1. #1
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    Default FOAM! Or, hey, things change!

    I innocently went to look something up, and realized technology has changed so much over the last 15 or so years, everything I knew about Class B foam -- was pretty much irrelevant.

    Not the least of which is the Class B foam we have isn't good for the Gasoline we have today!

    I'm putting several URLs to an excellent booklet (40 pages) put out by Task Force Tips at the end of this. The information below was taken from their, along with Angus and National Foam's websites, and some other research. This is generalization, so talk to your foam supplier for more "technical" information (if your salesmen doesn't know, talk to the manufacturer!)

    3%/6% ATC AFFF
    This was the "gold standard" when I first joined the fire service.

    Prior to AFFF, protein-based foams were the norm and they smothered the fire. AFFF not only smothered the fire, but left behind a layer of Aqueous Film that floated on the petroleum or alcohol to continue suppressing vapors. Indeed, some industrial applications simply injected AFFF at the bottom of a tank to let it float up and seal the vapors. You didn't have to worry much about the foam blanket, it was secondary.

    For petroleum fires, 3% on the eductor and deliver 100gpm/1000sq. ft. for 15 minutes.

    "ATC" meant Alcohol Type Concentrate, putting the eductor up to 6% and doubling the flow to 200gpm/1000sq. ft. meant you could tackle alcohol based fires, too. (Nowadays it's called AR Alcohol Resistant)

    Then the EPA wanted less air pollution. Gasoline manufacturers in many areas, including mine, started adding MTBE (you see the big square yellow stickers on gas pumps). MTBE and AFFF don't mix -- the MTBE breaks down the foam blanket and aqueous film. Combining from multiple sources, while it's better not to use AFFF on Gasoline in MTBE areas, if you must
    1) Set to the higher alcohol 6% rate
    2) Increase flow by 50% -- from 100gpm/1000sq. ft. to 150gpm/1000sq. ft.

    1% AFFF
    Has been out for a while. First, it's not designed to be used on alcohol fires. But AFFF has a great property -- it's very "fluid," and flows over the surface of burning liquids quicker than any other type of foam. This is very handy say, you have an aircraft go down on the runway -- 1% AFFF lets you make a lot of foam and smother/suppress the fire very quickly.

    MTBE isn't added to Diesel, Heating Oil, or Kerosene/Jet Fuel, so it's not a concern for airports.

    What to do?

    Well, we know have FFFP -- Film Forming Flouro Proteins which seem to be the best option for most municipal fire services if they feel they absolutely need Class B capability (more on that later).

    3/3 AR FFFP and 3/6 AR FFFP both can be used against MTBE Gasoline, and at standard 3% petroleum rate & 100gpm/1000sq. ft. flows. Premium FFFP will also handle alcohol type fires at that same concentration, and so will 3/6 if you set the foam system to 6%. 200gpm/1000sq. ft. is still used for alcohol fires.

    FFFP also form a film for vapor suppression, but it takes them longer to flow over and completely seal a fire compared to AFFF. Since most municipal services aren't going against jetliner crashes, that's probably not a big drawback.

    Do you even need Class B capability?

    That's a valid question. Class B has a big drawback -- all the Class B foams are considered pollutants, and need to be cleaned up. For the very few times we ever might need them, it's an investment that's likely to become a disposal liability to throw out the unused but expired cans of foam.

    In Connecticut to train with them or test equipment, at the very least, you have to use them on dry days in areas they'll evaporate from afterwards. Big, big no no to allow them to enter storm drains or other wetlands! If you constantly use the same drill location, there's a good chance the soil will become contaminated, too.

    Class A foams offer a good compromise for many departments. While no where near the effectiveness of modern AFFF and FFFP on flammable liquids, we know Class A is excellent for our bread & butter structure and wildland firefighting -- and they also offer performance like the old Protein foams in producing a smothering blanket. You'll want aerated Class A foams, or CAFS. CAFS, due to it's higher energy, can be tricky to apply without splashing or spreading the burning liquid though. If the concern is knocking down the fire from a car's gas tank, or suppressing vapors from a leaking gasoline tanker the Class A foams can do an adequate job if you don't have Class B available. We are not forming a vapor-sealing film with Class A foams, but we do get a smothering blanket.

    Plus Class A is easier to train with. Still avoid wetlands for training, or training in the rain. Let the foam evaporate. If it does enter waterways in low concentration it's not poisonous like Class B and will within a few months simply harmlessly rot away. Don't go dumping an entire pail in the swamp though -- a high enough concentration of anything is never good.

    One last interesting point is Compressed Air & Class B foam. It can be done -- but the question becomes a pointed, "Why?" AFFF and FFFP both want to form a film. One of the advantages to CAFS is it's uniformity and extended "drain times" which lets water drain out slowly and continue to wet the Class A fuels below. But AFFF and FFFP both need to drain relatively quickly in order to form a vapor-sealing film over the Class B liquid films.

    That's kinda the 10 minute version -- foam's changed a lot and I didn't even realize till this week!

    TFT's good book:
    (four sections, need Adobe's Acrobat reader, free from www.adobe.com)
    http://www.tft.com/library/files/foam-a.pdf
    http://www.tft.com/library/files/foam-b.pdf
    http://www.tft.com/library/files/foam-c.pdf
    http://www.tft.com/library/files/foam-d.pdf

    Also
    Angus' How to Buy Foam:
    http://www.angusfire.com/Foam/How%20to%20Buy%20foam.htm

    National Foam's website:
    http://www.kidde-fire.com/nf/fcp/fc/3.htm

    (It's interesting that Angus says don't use AFFF, use FFFP; while National says yes, at higher concentrations/flows our AFFF can handle MTBE. Then again, Angus makes FFFP and National doesn't. And at the risk of sounding like an Austin Powers movie, Angus & National are both owned by the same parent, Kidde.)

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    Since the introduction of AFFF type foams years ago mnay departments have never used the old FFFP type foams. IF they had the first thing they remember is the smell when its left on your gear.

    For those that choose to use FFFP remember it needs to be aspirated to be effective. NFPA412 is a good source of requirements regarding this issue.
    Kirk Allen
    First Strike Technologies, Inc

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    Default Replacing Foam...

    LOL ohhhhhh man.

    I was part of a crew that was tasked with removing all the old FFFP from one of our older Pirsch's... man oh man. That stuff had been sitting in the tanks for yearrrrrs "ripening." A long time ago we added Class A foam and separate foam tanks. The old Class B eductor system and its 2 tanks were ignored until someone had the bright idead that maybe it should be cleaned out...

    Let me tell you... I will never EVER--I mean NEVER--get within a mile of that stuff again. I don't dare to say what we did with the tools, garden hose, and rotary hand-pump we used...


    MTBE... didn't we ban that stuff up in Maine? It's supposed to allow for more complete combustion (good for the air), but a side-effect is that it pollutes water systems (bad for the water). I thought we banned it up here.

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    Back to the research: Yes, indeed Maine has banned MTBE, and Connecticut is looking to.

    States under the first column of the below link use ReFormulated Gas, which is almost always an euphmism that they use MTBE (the easiest way to meet that standard)
    http://www.hartenergynetwork.com/mot...ce/glncrfg.htm

    ========
    Many, many years ago we were directed to dispose of some old FlouroProtein foam. We started pouring it down the sink, and the goo that came out stopped us in our young buck tracks. Told the Chief that somebody must've put some old motor oil in the cans, and man the stuff stinks. Chief chuckled, went downstairs, looked in the sink (where we were having a hard time cleaning out the "oil" that poured out before we stopped) and verified indeed that nasty stuff was old Protein foam.

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    Hi Dalmatian90,

    I think you need to read a little bit more on the topic of FOAM and CAFS. You stated in part;

    "One last interesting point is Compressed Air & Class B foam. It can be done -- but the question becomes a pointed, "Why?" AFFF and FFFP both want to form a film. One of the advantages to CAFS is it's uniformity and extended "drain times" which lets water drain out slowly and continue to wet the Class A fuels below. But AFFF and FFFP both need to drain relatively quickly in order to form a vapor-sealing film over the Class B liquid films."

    SAY WHO!!!!!

    AR foams do nothing to suppress the MTBE, because you need a polar solvent fuel to make the Polymeric membrane!!!

    What is most FD's back up for a fuel tanker situation???

    THE AIRPORT!!!
    What are they carrying??? AFFF

    WHY IS IT THAT THE AIRPORT CRASH TRUCK IS CARRYING 3% AFFF, not AR-or ATC AFFF?

    Most of the class B foams that work well on MTBE are protein based, why, because MTBE have a very high vapor pressure release and it basically goes up between the foam bubbles. CAFS makes very tight uniformed bubbles that will help to suppress the vapors, which is what you want. Protein based foams make a very tight bubble structure, that is why it is effective on MBTE. It has nothing to do with the water draining out slowly.

    Hope this helps.

    Be Safe,

    Capt. Lou
    "Got Foam?"

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    Hey Capt Lou, you forgot one huge advantage with CAFS, range. I've yet to see any foam aspirator or play pipe that could shoot a stream of foam like a CAFS deck gun.

    If memory serves me, the problem with AFFF in polar solvents is that it breaks down fairly quickly, not that it will not put a fire out. In short order you'll find your protective blanket thinning and seperating, danger of reflash once the vapors start exiting the spill again. An airport crash truck is the best way to aproach a hot large fuel fire with minimum risk to FF'rs. Once the fire is out local appartatus with the "right stuff" can come in and reblanket the spill, assuming the local FD carries class B (we don't).

    Resq14, we still have MBTE in our fuel in ME, that's why, despite the law, the little yellow stickers are still on the gas pumps. There always was MBTE in gas, we are just not adding large quantities any anymore.

    The nice thing about protient foams is that if WWIII hits you can grab a bucket and live off it for a good long while.

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    I’m not sure it is accurate to say Class B foam isn’t good for flammable liquids today due to polar solvent content. You can always spray the spill with water fog first and the magnetic attraction in solvents to water will dissolve what ails you, then apply stand old foam. Very few flammable liquids are polar solvents or require polar solvent foam. RTFC with 108 plants in 4 states only has a handful of polar solvent risks. You’d be hard pressed to find any reason to carry Polar foam. Burn rates are so high on polars and the light ends that the risk say a tanker would pretty much take care of itself. With flash rate and speeds of 100 feet per second or more why would you want to put it out? With vapor suppression rates of as little one minute with most polar foams one would should ask why are we coving the spill. A spill of any size will use lots of concentrate. Odds are more than you own.

    FAA tests prove regular old AFFF is much faster than FFFP (film Forming Flouro Protein), has much better urn back resistance too. The post about FFFP on a ship isn’t accurate, that was protein foam the Coast Guard requires not FFFP. FAA test show regular low cost AFFF is much faster than any polar foam at knock down but the polar foams may provide better security in some cases.

    In other words save your money. Burn back is more a function of the use or lack of use of a foam nozzle than the foam. If all you want is to put out a fire fast use a fog nozzle. If your goal is to put it out and stop a re-ignition then don’t ever use a fog nozzle use a good foam nozzle. On treated gasoline, if you want to use the least amount of foam and spend the least amount of money and still offer the best security, use 1% AFFF with a medium expansion foam tip, and hydrate the spill with a fog tip first.

    If you really believe all the talk about polar solvents in gasoline eating your foam you can do a very simple test with your gas to see if it is true. Simply fill a cup with some gasoline, mix your non-polar foam concentrate with the right amount of water and shake it up to make foam. Then poor a little foam over the gasoline. If your gasoline is as bad as all the press says it is AND IT ISN’T…AFTER ALL THE GUY WHO SELLS THE STUFF WROTE THE BOOK…grain of salt, your foam will dissolve in seconds. If not the foam won’t dissolve telling you your foam is fine for your gasoline fires and spills.

    That Aqueous film you are talking about so fondly the biggest component of AFFF will not form on grass, dirt, railroad siding, or on crowned roadway. So short of a totally flat surface or storage tank you really don’t have AFFF you have regular foam. In all the other cases you need to use a foam tip. No foam nozzle no foam, no film formation either…ever!

    Oh, changing the foam percentage by 50% will not in any way help on your polar solvent risk. Want proof? Simply dump rubbing alcohol in a pan, mix your foam up 50% or 1000% thicker and shake it up and dump a bit on the alcohol. In about 3 seconds it will all be gone. In other words no protection no knockdown.

    FFFP is hardly the best option for municipal fire departments. It sucks in the FAA tests, is of limited production and has the highest costs. SO YEAH IT IS THE IDEAL FOR THE SOLE SOURCE SALESMAN.

    The 3/3 and 3/6 polar foams are really poor choices for polar fires also. 1%/3$ concentrates are a much better choice, you’ll use 1/3 the concentrate and spend half to one third the money on the same fire. Gee, that must be why Williams fire control keeps putting out all these tanks using the stuff. Yeah even NFPA says you cannot put out a tank bigger than 120 feet, but Williams has done many bigger than that including a 300 footer. It is the foam and nozzles.

    CAFS and Class A will in fact with a foam nozzle do just as good a job as any AFFF where you’ll actually have a fire or spill. After all, most fuels will not allow film formation nor will most firefighting or spill locations.

    Vapor sealing will be close to the same except on hot surfaces. If you care about hot surfaces or long term vapor suppression, protein is about the only choice. Allthe other foams are a compromise.

    Your point about drain times and CAFS is only accurate if you are at a tank fire or absolutely flat surface. Film formation does not occur unless you have a liquid surface for it to form and will not be created on 8 of the 10 most common hydrocarbon fuels and won’t happen on any polar solvent, ever! So always use a foam tip.

    AFFF was designed for witnesses knockdowns of plane crashes to save pilots, knockdown was given up for speed. Municipal firefighting is the exact opposite.

    FFFP foam doesn’t stink that was protein ( P ) foam. One is blood and guts the other is protein animal based.

    Most references you all have used to FFFP is inaccurate it is protein foam you are talking about. Shoot you are more likely to have to shovel out a AFFF polar foam than any protein or FFFP foam. And with a polar foam in a Class A and B system you are almost certain to have many clogged foam lines in your system. It is best not to use polar foam in an A/B system but to buy two separate foam systems.

    Class B CAFS is an awesome fire eating sight! As is polar AFFF CAF’s ask MERCK one of the largest protectors of true polar solvents in the U.S.


    Just a few facts.

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    AR foams do nothing to suppress the MTBE, because you need a polar solvent fuel to make the Polymeric membrane!!!

    On this, I am the victim of bad/sloppy editing and repeating half-truths!

    I try to avoid the pitfall of, "Don't teach don't" but I have to quote some poorly written stuff first so this makes sense in what I originally wrote:

    http://www.tft.com/library/files/foam-b.pdf
    MTBE or methyl tertiary butyl ether, in the past a
    by-product of the fuel processing industry, is now
    present in fuels in levels above 15% of total volume.
    The challenge to the fire service surfaces as these
    chemicals are more understood. They are polar
    solvents, and as such must be treated in a different
    way.

    http://www.kidde-fire.com/nf/fcp/fc/...ldBrochure.pdf
    Universal Gold has the most
    comprehensive UL polar solvent
    listings, including most fuel
    oxygenates such as MTBE, ETBE,
    TAME, Ethanol and Methanol.

    http://www.ushalonbank.com/foam5.html
    and 3 parts concentrate to 97 parts water on polar solvent/water miscible fuels (alcohol, ketones, methanol and MTBE products).

    http://www.hess.com/about/msds/MTBE_9922_clr.pdf
    LARGE FIRES: Water spray, fog or fire fighting foam suitable for polar solvents. Water may be ineffective
    for fighting the fire, but may be used to cool fire-exposed containers.


    But then we begin to find quotes like:

    http://www.tycoasia.com/products/dat...am_arc_3x3.pdf
    When applied on polar solvents a polymeric membrane
    makes it possible for the foam blanket to extinguish fires
    effectively. This works also on foam destroying liquids
    such as MTBE.

    http://www.angusinfo.co.uk/foamconc/jargonbu.htm
    Polar Sovent: A liquid whose molecules possess a permanent electric moment (eg. alcohols, amines, ethers, esters, aldehydes, ketones). In fire fighting any flammable liquid that destroys standard foam is generally referred to as a polar solvent. Polar solvents are generally miscible with water.


    So the long and short is:
    MTBE is not a polar solvent by definition.
    But we in the fire service have gotten sloppy with we call a polar solvent is.

    Is MTBE a polar solvent? No.
    Do we use polar-solvent (AR) type foams on MTBE? Yes.

    WHY IS IT THAT THE AIRPORT CRASH TRUCK IS CARRYING 3% AFFF, not AR-or ATC AFFF?
    Jet fuel is essentially the same as Kerosene.
    You don't mix MTBE with Jet Fuel.
    You don't use Ethanol in airplanes.

    What's the hazard at the airport? Kerosene, not Gasoline. That's why they can save money and just carry 3% AFFF. They may help out the municipal service for gasoline fires, but that's not what their buying their foam for.

    Protein based foams make a very tight bubble structure, that is why it is effective on MBTE. It has nothing to do with the water draining out slowly.
    Let's not confuse statements here.

    On FP (Fluro Protein) foams, their primary mechanism is the foam blanket. I believe Class A CAFS used on (small) Class B fires would achieve a similiar affect -- tight bubbles, smothers the fire. In both cases you need a solid foam blanket to be effective.

    FFFP -- Film Forming Fluro Protein and AFFF -- Aqueous Film Forming Foam rely on a film forming on the surface of the fuel to suppress vapors. The foam blanket helps smother initially, then the foam mixture needs to drain quickly to form the film. At least in the case of AFFF, the film layer is a primary mechanism that spreads ahead of the foam and helps spread the foam layer faster over the fire.

    You could suppress MTBE/Gasoline vapors using a thick, tight foam blanket from FP foams, or you could suppress MTBE/Gasoline vapors using FFFP or some AR-AFFF foams set to polar solvent levels to form a vapor sealing film.

    Good challenge though Cap'n -- wouldn't have done the research to find out MTBE isn't a true polar solvent otherwise.

    Matt

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    Thanks for bringing this up, Dal. Much like the art of auto extrication has changed over the years with air bags and hybrid car technology, the fuel in the car and the fire load in the building changes with new technology as well. Keeping up with the changes is an absolute necessity if we are going to be effective firefighters.
    Chris Minick, P.E., Firefighter II
    Structures Specialist, MD-TF 1

    These statements are mine and mine alone
    I.A.C.O.J. Building crust and proud of it

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    Originally posted by erniefire
    And with a polar foam in a Class A and B system you are almost certain to have many clogged foam lines in your system. It is best not to use polar foam in an A/B system but to buy two separate foam systems.

    Class B CAFS is an awesome fire eating sight!
    Ernie, you make some excelent points about salesmen and their products (I've gone on a simular tangent about 800Mhz radios, aren't they the best thing since sliced bread?). We all get a little lazy from time to time about doing our homework and take the word of "experts" to save time.

    We had horrible problems with our combined A/B systems, so much so that we stopped carrying B altogether and use A on small fuel fires. Run .3% A at 1% and you get a real nice blanket of foam! Our new CAFS engine did not even have any B capabilities planed into it, and man will that deck gun throw down a blanket of nice foam!

    drkblram, I believe the USCG's dislike of AFFF is based on the fact that it is, at its heart, a soap product. Soap will cause oil to mix with water, so in a fire with a spill they'd rather have the oil on top of the water where it can be recovered or burned off. If AFFF were used on it, well I'm sure you've never sprayed simple green on a little slick, now have you ? For those who have not done this, soap will make an oil spill disapear, and is strictly verbonden by MARPOL and IMO regulations. The spill is still there, it just mixes with the water and becomes undetectable while still presenting a hazard to wildlife and shorelines.

    Interestingly enough, last I knew, the USN still uses nothing but AFFF on its ships.

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    Comment from the sidelines, not exactly on this topic, but about foam...

    What is the point of the 30ish gallons of Class B foam commonly found on trucks? I mean, when a truck is spec'd and a need for Class B foam is determined, what are people expecting to do with 30ish gallons of it? If it's the big Class B fire like people have in their heads when they envision a Class B foam system, do they think this will handle it? Honest question. In reality, aren't there basically 2 types of Class B incidents: a small leak you are worried about getting bigger and/or igniting, and an "Oh %&@^" type deal? I haven't seen too much use of high expansion stuff lateley. Small Class B fires usually burn out quite fast.

    If you say it's for a leaking fuel tank at a MVC or something, couldn't you get by with a TFT Pro-Pack or equivalent?

    If you really want to plan for a Class B fire, imho, it would be better to simply get a trailer that carries barrels of Class B (this way you could carry different types of Class B), and use a pick-up tube system to tie it into the truck. Or if you are rolling in the dough, get yourself a foam truck.

    Check out this 200g/500g Class A/B system the town of Brookhaven, NY.
    http://cms.3m.com/cms/US/en/2-68/ciRclFM/view.jhtml

    Or, maybe get a military surplus vehicle, like our foam truck below:
    http://www.fireseat.com/EAFBP15.jpg

    Haha I wish.

    Anyway, am I off in left field here or does anyone agree?
    Last edited by Resq14; 10-17-2002 at 03:40 AM.

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    Hi Resq14,

    WOW! You're right on target. I couldn't agree with you any more!!!!! It is amazing how departments will spec a 30-gallon "B" foam tank on a new apparatus only because "they can". They should be thinking more on the lines of "A" foam, since, when you think about it, we as a fire service fight "A" type fires day in and day out. Gee what a concept, something that make our job a little easier! "A" foam!

    Try this. The next time you are with a group of firefighters bring up the topic of "foam". See if the same thing happens to you that has happened to me. I find it so amazing that when I mention FOAM to most firefighters, if you look real hard just above the their heads you can see a great big letter "B" appear next to a "fuel tanker". And then they start to talk about their 30 gallons of foam and how they are ready for the "big one".

    The trailer concept is a great "shared resource" idea that multiple departments can all utilize and share in the expense. The only problem is that the day you need it the tires will probably be flat!

    Be Safe!

    Capt. Lou
    "Got Foam?"
    Last edited by CaptLou; 10-17-2002 at 10:49 AM.

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    drkblram, glad to see you are an upstanding and exepliary sailor in the eyes of the USCG!

    When I went through the Navy's FlightDeck Firefighting (I was a Marine who deployed to carriers) we were taught that protien foam blankets had a tendancy to fall apart, especially if you walked through it, where AFFF would "heal over" and reseal the spill after you stepped in it. Of course they also taught us the superiority of the OBA over the SCBA, but that's another thread.

    On a seperate thought train, have you seen and what do you think of micro mist systems for fire suppresion? The reports I've seen in Profesional Mariner indicate its gaining acceptance as a replacement for Halon and small fixed foam systems.

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    Resq14 and CaptLou, in defence of the 30gal B tank, that's 1000gal of finished foam, or about 7 minutes of flow with a 1 3/4 TFT nozzle&cone tip. I feel that is enough to put a fuel fire out and then blanket the area at a typical MVA with a minute or two of reserve in case of a reflash.

    Don't get me wrong, I'm with you on the practicality of a good A system used as a dual purpose system and I would not spec a B system in most new trucks, but I feel there is a use for the 30 gal B systems.

    Consider this one, a tractor trailer v car, truck ends up into a pole with wires down on the truck and street, one of two 100gal saddle tanks on the truck ruptured and leaking from hitting the pole (this was actually my first class-b foam call many moons ago). Water was not much of an option due to the wires down. The spill covered a significant area, running down the street threatening to involve the car which was still in the road. We were able to bank up the foam and push it onto the spill w/o endangering ourselves from the power wires (7200V 3 phase primaries).

    By no means is this enough for the "big one" but it is enough to run a nice safety margin in what I would consider a typical accident. As an officer on such a truck I would have to keep in mind that there is a maximum upper limit to what I will be able to put out. Had the tractor been a tanker and fire was showing I would like to think my Lt that day would have run a different thought process. Of course, given that the nearest crash truck was 45min to an hour away, maybe we should have had a bigger foam tank?

    You're right, a trailer is a better way to go if you're gonna deal with a tanker or static tank fire, but do you drag the trailer to every call? How long will it take to get the trailer from the barn to the scene?

    Here's a thought, run Class A into one of those TFT ProPacks filled with B, the resulting coagulant which sprays out the end ought to blanket just about everything in a thick sticky gel!

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    Originally posted by drkblram
    I love how informatively they taught us stuff at school.
    What's that saying, a little bit of knowlege is________ (you fill in the blank). Typical military schooling I really hated that in boot camp where they'd tell us things like "never step on a mine", "throw the grenade, not the pin", or my favorite "don't **** off the DI's" (boy was that a hard lesson) without explaining exactly why we were supposed to do that stuff!

    BTW, my "formula" was 150gpm at 3% which is 6 minutes 40 seconds to empty the 30gal tank. Not really very much flow time if its cooking, although if you're running a decent expansion ratio it should cover a fairly large area. Of course if you're running 6%, its only 3min 20!

    Our new rescue pumper has a 55gal foam tank w/750 water, but that tank is class A (0.2%) so it'll last a much longer time. We are looking forward to the much promised, as yet undelivered dual purpose A/B foam.

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