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ESFR System - In this case I suppose I calculate 3 heads per line for 4 lines?

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SprinklerDesigner2

Mechanical
Nov 30, 2006
1,251
I knew three heads per line for four lines would get your attention.

I am pretty sure I can do this, 99% sure, but whenever I have any doubt I like to check with those here.

I have an existing 100'x120' bent metal purlin building that is fully sprinkled using K8.0 pendent sprinklers which was installed about 35 years ago.

It's your typical bent metal purlin building and the peak happens to be exactly 30'-0" AFF. The original contractor installed his branch lines parallel with the purlins running 2" lines just above the rigid frame hanging from the top lip of the purlin. 2" branch lines with 3 heads per bay spaced 8'-4" apart, 4" far main, 6" near main and 6" riser. System is supplied by a 1,500gpm fire pump and I have plenty of pressure to work with.

There is a full height wall separating the rack storage bay from the rest of the building which is used for manufacturing product. This wall has a single 14'x14' opening at the south end so we have a 12' baffle and the closest rack to this opening is 25' distant. The wall is your typical 8" girts with insulated siding you find on any metal building of like construction.

ESFR_3_hds_per_line_copy_wzerca.jpg


The end 25' bay is used for rack storage to 20' and the owner was told to install in-rack sprinklers which, if you saw the rack system, is problematic. Just the way they operate we'd be there every three days repairing heads the forklift operators whacked.

I check and all I need to do is replace the heads with K16.8 pendants in the rack storage bay. I did the calcs @ 42 psi I have a solid safety factor even though I am dealing with 2" sch. 10 lines.

I don't see a problem calculating the three heads on the line for four lines.....

I suppose I could rip out the rack storage bay and install lines perpendicular to the purlins so I would have three lines..... with three lines I could calculate four heads per line but what would be the point?

In this scenario I really doubt there is a problem but something little is nagging at me and I like being 100% sure.

What say you all? Would you do three heads per line for four lines?
 
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As long as the full height metal wall does not allow the heat of fire or at least delay it (12' lintel or draft curtain above door if I got you right, seems more than enough), I would say you are just fine.
 
UFT12,

I should also add the wall opening is at least 20' away from the nearest rack or storage.

Funny thing is if the lines ran perpendicular to the purlins, so there were three lines in the bay, I wouldn't think twice about it.

Something about this just wants to make be double check.

 
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