Michael Hazell

Do we already have a solution for high-challenge warehouse fires?

Blog Post created by Michael Hazell Employee on Mar 25, 2010

This workshop has come and gone, but I would like to comment...anyway.
According to statements made in the Annex to NFPA 13, "control-mode" sprinklers are capable of returning temperatures in a high challenge fire to ambient in 30 minutes without fire department intervention utilizing the concept of "pre-wetting".
The data from the five large-scale tests sponsored by the National Fire Protection Research Foundation (NFPRF) in 1997/1998 demonstrates that the statements included in NFPA 13 are correct (although technically the sprinklers used in these tests were not "control-mode" sprinklers).
Given this, it is my opinion that we already have a solution to the issue which the Research Foundation is interested in investigating. The NFPFR large-scale tests contain a treasure of useful data which is applicable to the issue being discussed above.
Note that the "control-mode" sprinklers which are utilized today are far better than the old "link and lever" sprinklers used in the high challenge fire testing back in the 1970's. Hence, the performance of new sprinklers should far exceed that of the sprinklers manufactured 30 years ago. This means that the densities and areas of operation presently included in NFPA 13 for high challenge fires are conservative.
The NFPRF tests back in 1997/1998 indicated that the sooner the first and second sprinklers operate over a fire, the better the performance of the system. In Tests P-4 and P-5, only 5 sprinklers and 7 sprinklers operated respectively. Note that the density used in these tests was 0.50 gpm/SF, rather than 0.60 gpm/SF. If the minimum required density had been used, it is likely that the sprinkler system would have performed even better than it did in these two tests.
Richard Schulte
Schulte & Associates