15. June 2012 07:44
Hey FireIce bloggers. You are the Chief of a rural fire department and you were just toned out to a motor vehicle fire. You, your District Chief and your engine company of 2 firefighters are responding.
Upon arrival you find a 2000 Ford Expedition with heavy fire coming from the engine and passenger compartments. The vehicle is 20’ from a structure…
During attack you find the engine compartment has magnesium components in it as it starts to explode with sparks…
What Do You Do?
FireIce instructor's synopsis is below…
Upon arrival the firefighters attacked the vehicle fire with a 1 ½” pre-connect. Upon discovering the magnesium components in the engine compartment the firefighters went defensive and began to protect the structure. The Chief pulled a 2 ½ gallon pressurized water extinguisher loaded with FireIce and attacked the engine compartment fire with magnesium…
Here are the quotes from the Chief on scene:
“There was none of the usual sparks or small explosion associated with putting water on the fire.”
” The FireIce gel coated and cooled the magnesium as soon as it made contact with the fire.”
“All in all great product can’t wait to use until we can try it on a larger scale like a house fire.”
The District Chief quoted:
“FireIce did exactly what we have seen in the videos.”
“Then it was used on the rest of the interior and put down all the smoke and steam within seconds.”
“Great Stuff, it’s always better to see it in action on a live burn rather than a controlled environment conducted by the seller.”
Many of you said to use foam, but why?? Whether it’s wet foam or dry foam what are you achieving??
Faster knockdown, better cooling abilities, better suffocation??
Here is what foams definition of Heat Resistance: Foam's ability to resist the actual heat of the liquid or surface on which it is applied.
The Firefighters Guide to Foam by National Foam: Rates its AFFF’s heat resistance ability as fair (page 7).
What happens to foam when absorbs heat? Does foam displace heat?
Let's take a moment to look at how foam works and what it can do and CANNOT do.
When foam concentrate is mixed with water, whether you are using a Class A or B product, its main action is to break the surface tension of the water. Thus, the water becomes "lighter" (hence the term "light water"). The principle theory behind Class A foams is that the reduction in surface tension (or separation of the molecular structures of water through adding a surfactant) will allow the water to "penetrate" into tiny cavities, like cracks, crevasses found in porous materials.
By making the water lighter with a Class B product, it allows water to float across the top of hydrocarbon fuels (which normally have a lower specific gravity than water alone). Once the finished foam product is on top of the fuel, the surfactant is then released from the mix, creating a film which covers the fuel and separates it from the oxygen available in the ambient air. This action works very well and I am certain will continue to be a great asset to the fire service for fighting flammable/combustible liquid fires.
What can foam NOT do?
First, with its mediocre heat resistance, it has a hard time standing up to extreme temperatures for any length of time. Even if we aerate the mix, we have to be cognizant of how high heat will affect the finished product. Finished (B) foams are laden with air bubbles to "lighten" the water. What happens to heated air? It will have a drastic increase in molecular activity and will expand, causing the bubbles to burst.
Secondly, if using Class A foam, you cannot "penetrate" a non-porous material (i.e.-solid steel or magnesium). The product will simply run off the fuel.
So.....we are fighting a magnesium engine block fire. It is non-porous AND produces very high heat! Can we put out magnesium with water or foam? Yes, but only from a great (safe) distance and using COPIOUS amounts of either agent. Foam or water will run off of the block easily and will rapidly vaporize under the intense heat.
FireIce is a water enhancer! It will: A) stick to the block and allow more heat absorbing water molecules to continue to "stack" on top of itself, absorbing the heat at a faster rate and for a longer period of time and B) allow us to be closer to the burning product without the explosive effects of applying water to burning magnesium. FireIce will also "coat" the burning block, excluding ambient air from the combustion process…
By Rob Rosovich, Fire Protection Engineer