Rate-of-flow formulas for larger fires
There is one more statement that is true. The initial fire attack certainly controls a confined fire but it may not completely extinguish the fire. Thus more water may be needed to overhaul and extinguish the fire. This is ok. Finally Kimball discusses the issue of factor of safety. He ignores the fact that a factor of safety is already built into the Royer Nelson formula. Kimball argues that a factor of three or four to one appears to be justified. Saying that something is apparent is not a very strong argument, since what is apparent to one person may not be apparent to another.
Kimball’s statement is not apparent to me because one of the important results of the research at Iowa State University is the following fact. If too much water is applied for a confined fire, this disrupts the fog attack and creates massive thermal imbalance. There is no doubt about this since the research done by the U.S. Naval Research Laboratory produced graphs showing the creation of thermal imbalance and also showing an effective fog attack that did not. For this reason I do not believe that Kimball’s factor of safety is needed to make and effective fog attack on a confined fire.
An initial fire attack using two preconnected small attack lines does control or extinguish 75% of all structure fires in the United States. So Warren Kimball’s challenge to the Royer Nelson formula and the combination method of attack that is based upon that formula must be rejected. An initial fire attack using two preconnected small attack lines does control or extinguish 75% of all structure fires in the United States. This r.o.f. of (0.01 gpm) per 1 ft3 is sufficient to handle these fires with ease. If the fire is larger, the first alarm response can increase the flow to 500 gpm by putting a 2.5 in hand line into operation flowing 250 gpm. This increases the r.o.f. to 500 gpm or (0.02 gpm) per l ft3.
If this flow is still not enough, then the first alarm crew can place a master (heavy) stream into operation flowing 500 gpm. This raises the flow to 1,000 gpm at a rate of (0.04 gpm) per 1 ft3. AT this level, the r.o.f. is sufficient to control the largest fire possible in the 25,000 ft3 structure. For even larger fires, a 50,000 ft3 building for example, a second alarm response would provide an additional 15 firefighters and an addition 1,000 gpm flow. The total flow of 2,000 gpm provides a r.o.f. of (0.04 gpm) per 1 ft3 that is sufficient flow for a building of this size.
What is our answer to the question: how much water is needed to fight a larger fire in a larger structure? The answer is 1,000 gpm for each 25,000 fr3 in crease in building size. Another way to answer the question is to say: (0.04 gpm) per 1 ft3. As an equation the answer is:
0.04 x Vol = NFF
