some ones doodling, or example, or hydraulic exercise???
You might post here to see if someone recognizes it ::
They appear to be stating that a K 8.0 is insufficient for the demand posed by current storage factors.
They seem to believe that a density .045 / 2000 or that 12 heads operating at 50 psi is required.
NFPA 13 2013 sections 12.6.2 defines the density range for a k 8.0 at between >.20gpm/ft - <0.34gpm/ft2
12.6.2 For general storage applications, rack storage, rubber tire storage, roll paper storage, and baled cotton storage being protected with upright and pendent spray sprinklers with required densities of greater than 0.20 gpm/ft2 to 0.34 gpm/ft2 (8.2 mm/min to 13.9 mm/min), standard-response sprinklers with a nominal K-factor of K-8.0 (115) or larger shall be used
Looks to me like a table out of Loss Control survey from an insurance carrrier where they are stating what exisits (.495/2000) and then they are making a recommendation for and ESFR system, probably K14's, 12 heads at 50 psi.
Chapter 13 deals with miscellaneous/low piled storage. The 12@50 reference is a pretty common design point for ESFR heads, and there is no reference to ESFR protection in chapter 13. In Chapter 12, there are criteria for indoor idle pallet storage and one option is for ESFR protection, K14 heads, designed for 12 heads operating at 50 psi. This will allow protection of idle wood or plastic pallets up to 25 feet high in a 30 foot high building. If your building exceeds 30 feet to the deck you can't use this.
There are other options to protect indoor pallet storage, notably reducing the height and quantity, but these are not always viable. For example, food manufacturers have sanitation requirements, some local authorities prohibit outdoor storage, etc. If the consultant was referencing anything other than idle pallets, he cited the wrong chapters.
I would respond back to the engineer that their "Sprinkler Systems Table has multiple errors and does not help to clarify the requirements. Unless this table is a review response to your design submittal. in which case I would revise my design to be inline with NFPA requirements.
1. A density of .495/2000 would require a minimum sprinkler K of 11.2 per NFPA 13 12.6.3.
2. The sprinkler spacing of 120 Sq ft is not correct for a warehouse with storage. NFPA 13-table 18.104.22.168.1 (d) when the density is greater than .25 the protection area per sprinkler is limited to 100 Sq ft.
3. The reference to 12@50 is not used with an area density method and applies to other types of design.
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