Thread: Multi-Use Foams
11-07-2006, 05:46 PM #1
- Join Date
- Sep 2004
Anyone had any experience with multi-use foams? Kidde makes one called Niagara. Supposedly it is a 1% hydro-carbon 3% polar solvent foam that can be used from .01%-1% on class A fires.
11-08-2006, 01:12 AM #2
- Join Date
- Oct 2005
Firstly, all Class B foams can be used on Class A fires -- they will all act as surfacants, which proportions you need I don't know but I suspect all of them would be low like the 0.1% range.
Class B foams typically add features to improve performance on flammable liquids -- such as film forming, having blankets that drain slower, or having higher heat resistance.
FOR THAT MATTER...Class A foams can still be used to form a mechanical foam blanket for Class B fires -- they just won't be *as* good as Class B, but it becomes a question of what is good enough.
My primary concern is if dual-purpose foams have addressed the additional, negative environmental impact of Class B foam v. Class A foams.
While some of that impact is simply the application rate is that much greater with Class B foams, some of it is differences in the chemicals.
One famous case from Connecticut -- and I apologize since I never remember which "W" town near Hartford it happened in -- Windsor or Wethersfield. At any rate, they experienced a fish kill in a pond following a FD drill -- the AFFF went down the drain and into the pond. When the AFFF decomposed, it used up the oxygen in the pond killing the fish.
As part of the settlement with the State DEP for the pollution, the FD sent a letter explaining the dangers to every fire department in the state. (That was actually a really cool thing -- speak about having to share bad experiences!)
This link: http://www.haifire.com/publications/...ting_Foams.pdf is probably way more information then anyone ever wants to know about foams and the environment.
But if you scroll down to Chart 7 it reinforces the point above -- AFFF sucks up 12x as much oxygen as Class A foam. Now use it at 30 times the concentration, you're talking a 360 fold swing! But like I said, you're not necessarily using dual-use foam on class A fuels at class B rates.
Overall, my State DEP's advice is to use extreme care with AFFF both in use and especially with Drills. However, with Class A foams they only ask to use reasonable caution -- spray it were it will primarily evaporate at drills, don't drill in the rain with it (which would flush it into wetlands before it could evaporate), and at fires try to avoid using it along wetlands but you can if it's necessary.
All of which comes down to this question for the salesman (get ready to see the deer-in-headlights stare):
Is this just a marketing department re-label of a traditional Class B foam -- since all of them are effective on Class A fuels since they're all surfacants, or were their formulation changes made to reduce the impact of the foam on the environment to make it more suitable for Class A applications?
11-10-2006, 02:00 AM #3FOR THAT MATTER...Class A foams can still be used to form a mechanical foam blanket for Class B fires -- they just won't be *as* good as Class B, but it becomes a question of what is good enough.
BUT, there is no lasting foam blanket. The Class A foam is used only as a wetting agent and it will put that fire out.
But, what would take 5 gallons of AR-AFFF mixed would take 60 gallons of Class A mixed.
Class B can be used on class A Fires but unless your in a pinch.. its a real waste. You'd be better off using Dawn Dish soap and A lot cheaper
11-10-2006, 10:41 AM #4
- Join Date
- May 1999
- Berks County, PA
We've used Pyrocap B-136 in the CAFS unit on our squad for several years. It has done a good job for us on brush and grass fires and trash fires (including tires, plastics and similar materials). We've also had success using it on fires in pooled hydrocarbons (although it does not work on alcohols and other polar solvents) and on vehicle fires. It is supposedly effective on metals such as magnesium, but we haven't tried that out as yet.
The US Forest Service and other federal agencies apparently use Pyrocap as an environmentally friendly water additive and Amerex has started offering it for extinguisher use. We've changed all of our PW extinguishers over to a 1:9 Pyrocap mix to improve their extinguishing capability.
More information here:
11-20-2006, 03:20 AM #5
- Join Date
- Jan 2006
- Houston, Texas
There are really no multi-use foams by design.
Class A's are wetting agents. They are designed to mix with the fuels quickly. The specifications (UL, NFPA) do not even call for them to foam at all, hence the term, wetting agent. If they do foam, the blanket breaks down quickly, known as drain time.
Class B's, including AR's, are film forming and are fuel tolerant, meaning they do not readily mix with the fuels. They are designed to provide a foam blanket through mechanical agitation, and the drain time is longer than that of class A's. Class B's have a quicker knockdown than A's on flamable liquids.
Can A's be used on B fires, absolutily, as stated in UL tests. But, the product actually mixes with the hydrocarbons and you can have fire on top of the foam if that happens. Also, vapor securment is short because the foam drains quickly.
A's will not work on polar solvents. This includes most gasolines today that are blended. E-85 is a good example, with ethanol constituting 85% of the mixture and 15% gasolene. Use anything other than a UL listed AR, and the foam dissapears as soon as it hits the surface of the fuel.
Can B's be used on A's, absolutily. On a 1% product, you can probably go down to .5%, ask the manufacturer.
The Angus Niagra is a FFFP-AR, it is a very thin viscocity concentrate in contrast to the other 1x3 AFFF's, and has a use temperature below 0 degrees F. Protien foams have a slightly slower knockdown than AFFF's, but not by much. Their drain time is longer than AFFF's, so you don't have to re-apply it as much as the AFFF's.
FYI, Class A concentrates are the strongest made, despite what we think of the 1x3 AR-AFFF products. In some cases, they can be used at .1% and still foam. Class B's won't do that.
But here is the rational of most FD's in my area, west of the Mississippi.
99% of the time when concentrates are needed, its for class A fires. When B type is needed, we usually find that most trucks don't have sufficient quantities on board to fight the fire, and have to call for reserves. Most B fuels require substantial quantities of concentrate, more than can be carried on a municipal truck.
In most cases, it doesn't make sense to carry more than the required 10 gallons of ISO required AFFF.
In addition, class A's cost about $15 per gallon, AR-B's about $30 per gallon. It doesn't make financial sense to put expensive B's on an A fire.
One last thing, some companies do brag about their foams being A/B concentrates. Unfortunatily, they don't tell you that its per UL's GOHR listing for wetting agent use only. Oh, and in most of those UL listings, the application jumps from 1% up to 6%.
One easy way to determine what foam is best, is to ask the fuel manufacturers. Exxon, Shell and Conoco would never consider using a class A on thier flamable liquid fires.
Coal mines and paper mills would never consider a B over an A in their facilities.
But, the foam salesmen would love for you to use a $30 AR-AFFF instead of a cheaper A product.
I should know, I am one.
Kidde Fire Fighting
Last edited by jtstoney; 11-20-2006 at 03:40 AM.
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