Improvements in and relating to Fire Extinguishing Compounds.
Year: 1894

page_text: Date of Application, 15th May, 1894-Accepted, 16th June, 1894
COMPLETE SPECIFICATION.
Improvements in and relating to Fire Extinguishing Compounds.
(I, ALBERT CHRISTIAN SCHUMACHER, a citizen of the United States of
America, residing at Ann Arbor, in the County of Washtanaw and State of
Michigan, one of the United States of America, Chemist, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
My invention consists of an improved fire extinguishing compound, and in a
process for using the same in extinguishing fires, which will be hereinafter fully
described and particularly pointed out in the claims.
Heretofore fire extinguishing compounds have usually consisted of those wherein
carbonic acid gas is liberated by the intimate mixture of a strong acid with an
alkali, (sulphuric acid and bicarbonate of soda being commonly employed,). the
mixture being effected quickly and rapidly by precipitating the acid into the alkali,
which alkali is contained in solution in the body of water in the main tank of the
apparatus. The almost instantaneous generation of carbonic acid gas which takes
place under the above mentioned conditions causes the formation of an operative
pressure in the tank sufficient to expel the water from the same and to cause the
absorption in the outgoing stream of a considerable quantity of the carbonic
acid gas.
Among the disadvantages of the above system is that it requires a very high
initial pressure to cause the necessary absorbation of the gas in the water at the
beginning of the discharge, in order that the stream may exert its due extinguishing
effect on the fire. The length of effective propulsion of the stream from the nozzle
of the hose is also shortened by the tendency of the absorbed gas to escape from
the stream, thus breaking up the same, and the loss of carbonic acid gas resulting
therefrom is disadvantageous, as the stream is dependent for its extinguishing
quality upon the amount of absorbed gas it carries to the fire.
A further disadvantage of the present fire extinguishing compounds is that the
reagents used are liquid in form, and, since they must necessarily be strong and
concentrated to exert a vigorous action in liberating the carbonic acid gas, they
must be handled with considerable care, and be carried in strong vessels.
One object of my invention is to provide a fire extinguishing compound which
can be transported and held until the time for its use in a dry state in the form of
a powder. Ease and economy in transportation is thus acquired.
Another object of my invention is to produce a fire extinguishing compound
which will be carried in solution or suspension in the stream of water propelled
from the extinguishing apparatus, and the ingredients of which will have no
chemical reaction upon each other until exposed to the heat of the fire, but which
will, when exposed to such heat, generate at once and with certainty a large
amount of fire extinguishing gas. I thus secure the generation of the gas at the
time and place where it is most needed, and secure myself from loss of extinguishing
gas during the transit of the stream. I also preserve the fabrics upon which the
stream of water may fall from injury due to heat caused by the reaction of the
ingredients of my compound, unless the said fabrics themselves be in a place where
the heat is sufficient to cause such reaction of ingredients.
Since I thus rely for the gas used in extinguishing the fire, not upon such gas as
may be absorbed by the stream of water before expulsion from the generator, but
upon the mutual action of ingredients carried by the stream, which are themselves
inactive unless exposed to beat, I do not require as strong an initial pressure to
expel the stream from the generator as is required when carbonic acid gas is to be

page_text: absorbed in and carried by the stream, and the stream is thus not subjected to the
dispersing action above noted in connection with such carbonic acid gas streams,
and has a longer range of effective throw.
I attain the objects thus -noted by the use of a compound composed of the
following ingredients, viz., oxalic acid, an oxalate, and suitable oxidizing agents,
such as manganese dioxide and potassium permanganate. These compounds are all
used in their dry form, as powders.
I may use any convenient oxalate in my compound, preferring, however, to use
either sodium or potassium oxalate, on account of their cheapness. I may also use
any other oxidizing agents than those above mentioned, citing manganese dioxide
and potassium permanganate merely as examples, but the oxidizing agent used to
oxidize the oxalate should be such that it will have no action upon the oxalate
either when dissolved in water or otherwise, unless exposed to heat. Two oxidizing
agents may be, and are preferably used, one to act upon the oxalic acid and one to
act upon the oxalate, but only one may be used if desired. By the use of two
oxidizing agents, a more rapid and responsive action of the ingredients of the
compound is obtained.
The proportion in which these ingredients are preferably used is the following.
A charge for a chemical engine is made up by mixing forty parts of dry oxalic
acid with one hundred parts of dry oxalate. To these are added, when the
generation of gas is to be caused, twenty parts of manganese dioxide and three
parts of potassium permanganate. All of the proportions are given by weight.
The charge when so made up is proportioned in quantity to the capacity of the
generator of the fire extinguisher, in substantially the proportions of sixteen pounds
of the mixture to a generator of twenty-five gallons capacity.
I do not limit myself to these exact proportions, but mention them as an example
of proportions which will produce good results. From the proportions given, it will
be apparent that the manganese dioxide is intended to act upon the oxalate, and the
potassium permanganate upon the oxalic acid.
The charge so made up is kept from the liquid contents of the generator until
desired for use, in two separate receptacles, one containing the oxalic acid and the
oxalate, and the other the mixture of the oxidizing agents. When required for use,
the charge is precipitated by dumping or breaking the receptacles in which the
ingredients are held into the water in the main tank of the generator, where the
mass should be thoroughly agitated, in order that all of the oxalic acid may be
oxidized, as none of the acid should be expelled from the generator. Immediately
a vigorous oxidizing action takes place between the oxalic acid and the oxidizing
agents, potassium permanganate especially, and in consequence of the reduction of the
acid, carbonic acid gas is set free in large quantities, and creates a pressure sufficient
to throw a stream containing the oxalates and the manganese dioxide to the desired
point. The evolution of gas this produces is very uniform, and the pressure
produced is consequently uniform, and is not sudden and violent, as is the case when
an acid and an alkali are used. Since the main object of the evolution of gas at this
time is to produce a pressure, sufficient to expel the contents of the generator, as
high an operative pressure is not required as when it is necessary to cause the
outgoing stream of liquid to absorb large quantities of carbonic acid gas, and a
pressure of about two-thirds of that now usually employed will throw a stream quite
as far as the same can be thrown now by the higher pressure. Of course such
carbonic acid gas as is absorbed by the stream has its usual extinguishing effect.
The stream produced in this manner has but little tendency to spread, on account of
the small proportion of gas absorbed thereby.
The stream propelled from the apparatus contains the oxalate and the oxidizing
agent which is to act upon it, the chemicals being inert with reference to each other.
as they are carried by the stream. The mixture thus conveyed, when it strikes the
fire, will become active, and carbonic acid gas will be evolved rapidly and at the
point where it is most needed. If the stream does not strike a place where the heat
is intense, no evolution of gas will take place, and the fabrics with which it comes

page_text: in contact will be saved the injury which the heat produced by the chemical action
of the ingredients might otherwise cause.
It is to be noted that my improved compound generates the carbonic acid gas by
the chemical process of oxidization and reduction, instead of that of liberation by
the substitution of an acid radicle for carbon dioxide in its combination with a
base. This of itself is a great improvement, as it enables me to utilize as a fire
extinguishing agent very nearly the whole amount of the chemicals employed, a
thing which has heretofore been impossible in the ordinary processes of the
substitution of sulphuric acid radicle for the carbonic acid in combination with
soda, the resultant sodium sulphate being practically inert so far as fire destroying
properties are concerned.
It is obvious that the oxalates and oxidizing agents alone could be used in
solution, and be precipitated upon the fire by any mechanical means, as by air
pressure forced into a generator, or other equivalent means, and I do not limit
myself to the employment of oxalates when thrown upon the fire by the pressure of
gas generated by the oxidation of oxalic acid. It is also obvious that instead of the
oxalates being mixed with the oxalic acid, when such acid is used to generate the
operative pressure, it may be in solution in the main tank of the apparatus, as may
also the oxidizing agent which is to act upon it, and the oxalic acid may be so
placed that it will generate the carbonic acid gas forming the operative pressure,
without being thrown into the main tank.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein described process of extinguishing fires, which consists in throwing
upon the fire a stream carrying in solution an oxalate and a suitable oxidizing agent
therefor, producing a fire extinguishing gas by the combination of the said chemicals
when exposed to the heat of the fire, and thereby extinguishing the fire, substantially
as described.
2. The herein described process of extinguishing fires, which consists in producing
an operative pressure in the generator by the oxidization of oxalic acid by an
oxidizing agent, propelling upon the fire by the pressure thus formed a stream
carrying in solution an oxalate and suitable oxidizing agent therefor, producing
a fire extinguishing gas by the combination of the said chemicals when exposed
to the heat of the fire, and thereby extinguishing the fire, substantially as.
described.
3. The herein described process of extinguishing fires, which consists in throwing
upon the fire a stream containing in solution an oxalate and manganese dioxide,
producing carbonic acid gas by the action of the said chemicals when exposed to
the heat of the fire, and thereby extinguishing the fire, substantially as described.
4. The herein described process of extinguishing fires, which consists in forming
an operative pressure in the generator by the action of oxalic acid and potassium
permanganate, throwing upon the fire by the pressure thus formed a stream carrying
in solution an oxalate and manganese dioxide, producing carbonic acid gas by the
action of the said chemicals when exposed to the heat of the fire, and thereby
extinguishing the fire, substantially as described.
5. A fire extinguishing compound cousisting of the mixture in suitable proportions.
of an oxalate and manganese dioxide, substantially as described.
6. A pressure producing and fire extinguishing compound consisting of the
mixture in suitable proportions of oxalic acid, an oxalate, potassium permanganate,.
and manganese dioxide, substantially as described.
Dated thin 1
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.