Note: Descriptions are shown in the official language in which they were submitted.
3~2
FIRE-RESISTANT SAFE AND PANEL
Background of the Invention
=
In the art of fire-resistant safes, it is known that
one of the important factors in keeping the contents of the
safe cool when there is a surrounding fire, is that the
composition or filling which makes up the thickness of the
wall of the safe includes a large amount of water in various
forms or retained in various ways, as for example by absorp-
tion or adsorption. The water is valuable in helping to
keep the interior of the safe cool, because it absorbs a
great deal of heat when passing from liquid phase to vapor
phase, since this requires the input of the heat of vapor-
ization. It is therefore desirable, when constructing safes,
to use a composition or filling in the wall which contains
as much water as reasonably possible.
These principles apply equally to fire-resistant
storage boxes, drawers, filing cabinets, or other containers
intended to provide some degree of fire protection, and are
not limited to safes which are intended to provide burglary
protection as well as fire protection. The term fire-
resistant container as used hereafter is intended in a
generic sense as including safes which may give at least
some degree of burglary protection in addition to fire
resistance or fire protection, as well as the other men-
tioned types of containers which may give fire resistance
or protection without necessarily providing burglary pro-
tection. The principles of the invention apply also to the
walls of fire-resistant vaults or rooms permanently built into
buildings, and to construction panels which may be utilized in
various specialized construction projects, including the
construction of walls, roofs, or other parts of special struc-
tures where cooling effects or heat-absorbing effects are
desired.
113~2
In order to retain a large ~ount of water, various safe
manufacturers use a n~nber of known materials, including asbestos
perlite, diatomaceou~ ea~h, and vermiculite in the composition
used in the filling in the wall of the safe or other contalner.
When vermiculite is used, it has customarily been used, for
example, to the extent o~ about lO percent by weight of the
ingredients making up the filling conposition. Eowever,
vermiculite i5 becoming increasi~gly scarce and ~ncreasingly
expensive, so that an acceptable substitute for vermiculite i9
highly desirable. lhe present invention relates to the discover~
of une~pected and valuable properties of c~rtain other materials
which can be used satisfactorily to hold the desired amount o~
water in the filling composition and ~hich will give the
composition sufficie~t strength, enaoling the elim;nation of the
vermiculite heretofore thought to be desirable~
Summary of the invention
According to the Invention it is found that cellulose fiber~
(either new or recycled) produced for example by recycling
new~print stock or corrugated kraft scrap, or a mixture of both,
can be used to a substantial extent a~ a component of the filling
compo~ition~ ~rith the surprising re~ult that these cellulose
fibers not only will retain a ver~ de~irable amount of water in
the composition but also will not adversely affect the strength
of the composition for present purposes. Moreover, it is found
according to the invention that certain pla~tic fibers,
particularly polypropylene fibers, can be used in place of
vermiculite, either alone or in combination with the above
rnentioned cellulose fibers, and these polypropylene fibers not
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113~0Z
only help to keep the mixture from separating while it is setting
up or hardening, but also serve as reinforcement to strengthen
the composition. This is especially ~aluable in a safe or other
container which does not have a permanent outer jacket such as
a metal jacket, but which has a plastic jacket which burns away
during the early stages of a fire, leaving the wall filling
exposed. With such a construction, a high strength wall filling
is important, because the plastic outer jacket may burn off
before the floor of the building burns out and gives way, so that
when the safe or container falls through the floor to a lower
floor or to the basement of the building, there is no jacket to
protect the wall from shattering.
Thus, the invention contemplates a process of making
a shaped heat absorbing article from a flowable composition
which is pourable into a confined space and which will solidify
in such space to provide a body containing and retaining a
relatively and unusually large quantity of absorbed water capable
of absorbing a large quantity of heat required to vaporize such
retained water. That process comprises the steps of subjecting
to the action of a harnmer mill fibrous products chosen from the
group consisting of newspaper, kraft paper, and wood chips, to
produce therefrom cellulose fiber masses, mixing the fiber
masses with other lngredients including water and Portland cement
and a foaming material in such proportions as to provide a flow-
able composition which, in its flowable state ready to be poured,
contains by weight of the entire composition, not less than 29~
nor more than 70~ of water, and not less than 1% of said cellulose
fiber masses, and pouring said composition into a confined space
and allowing it to solidify therein without subjecting it to any
dewatering action.
~3~s~a~
A further embodiment of the invention is a heat absorbing
body which in solid hardened form is capable of absorbing sub-
stantial amo~nts of heat by providing relatively and unusually
large quantities of absorbed ~later capable of being vaporized
by heat and thus absorbing the quantity of heat required to
vaporize the absorbed water. This body in its final solidified
hardened state ready for use comprises a mixture containing, by
weight, not less than 29% nor more than 70% of water, and not
less than 33~ nor more than 54% dry weight of Portland cement
as primary ingredients, and also includes as secondary ingredients
not less than 1% nor more than 10% dry weight of recycled cell-
ulose fibers having high water absorption and retention capacity,
and sufficient foaming agent to cause foaming of the body, before
hardening thereof, to a density of not less than 40 nor more than
80 pounds per cubic foot.
B ef description of the drawing
Fig. 1 is a schematic cross section through a iragment
of a plastic jacketed safe in accordance with a preferred
embodiment of the invention;
Fig. 2 is a similar section through a fragment of a steel
~acketed safe according to another embodiment of the invention;
and
Fig. 3 is a similar section through a fragment of a con-
struction panel~
Description of the preferred embodiments
__
Referring now to Fig. 1, there is shown a fragment of a
fire resistant container indicated in general at 11. This may be
a safe having some degree of burglary protection or resistance in
addition to fire resistance, or may be a filing cabinet, a
storage box, a drawer, or any other desired kind of a container.
It may also be a fire resistant vault or room b-~ilt into a
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1~38~(~2
building. The fragment here shown has an inner liner 13, an
outer jacket 15 (both collectively referred to as shells) and a
filling 17 between the inner and outer shells, the wall thickness
of the filling 17 being of any desired extent. It may, for
example, vary in thickness from perhaps half an inch, in a small
drawer or box, to six inches or more in a large safe or large
box, or perhaps even a foot or more in the walls of a vault or
storage room in a building.
The container may be of any desired size or shape. What
is here illustrated is intended merely as a schematic showing
of a container, regardless of size or shape. The container in
general, except for the different composition of the filling
between the inner and outer liner, may be of any conventional kind,
as for example the kind disclosed in Brush and Burgess U.S. patent
4,048,926, granted September 20, 1977, and the present invention
may be considered in some respects as an improvement on what
is disclosed in that patent.
In Fig. 1, both the inner liner 13 and the outer ~acket
or shell 15 may be of plastic material, as disclosed in said
'0 patent. It is now preferred, however, to use plastic material
for the outer jacket 15, but to use steel for the inner liner
13. However, it is to the composition of the wall filling 17
that the present invention relates, rather than to the material
of the shell members 13 and 15 or the shape or size of the
container or the shape or characteristics of the door or closure
which may be used in connection therewith.
Fig. 2 i5 intended to show, likewise schematically, a
container 21 of any desired size or shape, similar in general
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113~ Z
to ~ig. 1 except that the outer jacket 25 is here of steel or
other strong metal? ra~her tha~ plastic. ~he inner li~er 23 is
preferably also of metal such a~ steel. The filling 271 like
the filling 17 in Fig. 1, i9 of the novel composition of the
present inve~tion, a~ described below.
~ s already indicated, one of thc important features of the
present invention is the us~ of cellulose fibers in the filler
composition, as a mean3 or rëtaining a de~ired amount of water
in the composition, while eliminating the vermiculite heretofore
frequen~ly used in such composition~. New fibers may be used,
but because of their abundant availabilit~ and moderate cost,
it is ordinarily preferred to use recycled cellulose fibers
(here~nafter someti~e~ xeferred to for brevity as RCF)~ In
addition to the RCF~ which is used to a significa~t amount, the
composition also includes a major amount of Portland cement
(hereinafter re~erred to for convenience as pc) and a foa~ing
agent or material, ~s well as water. In addition, when the
container is intended to be able to withstand ~ severe drop or
impact and when it is not protected by a permanent or non-
burning metal shell or jacket, the wall filling compositionalso contains ~einforcement, preferably polyprop~lene fibers.
A typical ~ormula found to give good results when a steel
~acket is used or when ability to withstand impact is not
impo~tant, i~ glven i~ the following example. Hereg and in all
other for~ulas, percentages are by weight.
Example 1.
Water 50 ~ 0~
Rec~cled cellulose ibers (RCF)1. 5,o
Portland cement (PC) 45.5/Cto
~oaming Age~t ~F~ 2.3~o
37h Sodium silicate (water glass) 0.7/o
100. 0,b
~3~ Z
To produce this mixture, the following procedure may
be used:
The recycled cellulose fibers (RCF) may be produced
from newspapers, or kraft paper, or even from wood chips, or
from any desired mixture of these. In general, newsprint
gives shorter fibers, and kraft paper gives longer fibers and
therefore greater reinforcement strength. The paper or chips
are shredded in a hammer mill, and the output of the hammer
mill will separate into fibers when added to water and mixed.
The recycled newsprint, mixed paper, and corrugated
waste, is cut, torn, or sliced, and fed into a small hammer
mill, either wet or dry.
Using the material that comes from the hammer mill, a
slurry of 2~ to 8% of cellulose fibers in water is prepared,
by adding the shredded material coming from the hammer mill to
water in a high speed rotary mixer fitted with a specially
designed non-clogging turbine impeller, and mixing for from 2
to 5 minutes at 200 to 1,000 revolutions per minute. The non-
clogging turbine impeller is made from a sheet metal plate
attached to the lower end of a vertical shaft in the mixing
tank. The sheet metal plate is approximately square in
shape, with two opposite corners bent down at an angle of 45
degrees to the plane of the central part of the sheet (which
central part is perpendicular to the shaft) and the other two
opposite corners are bent up at an angle of 45 degrees.
This special shape of turbine impeller is found to
produce rapid and thorough defibrating and dispersing of the
fibers and particles rather than agglomerating them as
occurs with conventional paddle wheel or mortar mixers.
This special design of the mixing impeller is the separate
invention of Roland M. Avery, Jr.
After the slurry of cellulose fibers and water has been
sufficiently mixed, any desired reinforcing fibers may be added
while mixing continues, if such fibers are wanted in accordance
with other examples given below. But there are no such re-
inforcing fibers in the specific formu~a of this example l.
The Portland cement is then added in dry form, to the
slurry, while mixing continues until a smooth mixture is
obtained. Mixing for about 5 minutes after adding the dry
Portland cement is usually sufficient.
Then the foaming agent is added. This may be done in
either of two ways. The foaming agent may be prefoamed, and
then may be added to the mixing vessel in an already foamed
condition, or the foaming agent in its original unfoamed con-
dition can be added to the mixing vessel while mixing continues,
adding it preferably to the central vortex created by ro-
tation of the special turbine impeller above mentioned. In
either case, mixing is continued until the mixture reaches the
desired density, and then the mixer is turned off. The mix-
ture is withdrawn through an outlet at the bottom of the
mixing tank, and poured into the space between the liner 13
and the jacket 15 in order to form the filling 17, if it is to
be used to form a wa]l of a plastic jacketed container, or is
poured into the space between the liner 23 and the jacket 25
to form the filling 27 in Fig. 2, if it is to be used to form
a container with a steel or other metal jacket.
The foaming agent used is preferably the material known
as "Mearl Airocel *PK foam liquid", available on the market from
the Mearl Corporation of Roselle Park, New Jersey. If it is pre-
foamed before adding it to the mixing tank, which is preferably
*trade mark
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113~9(~2
the case, this foam liquid i3 added to water in a concentration
of 2% to 10~ b~ weight, and is foamed into the mixing tank
through kno-.~n apparatus available on the market under the name
"Mearl ~oam Generator." Other foaming agents a~d apparatus may
be used, e~g~, that made by Waukesha.
~ he sodium silicate,.. 37% stren~th, of the~kind commonly
called water glass, is added to the mixing tank preferably
after the foaming operati.on is completed, a~d mixing is continued
for 2 to 4 minutes a~ter this addition~ Then the den~ity of the
mixture i5 checked, and adjusted if necessary, by addition of
s~all amount~ of water, cement, or foam as needed to bring th~
~ixture to a density of 50 pounds per cubic foot. Then the
mixture is read~ for remo~al from the mixing chamber and pouring
into the wall o~ the safe or other container, or into a fo~ or
mold or other confining or shaping structuxe for forming a wall
of a room or vault, or forming a constructio~ panel.
This formula or composition accordin~ to example 1 has, as
compared with the usu~l prior composition, the advanta~es of
increased water ab~orptîon, increa~ed ~tability when poured,
increased impact resist~ce and ability to absorb crush ~er~y,
and increased elo~sation and tensile strength.
~ he cellulose fiber~ also have the important advantage that
they.tend to plug leaks in the metal shell (either liner or
~ac~et or both) during the fillin~ operation. ~his is importa~t,
because it enables the metal shell to be mannfactured with
greater tolerances, with less care to producin~ ab~olute water
tight ~oints at the corners, thereby reducing the cost. ~lso,
the use of the sodium silicate improves the stability of the
mi}~ure when poured, and improves the bonding of the fibers to
30 each other. The preferred proportions of the mixture or
3F~
composition are those set forth above ln the table for example 1.
~owever, some of the advan~ages of the i~vention ma~ be attained
even when the proportions are varied to a considera~le e~te~t.
~or example, the water in the mi~ture may vary from 30,b to 70Yo
of the total mixture, the recycled cellulose fibers may var~
from 1% to 10%, the Portland cement may vary from 20% to 70%, the
.foaming agent ma~ vary from zero to 6S~, a~d the ~odium silicate
may vary from zero to 2%. By appropriate changes in the propor-
tion~ of these ;ngred~ents, ~he den~ity may be ~aried from 20
lbs. to 9~ lbs. per cubic foot.
EYample 2.
~ hen greater impact resi~tc~nce is required, as for example
in a safe having an outer covering or jacket of burn-away
material such as plastic, a good composition for the wall filling
is the followin~:
Water 43.0%
Plastic fiber (PF) 0. 5,h
Portland cement (P~) 53~5%
~oaming agent (F) ~_~. 0%,
100. 0%
~ he plastic fibers are preferably polypropylene fiber~ of
the ~ize nomi~ally k~own as 15 denier 1~ ~nche~ long. ~ibers
from ~ inch to 1~ inches lo~g are useful, but it is preferred
to have at least a very high percentage of them with a len4th
of about 1~ inches. ~he thickness may varg from ~ de~ier to 20
or more denier, and a mixture of various deniers within this
range i~ acceptable, but it is preferred to ha~e a lar~e proporti~n
of the fibers of a size at or close to 15 denier.
The . composition is mixed preferably by the same procedure
described in connection with example 1, ~lith only those changes
nece~sary because of the different ingredients. ~hus the
polyprop~lene fibers and water are ~dded to the mixing tank
~L3~
and are mixed by the use of the special non-clogging turbine
impeller described in connection with example 1, to form a
slurry. Then the dry Portland cement is added, and mixing
is continued in the same mixing chamber or vessel, as in the
previous example. The foam is added in the same manner as
in the previous example. Before the composition is poured,
the density is tested and is adjusted as necessary, by
addition of water or cement or foam as needed to bring the
mixture to a preferred density of 50 lbs. per cubic foot.
The mixture or composition is then poured into the space
between the inner liner 13 and the outer jacket or covering
15, to form the filling 17 as shown in Fig. 1.
In this construction, the outer liner 15 is of plastic
material which burns away in the early stages of a fire.
Then if the building collapses or the floor burns away so
that the safe or container falls, the ability of the wall
composition 17 to survive the impact of falling is very
important, since there is no outer protection as would be the
case if there were a steel jacket around the wall. The poly-
propylene fibers as above described form a sufficient re-
inforcement for the concrete to give gocd impact resistance
in a situation of this kind.
The use of polypropylene fibers gives improved impact
resistance as compared with glass fibers which have been used
in the past for reinforcing compositions of this kind. Also,
the polypropylene fibers have improved resistance to the
alkali in the concrete~ as compared with the resistance of
alkali resistant glass fibers. Also, when the polypropylene
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, ~,.
~138~Z
fibers are used instead of alkali resistant glass fibers,
the composition ha~ improved pouring or placing ~ualitie3~
Also the m~xture has improved dispersion characteristics, as
compared with a similar mixture reinforced with alkali
resistant ~lass fibers.
~ he proportion ~et forth in the above table for this
example are the preferred propor~ions. ~owever, the proportions
may be varled while ~till retaining some of the advantages
derived from using polypropylene fibers. ~he density may be
varied from 20 lbs to 100 lbs per cubic foot. The water may
vary from 2~% to 63%, and the plastic fibers ma~ vary from
0.1% to 2.0Yo, and the Portland cement may vary from 33% to 74%.
~he foam material may be entirely omitted if a very de~e
composition is wanted7 or may be used in any ~uantity from
zero to 6Ch.
It will be noted that in example 1, recycled cellulose
fibers are used for retaini~ water in the co~position, and
the~e serve also to strengthen or rc~nforce the cementitous
composition, at least to some slight extent. In example 2,
polypropylene plastic fibers help some~/hat for water retention
in the composition, but mainly serve as rei~forcement. ~he
polgpropylene pla~tic fibers ~ive better reinforcement than
the cellulose fibers, making this composition more suitable
for a wall ~illing where there is a plastic or burn-awa~
outer jacket or la~er with no permane~ metallic outer jacket.
It i9 pos~ible, to combine the use of recycled cellulose
fibers with the use o polypropylene plastic fibers, and
thereby to produce a composition of li~hter weight than the
compositions of the standard preferred formulas in example 1
1~3~
and example 2, and a preferred formula for such a composition
will now be given.
Example 3.
Water 49.1%
Polypropylene plastic fibers (PF) 0.5%
Recycled cellulose fibers (RCF) 1.5%
Portland cement (PC) 44.6%
Foaming agent (F) 3.6%
37% Sodium silicate 0.7~O
100.00%
The ingredients are mixed according to the procedures
previously explained in connection with examples 1 and 2.
When the ingredients are in the preferred proportions or
percentages set forth in the above table, they will yield a
mixture having a density of about 40 lbs. per cubic foot. The
density is tested before the mixture is removed from the mixing
chamber, and if necessary small amounts of water, cement, or
foam are added as needed to adjust the density to the desired
40 lbs. per cubic foot. When this has been achieved, the
impeller or rotor of the mixer is turned off, and the mixture
is taken out and poured into the previously readied mold or
other structure to form the desired wal], such as a wall
filling 17 between the confining liners or jackets 13 and 15
in Fig. 1. This mixture can, of course, be used for the
filling 27 in Fig. 2, where the outer jacket 25 is of metal,
but it is also suitable for use as a comparatively lightweight
wall structure where the outer jacket is of plastic material
(as in Fig. 1) which burns away during a fire, leaving the
outside of the wall composition 17 unprotected during the
remainder of the fire. This is because of the presence of the
plastic fibers which, as previously described in connection
with example 2, give sufficient reinforcement to the composi-tion
1~3~ 2
to withstand the impact of dropping from one floor of a
burning building to another, at least under favorable con-
ditions.
In the standard or preferred formulation of this example
3, the density of the composition is 40 lbs. per cubic foot,
as already mentioned, and as compa~ed with a density of 50
lbs. per cubic foot in the standard or preferred formulations
of example 1 and example 2. So this represents a weight
saving of 20%, as compared with the prior examples. It is
an excellent formulation for lightweight fire resistant
safes and boxes and containers of various kinds, especially
with burn-away outer jac~ets, and provides good water
absorption for lighter weight products, and an improved R
factor.
As in the other examples, variation from the above given
preferred percentages of the ingredients is possible, while
still retaining some of the advantages of the invention. For
example, the water may be varied from 29% to 69% of the total
weight, the PF may vary from 0.1% to 2.0%, the RCF from 1.0%
to 10.0%, the PC from 30% to 60%, the F from 5.0% to 6.0%,
and the sodium silicate from zero to 2.0%. Such variations
in proportion of ingredients may cause the density of the
mixture to vary from 20 lbs. per cubic foot to 92 lbs. per
cubic foot.
Sometimes it is especially desirable to provide a
composition which has relatively great heat absorbing power
at a fairly low temp~rature, such as a temperature of 80 or
90 degrees Fahrenheit, for protection of especially
sensitive or delicate objects. An example of a composition
which will accomplish this will now be given.
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Z
Example 4.
Water 37.6%
Recycled cellulose fibers (RCF) 1.1%
Portland cement (PC) 34.1%
Foaming agent (F) 1.7%
37% Sodium silicate (WG) 0.5%
Anhydrous sodium sulfate (NS) 25.0%
100.0%
The ingredients are mixed using the same mixing technique
explained in connection with the previous examples. These
ingredients in these percentages produce a composition
having a density of approximately 56 lbs. per cubic foot.
As in the other examples, a test is made before removing the
mixture from the mixing chamber, and small quantities of
water or cement or foam are added as needed to adjust the
density to 56 lbs~ per cubic foot. When any necessary ad-
justments of density have been made, the mixture is ready to
be removed from the mixing chamber and poured into the mold.
It will be noted that this mixture does not contain the
polypropylene plastic reinforcing fibers used in some of the
other examples, so this mixture does not have the same degree
of impact resistance as some of the other compositions which
do contain such reinforcing fibers. Therefore it is de-
sirable that this mixture be used with a structure such as
shown schematically in Fig. 2, that is, one having a steel
or other permanent metallic jacket on the outside, to give
the finished article strength against disintegrating when
dropped. Of course this mixture can be used without an
external metal jac~et for producing articles in locations
where impact strength is not important, as for example
containers on solid ground with no space beneath so that
there is no danger of their falling to a lower level, and
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3S~
with adequate protection above the container so there is no
danger of having heavy objects fall upon it.
Containers made with wall fillings according to this
example 4 are particularly useful in absorbing heat in the
early stages of the temperature rise, so as to keep the
contents quite cool at least in the initial stages of a fixe.
Hence in those situations where a fire is quickly ex-
tinguished, delicate heat-sensitive contents of the container
will not be damaged, where such contents might be damaged in
a fire of the same length of time, if stored in a container
with a wall composition according to one of the previous
examples. The factor in this example which gives the large
amount of cooling in the early stages, is the use of the
sodium sulfate. It is originally added to the mixture, in
the mixing tank, in the form of anhydrous sodium sulfate,
but during the mixing process, it takes up water in the mix-
ture and is transformed into what is known as Glauber's salt
containing ten molecules of water of crystallization for each
molecule of sodium sulfate. Because of the large amount of
water thus chemically bonded in the composition, a great deal
of heat must be absorbed in raising the temperature at the
beginning of a temperature rise such as would be caused by
a surrounding fire. It takes approximately ~,030 British
Thermal Units (BTU) per cubic foot to raise the temperature of
this composition from 80 degrees to 90 degrees Fahrenheit. By
the time the 90 degree temperature is reached, the hydrated
sodium sulfate has been largely melted but many BTUs have
- 15 -
(
1~3~3~()Z
been absorbed in ~upplyi~g the he~t of fusion required to melt
the material, so that the content~ of the con-tainer have been
kept rela~ively cool in ~hese early ~-t~ge~ of the ~ire If ~h~
fire can be extin~ulshed quickl~, even very delicate content~
are saved. I~ the fire co~tinues and the surrounding temperature
rises higher, still further pro-kection is obtained a~d more heat
is abosrbed, especially i~ the vicinity of 212 degrees F~ where
Glauber's salt is decomposed and thus absorbs the heat of
v~porization. ~hen raising the temperakure fro~ 212 degree~ to
220 degrees requires input and absorptio~ of much more heat but
this is true also o~ the other mixtures disclosed i~ examples
1, 2, and ~. All o~ these have great heat absorption capacity
in this range from 212 to 220 due to t~e presence of water
entrapped mainl~ in the cellulose fibexs and to a slight extent
in the plastic fibers. But this composition of example 4 is
superior to examples 1, 2, a~d ~ in it~ capacity for heat
ab~orption in the lower range of 70 to 90 degrees, which ha~
the great advantage above mentioned, and also in it~ capacity
for absorption at ~bout 212 while the salt i~ decomposed.
In additlon to being useful in the walls of containers, thi~
composition of example 4 i3 useful in making panels for fire
doors in buildin~ structures, and in making panels for modular
fllrniture, and wall and ceiling panels for rooms, and panels for
shelvi~g, as fur~her discussed below~ Also, one po~sible use
ls for m~king drawers for furniture or drawers or chests to be
placed in old st~le standard safes ~hich are intended mainly ~or
burglary protection and which do not give much fire protection.
Drawer~ or chests or oth~r smalI container~ having wallQ made of
this composition would ~ive si~nificc~nt protection to contents
against damage by surrounding te~peratures caused by moderate fires
~ he ingredients of this composition i~ exa~ple 4 are
preferably in the proportions stated ir. the above table,
w~ich may be con~idered a standard or preferred ~ormula for
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1~3~ 2
this composition. However, just as in the other examples,variations are possible. For example, the amount of water may
vary from 17.5% to 57.5% of the total composition, the RCF
from 0.1 to 10.0%, the PC from 14.1 to 54.1%, the foaming
a~ent from zero to 6%, the WG from zero to 2%, and the NS
from 15% to 35%. Depending on such variations, the density,
which is 56 lbs. per cubic foot in the preferred or standard
mixture, may vary from 36 to 104 lbs. per cubic foot.
It has been mentioned that this composition of example 4
does not contain the polypropylene reinforcing fibers used in
some of the other examples, and that, accordingly, this com-
position should not be used where high impact resistance is
needed, unless a steel or other permanent structural outer
jacket is employed. It is possible, however, to use the re~
inforcing fibers in a composition basically similar to that
of example 4, thus enabling the composition to have sufficient
impact resistance so that a plastic or burn-away outer jacket
may be used in place of a steel jacket. Such a modification
of the composition will now be described.
Example 5.
Water 37.3~
Reclaimed cellulose fibers (RCF)1.1%
Polypropylene fibers (PF) 0.5%
Portland cement (PC) 34.0%
Foaming agent (F) 1.7%
Sodium Silicate (WG) 0.5%
Anhydrous sodium sulfate (NS)24.9%
100. 0%
The ingredients are mixed in the manner previously
described in connection with the other examples. It is
believed that in view of what has already been said above,
the exact mixing technique for this and the other examples
, ,,,~
1~3~ 2
will be understood by those skilled in the art. But for the
sake of giving an exact and specific account of the mixing
technique that may be used, for example, in prepari~g the
mixture of example 5, the following information is offered.
Using the mixing equipment previously described, with
the special impeller or rotary mixer blade, place in the mixing
tank 1,047 lbs. of water, 31 lbs. of shredded cellulose fibers,
and 14 lbs. of polypropylene fibers of from 1/2 inch to
1 1/2 inches in length, and with a thickness from 3 denier
to 20 denier. Start the mixer rotating at a speed of from
200 to 1,000 revolutions per minute. While the mixer is
rotating, add 952 lbs. of Portland cement, type 1 or 3.
Continue mixing for 5 minutes after completion of adding the
Portland cement. Add 48 lbs. of 8% foam through a Mearl
foam generator, the foam being produced from Mearl Airocel
PK foam liquid. The impeller blade continues rotating while
the foam is added. Then, while still rotating the impeller,
add 14 lbs. of 37~ sodium silicate and continue mixing for 2
minutes. Then add 697 lbs. of anhydrous sodium sulEate, and
continue mixing for 2 minutes more. Check the density of the
mix, and adjust it to 56 lbs. per cubic foot by adding small
quantities of water, cement, or foam as needed to obtain this
density. Thc mixture is then ready for pouring into the mold
formed by the liner and jacket of the safe or container, or
any other desired mold for forming this composition into any
desired shape.
This composition according to example 5 has the same
advantages above mentioned in connection with example 4, and
in addition it has the further advantage of higher impact
resistance than the composition of example 4, so that it may
be safely used, as already stated, as the wall filling for a
- 18 -
container with a plastic or burn-away outer jacket rather than
a steel or other permanent outer jacket. The heat absorption
is approximately the same as mentioned in connection with
example 4.
In this example, and in any of the other examples where
sodium silicate has been mentioned as an ingredient, ordinary
water glass is normally used. However, sodium metasilicate
may be substituted. Also other sodium salts with relatively
large amounts of water of crystallizati~n may be-substituted,
such as sodium carbonate decahydrate, or sodium tetraborate
(borax). Any of these salts are added as anhydrates or lower
hydrates, and are hydrated to their highest state from the
free water in the mix.
Another mixture suitable for purposes of the present
invention is the following.
Example 6.
Water 37.1%
Reclaimed cellulose fibers (RCF) 1.1%
Steel fibers (IF) 1.8%
Polypropylene fibers (PF)0.3%
Portland cement (PC) 33.8~
Sodium silicate (WG) 0.5%
Anhydrous sodium sulfate (NS) 24.8~
8% Foaming agent (F) 0.6%
100. 0%
These ingredients mixed in the proportions above stated
in example 6 will yield a mixture having a density of about
80 pounds per cubic foot. The ingredients are mixed in the
manner already described above in connection with other
examples, and near the end of the mixing operation are tested
and adjusted to add a little more of one or another of the
main ingredients of Portland cement, water, sodium sulfate,
or foaming agent in order to bring the mixture to exactly the
standard density of 80 pounds per cubic foot as intended for
this example, or whatever other density may be desired in
-- 19 --
1~3~C~2
place of the standard density. As in the other examples,
proportions may be varied within reasonable limits without
departing from the invention. For example, the amount of water
may vary from 20~ to 60% of the total composition, the RCF
from 0.1 to 10%, the IF from 0.1 to 10%, the PC from 14 to
54%, the WG from zero to 2%, the NS from 15% to 35%, and the F
from zero to 6%. Depending on such variations, the density,
which is 80 pounds per cubic foot in the preferred o~ standard
mixture, may vary from around 40 or 50 pounds per cubic foot
up to around 106 pounds per cubic foot.
It will be noted that this example 6 includes the use of
steel or iron fibers. They may be of approximately the same
diameter and same length as the polypropylene fibers already
described, and they add to the strength of the material,
especially giving it higher impact strength. Therefore, this
mixture of example 6, because it contains the steel fibers,
is suitable for use as the filling for a safe having a burn-
away outer jacket, since the steel fibers add sufficient
impact strength so that the safe will survive a drop after
the outer jacket has burned away, without serious dis-
integration. Steel or iron fibers may be added also to the
mixtures disclosed in the other examples previously given, to
give additional impact strength to those mixtures.
The mixture as disclosed in connection with example 6 is
particularly suitable for forming parts or panels of modular
furniture. The structural strength of the composition or
mixture enables panels to be made comparatively th~n, yet have
sufficient strength for furniture purposes. I,ikewise, this
composition of example 6 is, for the same reason, particularly
suitable for forming structural panels intended for building
- 20 -
1~3~Z
walls, ceiling, partitions, storage boxes, and so forth. The
compositions disclosed in any of the examples could be used
for these purposes, and it is not intended to rule them out for
use in making structural panels, but it is believed at present
that the composition of example 6 is more suitable than the
others for this particular purpose.
An example of such structural panels is shown schematic-
ally in Fig. 3. Liners 33 and 35, of thin sheet metal or of
rigid or semi-rigid plastic material constitute a mold or
form which is filled with the filling 37, such as the com-
position disclosed in foregoing example 6, although it could
be a composition according to any of the other examples. The
liner material is carried around the edge as at 34. Small
holes 39, say 1/4 or 1/2 inch in diameter, are placed at
intervals on one or both facing liners 33 and 35 to allow
escape of steam or other vapor if the structure is heated to
the vaporizing temperature. If some provision were not made
for escape of vapor, an explosion might result when vaporizi.ng
temperature is reached, due to the large amount of water con-
tained in the mixture.
These panels may be of any desired size. One of the fea-
tures of the invention is that such panels be made in conven-
tional lumber dimensions, say 1 inch or 1 1/4 inches or 1 1/2
inches thick, 12 inches or 24 inches wide, and in various con-
venient lengths, such as 4 feet, 6 feet, and 8 feet. Then such
panels may ~e nailed to conventional studs or rafters, to make
walls or ceilings, th-efacings 33 and 35, if of sheet metal,
being sufficiently thin so that nails can be driven through
them.
In this way, a "cool room" could be constructed within a
building, at modest expense. If a fire occurs in adjacent parts
- 21 -
(~ (
1~31~ Z
of the building, the walls of the "cool room" co~structed as
above described would absorb much of the ~mbient heat and keep
the interior of the room a~ a lo~er temp~ratllre than the
exterior. A small "cool room" constructed of panels abo~e
described~ located in a basement or a wing of a build~n~, could
quite likely keep the interior of the room at a temperature
below 150 degrees Fahrenheit even during a fire of moderate
inten~ity ~nd length of time, and this would be especially
valuable ~or protecting electronic records and electronic
equipment, which ordinarily should not be subjected to heat
above 150 degrees. ~he coolness of the room ~would be enhanced
by making the storage shelves within the room from panel~ of
this same material, and using this same material ~or any desired
storage ~ins, tables, or other furniture within the roo~, ~ince
the greater the quantity of this material within the room as
well as in the ~.rall~ o~ the room, the more heat would be
absorbed by this material.
~ ccordin~ to cmother aspect of the inven-tion, the muterial
or composition of any of the examples above given, but especially
the composition of example 6, may be used to ca~t a buildin~
wall in place, between forms erected to hold the mixture while
it is in a plastic or flowable state, and later removed after
the mixture solidifies, similar to the way that ordinarg con-
ventional concrete walls are cast in place. ~his applies also,
of course, to ~loors, ceilings~ and roofs. Thu~, an entire
building may be built using one or another of the compositions
~ere disclo~ed (preferably the composition of example 6) with
the various parts cast in place and with conventional re-enforcin~
rods imbedded in the composi-tion, similar to the ~ay a re-en~orced
(~ (
~3~ 2
concrete building is co~ven~ionally constructed. Alternatively,
the main part o~ the buildi~g m~y be co~Structe~ in other ways~
and a "cool room" with~ n the buildin~; may be co:nstruc-ted by
pour~g the composition oï exa~ple 6 (or other desired cxample)
between forms, and likewise pouring the ceiling, rather than
building up the wall a~d ceiling ~rom panels nailed to 5tuds,
joi~ts, or other supports~ !
In the foxegoin~ de~crip,tion, empha~i~ ha~ been placed
mainl~ o~ the heat ~bsorbing characteristics of the compo~ition~
o~ the present invention, as a mea~s of absorbing heat ~ a~ ~o
keep the interior oY a safe or room or ~tora~e container
relatively cool duri~g a fire~ ~here is, however, another
important feature or a~pect of the i~vention, not ~eces~arily
: related to ~ire~. This other aspect of the i~vention i~ the
use o~ the variou5 compositions above disclosed a~ what may be
called a "heat si~", to absc-b excess heat ~rom any source
(for example, solar heat) a~d to r~diate it back into the
environment when the ambier~t temperature cools do~n below the
temperature at which heat was absorbed.
In climates where t~pical daytime temperatures are hotter
than comfortable temperature3 and where nightti~e temperatures
are cooler than comfortable, a buildin~ havi~g walls and roof
made from a composition accord~ng to the present invention
(preferably according to exa~ple 6~ would be especi~lly
beneficial. The walls and roof ma~ be either cast in place,
or built up of panels containing the compositio~ of the
in~ention. I~ either event, the walls and roof would tend to
absorb the excess heat during the day, keepin~ the interior o~
the building cooler than the surrounding temperature, and then
1~389C~Z
at night the heat stored in the buildin~ structure woul~ be
radiated, warming -the building at ni~ht. ~his beneficial
effect would be enhanced if interlor partitions and ceilings
are also made of a compo~ition according -to the present
invention.
The compo~itio~ of the pre~ent i~ention is u~eful also
in making growing ta~les for residential or commercial green-
house~, which tables may be either cast, or made of the
described panels~ During the day, such tables tend to absorb
the excess heat and pre~ent overheating of the ~rowing plant~
and vegetables, and at nigh~ they radiate the heat absorbed
during the day, grea-tly reducing night heating costs.
~ he above described action of heat absorp-tion and re-
radiatiQn is limited by the -temperature to ~Jhich -the composition
is subjected during the heating part of the cycle. So lo~g as
the temperature does not rise to the point ~rhere the salts are
bro~en do~n or llhere the contained water is vaporized and
escape3 a~ steam, th~ heat ab~orb~n~ pha~e of the c~cle i~
followed by the radiatin~ phase when the ambient temperature
cools, and the cycle may be repeated over and o~er again in-
definitely. ~his would be the noI~al cycle, from solar heating.
~ut when a fire occurs and much higher temperatures are
encountered, the contained water is driven off as ~team, and
the alkali metal salts may be broken down, ~o that thereafter
the heat absorbing and subsequent heat radiating cycle may not
operate e~ficiently. But it is intere~ting to note that uutil
a fire occur~, the heat absorbing and re-radiation c~cle does
OCCllr, and then when the fire occurs, the very large heat
absorbing capacity is a~ailable to cool the f~re, ~ith much
-- 24 _
1:~L3~ 2
greater heat absorb~ng capacit~ thcln i3 u~èd~in the repetitive
cycle before the fire.
The follo~ing table is provided a3 a rou~h guide to the
approximate heat absorbin~ capacity of the ~arlous mixtures
or compositions ~et forth i~ examples 1 throu~h 6. The
fi~ures refer to absorption in British thermal units in
~arious temperature ranges expre.ssed in degrees ~ahrenheit,
per cubic foot of the mixture.or composition.
- 25 -
1~3~
o~ ~1 o O ~D C~
. L'~
O ~ O O
O ~ O ~ 1:0
~, :* (~J O ~D (~.1
E I ~ N ~ l t5)
t ) ,-1 ClJ
C~ ~ O C
O u~ o 1~ a~
C
N
~ .
o
;~ O O tl~
,I V ,-1~D ~I V
V
El h
~>
P~
O
r~,~ O
~n o
H ~U C`~
' .
O ~ r-l
~1 0
P~ ~ O ~D ~ ~1
tl~ I~) (U O O
O--J ~L'~
~;1 0 1 1 1 1 ~
~1 0 0 ~ O O
-- 26 --
~13E~ Z
It will be noted that there is considerable difference in
the heat ab~orbing characteristics of the different compositions.
Examples 1, 2, and 3 give ~oo~ total heat absorp-tion, but not
very much in the ra~ge below 90 degrees. Examples 4 and 5
pro~ide a great amount of heat absorption below 90 degrees,
together with a ~ood amount betwee~ 90 and 212 de~rees, so these
compositions of e~amples of 4 and 5 are particularly suitable
for use in making safes or containers for protecting delicate
ar-ticles which c~nnot stand heat, as for example electronic or
magnetic tape record~.
The table shows that the compositio~ of exa~ple 6 has e~en
greater heat absorbing capacity than the examples of exhibits
4 and 5, both in the low ranges and in total This is partly
due to the fact that the composition of example 6 iq heavier
or more dense, weighing 80 pounds per cubic foot as compared
with 56 pounds per cubic foot in examples 4 a~d 5, but the
greater heat absorbing capacity is due only partly to the
density of the ~aterial and is due in lar~e measure to the
ingredient~ of the composition. This composition o~ example
6 i~ therefore the best of all the compo~itions, on heat
absorbing capacit~ on a cubic foot basis, wher~ weight i~
not important. However, where a lighter weight structure is
de~lred, the materials of examples 4 and 5, whlch weigh only
56 pounds per cubic foot in the standard mixture, may ~lve
suf~ic~ent fire protection to pres~rve delicate articles
contained in a safe or stora~e box or "cool rooml' using these
compositions rather than the heavier composltion of example 6.
~here is al~o a cost factor as well as a weight factor to be
considered, since the heavier weight requires more material
- 27 -
~3~
and therefore greater cost of raw material.
The compositions of examples 1 and 2, weighing 50
pounds per cubic foot, and the composition of example 3,
weighing 40 pounds per cubic foot, can be used to produce
lighter structures at lower cost. In many cases a safe or
other container with its walls filled with these compositions
will give sufficient protection for the intended purpose. In
selecting the particular composition to be used for con-
structing a particular safe or box or panel or room, it is a
question of balancing the various factors of cost, weight, and
intended use of the final product, including the heat vul-
nerability or sensitivity of the contents which are to be
preserved, the type of surrounding construction evaluated as
to whether a fire is likely to be a very hot fire or a
moderately hot fire and whether it is likely to be of a long
duration or quickly extinguished, the type of jacket used on
the exterior of the safe or storage container, and what drop
tests, compression tests, or other tests the safe or container
or other structure must pass in order to be approved by the
fire underwriters or other approving agency. Hence there is
no one formula or composition which is best universally for
all purposes. Enough different formulas and possible
variations have been disclosed to illustrate well the concepts
and important features of the present invention, and to teach
those skilled in the art how still other variations are
possible within the scope of the invention.
It may be mentioned here that steel fibers, specifically
referred to in connection with example 6, may be added to the
compositions referred to in any of the other examples, where
extra strength is desired, particularly strength in resisting
- 2a -
.~ ~
~3~ 2
shattering when the safe or other article is dropped. However,
steel fibers (or other metallic fibers) have the disadvantage
that they tend to conduct heat through the thickness of the
wall of the safe or container or panel or other structure in
which such fibers are used. Therefore, it is not ordinarily
desirable to use metallic fibers unless very high strength is
required. In many cases, the requisite resistance to shat-
tering when dropped can be given by encasing the safe or
container in a steel jacket, so that no metallic fibers in the
thickness of the wall are needed. In example 6, steel or
iron fibers are included in the preferred formula for the sake
of strength, and this formula has such a very large capacity
for absorbing heat that the slight increase in heat trans-
mission through the thickness of the material, on account of
the metallic fibers, is not seriously detrimental.
With regard to the use of cellulose fibers (whether new
or reclaimed) which are used in many of the examples, it is
pointed out that the use of cellulose fibers act as any other
diluent and reduce somewhat the compression strength of the
concrete mixture. However, they increase the impact strength
and tensile strength, which in general are more important of
the present invention than the compression strength. More
importantly, the cellulose fibers seem to serve to hold the
salt containing mixes together when they expand slightly on
crystallization. This expansion would tend to disrupt or
crumble the mixture as it solidifies, if it were not held
together by the fibers, such as the cellulose fibers used in
most of the examples, or the plastic fibers used together
with the cellulose fibcrs or in the examples where there are
no cellulose fibers.
- 29 -
~3~
Another point briefly mentioned above, but worth
repeating and emphasizing in connection with the discussion
of fibers, is that the fibers, especially cellulose fibers,
serve very well in plugging small leaks in a metal jacket as
the flowable or semi-liquid mixture is being poured into the
wall structure of a safe or other container, between the outer
jacket and an inner liner. A sheet metal jacket can be made
much more quickly and at less expense if it is not necessary
to take extra care in making it absolutely watertight along
the edges and corners, and if very slight cracks at edges
and corners can be tolerated. Then when the mixture is
poured in, the fibers, either the polypropylene plastic
fibers or the cellulose fibers, but especially the latter,
will tend to enter the small cracks or leaks and plug them
up, preventing further leakage of significant amounts. The
same is true when using these compositions to manufacture
articles such as metal clad fire doors, where the mixture is
poured between metal sheets forming the outer faces of the
doors, and where the fibers in the m.ixture make it unnecessary
to ensure absolute watertightness along the edges of the door
structure.
- 30 -
