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Thread: Foam Question?

  1. #1
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    Default Foam Question?

    Is there anyone who can direct me to info or knows themselves about AFFF foam on class A fires. My co-workers say there are tremendous benefits on class A and car fires. I say there is not, however, a salesman showed them some dog and pony show using a piece of cardboard and spraying it with AFFF. Any help would be appreciated.


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    Cool foam

    Don't really know if this will help but we have had dual foam systems, A&B in sperate tanks on our units for some time. The time has finally come to say NO to carrying two kinds of foam. The trouble is that if you accidentally mix foams there is a tendency for coagulation(the stuff turns to a gel)and won't properly dispense if at all. If you crank up the percentage on Class A foam it works just fine in lieu of Class B.

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    Im not a foam expert, but I dont belive that imformation to be accurate.

    Each type of foam works in a different way. Class "A" breaks down the surface tension of the material which allows water to be more effective. Class "B" works to smother the fire.

    While I can see how class "A" may work with certain class "B" materials, I dont think it would be effective for others. Take a fuel spill, with or without fire. You need the class "B" to smother the fire or to "coat" the spill to prevent ignition. If you applied class "A" , all you would do is spread the spill and do little, if anything, to prevent an ignition.

    We have had multiple agent tanks for years, and will continue to do so. Each type of foam has its "place" and dropping one will only limit your options and capabilities.
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    Actually Dave, I belive Class A foam breaks down the surface tension of the WATER, not the actual material, but you were close.

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    Forum Member Station2Capt's Avatar
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    Dave is correct with his post. Class A foam and Class B foam are two different products with two different uses. Class A foam is not sutiable on liquid hydorcarbon spills because it lacks the Film Forming action (2 of the F's in AFFF) found in Class B foam. There are too many things about foam to discuss here. If you want to learn more about foam to www.usfoam.com I know the owner of this company and if you dont find what you need just drop him an email he loves to talk foam and would help out anyone.
    A "Good" fire is not measured by how big it is, but by the fact that everyone is going home safe, and that we possibly learned something new about firefighting. Member:IACOJ

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    If you think about what is actually burning in most car fires, "A" class foam may be the right call. Rubber, cloth, vinyl, and plastics are easily handled with the "A" class. Its very rare we are dealing with flammable liquids with car fires, around here anyway. Just a thought. Also, we have a/b foam on our units. Never had trouble keeping them apart.
    Last edited by hvfd507; 04-27-2005 at 09:16 PM.

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    I'm Confused.Foam rubber,plastic,fibreglass etc are CLASS B MATERIALS.Therefore they are B foam.Class A is for A materials(THAT LEAVE AN ASH).Not much in a vehicle fire fall in that category.Will Class A "work"on a car fire? Yes,but that's not what it was specfically designed for. T.C.

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    This may help - just grabbed it off the website.

    CHEMGUARD CLASS A PLUS FOAM
    Chemguard's Class A foam concentrate is a mixture of foaming and wetting agents. When proportioned with water it changes the properties of the water, reducing the surface tension and allowing for greater penetration in all Class A fuel and wild land fires. It also gives the water a foaming ability allowing it to remain and cling to the surfaces without run off. Class A is effective in fighting forest fires and many deep-seated fires such as tires, paper, and wooden structures.

    -Chemguard's Class A Plus is a noncorrosive, non-toxic biodegradable Class A fire fighting foam concentrate and is suitable for use through medium expansion discharge devices, compressed air foam systems (CAFS) and arial bambi buckets
    -Recommended application rates from 0.1% to 1.0%. Class A Plus is manufactured, tested and evaluated in accordance with NFPA 298, specifications for Class A foams for wild land fires, helicopter bucket operations, and ground applications
    -Benefits: 3 to 5 times more effective than plain water
    -Can be used with either fresh or salt water
    -Can be used with non-air-aspirating or aspirating handline nozzles
    -Suitable for use on rubber (tires), coal, paper and many other types of Class A fuels

    (CLASS B, 3% OR 6% SYNTHETIC AFFF FOAM)
    Application of AFFF provides the fastest knockdown on hydrocarbon fuel fires (gasoline, kerosene, diesel, etc.) and quickly covers the fuel surface.

    -AFFF may also be used on Class A fires
    -Biodegradable and environmentally friendly
    -Suitable for use with both fresh or salt water
    -Suitable for use with all siliconized dry chemical agents
    -Suitable for use with air-aspirating and standard water fog nozzles
    -Suitable for use with the following types of proportioning equipment: Fixed or in-line eductors, in-line balanced pressure and pump pressure proportioning skid, bladder tank balanced pressure proportioning system, and handline air-aspirating nozzles with fixed eductor pickup tube
    -Suitable for use with the following discharge devices: Foam chambers, air-aspirating and non air-aspirating sprinkler heads or spray nozzles, standard water fog nozzles for handlines and monitors, air-aspirating foam nozzles, foam makers for use with either floating roof storage tanks or dike/bund protection systems, and high back pressure foam makers for sub-surface base injection system (hydrocarbon type fuel only)
    -Will provide quality protection in areas such as: Crash fire rescue, storage tanks (non-polar solvent type fuels only), truck/rail loading or unloading facilities, processing/storage facilities, docks/marine tankers, flammable liquid containment areas and mobile equipment
    -I have learned people will forget what you said,
    -People will forget what you did,
    -But people will never forget how you made them feel!

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    Unhappy Class 'Whaaaa........'

    I'm Confused.Foam rubber,plastic,fibreglass etc are CLASS B MATERIALS.Therefore they are B foam
    Errrr.... actually, Rubber, plastic etc. are actually class 'A' materials. I understand that your belief perhaps comes from the high quantity of hydrocarbons present in the product, but as a solid they are considered a class 'A' product. Class 'B' products are Flammable Liquids, e.g. gasoline, kerosene, oil etc.

    A car fire, unless your dealing with a ruptured fuel tank with resulting spill, is a class 'A' fire, and is very effectively extinguished with a class 'A' foam, whether it be Air Aspirated or compressed Air generated, or even a wet water solution, class 'A' concentrate mixed with water. With the size of most car fuel tanks even the burning class 'B' product is easily extinguished with a class 'A' foam.

    Fuel spills of any appreciable size are best dealt with by using a class 'B' foam with film forming properties (not all 'B' foams form film (try saying that three times fast)). However, if your department is equipped with only class 'A' foam, a blanket of 'dry'(if you are using CAFS) foam can be applied to prevent vapor formation and assist in isolating the fuel from an ignition source. However, provided you understand that the hydrocarbon fuel will cause class 'A' foam to break down more rapidly than under normal circumstances, and that it does not provide any protection for gaps in the foam blanket.

    I've had the experience to work with many foams, and with the exception of alcohols, it's suprising how well you can use one foam for a multitude of different problems.. provided you know their limitations.

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    Forum Member DennisTheMenace's Avatar
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    Default Re: Class 'Whaaaa........'

    Originally posted by Fawlty


    Errrr.... actually, Rubber, plastic etc. are actually class 'A' materials. I understand that your belief perhaps comes from the high quantity of hydrocarbons present in the product, but as a solid they are considered a class 'A' product. Class 'B' products are Flammable Liquids, e.g. gasoline, kerosene, oil etc.

    A car fire, unless your dealing with a ruptured fuel tank with resulting spill, is a class 'A' fire, and is very effectively extinguished with a class 'A' foam, whether it be Air Aspirated or compressed Air generated, or even a wet water solution, class 'A' concentrate mixed with water. With the size of most car fuel tanks even the burning class 'B' product is easily extinguished with a class 'A' foam.

    Fuel spills of any appreciable size are best dealt with by using a class 'B' foam with film forming properties (not all 'B' foams form film (try saying that three times fast)). However, if your department is equipped with only class 'A' foam, a blanket of 'dry'(if you are using CAFS) foam can be applied to prevent vapor formation and assist in isolating the fuel from an ignition source. However, provided you understand that the hydrocarbon fuel will cause class 'A' foam to break down more rapidly than under normal circumstances, and that it does not provide any protection for gaps in the foam blanket.

    I've had the experience to work with many foams, and with the exception of alcohols, it's suprising how well you can use one foam for a multitude of different problems.. provided you know their limitations.
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    Default Re: Foam Question?

    Originally posted by Spencer534
    Is there anyone who can direct me to info or knows themselves about AFFF foam on class A fires. My co-workers say there are tremendous benefits on class A and car fires. I say there is not, however, a salesman showed them some dog and pony show using a piece of cardboard and spraying it with AFFF. Any help would be appreciated.

    From your posted location by looking on the atlas, why don't you check with the guys in the bigger departments West of your location and see what they are using. I would also think the since there ia a major airport near you, that they and maybe the Air Guard, if one is there, may be using what you are looking for.

    Just a suggestion.
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    .
    Last edited by Resq14; 04-29-2005 at 01:05 PM.
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    We are considering giving F-500 a try. It is not an actual foam, but is rated for both class A and B fires. Does anyone have any experience with using it? Also comments on its effectiveness are requested. We would like to know both sides of the story, anything good or anything bad.

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    We have class A foam on our brush truck, we have found that it will put out a (fat lighter) house much better than water. Our 30+ year old trucks are not equiped with foam
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    It isnt very hard to set up a foam system, im not an expert on it, but we jost got a new truck and our first officer put the foam proportionng system on and set up the hoses in about an hour.
    (took him about 6 weeks to get around to actually doing it though)
    Surely it cant be too much hassle for you guys to put one on.
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    We had both class A & B foam tanks on three of our engines, but changed them all to Class A. I have used class A on many car fires in the last three years and it is not a solve all extinguishing agent. But, faced with a fully involved auto, class A works very nice. Even better when you have exposures. It will buy you some time.
    For structure fires though...still very effective and my first choice. But I have noticed that the compartment is much hotter, especially when using compressed air foam systems.

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    Thumbs up Good point..

    For structure fires though...still very effective and my first choice. But I have noticed that the compartment is much hotter, especially when using compressed air foam systems.
    Absolutely, there is considerably less water in a CAFS line and subsequently less water in the fire compartment. That can be good of course to help minimize water and run off damage, lighten hose lines etc... I was always instructed to keep a CAFS line flowing after the fire is extinguished for about an equal time that it took to achieve knockdown. This assists in cooling and prevents rekindle.

    Personally I like working with CAFS.. makes a little water go longer (yeah yeah, I know, for a big fire, you still need big water!!)

    Cheers

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    I don't think I explained myself with my original question. I have never used foam except in these two situations: AFFF on fuel spills/fires and Class A on brush fires. The 2 guys I am on shift with swear by using AFFF on car and structure fires. I have found that water (when applied correctly) works fine on those calls and have never needed to use foam, nor since working with them have I seen a difference when it was used. The larger departments around me (including the Air Guard) use foam in the same way I have been taught. I don't want to miss out on a good thing if AFFF should be used. One co-worker even wants to put AFFF in the water can. I have heard of separate cans with AFFF for oil furnace/Class B fires, but not for structure fires. Are there firefighters who are using AFFF for structure/car fires and if so, can you explain the science behind it and is it cost effective (water is cheap and plentiful!)?

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    Originally posted by Spencer534
    I don't think I explained myself with my original question. I have never used foam except in these two situations: AFFF on fuel spills/fires and Class A on brush fires. The 2 guys I am on shift with swear by using AFFF on car and structure fires. I have found that water (when applied correctly) works fine on those calls and have never needed to use foam, nor since working with them have I seen a difference when it was used. The larger departments around me (including the Air Guard) use foam in the same way I have been taught. I don't want to miss out on a good thing if AFFF should be used. One co-worker even wants to put AFFF in the water can. I have heard of separate cans with AFFF for oil furnace/Class B fires, but not for structure fires. Are there firefighters who are using AFFF for structure/car fires and if so, can you explain the science behind it and is it cost effective (water is cheap and plentiful!)?
    For the situations you mentioned (car & structure) you CAN use both types of foam. Its up to your department and what they feel works best. For us, a structure would get class "A", a car class "B".

    Yes, water works, its just that foam works better. This realy comes into play with class "A" on structure fires. The foam makes the water more effective. The fire goes out faster and you use less water. If you ever use it, you will see what I mean.

    We used to put AFFF in our water cans, now we put class "A".

    As for rubber/plastic being a class"A" material, yes and no. In its solid, unburned form it is. But when it burns and melts, its degradeing and returning to its original "form". Thats why we use AFFF on car and fiberglass boat fires
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    The AFFF we use is suitable for class A fires at low percentages (says so on the instructions). The foam acts as a wetting agent, breaking down the surface tension of the water, allowing it to penetrate better and put the fire out quicker. Not surprisingly it also works well at 3% and 6% for class B fires - since that's what it is primarily used for. (For anyone who doesn't know, big drops of water don't penetrate class A materials like baled hay or fabric particularly well. Reducing the surface tension allows the water to flow into the pores and voids instead of beading up and rolling off.)

    If you want to know if you should use it at every fire you also need to look at things like cost, how the concentrate acts when open to air for long periods of time, how corrosive the concentrate is to your pump and piping, and whether or not it will gum up the works if you don't get it all flushed out.

    My department also use F-500. Keep in mind that F-500 is an emulsifier that also acts as a wetting agent - there's no magic going on here. I've posted about it several times (do a search and you'll find some examples).
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