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I'm laying out the fire sprinklers for a building where the architect has used the IBC exception in Section 403.2.1.2 that requires sprinklers to be installed at the top and alternating floor levels of a vertical shaft. This reduces the required shaft enclosure to be 1-hour for highrises up to 420 feet.
NFPA 13 doesn't seem to address this specific arrangement. I've looked and I'm not finding any installation requirements. I have concerns with just putting sprinklers in the shaft. What's the best type of sprinkler for this? Should they have water shields? Should I have concerns for obstructions? Any guidance would be greatly appreciated, thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
10 Comments
Pete
8/20/2021 06:34:40 am
I think it might be mentioned in NFPA 13 8.15.2 (2016 edition.)
schulman
8/20/2021 08:12:06 am
linen and trash chutes ? .... NFPA 13 Ch. 22 maybe ?
Matt
8/20/2021 08:15:24 am
I don't know if the guidance of NFPA 13 8.15.2 would apply here. This would be an application in excess of NFPA 13 minimums.
Glenn Berger
8/20/2021 08:19:20 am
Matt has it right! More information is required to provide good guidance.
Jesse
8/20/2021 08:19:33 am
Vertical shafts are covered in 2016 NFPA 13 Ch. 8.15.2
Kenneth Casey Milhorn
8/20/2021 09:08:43 am
Besides the info in Chapter 22, just applying some common sense, I wouldn't think water shields wouldn't really do a whole lot to help heat collection, but could maybe help protect from mechanical damage if someone is doing maintenance on something in the shaft. Just like in trash and linen chutes, the alcove or shield provided is more to protect from mechanical damage or collection of trash/linen. Dangerous to assume, but I would think a pendent head, with guard and shield, stubbed 6 inches into the shaft on alternating floors would meet the intent, but that's just my opinion. It would be interesting to see if any fire testing has been done to prove the reduction in rating based on sprinklers in the shaft. I would feel very confident that that many heads in basically what is a chimney, will activate quickly and flood that shaft. The most difficult part of it might be trying to find a clean entry point into the shaft that is free of mechanical equipment.
Franck
8/20/2021 02:51:28 pm
Just one additional comment regarding the water shield: they won’t be beneficial at all to collect the heat (many studies have demonstrated that even larger plates above the sprinkler has limited added value), but would prevent water from above sprinklers to wet the thermal element and delay the sprinkler activation (just as for in-racks). In a vertical shaft, there are high chances that the top sprinkler will activate first. Sprinklers at lower levels would only be required in case of dramatic fire to avoid a possible lateral fire spread at lower levels. Thus the “umbrella” (water shield) to avoid a delayed activation.
Franck
8/20/2021 02:53:38 pm
As indicated above, more info is needed, in particular regarding what is expected in the shaft : cables, trash, linen, nothing…)
Alex
8/21/2021 09:56:13 am
HI Anonymous,
Shawn G
8/23/2021 08:49:08 am
The shafts vary in size and purpose, but in general they are mechanical shafts that will not be accessible. There are openings from floor to floor that vary in size, but many of them have openings roughly the same size as the interior of the shaft. Leave a Reply. |
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