Fire extinguishing composition

A fire extinguishing composition including potassium carbonate, a boron-containing compound, and water. In another embodiment, the fire extinguishing composition, in addition to the above, includes a potassium salt of an organic acid having from 1 to 6 carbon atoms. The fire extinguishing composition is non-corrosive to metals.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved fire extinguisher composition 
that is non-corrosive to metals such as aluminum, copper, and steel. The 
composition of the invention further has minimum volatility and excellent 
reignition protection. 
Numerous types of fire extinguishing compounds are known, such as carbon 
dioxide, liquid extinguishing compounds, and various powder sprays. Liquid 
compounds are generally corrosive to metals. This is of particular concern 
in extinguishing fires on a cooking surface, such as a stove top. 
Specifically, even if the fire is successfully extinguished, the stove 
top, which is invariably a metal surface, may be damaged due to corrosion. 
Most stove-top fires result from the ignition of cooking grease. When 
extinguishing grease fires of the type wherein a pan of grease, or any 
other grease-bearing flammable medium, bursts into flame, the various 
methods of extinguishment consisting of fully covering the flaming body of 
grease with a coating of fire extinguishing agent applied by spraying. 
This has required a person to aim the fire extinguishing material, or if 
the material were being applied by an automatic apparatus, the latter 
would have to cover a relatively large expanse. If the fire extinguishing 
material did not completely cover the fire, the fire was not effectively 
extinguished. 
There is thus a need in the art for a liquid fire extinguishing composition 
which is not corrosive to metals, for example, cooking equipment and 
utensils. There is also a need in the art for a fire extinguishing 
composition which is capable of extinguishing grease fires without the 
need for completely covering the fire. 
DISCLOSURE OF THE INVENTION 
It is accordingly an object of the present invention to provide a fire 
extinguishing composition which is not corrosive to metals. 
It is another object of the invention to provide a fire extinguishing 
composition, as above, which is effective in extinguishing grease fires. 
These objects, and others described hereinafter, are achieved by an aqueous 
fire extinguishing solution, which comprises water, potassium carbonate, 
and a boron-containing compound, wherein the potassium carbonate and the 
boron-containing compound are dissolved in the water to form the aqueous 
solution, the solution being sprayable on the fire. 
The objects of the invention are also achieved by an aqueous fire 
extinguishing solution, which comprises potassium carbonate, a 
boron-containing compound, a potassium salt of an organic acid, and water, 
wherein the potassium carbonate, the boron-containing compound and the 
potassium salt of the organic acid are dissolved in the water to form the 
aqueous solution, the solution being sprayable on a fire. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In one embodiment of the invention, an improved fire extinguishing 
composition comprises a mixture of potassium carbonate, a boron-containing 
compound, and water. In another embodiment, the composition, in addition 
to the above, contains a potassium salt of an organic acid. It has been 
found that when either of these compositions are applied to a stove-top 
fire, such as a grease fire, or to a charcoal fire, the fire is 
immediately extinguished. 
By dispensing a relatively small amount of the improved fire extinguishing 
material onto a small portion of a flaming pan of grease, or an expanse of 
grease which is burning, the flames will be extinguished immediately 
because of the interaction of the material with the grease and the spray 
of the material over the surface of the grease. It is believed that the 
placement of a small area of fire extinguishing compound into a large 
expanse of grease causes a matrix barrier blanketing composition to be 
formed which seeks out grease and flame, then covers the entire expanse of 
grease The flames are thus extinguished by shutting off the oxygen supply 
as well as interfering with the chemical reaction of rapid oxidation. The 
composition is capable of ascending an incline in order to seek out and 
blanket hot grease. 
In the first embodiment of the invention, which comprises water, potassium 
carbonate and the boron-containing compound, the potassium carbonate is 
present in an amount of between about 20% and 40% by weight, more 
preferably between about 25% and 26% by weight and most preferably between 
about 30% and 42% by weight. 
The boron-containing compound is preferably boric acid, but it may be any 
other suitable boron-containing material in addition to or in place of 
boric acid, including ammonium, sodium, potassium, calcium, iron and zinc 
borates, boron phosphate, boron and boron oxide. Where the 
boron-containing compound of the first embodiment is boric acid, it is 
present in an amount of between about 0.5% and about 10% by weight, more 
preferably between about 2% and 8% by weight, and most preferably between 
about 3% and 6% by weight, the remaining portion being water. When one or 
more of the other boron compounds are used in addition to, or in place of 
the boric acid, the quantity should be such as to provide an amount of 
boron equivalent to the amount that will be provided by the amounts of 
boric acid disclosed above. In other words, one or more of the other boron 
compounds listed above can be substituted in whole or in part for the 
foregoing quantities of boric acid, provided that the amounts employed 
contain the ratio equivalent stoichiometric quantities of boron that will 
be present in the above-disclosed amounts of boric acid. 
Converting the above amounts of boric acid to a boron basis, the amount of 
boron is between about 0.085% and about 1.7% by weight, more preferably 
between about 0.34% and about 1.36% by weight, and most preferably between 
about 0.51% and about 1.02% by weight. 
In the second embodiment which includes the potassium salt of the organic 
acid, the potassium carbonate portion is present in an amount of between 
about 20% and about 47% by weight, more preferably between about 25% and 
about 26% by weight, and most preferably between about 30% and about 42% 
by weight. The potassium salt of the organic acid is present in an amount 
of between about 5% and about 30% by weight, more preferably between about 
12% and about 25% by weight, and most preferably between about 17% and 
about 22% by weight. 
Where the boron-containing material is boric acid, the boric acid portion 
of the composition is present in an amount of between about 0.4% and 10% 
by weight, more preferably between about 2% and about 8% by weight, and 
most preferably between about 3% and about 6% by weight. 
As with the first embodiment, the same stoiciometric amounts of boron must 
be maintained if a boron-containing compound other than boric acid is 
used. Converting the above amounts of boric acid to a boron basis, the 
amount of boron is between about 0.068% to about 1.7% by weight, more 
preferably between about 0.34% and about 1.36% by weight, and most 
preferably between about 0.51% and about 1.02% by weight. 
The potassium salts of organic acids are preferably potassium acetate, 
potassium tartrate or potassium citrate, but can generally be an acid salt 
having from 1 to 6 carbon atoms, and having a minimum solubility of about 
150 g/100 ml. cold water. 
If there is an excess of the boron-containing material or the potassium 
salt of the organic acid, in the solution, it will remain in undissolved 
form. This will not, however, affect the fire extinguishing capabilities 
of the remainder of the solution. The solution composition must reach a 
saturated condition for the most preferred or effective fire extinguishing 
action. 
The solution may be dispensed from a pressurized can or a mechanical pump 
or any other device from which the solution can be projected. It has been 
found that the fire extinguishing solution is non-corrosive, that is, it 
will not corrode aluminum, copper steel or other metallic surfaces to 
which it has been applied during a fire extinguishing action, nor will it 
corrode metallic containers or piping used for containing or dispensing 
the solution. By contrast, most prior art aqueous fire extinguishing 
compositions have tended to dissolve metal. 
Furthermore, in spite of the fact that the composition is in aqueous form, 
it will not cause detrimental splattering when it is applied to, and 
reacts with, a flaming oil or grease. Rather, the composition forms a 
flow-controlled pasty matrix, in which the composition is spread rapidly 
across the surface of the grease fire to rapidly extinguish it. A thick 
crust forms on the surface of the grease after extinguishment, which 
protects the surface from flashback. 
A composition of boric acid, water and potassium carbonate which has been 
found particularly effective comprises 40% by weight potassium carbonate, 
2.5% by weight boric acid, and 56.5% by weight water. 
A preferred composition incorporating the potassium salt of organic acid 
comprises 33.33% by weight potassium carbonate, 2.2% by weight boric acid, 
and 17.02% by weight potassium acetate, and the remaining water. 
The following examples illustrate the invention. Table 1 summarizes the 
compositions and results from the examples.

EXAMPLE 1 
An aqueous composition containing 100 parts of 47% potassium carbonate in 
water was mixed with 14 parts of water, 24 parts of potassium acetate and 
3 parts of boric acid. All components dissolved upon mixing; however, less 
than 1% by weight of precipitate formed upon refrigeration below 
32.degree. F. This indicates that the solution was a nearly saturated 
mixture. Three pounds of the composition were applied to and extinguished 
16 separate grease fires. The fires were preburned for one minute to two 
and one half minutes in pans of 4" diameter with oil 11/4" deep, 131/4" 
diameter with 1/4" of oil, and 11" diameter with 4" of oil, placed on top 
of a conventional stove. Instantaneous knock down of the flames occurred 
with minimum volatility. High volatility is considered to be detrimental 
to effective extinguishment under all circumstances. The residual aqueous 
composition would flow and seek involvement to react with any remaining 
hot grease or flame to form a pasty matrix barrier. This stable barrier 
would extinguish, seal and protect against reignition. It was estimated by 
Underwriters Laboratory that only 20% of the composition was required for 
extinguishment. The aqueous composition will attack a three dimensional 
fire involvement including flowing up a nominal 10.degree. incline. The 
composition and resulting reaction products from the fire were corrosive 
neither to aluminum and copper components utilized to apply the 
composition nor to the stove and pans involved in the fire. 
EXAMPLE 2 
An aqueous composition containing 100 parts of 47% potassium carbonate in 
water was mixed with 15 parts water, 10 parts potassium acetate and 3.5 
parts of boric acid. Three pounds of the composition were applied to and 
extinguished grease fires. Instantaneous knock down of the flames occurred 
with moderate volatility. Minimum flowability, stability and protection 
against reignition occurred. The composition and resulting reaction 
products were corrosive neither to aluminum and copper components utilized 
to apply the composition nor to the stove and pans involved in the fire. 
EXAMPLE 3 
An aqueous composition containing 10 parts of 47% potassium carbonate in 
water was mixed with 50 parts of water, 50 parts of potassium acetate and 
3.5 parts of boric acid. Three pounds of the composition were applied to 
and extinguished grease fires. Moderate knock down of the flames but with 
limited volatility occurred. Stability of the barrier matrix occurred but 
protection against reignition was moderate. The composition and resulting 
reaction products were corrosive to neither aluminum and copper components 
utilized to apply the composition nor to the stove and pans involved in 
the fire. 
EXAMPLE 4 
An aqueous composition containing 80 parts of 47% potassium carbonate in 
water was mixed with 50 parts of water and 3.5 parts of boric acid. Three 
pounds of the composition were applied to and extinguished grease fires. 
Instantaneous knock down occurred. Excessive volatility, minimum 
flowability, stability and protection against reignition occurred. The 
composition and resulting reaction products were corrosive to neither 
aluminum and copper components utilized to apply the composition nor to 
the stove and pans involved in the fire. 
EXAMPLE 5 
An aqueous composition containing 100 parts of 47% potassium carbonate in 
water was mixed with 15 parts of water and 1.5 parts of boric acid. Slight 
corrosion of aluminum wire was apparent within a seven day period. No 
corrosion was evident on aluminum wire when two parts or more boric acid 
were mixed with the aqueous composition. 
EXAMPLE 6 
An aqueous composition containing 100 parts of 47% potassium carbonate in 
water was mixed with 15 parts of water and 25 parts of potassium acetate. 
No boric acid was added. Instantaneous corrosion occurred on aluminum wire 
and the wire was completely dissolved within a seven day period of time. 
EXAMPLE 7 
An aqueous composition containing 100 parts 47% potassium carbonate in 
water was mixed with 15 parts of water and 5.5 parts of sodium borate or 
borax. No corrosion occurred on aluminum wire after standing for over a 
two month period of time. 
Other boron containing compounds such as potassium tetraborate but not 
limited to this boron-containing compound were mixed in parts equivalent 
to the stoichiometric quantity of 3.5 parts of boric acid. They were found 
non-corrosive to aluminum wire over extended periods of time. Excessive 
quantities of boron containing compounds are not considered detrimental to 
the environment preventing corrosion nor to the fire extinguishing 
properties of the composition. Excess boron containing materials will 
precipitate as a solid in the composition. 
EXAMPLE 8 
The same procedure as Example 1 was followed, except that potassium formate 
was substituted for the potassium acetate of Example 1. Instantaneous 
knock down occurred. Volatility was minimum. Matrix barrier and flow were 
moderate and the composition was non-corrosive over an extended period. 
TABLE 1 
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EX- 
AM- 
PLE PER- 
# COMPONENT CENT RESULTS 
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1. Potassium Carbonate 
33.33 Instantaneous knock down. 
Water 47.51 Minimum volatility. 
Potassium Acetate 
17.02 Excellent matrix barrier 
and flow. 
Boric Acid 2.12 Excellent reignition pro- 
tection. Non-corrosive 
over extended period. 
2. Potassium Carbonate 
36.57 Instantaneous knock down. 
Water 52.91 Moderate volatility. 
Potassium Acetate 
7.78 Minimum matrix barrier 
and flow. 
Boric Acic 2.72 Moderate reignition pro- 
tection. Non-corrosive 
over extended period. 
3. Potassium Carbonate 
4.14 Moderate knock down. 
Water 48.72 Limited volatility. 
Potassium Acetate 
44.28 Moderate matrix barrier 
and flow. 
Boric Acid 3.08 Limited reignition pro- 
tection. Non-corrosive 
over extended period. 
4. Potassium Carbonate 
28.16 Instantaneous knock down. 
Water 69.21 Excessive volatility. 
Boric Acid 2.62 Minimum matrix barrier 
and flow, minimum reigni- 
tion. Non-corrosive over 
extended period. 
5. Potassium Carbonate 
40.34 Limited corrosion on 
Water 58.36 partially immersed aluminum 
Boric Acid 1.28 wire within seven days. 
6. Potassium Carbonate 
33.57 Instantaneous corrosion on 
Water 48.57 immersed aluminum wire, 
Potassium Acetate 
17.95 completely dissolved in 
seven days. 
7. Potassium Carbonate 
39.00 Non-corrosive over extended 
Water 56.43 period 
Sodium Borate 4.58 
(Borax) 
8. Potassium Carbonate 
33.33 Instantaneous knock down. 
Water 47.51 Minimum volatility. 
Potassium Formate 
17.02 Moderate matrix barrier 
and flow. 
Boric Acid 2.12 Non-corrosive over 
extended period. 
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