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how foam..............work
Replies to This Discussion
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Permalink Reply by Alex Sharp on
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It depends on what type and how you are introducing your foam. If class A, we are able to select in .1% increments up to 1%. For structure fires we usually use .3% - .5%, for wildland fires we usually use .3% for fighting and .5% for mop up. We have a built in proportioner and we just set the percent. It doesn't matter if we flow 10gpm or 400gpm we still get our selected % of foam.
For class B foam I have only used 3% - 6% foam. Then we use 150ft. with the eductor after the first 50ft. section. I can't remember the gpm rate for that though.
If you could clarify what type and what type of system you have to get the foam in the water that would help.
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Permalink Reply by Andrew Salinger on
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The 2 types of foam do different things and are used on different types of fire. Class A foam is a wetting agent that soaks into A class type fuels such as timber
Class B foam sits on top and doesn't soak in and smothers the fire, used in petrochemical and flammable liquid fires
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Permalink Reply by Brandon Guttery on
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Class A foam breaks down the surface tension of the water which creates smaller droplets allowing the water to penetrate better (Called a wetting agent) we use it at .01%
Higher concentrations tend to create christmas but the fire can continue to burn under the blanket of foam. This can be dangerous because the fire can spread under the blanket, if hides holes and roots on the ground and if you walk through the foam and the fire is still burning underneath making you somewhat hotter very quickly.
Stay safe out there
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Permalink Reply by Pararescue on
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"Wet Water" http://www.ecki.com/vst/prdt233.htm
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Permalink Reply by FETC on
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That is an easy answer. 1% foam would be 1 gallon of foam and 99 gallons of water regardless of what type or kind of foam is used.
1% is 1%...
BTW: they make 1% class B foam, and fuel burning under the foam blanket?
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Permalink Reply by Mike Schlags (Captain Busy) Retd on
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FETC, as always, for this kind of technical knowledge, you are consistently the go to person that provides short, concise answers to the myriad of questions that folks here on the FFN present. For myself, the primary focus and reason I participate on this site is to provide assistance for others and to associate myself with professionals like yourself. I look forward to someday actually being able to meet face to face and others when I do a cross country driving trip this coming summer.
TCSS, Bz
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Permalink Reply by Alan McGuigan on
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As someone mentioned your best bet is to discuss this with your supplier they should be able to help you out. There are different types of foam, foam systems and applicators
Depending on your equipment application and what you’re trying to achieve will determine how you should apply the foam. Foam can do the following depending how it’s applied
1. Breaks the water tension and allows the water to penetrate into the fuel source, in between boards etc.
2. The foam creates bubble the bubbles create more surface area allowing the water/ foam to absorb more heat energy being produced by the fire a wet foam standard class foam using a standard system is about five times more effective than straight water a dryer foam let’s say from a compressed air foam system is about 15 to 20 times more effective than water
3. Foam also ads in providing a barrier to protect adjacent structures the dryer the foam the more it will stick to the wall this basically creates a wall between the fire and the structure your trying to protect The bubbles adsorb the radiant heat protecting the structure
You also have your AFFF aqueous film forming foam this foam it creates a film barrier let’s say on a fuel spill it prevents the vapors produced by the fuel from escaping as the bubbles break down they continue to replenish the film which is lying on the fuel creating a blanket effect
So to answer your question you have to be more specific as to what type of fire are you fighting, what type of equipment you have available and what foam do you have or are planning to use?
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Cap BzY would love to have you over for a coffee chat. I am also heading West to Indy this year.
TCSS
Bill
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Permalink Reply by John Dobson on
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At a recent fire we used foam as a blanket to help smother out the fire and keep it from spreading. Blowin in insulation we pull all we could from the gable end. Then just used our CAFS to lay in a nice easy blanket from the gable end so no to push any burning material further in. Then pushed it from the eves.
The top photo was after the line had been shut down awhile. Notice how the air has built up in the end of the line on reopening. We were letting some one from another dept run the CAFS line to give it a try. We normally bleed it again before starting fire attack again.
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Permalink Reply by Ben Weinberg on
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The best information on foam I've seen is the foam program from TFT. It explains foam proportioning and a lot of other stuff as well.
I found their contact information for you.
TFT's Contact Info
I don't think they charge for them, just give them a call and ask for one and give your address.
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