Class “A” (foam) is an incorrect term. Class “A” (Wetting Agent) should be the correct one. This is because operational personnel need to delineate the marked difference between classes “A” and “B”. This is akin to referring to all automobiles as “cars”. We know they are all transportation tools, but designed for quite different applications. You would not use a small vehicle to transport large amounts of equipment.
Class “A” Wetting Agents are degreasers designed to reduce surface tension of organic substances so that they can allow the water to “soak” in to these materials reducing the temperature and extinguishing the flames. Class “B” Foam uses the advantage of water surface tension to float across liquid surfaces forming a uniform blanket of finished Foam that also cools surface temperature but mainly provides a smothering affect extinguishing the flames and suppressing future vaporization of the hazardous product.
Herein lays the difference, these are two (2) opposing forms of chemistry that have opposite uses. Once this concept is firmly implemented into your response group, choosing the correct product to attack your hazard becomes simple!
Another factor to include in your operational program is one characteristic of “wetting agents” that is often over-looked. Since these liquids have degreasing properties, it is imperative that you appreciate these liquids are drying out your equipment. After use “re-lubrication” to your pump components, valves, nozzles, and any other appliance that the wetting agents flow through is imperative! Just like any tool, your equipment must have the proper lubrication to continue to function without damage. This is a separate subject that needs careful consideration by you and your equipment maintenance personnel.
If you use great amounts of these products, such as wild-land firefighters do, it behooves you to research these issues closely! Be proactive so that your equipment does not fail on you leaving you unprotected! Develop good relationships with your equipment maintenance staff and regularly discuss and refresh over these needs.
Class “A” wetting agent frequent use by your department should encourage you to have a vigorous relationship with your maintenance staff. Be sure that they too, understand the ramifications of continual use of these “wetting agents”.
The benefits of wetting agents can be seen in the “Foam 108 Class “A” Wetting Agents” article located in the left side-bar archive section of this website. They are numerous and useful as long as “you choose wisely” for the application needed.
Haz Mat Mike