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Патент USA US3063950

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United States Patent ??ce
Patented Nov. 13, 1962
Eric Edward Cooper Cawood, Elland, England, assignor
to Nu-Swift Limited, Elland, England
No Drawing. Filed Apr. 7, 1960, Ser. No. 20,535
Claims priority, application Great Britain Apr. 10, 1959
6 Claims. (Cl. 252—2)
This invention relates to the preparation of dry ?re 10
extinguishing powders which are intended for use on all
classes of ?res, such as ember ?res in carbonaceous ma
Ammonium sulphate, (NH4)2SO4 ______________ __ 4O
Ammonium di-hydrogen phosphate, NH4H2PO4_____ 40
Potassium chloride (KCl) _____________________ __ 10
Talc _______________________________________ __
Tricalcium phosphate _________________________ __
Water insoluble metal stearate _________________ __
The above proportions are by weight and the propor
tions of ammonium sulphate and ammonium di-hydrogen
phosphate may be plus or minus 10%. Potassium chlo~
ride may be between 10 and 15 parts and all the ?rst three
terials, surface ?res, gas ?res, ?res of combustible liquids
substances should be ?nely divided so as to pass a 100
and ?res in electrical equipment.
Dry ?re-extinguishing powders are known which may 15 mesh screen (i.e. a screen having 100 meshes per inch).
The talc, tricalcium phosphate and water insoluble metal
be used on surface ?res, combustible liquid and gas ?res
stearate should be more ?nely divided so as to pass a 300
and ?res in electrical equipment. These powders, how
ever, are not effective on ember ?res in carbonaceous
mesh screen (i.e. a screen having 100 meshes per inch).
Furthermore, the proportions of the tale, tricalcium phos
materials and consist mainly of sodium bicarbonate
treated to prevent caking. Furthermore, a powder has 20 phate and water insoluble metal stearate may be varied,
for example talc may be ‘from 10 to 15 parts, and any or
been proposed which was suitable for extinguishing em
all of these three substances may be replaced by equiv
rber ?res, but it su?ers from the disadvantage that it
alent substances which will maintain the mixture in a
does not maintain a free ?owing condition after pro
free ?owing condition.
longed storage, because it gradually absorbs moisture
What we claim is:
from the air and cakes after standing for several months. 25
1. A dry ?re extinguishing composition consisting es
In the speci?cation of our British patent application
sentially of a mixture by weight of 36 to 44 parts am
No. 783,656 there is described a dry ?re-extinguishing
monium sulphate, 36 to 44 parts ammonium di-hydrogen
powder for use on all classes of ?res, and the present
phosphate, 10 to 15 parts potassium chloride and up to 18
invention is designed to provide an alternative composi 30 parts of other substances which maintain the mixture in
a free ?owing condition.
tion which is particularly suitable for use in constant pres
sure type ?re-extinguishers, in which both the powder and
2. A dry ?re extinguishing composition as de?ned in
claim 1 which includes talc.
the expellent gas under pressure are stored admixed in
3. A dry ?re extinguishing composition as de?ned in
the same container and are ‘discharged simultaneously.
According to the invention, a dry ?re-extinguishing 35 claim 1 which includes up to 2% by weight of tricalcium
compound comprises a mixture of ammonium sulphate,
4. A dry ?re extinguishing composition as de?ned in
ammonium di-hydrogen phosphate (mono ammonium
1 which includes up to 1% by weight of a water
phosphate) and potassium chloride with the addition of a
insoluble metal stearate.
small quantity of other substances which maintain the
5. A dry ?re extinguishing composition as de?ned in
mixture in a tree ?owing condition. Any of the usual 40
claim 1 in which the ammonium sulphate, ammonium di
substances for this purpose may be used for example talc,
hydrogen phosphate and potassium chloride are all ?nely
tricalcium phosphate and water insoluble metal stearate,
divided so as to pass through a 100 mesh screen.
that is, any one or more of these substances or equivalent
6. A dry ?re-extinguishing composition as de?ned in
substances may be incorporated in the mixture.
45 claim 5, in which the substances other than ammonium
Ammonium (ii-hydrogen phosphate is used instead of
sulphate, ammonium di-hydrogen phosphate and potas
the diammonium phosphate of some other ?re-extinguish
sium chloride are ?nely divided to pass through a 300
ing powders, because ammonium di-hydrogen phosphate
is particularly suitable for pressurised storage. However,
a larger proportion of ammonium di-hydrogen phosphate 50
is required than would be the case if diammonium phos
phate was used, because of the lower ammonium content
of ammonium ‘di-hydrogen phosphate. A high ammo
nium content is desirable, so that the powder will evolve 55
ammonia gas when applied to a ?re, the ammonia gas
being a useful ?ame extinguisher.
The potassium chloride is used instead of the sodium
bicarbonate of other ?re-extinguishing powders on ac
count of the better storage stability and higher ?re ex 60
tinguishing ef?ciency of potassium salts.
A preferred composition is as follows:
mesh screen.
References Cited in the ?le of this patent
Eddison ______________ __ Oct. 6, 1885
Ferguson ____________ __ Aug. 27,
Warnock ____________ __ Dec. 17,
Reiss ________________ __ Apr. 7,
Steppe ______________ __ Aug. 25,
Schulenburg _________ __ Aug. 25,
Great Britain ________ __ Feb. 22, 1956
Great Britain ________ _. Sept. 25, 1957
Great Britain ________ __ Dec. 31, 1958
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