Note: Descriptions are shown in the official language in which they were submitted.
11163~ I
, ',.
,
i
!,
I I
., 11 ,'. .
i . - .
I;
The present invention relates primarily to the fighting'
, of fires o,n hydrophilic liquids.
Among the objects of the present invention is the
provision of novel compos~tions with which to fight such fires, i
as well as novel fire-fighting processes that make use of such
~ compositions. Il !
Ij These as well as further objacts of the present inven~
~ ~ tion will be more fully expoundad in the following descrlption
,1 of several of its examplifications~ ¦ .
.
,
`: : : ~
~ 2, ~ I ' .
,
~ '
.
3~f;i i
The fighting oE fires on hydrophilic li~uids such as
isopropyl alcohol, acetone, and the like, has heretofore not
reached the advanced state that has been attained in the art of
fighting fires on hydrophobic liquids. Aqueous foams are
considered the most desirable materials for fighting fires on
large bodies of flammable liquids, such as in storage tanks,
but hydrophilic liquids have an undesirable effect on such foams.
U.S. Patent Nos. 4,060,489 and 4,060,132 show that
the presence of a thixotropic polysaccharide in dissolved
condition in the aqueous liquid from which the foam is prepared,
causes the foam to gel and become a bubble-containina mat when
it contacts the hydrophilic liquid. Such mat floats on the
burning liquid and protects the ~oam above it so that the fire
is fairly rapidly extinguished.
Because the Eoams are generated by Eoaming an aqueous
concentrate that is diluted with many times its volume of water,
the concentration of the thixotropic polysaccharide in the
diluted solution is quite small so that it is difficult to
develop a very good, stable mat formation. Moreover it is not
too practical to merely dissolve a very high concentration of
the thixotropic polysaccharide in the aqueous concentrate,
inasmuch as this produces a concentrate that is too stiff a gel
to ~e rapidly diluted to foaming dilution or to be suitable for
use with the proportioning foamers that have been developed. As
a result special solvents have been used to make the concentrates,
or thic~eners have been incorporated in such a way that the
concentrat~s themselves are not too stable.
.,
bm~--
3~ ~
According to the present invention very desirable
i fire-fighting concentrates are in the form of solutions essen-
; tially in water~ which solutions have dissolved in them a
thixotropic polysaccharide thickener that increases their
Brookfield spindle 4 viscosity at 20C to not over about 3,000
centipoises at 60 rpm spindle speed, and the concentration of
the thickener in the concentrates being at least about 1% by
weight.
A particularly desirable thixotropic polysaccharide
is heteropolysaccharide-7 described in U. S. Patent 3,915,B00,
as well as somewhat degraded forms of heteropolysaccharide-7.
Among other advantages these polysaccharides yield more effective
foams when such foams are made with the help of sea water, as
compared to fresh water. I ~ -
Some working examples illustrate the present invention.
Exam~le 1
The following ingredients are combined: ¦
Water 9,240 ml.
; Chlorinated metaxylenol 3.6 gO
Urea 93 g
' /CH2~
Il I,~'CH2cH2cH2cO~a
li OH C 2 ! .;
(30% in water)357 ml.
HeteropolysaccharidF-7 122 g.
~ I
- .
., . ''`.
63~!~ .
i: '
,'
,CH2~
2 CH2cH2ocH2cooNa
OEI 2
(30% in water) 675 ml.
30% aqueous solution of equimolecular
mixture of sodium decylsulfate and .:
sodium octylsulfate 795 ml.
Monobutyl ether of diethylene glycol 300 ml.
Sl(C~3)3- ~~~ ~1 - O - -Si(C~3)3 -.
,C3H6 .
O
CH2
CHOH .
C,~2 .
~-C2H4SO3~a 3 :
(40 weight percent in 1:1
isopropyl-water mixture
~: by volume) 213 ml.
(C~3)2CF~CF2)nC NH3C2~5
where 20% of the n is 2,
30% of the n is 4,
~ 30% of the n is 6,and .'
;; . 20% of the n is 8 102 g.
~ MgSO4 204 g-
: ;
3~ ~
The heteropolysaccharide-7 is difficult to dissolve
directly in water in the abovc-specified amount, and it is pre-
ferred to begin by mixing together the first five ingredients;
', using only 12 ml. of the fourth ingredient (the Cg-substituted
imidazoline) and adding the fifth in small portions with stirring,
followed by pumping this pre-mix through a recirculating pump
until smooth. The remaining ingredients are then added and the
resulting mixture thoroughly mixedO Its pH should be about 7.1
to 8, and if necessary it is adjusted to that pH with acetic acid -~
or ammonia. Upon completion oflthe stirring associated with the
mixing, the product rapidly gels, but the gel is easily liquefied
by a little agitation. With a bit of stirring it flows fairly
easily. Under the influence of a suction of several inches of
mercury produced at the intake of a venturi jet, the gel flows
smoothly up into such a suction intake.
When ~e foregoing concentrate is diluted with ten times¦
its volume of water it is readily foamed with air to produce a
very effective fire-fighting foam having an expansion of 6 to 8.
When foamed with the apparatus of U. 5. Patent 2,868,301 the foam
can be projected a substantial distance. Projected onto a
burning liquid as hydrophilic or as polar as ethanol or acetone,
the majority of foam thus applied is not broken, but some forms
a gel-like mat that does not dissolve in cuch liquid rapidly
enough to significantly diminish the spreading of the projected
foam over the burning surface and the e~tinguishing of the fire
by the foam. The formation of the mat involves geIation of the
liquid contained in the foam and loss of water from the gelled
1,
6.
3~
liquid to the hydrophilic liquid through syneresis, and takes
place so rapidly that the foam bubbles are trapped in the mat
causing it to float on the hydrophilic liquid. This action takes
place with about eqllal effectiveness when the diluting water is
tap water or sea water or any combination of these two waters,
and resulting diluates have about the same fire-fighting effective-
ness.
Also when used to fight fires on hydrophobic liquids,
the foregoing foam shows about the same good results as the foams
of British Patent 1,381,953 and U.S. Patent No. 3,849,315.
Example 2
The formulation of Example 1 is modified in two
respects. Instead of the 122 grams of heteropolysaccharide-7,
there is added 138 grams of a degraded form of that polysaccharide,
. e~ /G f~ c
and instead of 102 grams of the ethyamine salt of the
perfluorinated mixed acids, 100 grams of the free mixed acids
CF 3 ( CH 2 )mCOOH are used,
where 40% of the m is 4,
` 35~ of the m is 6, and
25% of the m is ~.
The degraded form of the polysaccharide is prepared by
adding a little HCl to the fermentation broth in which it is
formed to brlng its pH to 6.5, and then heating the acidified
broth to 90C for thirty minut~es. The degraded product is then
recovered by the same technique used to recover the unde~raded
material.
--7--
bm~
~" .
3'~
ll
1.,
Other hydrolysis techniques can ~e used to degrads the
fermentation pxoduct if desired. Alternatively degradation can
be effected by heat alo~e or by oxidative attack. Thus a one
hour boiling of the fermentation broth causes degradation, or
the fermentation broth can be treated with 1/20 its volume of
30% H2O2 at 70DC for 30 minutes, and a similar degradation can
be effected with 1/10 its volume of acidified 2% potassium
permanganate at 50~C. The degradation is not major and the
degraded product is still quite insoluble in lower alcohols so
~.
-i that the recovery technique does not have to be modified~ It is
estimated that the degrading step shortens the polymer chains
about twenty to thirty percent and has no other significant effe~l .
The viscosity of a 1% aqueous solution of the polymer at low
shear is generally reduced about 1/3, and this is the important
result that is desired.
Because of the viscosity reduction the formulation of
Example 2 contains more of the polysaccharide and when diluted
and foamed it is somewhat more effective in extinguishing fires
on hydrophilic liquids. Thus when a typical concentrate of
Example 2 has its viscosity measured with a Brookfield LVF
viscometer using a ~o. 4 spindle, it gives the folIowing readings
at the designated spindle speeds:
'~Spindle Speed in Viscosity
I_evolutions ~ r Minute in Centipoises
0 3 142,000
0.6 95~000
i 1.5 53,600
3.0 32,000
6.0 17,700
12.0 9 450
' 30.0 4,200
6~.0 2,130
8.
3~
I.
,
!
Because the 60 rpm viscosity is below 3000 centipoises,
such a concentrate is well s~lited for use with standard propor- ¦
tioning foamers. Because of the high content of the poly- !
saccharide, over 1.1% by weight of the concentrate, it can be
diluted with more than 10 times its volume of water and still do
a very good job of extinguishing fires. A typical fire test
gives the following results on a burning batch of 60 gallons 9g%
isopropyl alcohol in a round pan providing a 40 square foot
surface. I
Preburn time 3 minutes -~*
Dilution with 16 2/3 its volume of
tap water
Application rate 0.15 gallons of diluate
per minute per square foot
of surface
Expansion 8.8
Control 2 minutes 20 seconds
Extinguishment 2 minutes 50 seconds
Sealability (the
application of the
foam is continued for
1 minute after
extinguishment) 11 minutes 30 seconds
A feature of heteropolysaccharide-7 as well as of the
thixotropic polysaccharides into which it can be degraded, is
that they~are more effective in extinguishing fires on hydrophili~
liquids when they are usea with sea water, as compared to their I ,;
use with fresh water. This appears to be largely due to the e
presence of maynesium ions in sea water, and the addition of
magnesium ions in the foregoing formulations, in a proportion of
at least about 1/6 the weight of the polysaccharide shortens
~ ~1 . .. ..
" 9' .
I i , . .
. ~ 3~fi~
~'-
their fire extinguishing times when they are diluted with fresh
water. It has no significant effect on the fire extinguishing
when sea water is the diluent.
Increasing the magnesium ion content to a~out 1/3 the
weight of the polysaccharide heightens the improvement, but
further increases in magnesium ion content do not further add
significantly to the effectiveness.
Adding too much magnesium ion can also produce problems
such as the precipitation of magnesium compound when the
concentrate is subjected to very low temperatures. Such
precipitation could interfere with the use of the concentrate
in standard proportioning foamers in extremely cold weatherO
~agnesium sulfate in a proportion of about 1.3 to about 1.7
times the weight of the polysaccharide is a preferred choice
and gives magnesium ions in a proportion of about 1/4 to
about 1/3 the weight of the polysaccharide. However, magnesium
chloride, nitrate, and/or acetate can be substituted for some
or all of the magnesium sulfate, if desired. Other metallic
ions such as of calcium, chromium and the others listed in
U.S. Patent 3,915,800 (Table VII) can be substituted for the
magnesium but are ~not as good at equalizing the effects of
sea water and fresh water dilution.
The urea in the foregoing examples can be reduced in .;
amount or entire]y eliminatea, inasmuch as its principal
effect is to speed up the solution of the polysaccharlde in
th~ water. 7Or th- deyraded forms of hetero7Olysaccharide-7
j lOo ~
', .
,, ,, . ~ .~
3~a~
,
the optimum urea content of the water in which the polysaccharide
is to be dissolved is not as high as for the undegraded hetero-
polysaccharide-7, From about 1/2% to about 5% urea in the water,
by weight, is a preferred range of concentration regardless of the
type of heteropolysaccharide-7, and the same concentration is
suitable for other viscosity-increasing thickeners such as
scleroglucan, mannan gum, etc. The increase in polysaccharide
dissolution rate makes itself felt however, even with lesser
concentrations of urea, and its effect is not changed much over
wide variations in the amount of polysaccharide being dissolved.
The urea also helps reduce the freezing point of the
concentrate. As little as 1/2% urea based on the weight of the
concentrate produces a noticeable improvement, particularly when
the concentrate also contains at least about 2% of a glycol or
an etherified glycol freezing point depressant.
The urea can be partially or completely replaced by
thiourea or even ammonium thiocyanate or ammonium cyanate, without
much change in effectiveness. All of these additives rapidly
dissolve in water to greatly improve lts solvent action on the
polysaccharide, even when the additive and the polysaccharide are
added to the water simultaneously.The stabilizing effect of urea
as noted in German Auslegeschrift 1,169,302 for protein hydroly-
zates, is not noticeable with the polysaccharides of the present
invention.
The diethylene glycol monobutyl ether in the above
examples can also be omitted, although it helps boost the expan- ¦
sion obtainable when the concentrate is foamed, and also helps
shorten the time required to extinguish a fire, particularly on
hydrophilic liquids. Only about 2 to 5% of such additive based
,'
11.
37~
on the total weight of the concentrate is all that is needed for
this purpose. This addit;ve also helps reduce the freezing point
of the concentrate, but this i9 not important. The concentrates
of the present invention ara freeze-thaw stable so that they are
not damaged by freezing, and as they cool to freezing temperature
their gelled condition becomes too stiff before they actually
freeze. They should accordingly be stored for use at temperatures
no lower than about 35F, unless the concentrates are to be pumped
through a diluting apparatus by a positive displacement pump.
It will be further noted that the dissolved magnesium
salt significantly reduces the freezing point of the concentrates,
whether or not other freeze-preventing additives are used.
Additives such as ethylene glycol and hexylene glycol can be
used in place of some or all of the diethylene glycol monobutyl
ether, if desired, but are not preferred inasmuch as they are
considered toxic to marine life and fire-fighting liquids can
eventually run off into streams.
The silicone surfactant and/or the fluorocarbon sur-
factant can also be omitted if desired. As noted in the parent
applications, their presence maXes the formulations, after
dilution and foaming, extremely effective in extinguishing fires
on hydrophobic liquids such as gasoline, so that these formula-
tions can be used for fighting fires involv mg either type of
liquid with excellent results. The silicone surfactant and the
fluorocarbon surfactant cause aqueous films to form over burning
hydrophobic liquids, and this greatly assists the fighting o~
fires on such liquids. ~owever, either of these two aqueous
film formers can be reduced in quantity or entirely eliminated,
and good aqueous film formation generally effected by increasing
the concentration of the other. Also as pointed out in ~he
parent applications other fluorocarbon surfactants and other ¦
12~
,
,. ~
silicone surfactants can be used to provide the aqueous film
formation. For sueh result the diluated concentrate should have
a surface tension of 19 or less dynes per centimeter, preferably
18 dynes or less. Higher surface tensions do not eause signifi-
eant aqueous film formation.
The omission of all fluorocarbon surfaetant from the
foregoing formulations also lowers the effectiveness with whieh
t};ey fight fires on hydrophilie liquids. At least about 0~03%
fluorocarbon surfactant, or better still 0.05% is particularly
desired to give sueh increased effeetiveness to the diluted eon *
centrate. The undiluted concentrate ean then have at least ten
times these amounts.
The formulation of Example 2 with its relatively high
eoncentration of thixotropic polysaccharide does a very good job
of extinguishing fires on hydrophilic liquids, even when diluted
with 16 2~3 times its volume of fresh or sea water. On the other
hand the formulation of Example 1 is best used when diluted with
only about 10 times its volume of fresh or sea water.
The formulations of both examples do not inelude the
resinous film~formers normally used in foam eoncentrates as
deseribed in the parent applications. Such film-formers ean be
added as for instance in eoncentrations that add about 1/2% to
about 1 1/2% solids based on the total weight of the eoncentrate.j
A partieularly good resinous film-former is the reaetion produet
of 3-dimethylaminopropylamine-1 with an equivalent amount of i
ethylene-maleicanhydride eopolymer, described in Example I of
British Patent 1,3~31,952.
,
~ 13.
'' .
:: I
, _ . .!. . . -
~ . . .
The chlorinated metaxylenol of the formulations of the
present examples is a biocide that prevents the growth of mold,
bacteria, etc. in the concentrates. Other biocides or preserva-
tives, such as methyl parahydroxybenzoate or any o~ those
designated in the prior applications can be used instead oE or
combined with the chlorinated metaxylenol, preferably in a total
concentration of 0.0l to about 0.~3~ by weight of the concen-trate.
When the concentrate is made by a sequence of steps extending
over a number of hours, as fcr instance when the polysaccharide
solution in the water is prepared and stirred or permitted to
stand overnight before the remaining ingredients are added, the
preservative should be added in the first stage of the preparation.
It will be noted that the formulations of Examples l
and 2 not only have fluorocarbon and silicone surfactants in
small amounts but they also have additional surfactants that
are not of the fluorocarbon or silicone types and are in larger
amounts to impart the desired formability to the compositions.
; Those foamability-improving surfactants are largely of the type
that ha~e a hydrophilic moièty weighing at least 80~ more than
the lipophilic moiety, and thus follow the teachings of U.S.
Patent No. 3,849,315.
The foamed compositions of the present invention do
a very good job of extinguishing fires when applied by projection
from foam-delivering nozzlesj~ either portable or fixed as for
example on towers, or from line-proportioning foamers, or foam
chambers. In each case standard equipment can be used without
modification.
,
-l4-
bm~
.
3~
.,
il .
,'
i
The formulation of Example 2 meets all commercial
, standards when used to extinguish fires after dilution with
¦l 16 2/3 times its volume of fresh or sea water, which is a
' standard dilution provided by standard foaming equipment~ At
;! this dilution it is preferred to apply it to fires on the fol-
lowing liquids at the designated rates in gallons of diluted ..
liquid per minute per square foot of surface on the burning
liquid, using a fixed applicator such as a foam chambero
Methanol .16 .
Isopropanol .20
n-propanol u 10
n-Butanol .10
t-gutyl Alcohol 35
Isodecanol .10
SDA-1-200 PF (Ethanol) .16
Ethyl Acetate .10 .
n-propyl Acetate .10
Butyl Acetate .10 .
ethyl ~nyl Acetate .10
Methyl Acrylate .10
~ Acetone .20
Methyl Ethyl Ketone .20
Methyl Isobutyl Ketone : .10
. Propionaldehyde .10
: Hexane .10
I Heptane .10
: Aut~motive Gasoline .10
::~ Lactol Spirits (Naphtha Solvent) .10
Mineral Spirits (Petroleum Spirit) .10
: Toluene .10
~ Petroleum Distillate .10
l Methyl Cellosolve .10
. ~ .
: j; The foregoing application rates are preferably
increased by about one-fourth when using movable discharge .;
nozzles to spread the applied foam ar.d speed the extinguishment. .
~owever, it is not desirable to increase~the rate of ~application
to t-butyl alcohol (on which fires are always difficult to
i extinguish) or to have a movable nozzle application rate less
I! than about 0.16 gallons per minute per square footO
l .'
, .,
-. . 1 15.
, . .
..
,. I
,
The formulations of Examples 1 and 2 can be applied
when diluted with 10 times their volume of fresh or sea waterO
The preferred application rates of the Example 2 formulation
when so diluted are about one-fifth less than listed above,
except that application rates lower than about 0.10 gallons per
minute per square foot are not desirable whether from fixed ;
or movable foam applicators. Also the tenfold dilution is not
recommended for fires on hydrophobic liquids where the 16 2/3
dilution has been a time-honored and widespread standard proven
to be highly effective and built into standard fire-fighting -~,
. equipment.
The formulations of the present invention can be
further varied. Thus the formulation of ~xample 2 can use
the fluorinated surfactant of Example 1, or major variations
can be made such as shown in the following exemplifications:
Example 3
....
ID this example some of the heteropolysaccharide-7 is
replaced by xanthan gum and good results are obtained, although
there is some loss of burnback resistance. The formulation is
water 6155 mls.
urea 62 g.
the degraded heteropolysaccharide-7
of Example 2 41 g.
xanthan gum 41 g.
o-phenoxy phenol 5.8 g.
the Cg substituted imidazoline
surfactant solution of Example 1 460 mls.
the mixed alcohol sulfates solution
of Example 1 530 mls.
I the silicone surfactant solution d,,
of Example 1 142 mls.
- the fluorinated surfactant of
Example 1 68 g,
acetic acid 35 mls.
'16.
,~ '' 11 ' . I
:
3~ ~
The formulation of Example 3 can also be modified by the
addition of 0.3% trls-hydroxymethyl aminomethane, about 0,07% of
the disodium salt of nitrilotriacetic acid, and about 3% butyl
carbitol, based ~n the total weight of concentrate,
Other very effective mixtures of perfluorocarboxylic
acids useful for the formulations of the present invention, are
those in which by weight about 55 to about 70% is C8, about 14 to
about 23% is C10, about 6 to about ~/v is C12, about 2 to about 7% j
is C14, and any balance is C6. Such a mixture in a concentration i
of 30 grams/gallon in a formulation also having 25 grams/gallon , ~r
of the silicone surfactant solution of E~ample 1 and 600 mls./
gallon of the mixed imidazolines of Example 1, 150 mls./gallon of
30% solution of the corresponding Cll-substituted imidazoline
surfactant, 295 mls./gallon of propylene glycol monobutyl ether
and 268 mls./gallon of butyl cellosolve, makes a very effective
fire extinguisher whether or not the heteropolysaccharide-7 is
added to it.
Instead of degrading the normal polymeric chains of
heteropolysaccharide-7 their formation by fermentation can be
stopped when it has proceeded about half to three-quarters the
extent practiced to produce the undegraded heterop~lysaccharide-7.
This early termination lowers the yield but also produces a
shorter polymer that can be considered a degraded form of hetero-
polysaccharide-7 in accordance with the present invention. The
undegraded polymer seems to resist degradation by high-shear
stirring. -
The degree of chain-shortening is best dete~nined by
measuring the viscosity of aqueous solutions of the chain-
shortened material. A 20~C viscosity of over 3,000 centipoises
for a 10% solution measured at 60 rpm of a number 4 spindle in
a Rrookfield viscometer, shows inadequate chain-shortening~
~ ~ .
Il 170, I ,
3~
Conducting the chain-shorteniny on a 1~ solution of the polysaccharide
permits convenient measurement of the viscosity as the chain-shortening
reaction is taking place.
As shown, non-thixotropic thickeners for aqueous systems can also
be used in amounts up to about half the total thickcners in the formulations
of the present invention. Thus, ]ocust bean gum can be used in an amount
about 1/3 that of the thixotropic polysaccharide. Some thickeners such as
guar yum and its derivatives impart to the concentrates a free-thaw instability
that is not desired,
Special solvents such as the N-methyl pyrrolidone-2 are not needed
in the formulations of the present invention, so that these formulations are
inexpensive to manufacture, Moreover N-methyl pyrrolidone-2 has an adverse
effect on fire fighting with heteropolysaccharide-7 or its degraded forms.
However, such solvents can be used in small amoun-ts, e.g. up to about 10%
by weight, to further reduce the viscosity of the concentrate.
It is helpful to buffer the concentrate as by the addition of some
tris-hydroxymethyl aminomethane in a quantity of 1/8 to 1/2% by weight,
unless the silicone surfactant is omitted.
- 18 -
,
.. ' !
~ 3~-3
The concentrates of the present invention can be stored
in mild steel containers that have their interiors uncoated, or
in plastic containers. No serious corrosion of the mild steel is
, produced after many months of storage in such a container, They
can be used very effectively to fight non-polar liquid fires in
tanks by introducing the foamed diluted concentrate below the
liquid surface in the tanX, This so-called sub-surface intro-
duction technique is particularly desirable in tanks of gasoline
or other petroleum products, and is not suitable for fighting
fires on polar, that is hydrophilic liquids~
' 19.
1~, ,
I'
3:~
,,. .
Obviously many modifications and variations of the
present invention are possible in the light of the above
teachings. It is, therefore, to be understood that within the
1l scope of the appended claims the invention may be practiced
: ¦ otherwise than as specifically described. .:
' .
. .
~ r
.` ~ .
","
~'
~c
.,- .
',.
