?? Chemistry of fire retardant??

I read in a recent Av Leak that the stuff fire-bombers drop is a
mixture of phosphate fertilizer and water.

Can anyone tell me how the phosphate functions as a fire retardant?
Is it ammonium phosphate, sodium phosphate, or what?

Thanks. vince norris

As my local firebomber base a block up the street told me, it is either an
ammonium nitrate or ammonium phosphate base with water, colorant, and something
to make it "sticky".

Nitrate or phosphate base is a function of the supplier of the goo. Don't get
it on you, it is a bitch to wipe off.

Jim

vincent p. norris
shared these priceless pearls of wisdom:

-I read in a recent Av Leak that the stuff fire-bombers drop is a
-mixture of phosphate fertilizer and water.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

As my local firebomber base a block up the street told me, it is either an
ammonium nitrate or ammonium phosphate base with water, colorant, and something
to make it "sticky".

Nitrate or phosphate base is a function of the supplier of the goo.

Thanks, Jim, but what I meant by "function" is, what does the
phosphate (or nitrate) DO?

Isn't ammonium nitrate the stuff used to make car bombs? If so, why
would it be dropped onto a fire?

"Ammonium" is loaded with hydrogen and "-ate" means lots of oxygen.
Neither would seem to ideal for quenching a fire.

vince norris

vincent p. norris wrote:



Thanks, Jim, but what I meant by "function" is, what does the
phosphate (or nitrate) DO?

Isn't ammonium nitrate the stuff used to make car bombs? If so, why
would it be dropped onto a fire?

"Ammonium" is loaded with hydrogen and "-ate" means lots of oxygen.
Neither would seem to ideal for quenching a fire.

vince norris


Ammonium nitrate, by itself, is not a hazard. Growing up on a farm, I
regularly hauled
8-ton loads of the stuff without any problems.

Ammonium nitrate, when mixed with a fuel such as a hydrocarbon, is a
great oxidizer. The
combination is what makes the truck bombs (I don't know if they use it
for car bombs)
go boom. You also don't need terrorists to set it off - do a search of
the Texas City disaster
(or the Grand Camp - the ship that set it off) to see an industrial example.

As for why it's used in arial drop flame retardants, I don't know if
there's any fire related
reasons. Maybe it helps modify the water's viscosity or something.
However, I suspect
that the fact that it's a good fertilizer is at least part of the
equation. You don't want
something that's toxic (save the trees from fire only to kill them
slower with a poison),
and this will help (a) the fire damaged trees in their recovery process,
and (b) the re-vegetation
process.

Rich Lemert

"vincent p. norris" wrote in message
...
As my local firebomber base a block up the street told me, it is either
an
ammonium nitrate or ammonium phosphate base with water, colorant, and
something
to make it "sticky".

Nitrate or phosphate base is a function of the supplier of the goo.

Thanks, Jim, but what I meant by "function" is, what does the
phosphate (or nitrate) DO?

Phosphates make suds, like detergent in the 1960's.

On 2003-11-16 16:21:37 -0800, vincent p. norris said

"Ammonium" is loaded with hydrogen and "-ate" means lots of oxygen
Neither would seem to ideal for quenching a fire

One would not think that applying a substance that was two-thirds hydrogen (great fuel) and one-third oxygen (oxidizer) to a fire would be helpful either, and yet somehow it is

It does make a mess. A news reporter at a TV station I worked for had
one of our video redorders dumped on while covering a forest fire. It
never worked again.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.



Nitrate or phosphate base is a function of the supplier of the goo. Don't get
it on you, it is a bitch to wipe off.

Jim

vincent p. norris
shared these priceless pearls of wisdom:

-I read in a recent Av Leak that the stuff fire-bombers drop is a
-mixture of phosphate fertilizer and water.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

One would not think that applying a substance that was two-thirds hydrogen (great fuel)
and one-third oxygen (oxidizer) to a fire would be helpful either, and yet somehow it is!

Good point, Larry, but isn't water 1/9th hydrogen and 16/18ths oxygen?

vince norris

The idea behind putting water on a fire is not oxygen deprivation, but
cooling. Takes three things to cause fi Heat, Fuel, Oxygen
(oxydizer) - remove (or reduce below whatever level is approprite in a
given situation,) any one of those three and cumbustion is no longer
supported.

The retardent, IMHO with a bit of stray knowledge thrown in, is
"sticky water" - initially, it cools by absorbing heat from whatever
burning thing it lands upon, secondarily, it coats the fuel (trees,
brush, houses, etc) with the goo, which itself doesn't combust or has
such a high flash point it won't combust in this situation, to help
prevent ignition. I imaging the coating tends to isolate the fuel from
the oxygen source, too.

See here for info:
http://www.fs.fed.us/r2/psicc/hayres/slurry.htm

Randy


(Gene Seibel) wrote in message . com...
It does make a mess. A news reporter at a TV station I worked for had
one of our video redorders dumped on while covering a forest fire. It
never worked again.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.



Nitrate or phosphate base is a function of the supplier of the goo. Don't get
it on you, it is a bitch to wipe off.

Jim

vincent p. norris
shared these priceless pearls of wisdom:

-I read in a recent Av Leak that the stuff fire-bombers drop is a
-mixture of phosphate fertilizer and water.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

"Larry Fransson" wrote in message
news:2003111700124016807%newsgroups@larryandjenny. net...
On 2003-11-16 16:21:37 -0800, vincent p. norris said:

"Ammonium" is loaded with hydrogen and "-ate" means lots of oxygen.
Neither would seem to ideal for quenching a fire.

One would not think that applying a substance that was two-thirds hydrogen
(great fuel) and one-third oxygen (oxidizer) to a fire would be helpful
either, and yet somehow it is!

Hold it. The percent of the weight of the atoms in a molecule has nothing
to do with the chemical properties of the molecule. These atoms are bound
together. It is not a simple mixture. Another example: Salt is sodium and
chlorine, but does not have the properties of either.