Are fog nozzles not the ans
First, make a progressive attack, that is, attack each room in succession, repeating the attack for each room until the entire fire is brought under control.
Second, use multiple attack lines so that each room is attacked simultaneously, or almost at the same time. This is nothing more than standard strategy for a structure fire which calls for 4 attack lines covering all 4 sides of a structure.
Third, a larger r.o.f. may be used provided one line can reach all of the fire perhaps with some movement of the nozzle.
How much water is needed to control a larger fire? Let’s take a 2,000 square foot (186 square meters) house with a volume of 20,000 cubic feet (566 cubic meters).
| Gpm x t = (Vol/1.5) | Lpm x t = (Volm/1.5) |
| Gpm x t = (20,000/1.5) | Lpm x t = (566/1.5) |
| Gpm x t = 100 | Lpm x t = 377,3 |
According to Royer & Nelson such a fire can be controlled in less than 30 seconds. Using the Iowa r.o.f. formula
| Gpm x 0.5 = 100 | Lpm x 0.5 = 377,3 |
| Gpm x (0.5/0.5) = (100/0.5) | Lpm x (0.5/0.5) = (377.3/0.5) |
| Gpm = 200/td> | Lpm = 754.6 |
The flow of 200 Gpm (754,6 Lpm) suggests that 2 attack lines should be used with each line flowing 100 Gpm (377,3 Lpm) for 30 seconds. The total amount of water needed is only 100 gallons (378,5 L). There is one catch--you must convert at least 90% of the water applied to steam.
What these examples show is how much water is needed to make a balanced fire attack. This phrase means that you must balance the heat absorbing power of water (steam) with the heat releasing power of a fire. By doing so, the thermal balance that existed before the attack will be restored quickly after the attack, but at a much lower temperature level. The principle governing a balanced fire attack has been stated by Bill Nelson as follows.
“In principle fire fighting is very simple. All one needs to do is put the right amount of water in the right place, and the fire is controlled”.
Notice that Nelson says that the principle is “very simple”. In fact, the tactics needed to put this principle into effect are simple enough as well
What is the right amount of water? The right amount, of course, is determined by the Royer Nelson formula. Where is the right place? It is the center of the fire where at least 90% of the water applied will be transformed to steam.
Perhaps we should add to Nelson’s principle the phrase, “in the right way”. The right way means that a fog nozzle must be used widening the fog pattern so that the stream just reaches across the room. In addition the ideal flow rate must be selected so that the water is distributed throughout the fire area in a few seconds. Finally, the nozzle must be shut down immediately when the flames are gone. So we may change Nelson’s principle by adding the following phrase.
In principle firefighting is very simple. All one needs to do is put the right amount of water in the right place in the right way with a fog nozzle, and the fire is controlled.
Truly Nelson’s principle is the most profound statement that has ever been made about fighting fires. Together with the Royer Nelson formula we can answer the question
How much water is needed to control a confined structure fire?
The answer is: surprisingly little water for fairly large fires. All one needs to do is transform liquid water to steam, and that is simple enough in principle and in actual practice.
