Are fog nozzles not the answer?
Discounting the error of limiting Thornton’s Rule to laboratory “findings”, this does count as a concession. I think that Fredericks is aware of this because he immediately shifts the argument to “other factors”. He then claims that these other factors suggest that “the dangers faced by fire fighters have increased dramatically in the past 50 years”.
The “other factors” that Fredericks lists are identical to those listed by T.T. Lie in his article “Fire Temperature Time Relations” in the SFPE Handbook on Fire Protection Engineering. He states that the intensity and duration of a fire in buildings can vary in a wide range as much as 50% from the most probable prediction. He says that it is not possible to predict the temperature course of a fire in a building. This uncertainty is created by parameters that change with time. He lists the following parameters.
- Amount of fuel surface area
- Arrangement of fuels
- Wind (direction, velocity)
- Fire load
- Ventilation
- Thermal properties of bounding materials
T.T. Lie states that it is only possible:
“to indicate the time-temperature curve with reasonable likelihood that will not be exceeded.”
Thus we are faced with scientific uncertainty in contrast to Fredericks certainty that there has been a dramatic change within the past 50 years.
The Standard Fire Curve used in North America (Canada and the United States) has been in existence since 1918. Engineers use these parameters to calculate time-temperature curves. These curves closely resemble the standard fire curves that have been used for years to test the fire resistance of various materials. The Standard Fire Curve used in North America (Canada and the United States) has been in existence since 1918. This curve has been adopted by the ASTM, the American Society of Testing Materials, and has been used for almost all fire resistance testing since then.
So there is no indication from any of this engineering work that there has been any dramatic change in fire behavior that would justify changing or modifying the standard fire curve. It is certainly true that scientific uncertainty was greater 50 years ago than it is today. As more engineering research is completed, the ability to predict fire behavior will increase our scientific certainty. This is just the opposite of what Fredericks claims.
