Fighting Fires with “Wet” Water
Fire fighting has emerged triumphant from its fight with the gods of war and, in fact, its victory has been so complete as to advance the science of fire fighting a decade. For example, only a few years ago it was not generally believed that water-fog, chemical and mechanical foam and carbon dioxide could be so effective in combating oil and gasoline fires on the high seas. However, true science can never stand still and by scanning the horizon very carefully now, we may possibly be able to detect some indication of additional advancements in fire fighting. Searching very thoroughly, we do find something that may possibly be our new wonder— namely, wet water.
The term “wet water” definitely sounds like a contradiction because water certainly seems wet enough to the unfortunate fireman who happens to get a soaking on a cold winter night. It is true that water is wet enough for general fire extinguishing, but it is also true that there are a number of cases where water is not wet enough. For example, water is generally incapable of penetrating into a smoldering bale of cotton and, strangely enough, such fires have been successfully conquered with kerosene due to its better penetrability.
Water has two properties that are an index of its wetness, namely surface tension and interfacial tension. It is surface tension which makes it possible to float a needle on the surface of a glass of water. A drop of ink falling on a blotter illustrates interfacial tension. By simply adding a chemical wetting agent called aerosol to water, we reduce both surface and interfacial tension.
In fire fighting, wet water will penetrate into a burning cotton bale and extinguish the fire. It is similarly effective on fires in mattresses and other materials difficult to wet, and on brush fires. Another interesting phenomenon is the fact that wet water, with its reduced tension, will give a finer fog than untreated water when discharged through a fog nozzle at a given pressure. It is generally recognized that the more finely atomized water fog is, the greater is its capacity for cooling.
It seems possible that after further experiments, wet water may become an accepted fire fighting agent for certain hazards. Incidentally, it is interesting to note that aerosol wetting agents have many additional uses in industry, such as in the processing of rubber, paints and printing inks, paper, metals, pigments, glass, leather, petroleum and petroleum products and in dry cleaning, flame proofing, ore dressing, moth proofing, cleaning of fruits and vegetable and in the preparation of adhesives.
