NFPA 13 Obstruction in ESFR protected warehouse

[fennecbe]

I have a question I could not find any answer in the NFPA 13.
A large storage building has a roof constructed of a very large beam which supports other beams. These beams supports the roof.
The main beam is very large (1 ft large and 6 ft high) and as result is in the flew space between the racks. Beam is about 30 cm (1 ft) large and the distance between the beam and the storage is about 10 cm (4 inch).
The storage goes about 1/2 of the hight of the main beam or 1 m (3 ft)
ESFR sprinklers are correctly installed on the roof and meet all specifications of NFPA 13.
I think (even nothing is mentioned in the NFPA 13) an additional sprinkler has to be installed under the beam. Reason: obstruction, too small space between beam and storage, flew space between rack under the beam is 1 ft and 8 inches or much too large, ...

What do you think about this?

 

[cdafd]

no would not require a head at the bottom of the beam

You basicaly have a draft cutain, whcih is more of a problem.


also, i would go back to the manufacter's sheet for the esfr and nfpa 13 for esfr and question you almost have storage to close, as in normaly I think it is three feet.

I am thinking the storage below the beam needs to be lowered????


Roof Construction
Unobstructed or obstructed construction; for example, smooth ceiling, bar joists, beam and girder, and so forth.
Where the depths of the solid structural members (beams and stem, for example) exceed 12 inches (302 mm), install ESFR Sprinklers in each channel formed by the structural members.

 

[fennecbe]

Thanks

The large main beam can not be considered as a draft curtain because above are other secondary beams. Heat and smoke can pass between two beams (See attachement).
Distance between 2 secondary beams is almost 20 ft or 6 m which allows exactly 2 lines of ESFR sprinklers. Distance between sprinklers and top of storage is between 5 and 7 ft depending of the roof slope.

For me question remains open. Do you have any other idea?

Thanks

Patrick
Belgium

 

[Cidona]

Fennecbe, I don't know from your post what if any levels of protection you are providing within the racks and I'm therefore an bit unsure of the obstruction you are wanting to overcome. However, if your flue space is 1'-8" it would seem you are in excess of NFPA flue requirements and are therefore operating outside the Standard. Would seem in order to comply with the Standard (without knowing the project details can't tell exactaly), you would have to (a) treat them as separate rack, in which case you have aisle width issues or (b) you install horizontal barriers so you are not requiring a flue space. Not sure if you were planning protection on all levels, if not option (b) would be more expensive but would get to keep clients aisle widths.
Such deviantion from the speced design criteria would have to be ok'd with the original specifier.
Or maybe I missed the point completly

 

[fennecbe]

Dear cdaft,
Dear Cidona,

Thanks both for your help.
I could suppose we are outside the standard.
What do you think of the addition of a sprinkler under the main beam?

IF this is a solution whcich kind of sprinkler?
The same ESFR as on the roof (included in the 12 + 2 sprinklers or not?) or another fast response? (Water density could ba a problem)

Thanks

Patrick
Belgium

 

[Cidona]

Sorry fennecbe, once dealing outside of the Standard I am of no use to you.
May need to forget the top layer of storage so the flue space can reduced in width to conform with NFPA as cdafd suggested or concider option a and b I mentioned or hire an FPE.
Good luck.