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jkirchner (Electrical) (OP)
8 Jun 11 17:57
we store computer chips, ICs, semiconductors, resistors capacitors etc.  we are considering a warehouse/storage area that is 10,000 sf with an OH2 sprinker.  We have 10' boltless shelving.

material chips are stored in plastic tubes or plastic reels which are placed in a cardboard box. each bay has 6 shelves. Each shelve holds 50-60 lbs of material (shelves rated to 260lbs).  

My question: is an OH2 NFPA 13 (2007 ed) sprinker design the right system for such a storage area?

thanks
pipesnpumps (Mechanical)
9 Jun 11 0:04
Short answer: NO

If the plastic tubes are <15% by weight and <25% by volume then that is cartoned class IV commodity.

If the % of plastic is greater, that would be considered Group A non-expanded plastic, cartoned.  

Even if it meets Class IV commodity definition, you can NOT use miscellaneous storage, because the storage area is >4,000 ft2 and likely >10% of building area (either triggers non-miscellaneous req'ts)

I am using 2002 version (what I have at home), so I'll forgo the citations, but using the fire control approach (area/density) for Class IV commodities, curve reads 0.305 gpm/ft2 over 3,000 ft2.   Reduce the density by 40% for 12 ft or less storage height = 0.305*0.6= 0.183 gpm/ft2 over 3000 ft2 required which is more than OH2 (0.17@3000)

That said, if you used high temp sprinklers you could use 0.17 gpm/ft2 over 3000 ft2 (which is OH2).  All that is assuming the plastic is <15% by weight or <25% by volume.

If the plastic is above these thresholds, then for cartoned non-expanded Group A plastic, shelf storage, is either 0.3, 0.5 or 0.6 gpm/ft2 over 2500 ft2; depends on roof height.  >15 to 20 ft roof is 0.5 gpm/ft2.




 

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.  

jkirchner (Electrical) (OP)
9 Jun 11 14:11
thanks pipsnpumps, this information was just what I was looking for.
 
TrippL (Mechanical)
9 Jun 11 15:13
Have you considered using a clean agent system. Would think this would be more appropriate for computer component storage if the budget allows for it.
Haldorson (Mechanical)
9 Jun 11 22:55

Pipenpumps, in NFPA 13 (1999) 7-2.3.2.2 it reads that for protection of "miscellaneous storage, miscellaneous tire storage, and storage up to 12' in height, the discharge criteria in Table 7-2.3.2.2 shall apply".

In Table 7-2.3.2.2 it declares Class IV commodities up to 10' in racks designed to OH-2 to be compliant.

Does the fact that they added "storage" to "miscellaneous storage" in this instance relieve us of having to comply with the limitations of "miscellaneous storage"?  
pipesnpumps (Mechanical)
9 Jun 11 23:54

I can only speak to the 2002 version I used to answer the question.

Misc storage is defined as >4000 ft2, OR >10% bldg area, etc.
I agree it is confusing what is misc and what is not.  Storage is always hairy.

I like the way they arranged it in 2007, it is easier to read.    Storage changes every version it seems.   It would not surprise me if 1999 allows OH 2 but the way I read 2002 it uses it's own set of curves for non-misc storage that were higher than OH2 for class IV, except taking high temp head reduction.   That's the best I can say.
 

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.  

stookeyfpe (Specifier/Regulator)
10 Jun 11 0:53
I don't want to piss in anyone's mess kit but this entire discussion fails to address the formulation of the plastics. Most every manufacturer uses Class B or C plastics in electronics after the toaster oven fire events in the 1990s. A large, eloquent boxer named Foreman lost over $11 Million because of fire safety litigation.

I feel comfortable saying that all of the plastics haven't been correctly evaluated. More work with calorimeters is needed.

Until that is done, everything is Group A. No need to speculate. However, talk to UL, FM or ETL because they may have the data you need to lower the commodity classification.


If they share it is another matter.

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