Firefighters in many places have embraced the use of “wetting agents” as part of their everyday operational tactics. In order to be more efficient in their work of distinguishing fires, they have recently started adding certain chemicals to the water. This results in breaking down the surface tension of the water, thus making it a “wetter” liquid.
These chemicals cause the outer surface or “skin” of the water to break with greater ease, and in this manner also permits the water to penetrate into objects more readily. The principal value of water in extinguishing a fire is its cooling effect. Cooling is obtained largely by absorbing heat from the burning material, and the major part of this takes place when the liquid is turned into steam vapor. The mass of water that actually contacts the burning material is what really counts, and wetness usually increases this area of contact, and, consequently, the rate of heat transfer.
The Underwriters Laboratories Inc. (UL) Directory defines wetting agents as: “liquid concentrates which, when added to plain water in proper quantities, materially reduce the surface tension of plain water and increases its penetration and spreading ability.” Water to which a wetting agent has been added to is sometimes referred to as “wet water” because of its increased ability to wet surfaces it is applied to.
So far, we know that water becomes “wetter” by lowering its surface tension. The surface tension of water defines its behavior. By making the water wetter we benefit economically because we maximize its efficiency, thus we need less water to put down fires. On top of it all, the wetting agents are biodegradable and pose no risk to the environment and living things.
Sources: Fire Engineering, International Fire Protection, Direct Chem
