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Foam 104.2 - How Foam Works

While past articles have given and listed the various components of Foam functionality, this issue will concentrate on the bottom-line of all Foam workings. Whether the Foam you use is for various materials or liquids, one set of physical concepts are at the base of the Foams successful outcome for your incident. These are best stated in four (4) words. If you grasp the concept of these ideas, your knowledge base will be able to choose the correct product, apply it properly, design a system of application that is best suited for your response, and mitigate a successful outcome to your responses.

The four concepts that sum up Foam workings are; interstitial interface limited solubility.

When we talk about “Interstitial” we are focused on the connective surface that lies between the bottom of your Finished Foam Blanket and the top surface of the hazard you are attempting to cover or suppress vapors from evolving. This space is where fire is extinguished, vapors are halted from escaping to the atmosphere, (to your exposures, environment, affected persons, and in general becoming the hazard source). It is here that the entire incident is either make or break. This surface contact space is “between” where the activating successful components of the finished Foam blanket stops further emanation of the hazard for a limited time period. Therefore, it is this area where “1/4 drain time” needs to be at its maximum length. By creating Foam “systems” for your response that maximizes this feature, reduces re-application times, provides post incident security, extinguishes combustion, halts future vaporization from the products source, and most importantly safe mitigation of your hazard product. When this is understood and completed, the emergency has ended and clean-up can begin safely.

Secondly, the term “Interface” refers to this space as it is directly connected between the bottom of the Foam blanket and the top of your hazard surface. Areas that become “plunged” or “exposed” to the atmosphere violate this area and are no longer protected by the finished Foam blanket. This can cause re-ignition and re-vaporization placing you back to square one while possibly endangering all responders that have moved into offensive forward positions to begin confining techniques towards final mitigation. Only where you have provided a pooled surface without atmosphere exposure and without sub-surface irregularities will this interstitial interface exist, and allow you to accomplish sustained smothering of the spilled hazard.

Thirdly, “limited” refers directly in this case to time length. As previously published in accompanying articles on “Foam” in our series, this can be thought of as ¼ drain time. As the Foam bubble and accompanying liquid content confine and make contact within the interstitial interface, this time length is critical for intact suppression of fire or vapors. Once the Foam bubble begins to degrade back into its normal state of a liquid, vapor suppression decreases and the danger factor increases. Therefore, this limited time is also dependent on its sister physical property of “solubility”.

Lastly, as we know from our basic hazardous materials “Technician” course, “solubility” is the percentage ability of a substance to evenly mix and stay in solution with another liquid. Most commonly in the environmental field “water” is used as the base solution. In finished Foam water plays a major role in Foam solution. This solubility affords the responder application of the suppressant Foam solution onto the top surface of the hazard. It is also the means by which the suppression will occur for this limited time frame before breakdown occurs. These four words/principles give true example to the phrase, “all things in life have balance”. This is the foundation of proper techniques and physics of the application of Finished Foam. It is this “balance” that suppresses fire, stops vaporization, and provides safety for “affected persons” and responders mitigating your incident. Keep these principles in mind when creating a Foam “system” for your Teams’ operations and your incidents will be safe and successful.

                            Haz Mat Mike

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