We cannot complete our journey through Foam and Foam 0.2, without a look at the important concepts to remember. These are;
2] Extinguishment process
3] Vapor suppression
The chemistry of Foam use and its Physics are the most important to remember when choosing a system to adopt into your department responses. This is that the two opposite concepts of chemistry, one to float across the surface, and one to reduce surface tension, cannot both be effectively and safely used on different fire situations. When your organization is approached by the economic community representing the sale of these modern marvels, they should be scrutinized with a wary eye. What one principle favors, may dis-favor safety or personnel security.
Whether you desire extinguishment of fire, or vapor suppression of hazardous material fumes/vapors, these two emergencies require a separation of the fuel source from the flame, or the vapor from the atmosphere. In both cases, a Foam blanket, or barrier is the only way to halt the combustion or vaporization process. Dispersal, encapsulating, or dilution only cures the symptoms and not the disease. In these cases, you will wind up with a greater environmental hazard or lesser personnel safety for on-site responders, or in most cases, both! A successful extinguishment does not include a re-kindle due to an improper chemistry approach.
Lastly; vapor suppression includes combustion as well as hazardous material mitigation. In the case of combustion, blanketing separates the burning surface from the fuel source thus extinguishing. In the case of vaporization, eliminating the formation of toxic vapors shall allow for; in-place sheltering without the transportation issues with a full evacuation, lowering of toxic exposure and contamination of “affected” civilians, reduction of contamination to nearby environmental concerns all the way from personal Pets to local fauna and flora for quite some distance.
By using class “B” low/medium expansion concentrates and equipment techniques you can eliminate fire and hazardous vaporization. With class “A” agents, you can de-escalate wild land fires and reduce urban combustible destruction. You cannot do both with one. Each of these demonstrates this opposing chemistry and is why the NFPA has separated the Foam classes. Each one gives you the data to make the correct choice after reflection. These tools give you the ability for safe and successful incident mitigation.
Haz Mat Mike