Area/Density curves larger range in 1999 vs. 2010?

[arion]

Hi,

The 1999 NFPA 13 Figure 7-3.2.2.2.1 vs. the equivalent 2010 NFPA 13 Figure 14.2.4.1. The 2010 edition only ranges between 2000 and 3000 sq. ft., whereas the 1999 edition ranges up to 6000 ft. of design area. What happened to the rest?

I am currently analyzing a sprinkler system designed at .33/3300 flow and there is no information to see if the existing system is designed to support the edition of a Class II commodity because the new area density curves stop at 3000 in the 2010 edition. Why is this? I am a little confused as to what it means when you match up an existing building's design flow and the intersecting point on the area/density curve ends up somewhere not on any of the curves.

Can someone please explain what to do in cases where you are taking the existing criteria and matching them up against commodity class curves to see if the system will hold? Am I completely on the wrong path here?

Thanks!

 

[LCREP]

I can not fully recall why they cut it off at 3,000 sq. ft. I THINK it is was based on all full scale testing done back many years ago, 1970's ??? were all done with a 3000 sq. ft design area and then extrapolated to 6,000. The area density is going away, just look at FM Data Sheet 8-9, all have been removed. Everything is going to specific application or ESFR.

So what to do??,look at any graph before 2010 for the commodity and use that to determine the required density. OR recalculate the sprinkler system at 3,000 instead of 3300.

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