ESFR heads and light fixtures

[Woodrow57]

Reference thread184-371238. To the posters and interested parties on ESFR heads and light fixtures. I have gone through an abbreviated review on the width of fixtures and as I am travelling I don't have my standards at hand, this is a question. The width was stated a number of times as a maximum of 24" in the original thread. I also pulled up some ESFR fire testing data from Tyco as well as FMG's 2-0, 2-2 and 8-9 and a presentation by Tyco on storage sprinklers, the Tyco presentation by one of their top men was informative but also referenced NFPA 13 and the 24" width of fixtures, it also quoted the NFPA 13 2013 standard (NFPA 13-13). A light fixture (the new LED warehouse style) is 23.78" x 47.78" and is listed by all the manufacturers as a nominal 24" wide by 48" long. Is the width stated (in the NFPA 13 standard) as the longest dimension of a light fixture? If not is the typical fluorescent style (LED or not) of a 2' W x4' L nominal dimension acceptable provided it is installed as required by the NFPA 13-13 standard's clear height and distance from opposing lines, presuming it is not installed parallel to the lights? In other words, in your opinion(s) provided the light meets all the NFPA 13 requirements for distances and clearances and is 24" or less IN WIDTH, is it an obstruction? Thanks-

 

[TravisMack]

I would say if it is less than 24" and the required horizontal distance away, then it is not an obstruction.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

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[MatthewJWillis]

I do not have it in front of me, nor is it in the section relating to your question.
But I believe the 2013 edition of 13 has under the 4' obstruction rule that the width is defined as the least of the dimensions.
One could almost argue intent here if the AHJ is a listener.....


R/
Matt

 

[TravisMack]

It goes to reason that the width is the least dimension in these references. Otherwise, I would have to put sprinklers under ductwork that is 8" wide and 10' long. No one would ever consider that. But when they get these obstructions that are, for example 18"x48", people get confused. I get asked this question by guys in the field at least a couple times per month. I always use the same duct example I gave above.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

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[Woodrow57]

I appreciate the replies. I noted the width being the determining factor by some, and wish to point out that I did a Sysco project a few years ago and in the freezer the air diffusers were 32" x 48" and below the bar joists. Their insurance man and Sysco's construction PM both said that in their opinion the diffusers might obstruct roof level distribution so we had to add eight drops under units in a freezer (with drum drips) so the 48" minimum does not hold up when an authority says it is an obstruction regardless of width.

Eventually I did find an FMG detail for ESFR that shows and dimensions the fixture's width as 24" BUT the length runs parallel to the branch line in the FMG-DS and now I have to go back and re-read NFPA 13 as I believe it said that the length of the fixture could not be parallel to the branch line for their spacing.

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