ARFF and Aspirating Nozzles

[16Scott]

We use an Oshkosh T-3000 and a Stryker with 1000 GPM roof nozzles, both TFT non-aspirating automatic versions. Our ARFF instructor recommends an indirect application of foam solution (water+foam) instead of the "rain-down" method. This makes sense to me, as the indirect method both agitates the solution to make a thicker blanket, and also prevents evaporation of the stream as it tries to penetrate a flammable liquid fire.

However, leading ARFF texts recommend the rain-down method.

Just looking for some opinions out there, maybe something I had not considered.

[DFurtman]

If you're using the indirect method against the wing or fuselage of an aircraft, you're also cooling that area, slowing ignition of vapors or protecting the skin from flame impingement.

-Damien

[FyredUp]

If you are using AFFF you don't need aeration for the foam solution to be effective in extinguishment. The polymer blanket doesn't really on a sudsy foam blanket to work. All the sudsy foam blanket does is slow the runoff of the foam solution.

[Dickey]

I agree with both my brothers in their reply.

It is the foam that makes the protective blanket so it really doesn't matter if it has lots of suds or not, in fact no suds or smaller bubbles is slightly better.

Both will work but the indirect method will also cool the area down better and quicker. If it is a windy day a rain down method might not be as effective either. The rain down method also takes a bit more time to see the same effects as the indirect method too.

To each his own I guess, depending on the situation. Some of those ARFF manuals haven't been updated in 10 years with the new nozzles, new foam formulas, and new equipment applications either. Keep that in mind.

[gunnyv]

I'm a believer in running the stream along the fuselage and letting the agent run down the sides. Agree with the previous posters here.

[ShredddinCali]

from personal experience, the bank down method seems to work way better than the rain down method. c'mon, you don't honestly follow everything from the books as the "best way" do you?