Multi-Class Aggregate Areas for High Piled Storage? 1

[arion]

Hi,

According to the 2010 CFC, this is the definition for High Piled Storage:
HIGH-PILED COMBUSTIBLE STORAGE. Storage of combustible materials in closely packed piles or combustible materials on pallets, in racks or on shelves where the top of storage is greater than 12 feet (3658 mm) in height. When required by the fire code official, high-piled combustible storage also includes certain high-hazard commodities, such as rubber tires, Group A plastics, flammable liquids, idle pallets and similar commodities, where the top of storage is greater than 6 feet (1829 mm) in height.

And this is the definition for Multi-Class aggregate areas:
2306.3.2.2 Multiclass high-piled storage areas.
High-piled storage areas classified as Class I through IV not separated from high-piled storage areas classified as high hazard shall utilize the aggregate of all high-piled storage areas as high hazard for the purposes of the application of Table 2306.2. To be considered as separated, I-hour fire barrier walls shall be constructed in accordance with the California Building Code. Openings in such walls shall be protected by opening protective assemblies having a I-hour fire protection rating.

Given these 2 definitions, I would like some advice on the following:

Let's say a warehouse owner wants to put some runs of storage rack up. They decide to stock High Hazard Group A Plastics up to 6 feet on the lowest level of the rack. They then stack the racks above 6 feet with Class I-IV commodities (let's say up to 13 feet). Is the array required to protect Class High Hazard or Class I-IV according to Section 2306.3.2.2? It seems at first glance that it would be Class High Hazard according to the definition of Section 2306.3.2.2, but if you look carefully, it says "classified as high hazard". Since the bottom load does not exceed 6 feet, couldn't one argue that the High Hazard Group A Plastics are not actually classified as Group A Plastics after all, since they are under 6 feet in total height, and we can therefore use Class I-IV protection requirements?

I am a bit mixed here because we are still mixing Class High Hazard with Class I-IV commodities, and the effective overall height of the commodities is in fact 13 feet.

Any thoughts on this?

Thanks!

 

[cdafd]

did you look at 2303.7.4? titled limited quantities of group A

and 2304.1 and 2304.2

 

[arion]

Hi cdafd, thanks.

Yes, but I was more concerned about flammable and combustible liquids, which are still high hazard, not Group A plastics. It would be nice if they had a table like 2303.7.4 for F/C liquids.

Thank you

 

[cdafd]

Away from the book, but looks like you would have to look at the flammable liquid chapter for protection and design first

You might be in a H than and the game plan changes

I think you have to many variables to do a what if

 

[stookeyfpe]

Pick the highest hazard commodity and base your fire protection design on the greatest hazard. It's not that hard.

 

[pierrepaul]

Following NFPA 13, one definitely needs to take the highest hazard commodity within the rack and dimension sprinkler protection accordingly.
Regards,
PP
sprinkler engineering