Are fog nozzles not the ans
The second scientific fact that is the foundation for the Royer-Nelson Formula is the following information. In 1955 the Factory Mutual Laboratories determined that one cubic foot (28,3 L) of pure oxygen combined with ordinary fuels produced 535 Btus (0,564 mJ (megaJoules)). Air contains 21 percent oxygen, and flame production stops when the oxygen level falls below 15 percent. Therefore
| 21 – 14 = 7 |
Only this amount of oxygen, 7 percent of air, is available for flaming combustion. Multiplying this number by the Btus (mJ) produced by a cubic foot (28.3 L) of pure oxygen gives
| 535 x .,07 = 37 | 28,3 x ,07 = 0,0039 |
37 Btus (0,0039 mJ) is the amount of Btus (mJ) produced by one cubic foot (28.3 L) of air. Because one gallon (3.785 L) expands to more than 200 cubic feet (5.669 L) of steam,
| 37 x 200 = 7,400 | 0,0039 x 5.669 = 7,8 (mJ) |
Since one pound of water absorbs 1 btu/lb to raise the temperature 1° F, one gallon (8.34 lb) absorbs 150 btus if the temperature is raised from 62° F to 212° F. At 212° F one pound absorbs 968 btus/lb to steam, and 1 gallon absorbs 968 x 8.34 btus, or 8,072 btus/gallon. Thus one gallon (3,785 L) converted to 200 cubic feet (5.669 L) of steam absorbs 9,330 Btus (9,84 mJ). Since 7,400 < 9,330 Btus (7,8 < 9,8 mJ), the conclusion is that one gallon (3,785 L) is capable of absorbing all the heat produced by 200 cubic feet (5.669 L) of air.
It is truly remarkable that both scientific facts converge on the same number. These two facts provide a solid foundation for the validity of the Royer-Nelson formula.
What was known quantitatively was largely in the area of combustion engineeringThe creation of the Royer-Nelson Formula is certainly a notable achievement in the history of the fire service. From our point-of-view today, what they did may seem to be quite simple. It is true that the expansion ratio of 1/1,700 was widely known in the 1950s. However, at that time very little was known about fire behavior in structure fires. What was known quantitatively was largely in the area of combustion engineering. So when most of the quantitative and qualitative information needed was unknown, the creation of the Royer-Nelson formula stands out as a significant achievement in answering the question
How much water is needed to control a confined structure fire?
