Are fog nozzles not the answer?
In previous writings, Fredericks has claimed that neither Layman nor Royer and Nelson, in any of their writings, specifically addressed the issue of the impact of steam on trapped occupants. After reading Layman’s ATTACKING AND EXTINGUISHING INTERIOR FIRES, Fredericks discovered that Layman did indeed discuss this issue. (See p 148). Layman said that he had been asked frequently two questions. One was: “What will be the effect of steam or fog on persons trapped in the structure?” Layman answered that “we can only state that we have never heard of any adverse effects.” Layman continued:
“Contrariwise, the much more rapid flame suppression with indirect application makes it possible to reach endangered persons more quickly so as to be able to remove them to safety and render aid as necessary.”
Amazingly enough, Fredericks claims that “this statement” does not specifically address the impact of steam exposure on trapped occupants. Once you are confronted with the truth, I suppose that it is hard to admit that you are wrong. I think that any reasonable person would agree that both of Layman’s statements specifically address the issue in question. In fact how could you make a stronger statement. Layman said that he had never heard of an adverse impact. What more do you want?
Fredericks continues to claim that insofar as Royer and Nelson’s writings are concerned, that there is no mention of the impact of steam on trapped occupants. Even though Fredericks cites Bill Nelson’s book, QUALITATIVE FIRE BEHAVIOR, apparently he had not read all of it. On p. 109 is a section whose title appears in red and in caps
EFFECT OF EXPANDING STEAM
In this section Nelson specifically addresses the issue of people trapped in the building. I will not quote the two paragraphs in this section, only the conclusion.
“In other words, immediate application of proper rates of flow of water can help occupants trapped in the building rather than endanger them.”
Here we have a statement equivalent to Layman’s “never any adverse impact.” If Fredericks is looking for an issue to force the abandonment of fog nozzles, he won’t find it here. Both Layman and Nelson state that fog nozzles are far superior in their ability to handle the top priority for any fire department.
Fredericks fears the effect of steam upon trapped occupants because I think that he does not understand one critical scientific fact about fighting fires. This fact is what is commonly called the Latent Heat of Vaporization of Water. This is not a good name because the phrase “Latent Heat” indicates that heat is a substance of which there are two types: (1) sensible heat that we can feel; and (2) latent heat that we cannot feel. Heat is not a substance, so there cannot be two kinds of something that does not exist. The correct scientific name is “The Enthalpy of Vaporization of Water.”
