U.S. patent number 3,889,754 [Application Number 05/400,623] was granted by the patent office on 1975-06-17 for fire extinguishing system.
Invention is credited to Byron G. Dunn.
United States Patent |
3,889,754 |
Dunn |
June 17, 1975 |
Fire extinguishing system
Abstract
A fire extinguishing system for extinguishing a fire on a
cooking range in which a hood is mounted above the range, an
elongated tubular container is mounted in the hood, a body of dry,
powder-form fire extinguishing agent, containing 50 to 95 percent
by weight of a metal carbonate, such as, sodium bicarbonate, 5 to
50 percent by weight of a metal silicate, such as, precipitated
calcium silicate, and up to 5 percent by weight of a desiccant,
such as, calcium stearate, is packed in the container between a
frangible, moisture impervious disc and a free-floating piston, the
disc end of the container terminates in a deflector head, adapted
to direct the extinguishing agent downwardly, which carries a
plurality of movable distributing nozzles, each of which is aimed
at an individual burner of the range and which are provided with
means for discharging the extinguishing agent in a vortical
pattern, the piston end of the container is closed by a second
frangible, moisture impervious disc, an actuating means, including
a bottle of pressurized CO.sub.2 and a pivoted, spring-loaded arm
carrying a pin to puncture the seal of the CO.sub.2 bottle, is
mounted adjacent the second disc to generate sufficient pressure to
fracture the second disc, drive the piston the length of the
container, and pressurize the extinguishing agent sufficiently to
fracture the first disc and discharge the extinguishing agent
through the nozzles, a spring clip is provided to clamp the
actuator arm in the cocked position with the spring under tension,
and an elongated, flame-actuated sensor means, resistant to
spontaneous ignition at the temperatures normally encountered in
the hood, such as, a fuse wire having an aluminum core and a
palladium sheath, is wrapped around the spring clip to hold it
about the actuator arm, extends through an aperture in a closure
cap on the container and is led across the lower lip of the hood
across two burners of the range, then along the length of the hood
to a point adjacent the other two burners and thence across the
other two burners, whereby a flame contacting the sensor burns the
sensor thereby releasing the spring clip and the actuating arm to
puncture the CO.sub.2 bottle, the CO.sub.2 fractures the one disc
and forces the piston through the container thereby pressurizing
the extinguishing agent, and the extinguishing agent fractures the
other disc and is discharged through the nozzles.
Inventors: |
Dunn; Byron G. (Dallas,
TX) |
Family
ID: |
26829373 |
Appl.
No.: |
05/400,623 |
Filed: |
September 25, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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131333 |
Apr 5, 1971 |
3773111 |
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237515 |
Mar 23, 1972 |
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Current U.S.
Class: |
169/59; 169/26;
169/33; 169/65; 169/77 |
Current CPC
Class: |
A62C
3/00 (20130101); A62C 3/006 (20130101); F24C
15/2021 (20130101); F24C 15/20 (20130101) |
Current International
Class: |
A62C
3/00 (20060101); A62c 035/02 () |
Field of
Search: |
;169/2R,26,28,30,31R,33,65,59,77 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Assistant Examiner: Mar; Michael
Attorney, Agent or Firm: Steininger; Charles F.
Parent Case Text
REFERENCES TO RELATED APPLICATIONS
The present application is a continuation-in-part of applications
Ser. No. 131,333, filed Apr. 5, 1971 now U.S. Pat. No. 3,773,111
and Ser. No. 237,515 filed Mar. 23, 1972 now abandoned by the
present inventor.
Claims
I claim:
1. An improved fire extinguishing system, comprising; container
means; a body of dry, powder-form fire extinguishing agent
comprising a metal carbonate selected from the group consisting of
alkali metal carbonates, alkali metal bicarbonates, alkaline earth
metal carbonates, alkaline earth metal bicarbonates and mixtures
thereof, in a major amount of about 50 to 95 percent by weight, and
a synthetic metal silicate, in a minor amount of about 50 to 5
percent by weight and sufficient to form an air-impermeable coating
on the burning surface to which it is applied and prevent
reignition of an extinguished flame for at least 10 minutes,
disposed in said container; expelling means for expelling said
extinguishing agent from said container; and a flame-actuated
sensor means, resistant to spontaneous ignition at temperatures
normally encountered in said area to be protected, operatively
connected to said expelling means to actuate said expelling means
when a flame contacts said sensor means and said sensor means
burns, extending from said container and freely exposed in said
area to be protected.
2. A system in accordance with claim 1 wherein the container means
is a generally-tubular container.
3. A system in accordance with claim 2 wherein a frangible disc
means is mounted in the container in contact with one end of the
body of extinguishing agent.
4. A system in accordance with claim 3 wherein a free-floating
piston means is mounted in the container in contact with the other
end of the body of extinguishing agent.
5. A system in accordance with claim 4 wherein a second frangible
disc means is mounted in the container on the side of the piston
means opposite the body of extinguishing agent.
6. A system in accordance with claim 5 wherein the expelling means
is a pressure-generating means for rupturing the second frangible
disc and forcing the piston means through the container whereby the
pressurized extinguishing agent ruptures the first frangible disc
means.
7. A system in accordance with claim 2 wherein piston means is
mounted in the container in contact with one end of the body of
extinguishing agent for expelling said extinguishing agent from
said container.
8. A system in accordance with claim 7 wherein the expelling means
is a pressure-generating means for driving the piston means through
the container.
9. A system in accordance with claim 2 wherein the body of
extinguishing agent is disposed in the container between a pair of
frangible discs.
10. A system in accordance with claim 2 wherein the body of
extinguishing agent is packed in the container.
11. A system in accordance with claim 10 wherein the body of
extinguishing agent is packed in the container by shaking said
container.
12. A system in accordance with claim 10 wherein the body of
extinguishing agent is packed in the container by vibrating said
container while introducing said extinguishing agent into said
container.
13. A system in accordance with claim 2 wherein the discharge end
of the generally-tubular container is closed by a deflecting means
having a passage in open communication with the interior of said
container for deflecting the extinguishing agent in a path
perpendicular to the axis of said container.
14. A system in accordance with claim 1 wherein at least one
distributing nozzle is mounted on the discharge end of the
container.
15. A system in accordance with claim 14 wherein the distributing
nozzle includes means for discharging the extinguishing agent
therethrough in a vortical pattern.
16. A system in accordance with claim 15 wherein the entrance end
of the distributing nozzle is closed except for a plurality of
passages, in open communication with the container and the exit end
of said nozzle, and said passages are parallel to and offset from
radii of said nozzle and inclined downwardly toward the axis of
said nozzle.
17. A system in accordance with claim 16 wherein the passages are
formed by a plurality of slots formed in the entrance end of the
nozzle parallel to and offset from radii of said nozzle and a plug
means is mounted in the entrance end of said nozzle, having a
generally-conical configuration with its apex toward the exit end
of said nozzle, and at least part of the walls of said conical
configuration is opposite the interior openings of said slots.
18. A system in accordance with claim 14 wherein the discharge end
of the distributing nozzle is movable in a manner to aim said
nozzle at a desired point in the area to be protected.
19. A system in accordance with claim 14 wherein the distributing
nozzle is mounted on the container by means of a nozzle support
head.
20. A system in accordance with claim 19 wherein the nozzle support
head is provided with an aperture for the nozzle and the discharge
end of said nozzle passes through said aperture.
21. A system in accordance with claim 20 wherein the nozzle support
head has a generally-hemispherical projection projecting outwardly,
the aperture is formed in said projection and the nozzle has a
generally-hemispherical, annular portion formed adjacent its
entrance end which conforms to the shape of said projection and
fits therein.
22. A system in accordance with claim 21 wherein a nozzle retainer
means has a generally-hemispherical portion formed on one end,
which conforms to the shape of the hemispherical projection of the
support head, and a central passage therethrough, which conforms to
the outside contour of the discharge end of the nozzle, and is
mounted over that end of the nozzle which projects through the
aperture of said hemispherical projection.
23. A system in accordance with claim 22 wherein the aperture
through the hemispherical projection of the support head is
sufficiently large to permit sliding movement of the nozzle and the
retainer over a relatively large area of the surface of said
projection.
24. A system in accordance with claim 1 wherein the extinguishing
agent comprises 85 to 60 percent of the metal carbonate and 15 to
40 percent of the metal silicate.
25. A system in accordance with claim 1 wherein the extinguishing
agent comprises 78 to 80 percent of the metal carbonate and 19 to
20 percent of the metal silicate.
26. A system in accordance with claim 1 wherein the metal carbonate
is sodium bicarbonate.
27. A system in accordance with claim 1 wherein the metal silicate
is calcium silicate.
28. A system in accordance with claim 27 wherein the calcium
silicate is precipitated calcium silicate.
29. A system in accordance with claim 1 wherein the metal silicate
is selected from the group consisting of alkali metal silicates and
alkaline earth metal silicates and mixtures thereof.
30. A system in accordance with claim 1 wherein the fire
extinguishing composition contains a small amount, up to about 5
percent, of a desiccant.
31. A system in accordance with claim 30 wherein the desiccant is
calcium stearate.
32. A system in accordance with claim 30 wherein the desiccant is
present in an amount of about 3 percent.
33. A system in accordance with claim 1 wherein the expelling means
is a pressure-generating means.
34. A system in accordance with claim 33 wherein the
pressure-generating means is a container of gas under pressure and
means for releasing said gas.
35. A system in accordance with claim 34 wherein the gas is
CO.sub.2.
36. A system in accordance with claim 34 wherein the means for
releasing the gas is a puncturing means for puncturing said
container.
37. A system in accordance with claim 36 wherein the puncturing
means is a spring-biased arm means carrying a puncturing pin.
38. A system in accordance with claim 37 wherein the arm is
normally held, with the spring under tension, by the sensor
means.
39. A system in accordance with claim 37 wherein the arm is held,
with the spring under tension, by a clip means and said clip means
is held in engagement with said arm means by the sensor means.
40. A system in accordance with claim 1 wherein the sensor means is
a wire-type fuse.
41. A system in accordance with claim 40 wherein the wire-type fuse
contains a noble metal.
42. A system in accordance with claim 41 wherein the noble metal is
palladium.
43. A system in accordance with claim 41 wherein the noble metal is
platinum.
44. A system in accordance with claim 41 wherein the wire-type fuse
contains a major portion of aluminum and a minor portion of a noble
metal.
45. A system in accordance with claim 44 wherein the noble metal is
palladium.
46. A system in accordance with claim 44 wherein the noble metal is
platinum.
47. A system in accordance with claim 1 wherein the metal silicate
is a precipitated metal silicate.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an automatic fire extinguishing
system actuatable by a flame as opposed to heat. More particularly,
the present invention relates to a fire extinguishing system,
having a dry, powder-form extinguishing agent therein and suitable
for use in extinguishing Class B fires, particularly as a part of a
hood over a cooking range or the like.
While a large number of fire extinguishers and fire extinguishing
systems have been developed and are available on the market,
numerous problems arise in connection with such fire extinguishers
and fire extinguishing systems. These problems are particularly
apparent in the operation of such devices, particularly for Class B
fires in oils, greases, flammable liquids, etc., where blanketing
or smothering by the extinguishing agent is of greatest
importance.
A large number of portable fire extinguishers have been designed
for extinguishing fires primarily at their inception and before the
fire has a chance to develop into a large conflagration. These
extinguishers have numerous drawbacks in use. First of all, they
are not automatic and must be operated by hand in some fashion or
another. The requirement of hand operation causes considerable
delay in extinguishing the fire, to the extent that the operator is
usually not familiar with the operation and usually must read the
directions attached to the extinguisher before use. Also, because
of unfamiliarity with the operation of the device, the operator
usually completely misses the area of the fire by pointing the
nozzle in the wrong direction and thereby wastes a substantial
amount of the extinguishing agent as well as wasting further
valuable time. In addition, such portable extinguishers are not
permanently located at the area to be protected and usually, they
are in the wrong place when needed.
Automatic fire extinguishing systems have also been developed, but
such systems are expensive to purchase and install, they are often
unsightly, and they are adapted for use where heat, rather than a
flame, will actuate the device. Since these systems are actuated as
a result of heat alone melting a fusible plug or link to actuate
the system, such systems cannot be utilized in areas where
considerable heat is normally generated. Therefore, at the present
time, there has been no practical means suggested for protecting
areas where considerable heat is generated and particularly, above
cooking ranges.
Fire extinguishers and fire extinguishing compositions, in general,
are designed for extinguishing incipient fires. Incipient fires are
divided into three general groups; namely, Class A, Class B and
Class C. Class A fires are those occurring in ordinary combustible
material, where the quenching and cooling effects of quantities of
water or solutions containing a large percentage of water are of
primary importance. This, of course, is the least difficult type of
fire to extinguish. Class B fires are those occurring in oils,
greases, flammable liquids, etc., where the blanketing or
smothering effect of the extinguishing agent is of greatest
importance. In this type of fire, liquid extinguishing materials
are generally useless, particularly since they cause splattering,
etc. of the liquid material which is aflame. Fires of this type are
also the most difficult to extinguish since it is also necessary
that the heat be cut off after the fire is initially extinguished
so that the fire will not flashback or reignite in the liquid
material. Hence, a fire extinguishing system for this type of fire
must not only extinguish the original flame in a very short time
but must have a holding capacity to maintain this condition and
prevent or abate flashback or reignition. Class C fires are
incipient fires of electrical equipment, where the non-conducting
property of the extinguishing material is of prime importance. In
this particular case, dry fire extinguishing agents are also more
useful than liquid types not only because of their nonconductive
properties but also because of their ability to abate reignition.
In short, the same types of fire extinguishing materials as are
useful for Class B fires are generally best for Class C fires
because of the possibility of reignition until the condition
causing the fire has been remedied.
Statistics show that approximately 14 percent of all home fires are
the result of Class B fires on kitchen ranges. Such fires are also
quite prevalent on cooking units in restaurants, ship galleys,
cooking units in recreational vehicles, etc. Under these
conditions, one is not only faced with the inherent problems of
Class B fires but the idiosyncrasies of use involved. As previously
mentioned, there is the problem of the extinguishing agent causing
the flaming oil or other liquid to splatter and thus spread the
fire. Under these circumstances, it is also necessary that the fire
be extinguished in an extremely short period of time, particularly
where a vented hood is utilized above the cooking unit. Where a
vented hood is utilized over the cooking unit, there is a tendency
for grease and oil to accumulate in the fan and vent and any flame
on the surface of the cooking unit will rapidly pass to the vent
and ignite the collected oils and greases. Also, in connection with
Class B fires and cooking units, most fires start while the cooking
unit is unattended, and, therefore, the heat under the cooking
utensil or other item will not be turned off immediately.
Consequently, even though the fire is initially extinguished, the
heat under the oil or grease in the cooking utensil will flashback
or reignite. One suggested solution to this problem has been to
provide elaborate automatic cutoff systems for the burners of the
cooking unit. However, this is, at best, an expensive and
unsatisfactory solution. Accordingly, the most simple and
inexpensive solution would be to provide a fire extinguishing
system which would not only initially extinguish the flame in a
very short time but would also hold this condition for an extended
period of time even though the heat on the burner is not cut off.
Finally, there is the problem of locating a fire extinguisher in
the vicinity of the cooking unit so that it can be automatically
triggered and extinguish the fire on the cooking unit. To date,
this has been virtually impossible because of the lack of suitable
extinguishing systems and extinguishing materials which are capable
of withstanding the high temperatures and moisture conditions
associated with normal cooking over an extended period of time.
Most known fire extinguishing compositions deteriorate over a
period of time and must be replaced or renewed, and the problem is
exaggerated by the heat and moisture to which the material is
subjected during normal cooking operations.
A large number of conventional fire extinguishers are charged with
liquid type fire extinguishing materials. Obviously, Class B fires
cannot be extinguished with water because of the extreme danger of
splattering caused by the water hitting the flaming oil or grease.
The same applies to any extinguishing composition containing
substantial amounts of water, such as, a calcium chloride solution.
Consequently, carbon tetrachloride is one of the few known liquid
extinguishing materials which is useful for extinguishing Class B
and Class C fires. Carbon tetrachloride also has the advantage,
over calcium chloride solutions and the conventional foam-type
extinguishing materials, that it need not be renewed on a yearly
basis as do the latter. While materials, such as, percloroethylene,
bromochloroethane and methyl bromide, have certain advantages over
the previously mentioned liquid or foam-type extinguishing
materials, these materials are rather expensive compared with the
more common types of extinguishing agents. Most importantly, all
known liquid type fire extinguishing materials have boiling points
below about 121.degree.C and therefore, these materials cannot be
depended upon to last for any significant length of time when
subjected to conventional temperatures encountered above a cooking
range. While percloroethylene does have a boiling point of
121.degree.C, all of the other liquids or solutions mentioned have
boiling points below about 100.degree.C. Thus, the materials will
evaporate quite rapidly under normal cooking range conditions, and
there is no guarantee that sufficient material will remain
unevaporated when the need arises. Consequently, extinguishing
materials for Class B fires, particularly on cooking ranges, are
preferably the dry type fire extinguishing materials.
Most of the more common dry type fire extinguishing materials are
useful in both Class B and Class C fires. This is due to the fact
that these finely divided powders or dusts generally do not cause
splattering of the flaming oil or grease and have a blanketing
effect. While potassium aluminum fluoride and mono- and di-ammonium
phosphates have certain advantages over the more common types of
dry chemical fire extinguishers, these materials are substantially
more expensive. Therefore, the ideal and most effective materials
in this catagory are the alkali metal bicarbonates and the alkaline
earth metal carbonates, such as, sodium and potassium bicarbonates
and calcium carbonate. The alkaline earth metal carbonates and
alkali metal bicarbonates release carbon dioxide when the
extinguishing material is heated by the flame of the ignited
material. This carbon dioxide is, of course, heavier than air and
blankets the flaming material, thus preventing access to ambient
air. One drawback of dry type fire extinguishing agents is their
tendency to cake or agglomerate when subjected to moisture, even of
the atmosphere, over long periods of time. Consequently, the free
flowing character of the material is reduced so that it may be
difficult to expel from the extinguisher when needed. This problem,
however, has been satisfactorily solved by the addition to the dry
chemical extinguishing agent of very small amounts of desiccants;
for example, calcium stearate, magnesium stearate, talc, silica,
silica gel, diatomaceous earth, calcium chloride, etc. While the
dry chemical fire extinguishing agents previously mentioned,
particularly the carbonates and bicarbonates, are quite effective
in initially extinguishing Class B type fires, it has been found
that these materials alone lack the capacity of holding the
extinguished condition and preventing or abating flashback or
reignition. As previously mentioned, such flashback or reignition
generally follows if the heat is not cut off beneath the cooking
utensil or the like item containing the grease or oil.
Finally, in both liquid and dry extinguishing materials, there are
those which release toxic gases or leave toxic residues.
It is therefore an object of the present invention to provide a
solution to the above-mentioned problems of the prior art fire
extinguishing systems. Another and further object of the present
invention is to provide an improved extinguishing system with a dry
fire extinguishing composition. Yet another object of the present
invention is to provide an improved system containing a dry fire
extinguishing composition which is particularly useful in
extinguishing Class B fires. Still another object of the present
invention is to provide an improved system containing a dry fire
extinguishing composition which is particularly useful in
extinguishing Class B fires on cooking units. A further object of
the present invention is to provide an improved fire extinguishing
system which is relatively inexpensive. Another object of the
present invention is to provide an improved fire extinguishing
system containing an agent which is non-toxic and has no serious
after effects when utilized for extinguishing fires on cooking
units. A still further object of the present invention is to
provide an improved fire extinguishing system which is capable of
rapidly extinguishing a Class B fire. Another object of the present
invention is to provide an improved fire extinguishing system which
is highly effective in preventing or abating flashback or
reignition after the fire has been initially extinguished. Another
and further object of the present invention is to provide an
improved fire extinguishing system which is highly effective in
rapidly extinguishing the initial flame and is also highly
effective in preventing or abating flashback or reignition even
though the heat adjacent the ignited material is not reduced. Yet
another object of the present invention is to provide an improved
fire extinguishing system which is capable of withstanding varying
temperatures and conditions of high humidity over extended periods
of time without deterioration. These and other objects and
advantages of the present invention will be apparent from the
following detailed description.
SUMMARY OF THE INVENTION
A fire extinguishing system to be mounted above an area to be
protected, comprising; a container, a body of dry, powderform fire
extinguishing agent, comprising 50 to 95 percent by weight of an
alkali metal carbonate, an alkaline earth metal carbonate, an
alkali metal bicarbonate, or an alkaline earth metal bicarbonate
and 5 to 50 percent by weight of a metal silicate, disposed in the
container, expelling means for expelling the extinguishing agent
from the container and a flame-actuated sensor resistant to
spontaneous ignition at temperatures normally encountered in the
area to be protected, disposed across the area to be protected and
operatively connected to the expelling means to actuate the same
when a flame contacts the sensor and the sensor burns. The system
is preferably mounted in a hood above a cooking range and the
sensor disposed across and above the burners of the range. Novel
distributing nozzles are constructed to be aimed at each burner of
the range and to expel the extinguishing agent in a generally
vortical pattern. The extinguishing agent is preferably packed in
the container between a pair of frangible, moisture impermeable
discs and a freefloating piston forces the agent from the
container. The actuator means includes a bottle of pressurized
CO.sub.2 and a spring-loaded puncturing means to puncture the
container and the sensor is attached to the puncturing means to
hold the same in a cocked position with the spring under
tension.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 of the drawings is a front view, partially in section, of
the fire extinguishing system of the present invention installed in
a hood over a range;
FIG. 2 of the drawings is a bottom view of the hood of FIG. 1;
FIG. 3 of the drawings is an exploded view of the cannister
assembly and nozzle assembly of the system of FIG. 1;
FIG. 4 is a side view, partially in section, of the cannister;
FIG. 5 is an end view of the cannister of FIG. 4;
FIG. 6 is a bottom view of the cannister of FIG. 4;
FIG. 7 is a side view, partially in section and partially exploded
of the end cap assembly of the cannister;
FIG. 8 is an end view of the actuator plate;
FIG. 9 is a sectional view taken along the line 9--9 of FIG. 8;
FIG. 10 is a sectional view taken along the line 10--10 of FIG.
8;
FIG. 11 is a side, cross-sectional view of the piston assembly;
FIG. 12 is a side view of the actuator bracket and actuator
assembly;
FIG. 13 is an end view of the actuator bracket and actuator
assembly of FIG. 12;
FIG. 14 is a top view of the spring clip of FIGS. 12 and 13;
FIG. 15 is a bottom view of the hammer bracket of FIGS. 12 and
13;
FIG. 16 is an end view of the hammer bracket of FIG. 15;
FIG. 17 is a side view of the hammer bracket of FIG. 15;
FIG. 18 is an end view of the nozzle base;
FIG. 19 is a side view, partially in section, of the nozzle base of
FIG. 18;
FIG. 20 is an end view of the nozzle base of FIG. 19;
FIG. 21 is a side, cross-sectional view of the assembled nozzle
assembly;
FIG. 22 is a top view of the distributing nozzle of FIG. 21;
and
FIG. 23 is a cross-sectional view taken along the lines 23--23 of
FIG. 22.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with FIGS. 1 and 2 of the drawings, numeral 10 refers
to a cooking range of conventional construction having top burners
12. While only two burners are shown, it is to be understood that
the stove will normally have four such top burners. Mounted
anywhere from 20 to 30 inches above the range surface (standard
installation) is a hood 14. Mounted under the hood 14 by means of
mounting bracket 16 is fire extinguishing cannister assembly 18
equipped with nozzle assembly 20 having distributing nozzles 22.
Leading from the rear of cannister assembly 18 is sensor 24. Sensor
24 is led through eyelets in mounting brackets 26 to a terminal
ring-type bracket 26' to cover the surface area above the burners.
Mounting bracket 16 is affixed to the bottom of hood 14 by means of
double-backed adhesive (not shown) or other appropriate mounting
means. Normally, prior to installation, each of the nozzles 22 is
rotatable throughout the entire area of a circle perpendicular to
the nozzles so that they may be aimed at each individual burner.
Each individual nozzle 22 is aimed at an individual burner 12.
After the aiming has been accomplished, the nozzles are sealed to
the nozzle cap so they will not be accidentally moved out of
alignment, the canister is sealed to the bracket and the nozzle cap
is sealed to the canister. To the extent that the hood 14 is
provided with a filter 28, the sensor 24 is led over the mounting
brackets 26-26' about the exterior of three sides of the filter.
The sensor should not cross underneath the filter since this will
interfere with removal and cleaning of the filter. If the hood does
not have a filter, then sensor 24 is mounted so as to cross over
all of the four burners of the range 10.
FIG. 3 of the drawings shows an exploded view of the canister
assembly 18 and the nozzle assembly 20 of the fire extinguishing
system of the present application. In FIG. 3, a main tubular body
portion 30 is provided. Body portion 30 is threaded at its rear end
portion 32. Mounted inside tubular body 30, adjacent the front end
thereof and resting against a reduced shoulder (hereinafter
referred to), is frangible disc 34. The tubular body 30 is packed
with a dry chemical fire extinguishing agent 36 (hereinafter
referred to in greater detail). Thereafter, a piston assembly 38 is
positioned in tubular body 30. The rear end of tubular body portion
30 is then closed by means of frangible disc 40 mounted on actuator
plate 42. Actuator plate 42 has mounted thereon actuator assembly
44. Actuator plate 42 rests on a shoulder (hereinafter referred to)
in end cap assembly 46. Cap 46 is screwed on portion 32 of tubular
body 30 and sealed by means of O-ring 48. The front end of tubular
body 30 is closed by an integrally-formed, deflector head portion
50. Head portion 50 directs the extinguishing material 36
downwardly where it exits through mounting head 52. Mounted within
an annular groove in mounting head 52 is O-ring 56 which forms a
part of nozzle assembly 22. Nozzle assembly 22 includes nozzle base
58 which mounts on mounting head 52. Nozzle base 58 has
hemispherical nozzle supports 60 provided with angularly-disposed
apertures 62. Passing through apertures 62 are distributing nozzles
64. Distributing nozzles 64 have mounted in their upper ends nozzle
deflectors 66 and in their lower ends temporary nozzle seals 68.
The free ends of distributing nozzles 64, which pass through
apertures 62, have slidably mounted on the outside thereof nozzle
retainers 70. Nozzle retainers 70 are press-fit on nozzles 64 in a
manner such that nozzles 64 and nozzle retainers 70 are freely
movable over a wide angular range about hemispherical supports
60.
FIGS. 4, 5 and 6 show, in greater detail, the main body portion 30,
the head portion 50 and nozzle assembly mounting head 52 of
canister assembly 18. As is evident from FIG. 4, body portion 30 is
provided at its forward end with inner, annular flange or shoulder
72 on which frangible disc 34 of FIG. 3 is sealably mounted. Nozzle
assembly mounting head 52 is provided with annular groove 54 and,
as shown in FIG. 6, with outwardly projecting flange elements 74.
Flange elements 74 cooperate with corresponding inner flange
portions of nozzle base 58 to form a bayonette means to lock the
nozzle base 58 on the mounting head 52.
FIG. 7 of the drawings shows, in cross-section, end cap assembly
46. In accordance with FIG. 7, end cap assembly 46 is provided with
shoulder 78 adapted to receive O-ring 48 (FIG. 3) and shoulder 80
adapted to receive actuator plate 42 (FIG. 3). End cap 46 is
internally threaded at section 82 so as to threadedly mount on
threaded portion 32 of body 30. End cap 46 is provided with a
centrally-disposed aperture 83 and an offset post or boss 84.
Sensor wire 86 passes through aperture 83 and is connected to or
forms a part of sensor wire 24 of FIG. 2 of the drawings. When gas
pressure is generated behind the piston 38 (FIG. 3) and frangible
disc 40 (FIG. 3) is fractured thereby, the aperture 82 through
which sensor 86 passes is closed by means of a flapper valve or
flexible disc 88 of neoprene or the like which is mounted on post
84. Flexible disc 88 is held in place by means of plastic washer 90
which, in turn, is held in place by means of push-on lock ring
92.
FIGS. 8, 9 and 10 show the detail of actuator support plate 42.
Actuator support plate 42 is provided with central aperture 94.
Central aperture 94 provides a passage through support plate 42
when gas pressure behind the support plate ruptures frangible disc
40 (FIG. 3). Actuator support plate 42 is provided with
generally-rectangular upstanding post or boss 96 and elongated
upstanding post or boss 98. Posts 96 and 98 are adapted to receive
therebetween a pressurized gas bottle, hereinafter referred to,
which is part of the actuating mechanism. Upstanding post 96 is
provided with protruding cylindrical posts or bosses 100 which are
adapted to receive an actuator bracket, hereinafter described with
respect to FIGS. 12 and 13. Post 96 is also provided with aperture
102 in which a screw (hereinafter referred to) is mounted to hold
the actuator bracket in place. Actuator plate 42 is also provided
with upstanding posts or bosses 104, which serves as a support for
the neck of the gas bottle, and 106, which serves as a stop for the
end of the gas bottle. Plate 42 is also provided with post or boss
108 having a central bore 110. The central bore 110 is adapted to
receive the pivot post for the actuator assembly (hereinafter
referred to in FIG. 12). Upstanding post or boss 112 is formed on
actuator plate 42 and extends across aperture 94. Post 112 is also
provided with a central bore 114 adapted to receive one end of the
clip (hereinafter mentioned with respect to FIG. 12) of the
actuator assembly. Finally, the actuator plate 42 is provided with
an upstanding post or boss 116 which is adapted to hold one end of
the power spring (hereinafter referred to in FIG. 12) of the
actuator assembly.
FIG. 11 of the drawings shows piston assembly 38 in detail. Piston
assembly 38 is made up of main piston body 118 and piston insert
120. Piston insert 120 has a slightly larger diameter than piston
118 and thereby forms the main seal against the walls of tubular
body member 30 (FIG. 3). By this means, the friction of the piston
being driven through body 30 can be reduced over that which would
exist if the entire cylindrical portion of piston assembly 38 were
made exactly the same diameter.
FIGS. 12 and 13 show the actuator assembly 44 in detail. Actuator
assembly 44 is held in place by actuator bracket 122. Actuator
bracket 122 is provided with a flange portion 124 which extends
over and holds pressurized gas bottle 126 in place. As previously
indicated, with respect to FIGS. 8 through 10, gas bottle 126 is
received between posts 96 and 98 of actuator plate 42. The neck of
pressurized bottle 126 rests on post 104 of actuator plate 42 and
the end of the neck fits against stop post 106. Actuator bracket
122 is provided with apertures 128 which fit on posts 100 of
actuator plate 42. Passing through a central aperture between posts
28 is a screw 130 which passes into aperture 102 of plate 42 to
hold actuator bracket 122 in place. Actuator bracket 122 is
provided with an aperture 132 which cooperates with aperture 110 in
plate 42 to receive pivot pin 134 of the actuator assembly. Mounted
on pivot pin 134 is hammer bracket 136. Hammer bracket 136 carries
hammer 138 with puncturing pin 140. The puncturing pin 140 is so
aligned that it will puncture the seal of gas bottle 126 at an
appropriate time. Hammer 138 is manufactured as a separate entity
from hammer bracket 136 and is attached thereto by swaging a
central post 142. Pivot pin 134 also carries helical, power spring
144 which has one end thereof resting on top of hammer bracket 136
and the other end thereof resting against post 116 of support plate
42. The solid line outline of hammer bracket 136, hammer 138 and
spring 144 show the active or released position of these elements.
Shown in dashed lines is the cocked or inactive position of hammer
bracket 136, hammer 138 and spring 144. Hammer bracket 136 is held
in the cocked position by means of clip 146. Clip 146 is held in
place by having two side extensions thereof pass into aperture 148
in the actuator bracket 122 and aperture 114 of plate 42. Clip 146
is therefore free to rotate or pivot to a limited extent making it
possible to align the clip with hammer bracket 136. However,
bracket 136 is thereby held in the cocked position by gripping the
same between the legs of clip 146 and then wrapping sensor 86 about
the free ends of the clip. Thus, it is obvious that the actuator,
once cocked, will operate as follows: The sensor 86 will burn,
releasing the tension on clip 146. Clip 146 will thereby release
hammer bracket 136 which is driven by power spring 144. In the
extreme, hammer bracket 136 will assume the position shown in solid
lines with the hammer 138 against the end of gas bottle 126 and the
puncturing pin 140 through the seal of gas bottle 126.
FIG. 14 of the drawings shows a detailed top view of clip 146.
FIGS. 15, 16 and 17 show bottom, end and side views, respectively,
of hammer bracket 136.
FIGS. 18, 19 and 20 of the drawings show top, side and bottom
views, respectively, of the nozzle base 58 (FIG. 3). Obviously,
internal flanges 76 of base 58 are designed to cooperate and lock
in a bayonette-type connection with external flanges 74 of mounting
head 52 (FIG. 6).
FIG. 21 of the drawings shows the nozzle assembly 22 (FIG. 3) in
its assembled condition. The assembly, of course, includes nozzle
base 58 having hemispherical projections 60 with apertures 62
formed therein. Passing into and through the apertures 62 is
distributing nozzle 64. Distributing nozzle 64 has temporary end
cap 68 mounted in one end thereof and nozzle deflector 66 mounted
in the opposite end. Distributing nozzle 64 is also provided at its
upper end with angularly disposed apertures 150. When pressure is
applied to the dry extinguishing agent 36 (FIG. 3) in body 30 of
the canister assembly, the pressurized extinguishing powder is
forced outwardly through apertures 150 and the interior of nozzle
64 and this pressure blows cap 68 out the end of nozzle 64.
Otherwise, cap 68 provides a seal to prevent grease moisture and
the like from entering the nozzle assembly. Apertures 150 also
serve a very distinct purpose. As will be seen from FIGS. 22 and
23, apertures 150 are disposed parallel to the radii of nozzle 64
and offset therefrom. By this placement, the powdered fire
extinguishing agent exits through nozzle 64 in a swirling or a
vortical motion due to the coaction of and placement of the
apertures 150 with respect to deflector 66. This has a critical
effect on the distribution of the powdered extinguishing agent over
the area to be protected.
The canister assembly and the nozzle assembly are preferably made
of a material having a high degree of toughness, impact strength,
heat resistance and dimensional stability and good electrical
properties. While there are a number of metallic or plastic and
resinous materials which can be utilized, the preferred material is
"Lexan 101" manufactured by the General Electric Company. This
material is a thermoplastic polycarbonate resin suitable for use in
molded or extruded structures and exhibits all of the properties
specified above. Any parts of the device which are metallic are
preferably zinc- or cadmium-plated ferrous parts or stainless
steel. Where parts of the system are to be bonded together, such
as, the nozzle retainer to the distributing nozzle, the piston
insert to the piston, the nozzle base to the canister assembly, the
canister to the canister support, etc., this can be accomplished by
the use of a suitable solvent for the Lexan, such as, ethylene
dichloride.
The sensor should be selected on the basis of the conditions to
which it is subjected. The primary requisite is that the sensor
should not be spontaneously ignited by heat alone but will be
ignited and burn rapidly when a flame strikes it. The sensor may
take the form of an organic filament, such as, cotton, rayon, silk,
etc. or a synthetic filament, such as, nylon (linear polyamide),
orlon (linear polyester), dacron (linear polyacrylonitrile), etc.
Under certain circumstances, however, and, particularly, for use in
the hood of a cooking range or the like, such organic filaments
will not ignite or burn rapidly enough to satisfy the needs of the
system. Accordingly, the sensor is preferably a fuse material, such
as, cordite or a wire-type fuse. A desirable sensor wire is one
having a minor proportion of a noble metal and a major proportion
of aluminum. A particularly preferred material is a wire-type fuse
known as "PYROFUZE" manufactured by Pyrofuze Co. of Mount Vernon,
New York. This sensor wire is a coaxially braided material having
an aluminum core and a palladium shell. Platinum may also be used
as the shell material. The wire is preferably 0.004 inch diameter
and withstands a breaking load of about 9 pounds. The wire normally
will not ignite or burn at radiant heat temperatures as high as
1200.degree.F but will ignite instantaneously and burn rapidly, at
a rate of about 0.9 foot per second, when contacted by a flame.
The frangible discs utilized in accordance with the present
invention are a laminate of paper-polyethylene-aluminum
foil-polyvinyl. They should have a rupturing strength of near or
below 15 pounds per square inch and a thickness of about 0.005
inch.
The nozzle seals are preferably of molded plastic lined with a
laminate of paper and aluminum foil.
The pressurized gas bottle is preferably a bottle containing about
8 g. of liquified CO.sub.2 and (as appears in the test data
hereinafter) develops an average pressure of about 46 pounds per
square inch during discharge of the extinguishing agent. In actual
practice, the gas ruptures frangible disc 40 (FIG. 3) and
pressurizes the extinguishing agent 36 (FIG. 3) which, in turn,
ruptures frangible disc 34 (FIG. 3). A suitable CO.sub.2 cartridge
is the type manufactured for "Mae West" life jackets. This
component is designated by the U.S. Military as MIL-C-601B, Type
I.
The power spring 144 (FIGS. 12 and 13) provides a torque, when
cocked, of about 3.75 inch per pound.
A critical component of the system of the present application is
the dry, chemical fire extinguishing agent. Such an extinguishing
agent must meet a number of very stringent requirements. First of
all, it must be capable of extinguishing a Class B fire, which is a
fire occurring in oils, greases, flammable liquids, etc. In
extinguishing such fires, it is necessary that the extinguishing
agent have a blanketing or smothering effect. Consequently, liquid
fire extinguishing materials are generally useless, particularly,
since they cause splattering, etc., of the liquid material which is
aflame. Class B fires are also the most difficult to extinguish
since it is also necessary that the heat be cut off after the fire
is initially extinguished so that the fire will not flash back or
reignite in the liquid material. Hence. The fire extinguishing
material for this type of fire must, not only, rapidly extinguish
the original flame but hold this condition and prevent or abate
flashback or reignition even if the burner of the range is left on.
The fire extinguishing agent of the present system meets and
exceeds all of these requirements. The fire extinguishing agent of
the present invention is a synergistic mixture of about 50 to 95
percent by weight of an alkali metal carbonate, an alkaline earth
metal carbonate, an alkali metal bicarbonate or an alkaline earth
metal bicarbonate and about 50 to 5 percent by weight of a metal
silicate. Because of its availability, effectiveness and freedom
from toxicity, the preferred carbonate is sodium bicarbonate.
Preferably, the sodium bicarbonate is present in amounts between
about 85 and 60 percent by weight of the composition. Specifically,
the most desirable composition contains about 78 to 80 percent by
weight of sodium bicarbonate. The metal silicate is preferably a
nontoxic alkali metal or alkaline earth metal silicate and of a
substantially pure character, such as, a material manufactured by
precipitation. A highly effective silicate for use in accordance
with the present invention is "Silene L", manufactured by
Pittsburgh Plate Glass Company, Pittsburgh, Pennsylvania. This
material is a precipitated calcium silicate and has an approximate
analysis of CaO 19 percent and SiO.sub.2 57 percent; and a loss on
ignition of about 14 percent. It has a specific gravity of about
2.1 and bulk density of about 15 to 16 pounds per cubic foot. The
preferred range of silicate is in the amount of 15 to 40 percent by
weight and, specifically, the most effective has been found to be
about 19 to 20 percent by weight. The composition may also include
minor amounts of, up to about 5 percent by weight of conventional
desiccants, lubricants, adsorbents and the like. Suitable materials
of this character include calcium chloride, diatomaceous earth,
silica gel, calcium stearate, etc. and preferably are present in an
amount of about 3 percent. Calcium stearate is a preferred
desiccant. However, this last component is not necessary to the
synergistic effect of the mixture of the present invention nor to
its free-flowing properties. It has been found in accordance with
the present invention that the mixture of bicarbonate and silicate
has free-flowing characteristics making its discharge from a
suitable extinguishing apparatus superior to most conventional
extinguishing agents. It also resists stratification in storage and
in the extinguishing apparatus. The mixture is also capable of
withstanding extreme temperatures without deterioration, thereby
providing long shelf life and useful life without recharging or
replacement and is relatively resistant to moisture deterioration.
The dry, chemical fire extinguishing agent of the present invention
is packed in body 30 of the canister between frangible discs 34 and
40 by vibration of the canister and is the only known dry, chemical
extinguishing agent which can be loaded in this manner. This
packing of the extinguishing agent has been approved by
Underwriters' Laboratories and, as indicated, is the only material
approved for packing in this manner. This, of course, also
contributes to non-stratification. The frangible discs not only
maintain the body of dry fire extinguishing chemical in the
container until it is to be discharged and prevent the material
from plugging the nozzle system or fouling the actuator mechanism
but maintain a moisture barrier which helps to prevent the
extinguishing agent from absorbing water or grease moisture from
the atmosphere under the most adverse conditions.
The system of the present invention has been subjected to numerous
demanding tests by the manufacturer and Underwriters' Laboratories
and has been approved by Underwriters' Laboratories for Class B
fires and given a 4 year shelf life without replacement. This shelf
life differs radically from that extended to any other system of
this character on the market, since other available units of this
character have a one year rating at most. The system is rated for
the protection of the maximum horizontal area of about 7 square
feet with a maximum dimension of 42 inches at heights anywhere
between 20 and 30 inches above the protected cooking surface. The
unit is also rated to withstand ambient temperatures between
32.degree. and 100.degree.F. Tests indicate that the system is
capable of extinguishing a grease fire in less than about 5 seconds
and preventing reignition for at least 10 minutes. However, the
data which follows clearly indicates that, in most cases, the
system far exceeded these minimal requirements.
In developing the system of the present invention, a number of
tests were carried out by hand application of the extinguishing
agent and nearly 400 tests were carried out by application of the
extinguishing agent from the extinguisher system. The testing was
carried out, in most cases, utilizing an off-the-shelf gas cooking
surface.
Various vessel sizes and materials were tested including cast
aluminum, sheet aluminum, cast iron, sheet steel and teflon coated
cooking utensils. A ten inch diameter stamped sheet steel skillet
was found to be the most problematical and was selected for most of
the tests.
Various common consumer flammables were tested including corn oil,
vegetable shortening, heavy duty peanut oil, animal fat (bacon
grease), used restaurant grease and safflower oil, with and without
foods in the oil. Heavy duty peanut oil demonstrated the greatest
tendency to reignite and was used in most of the tests.
The burners of the range were all rated for BTU output. It was
found that the greatest difficulty in preventing reignition was
encountered when using a 102 BTU burner.
The chemical extinguishing compositions were tested for their ease
and completeness of discharge from the extinguishing unit, their
tendency to cause splashing or splattering of liquid oils and
greases, their ability to quickly extinguish a flame, their ability
to prevent reignition for at least 10 minutes and their ability to
withstand prolonged extremes of heat and cold without
deterioration.
The best commercially available dry chemical fire extinguishing
compositions were tested as well as various combinations of the
ingredients of these compositions. The following Table 1 shows the
results of the testing of these commercially available materials.
In the following table, some of the tests, which were conducted for
the purpose of determining the reignition properties of the
extinguishing agent, were conducted by hand application of the
extinguishing composition. In this case, the material was
hand-shaken from a perforated, two-quart saucepan. In the remaining
tests, the extinguishing composition was discharged from the
extinguishing system. The material referred to below as "Super K"
is a material of unknown composition developed by the U.S Navy for
this purpose. Composition number 4 is a commercially available
extinguishing material, whereas composition number 5 represented a
mixture of 90 percent of this commercially available material mixed
with 10 percent calcium silicate. In rating the completeness of
discharge from the extinguisher, it was considered that discharge
of less than about 85 percent of the chemical fire extinguishing
composition from the apparatus was a failure, while discharge of
more than this amount was considered to pass the test. A passing
rating for reignition was based on prevention of reignition for at
least 10 minutes with the range burner still on.
TABLE 1
__________________________________________________________________________
(% by Wt.) Test Chemical Type of Manner of Fire Extin- Series
Composition Test Application guishment Reignition Discharge Remarks
__________________________________________________________________________
1 KHCO.sub.3 Chemical Canister Pass Fail Fail Tendency to "cake" 2
NaHCO.sub.3 System Canister 4 Pass-O Fail 2 Pass-2 Fail 4 Pass 1
Gas release incomplete Reignition Hand 4 Pass-2 Fail 2 Pass-2 Fail
-- 2 Boil-overs contributed to reignition 3 CaSiO.sub.3 Reignition
Hand Pass Fail -- -- 4 87KHCO.sub.3 System Canister Fail -- Fail
Chemical block 10CdSiO.sub.3 in extinguisher 3 Silica Gel 5 78.3
KHCO.sub.3 System Canister Fail -- Fail Gas channeled - 19.0
CaSiO.sub.3 through chemical 2.7 Silica Gel and nozzles plugged 6
67.5 KHCO.sub.3 System Canister 2 Fail -- 2 Pass Chemical too 20.0
NaHCO.sub.3 widely dispersed 10.0 CaSiO.sub.3 2.5 Silica Gel 7 57
KHCO.sub.3 System Canister 2 Fail -- 2 Pass -- 30 NaHCO.sub.3 10
CaSiO.sub.3 3 Silica Gel 8 80 NaHCO.sub.3 Chemical Hand Fail -- --
-- 20 CaCO.sub.3 9 70 NaHCO.sub.3 Reignition Hand 3 Pass 1 Pass-2
Fail -- 2 Boil-overs 30 Na.sub.3 B(PO.sub.4).sub.2 contributed to
reignition 10 50 NaHCO.sub.3 System Canister Pass Fail Pass Some
chemical compacted 50 Na.sub.3 B(PO.sub.4).sub.2 Reignition Hand
Fail -- -- -- 11 60 NaHCO.sub.3 Reignition Hand 2 Pass 1 Pass-1
Fail 2 Pass 40 Na.sub.3 B(PO.sub.4).sub.2 System Canister 5 Pass 1
Pass-4 Fail 4 Pass- 1 Boil-over 1 Fail contributed to reignition 12
72 NaHCO.sub.3 Reignition Hand Fail -- -- -- 18 CaSiO.sub.3 10
Na.sub.3 B(PO.sub.4).sub.2 13 80 NaHCO.sub.3 Reignition Hand Pass
Fail -- Boil-over con- 10 CaSiO.sub.3 tributed to re- 10 Na.sub.3
B(PO.sub.4).sub.2 ignition 14 90 NaHCO.sub.3 Reignition Hand Pass
Fail -- Boil-over con- 5 CaSiO.sub.3 tributed to re- 5 Na.sub.3
B(PO.sub.4).sub.2 ignition 15 "Super K" Discharge Canister -- -- 9
Pass- Piston stopped 8 Fail in several runs System Canister 4 Fail
-- 3 Pass- 1 Fail
__________________________________________________________________________
The results of the series of tests set forth in Table 1 make it
obvious that the compositions tested had an inordinently large
number of failures in one respect or another and therefore, are not
suitable for a reliable extinguishing system of this character.
It was then surprisingly discovered that a mixture of sodium
bicarbonate or other alkali metal or alkaline earth metal
carbonates or bicarbonates in combination with a metal silicate,
such as, calcium silicate, produced a synergistic effect and that
this combination was highly successful in extinguishing Class B
fires when used in the system of the present invention. The
following Table 2 sets forth the results of a series of tests
conducted with sodium bicarbonate alone and calcium silicate alone
as well as various mixtures of these two materials.
TABLE 2
__________________________________________________________________________
Chemical Test Composition Type of Manner of Fire Extin- Series (%
by Wt.) Test Application guishment Reignition Discharge Remarks
__________________________________________________________________________
1 NaHCO.sub.3 System Canister 4 Pass-0 Fail 2 Pass-2 Fail 4 Pass 1
Gas release incomplete Reignition Hand 4 Pass-2 Fail 2 Pass-2 Fail
-- 2 Boil-overs contributed to reignition 2 95 NaHCO.sub.3 System
Canister Pass Fail Pass Considerable splatter 5 CaSiO.sub.3
Reignition Hand 2 Pass 2 Pass -- -- 3 90NaHCO.sub.3 System Canister
4 Pass 3 Pass-1 Fail 4 Pass -- 10CaSiO.sub.3 Reignition Hand 14
Pass 8 Pass-6 Fail 14 Pass 3 Boil-overs contributed to reignition 4
85NaHCO.sub.3 Reignition Hand 11 Pass-1 Fail 7 Pass-4 Fail --
15CaSiO.sub.3 System Canister 9 Pass 7 Pass-2 Fail 8 Pass- -- 1
Fail 5 80NaHCO.sub.3 Reignition Hand 3 Pass 2 Pass-1 Fail -- --
20CaSiO.sub.3 System 45 Pass-1 Fail 30 Pass-11 Fail 38 Pass- 4
Inconclusive 8 Fail reignitions due 4 Inconclusive to putting
burner out 2 Reignition fai- lures due to poor placement of
chemical 1 Discharge fai- lure due to gas channeling 3 Discharge
failures due to equipment failure -6 75NaHCO.sub.3 System Canister
2 Pass-1 Fail 2 Fail 2 Pass- 1 Reignition 25CaSiO.sub.3 1 Fail
failure and 1 ex- tinguishment fai- lure due to poor placement of
chemical 1 Reignition failure 1 Discharge fai- lure due to gas
discharge incom- plete 7 70NaHCO.sub.3 System Canister Pass Fail
Pass -- 30CaSiO.sub.3 Reignition Hand 2 Pass 1 Pass-1 Fail -- -- 8
60NaHCO.sub.3 System Canister 3 Pass 3 Fail 3 Pass -- 40CaSiO.sub.3
Reignition Hand 1 Pass-2 Fail 1 Pass -- -- 9 50NaHCO.sub.3 System
Canister 5 Pass-1 Fail 1 Pass-4 Fail 6 Pass 1 Extinguishment
50NaHCO.sub.3 failure and 2 reignition fail- ures due to poor
placement of chemical Reignition Hand Pass Pass Pass 10 CaSiO.sub.3
Reignition Hand Pass Fail -- --
__________________________________________________________________________
It is apparent from the above that a composition containing from
about 95 to 50 percent by weight of sodium bicarbonate and from
about 5 to 50 percent by weight of calcium silicate was highly
effective for the purposes indicated. Where less than 5 percent
calcium silicate or no calcium silicate was used, it is obvious
that the results are little better than those with the previously
tested materials of Table 1. Likewise, a large number of failures
were found to occur, particularly on the tendency to reignite, when
50 percent of sodium bicarbonate is mixed with 50 percent of
calcium silicate. It is also significant that at less than about 15
percent calcium silicate, and at more than about 40 percent calcium
silicate, the results were relatively poor compared with
compositions contaiing between about 15 and 40 percent of calcium
silicate. Consequently, the preferred compositions in accordance
with the present invention contain about 85 to 60 percent sodium
bicarbonate and 15 to 40 percent of calcium silicate. These ranges
were also applicable to use of other alkali metal and alkaline
earth metal carbonates and bicarbonates and other metal
silicates.
While it is not intended to be limited to any specific theory of
the effectiveness of the composition, it is believed that the
ability of this composition to prevent reignition is due to the
formation of a hard, air impermeable crust on top of the flammable
liquid, thereby preventing air from reaching the flammable material
which would cause auto-ignition. This is particularly significant
since in many of the tests, a six-channel temperature recorder was
employed having sensors in the oil, at the nozzle of the
extinguisher, at the actuator of the extinguisher (gas bottle),
between the heat shield of the extinguisher and the extinguisher,
at the hood filter and at room temperature. As a result of checking
these temperatures, it was found that the temperature in the oil
after extinguishment of the initial fire and with the range burner
still on was substantially higher than the initial autoignition
temperature of the oil (as high as 600.degree.C).
It was also determined that the most effective composition was one
containing 78 to 80 percent sodium bicarbonate and 19 to 20 percent
of calcium silicate. The effectiveness of this composition is best
illustrated by a series of tests carried out to establish
compliance with the standards of Underwriter's Laboratories, Inc.
for the classification, rating and fire testing of Class B-1 fire
extinguishers. Some of the more significant criteria set forth in
these performance specifications include, fire tests utilizing a
square steel pan 8 inches in depth made from 1/4 inch thick steel,
21/2 feet square, having 2 inch layer of oil or n-heptane and
partially filled with water, if necessary, to reach a height of
about 6 inches plus or minus 1/4 inch below the top edge of the
pan. The extinguisher is to be located 24, 28 and 30 inches above
the oil surface. The sensors and actuation system must be capable
of discharging dry chemical within a maximum of 5 seconds. The
tests must also be conducted so that the chemical will be
discharged over an area 40 inches by 30 inches (the largest
standard range surface). If a range hood is utilized with a blower,
the blower must be operated at its rated capacity and if it has a
variable speed, at its highest rated speed. The duration of
discharge of the chemical must be at least 8 seconds. The dry
chemical must be capable of being discharged when the extinguisher
is conditioned at any temperature in the range of about 32.degree.F
to 150.degree.F. The extinguisher must also discharge at least 85
percent of the dry chemical charge. The following Table 3 sets
forth the results of a series of tests carried out to meet the
Underwriters' specifications. In some runs in this series of tests,
the extinguisher was "preconditioned" by storage for the specified
period of time at either 32.degree.F or 120.degree.F. It should
also be noted that in tests 4 and 7, which are the most severe, the
sensor wire, the extinguisher and the inside of the hood were
coated with used grease prior to the test in order to determine
whether the grease would be ignited at any time during the course
of the test. In tests 1 through 22, the unit was charged with 800
g. of extinguishing agent and in the tests 23 through 25,
production models were charged with 950 g. of extinguishing
agent.
TABLE 3
__________________________________________________________________________
Type Nozzle Test of Conditioning Height Test Test Time in Sec.
Reignition- Delivery No. Test Test & Time (In.) Vessel Fuel
Actuation Extinguish Test Time or
__________________________________________________________________________
Splash 1 Extin- 32.degree. 30 Dutch oven 1/4in. 37.6 45.5 Pass Pass
guish 20 hrs. (11 .times. 7 in.) Peanut 17 min. Oil Extin-
32.degree. 30 Cast iron 0.37 in. guish 21 hrs. skillet Peanut (13
1/4 Oil (1 lb.) 63.0 70.0 Pass Pass .times. 2 in.) 29 min. 3 Extin-
32.degree. 30 Steel 0.35 in. 43.0 45.8 Pass Pass guish 22 hrs.
Skillet Peanut 22 min. (10 .times. 2 in.) Oil (1/2 lb.) 4 Extin-
32.degree. 30 Steel pan 0.40 in. 25.0 29.0 Pass Pass guish 14 hrs.
(24 .times. 30 .times. Peanut 75 min. 3 in.) Oil (4.4 lb.) 5 Extin-
32.degree. 30 Steel 0.40 in. 28.6 33.7 Pass Pass guish 16 hrs.
Skillet Vegetable 63 min. (10 .times. 2 in.) Oil (1/2 lb.) 6 Extin-
32.degree. 30 Steel 0.40 in. 41.6 45.9 Pass Pass guish 6 hrs.
Skillet Corn Oil 22 min. (10 .times. 2 in.) (1/2lb.) 7 Extin-
32.degree. 30 Steel 9 strips 33.3 36.5 Pass Pass guish 7 hrs.
Skillet bacon- 24 min. (10 .times. 2 in.) 0.32 in. grease 8 Splash
120.degree. 20 Cast Iron 0.25 in. 49.8 51.8 Pass Pass 8 hrs.
Skillet Peanut 20 min. (6 .times. 1 in.) Oil (50 g.) 9 Splash
120.degree. 20 Steel pan 0.40 in. 26.8 29.2 Pass Pass 19 hrs. (24
.times. 30 .times. Peanut Oil 86 min. 3 in.) (4.4 lb.) 10 Splash
120.degree. 20 Cast Iron 0.25 in. 46.3 49.6 Pass Pass 15 hrs.
Skillet Peanut Oil 17 min. (6 .times. 1 (50 g.) in.) 11 Splash
120.degree. 20 Dutch Oven 1/4in. 11.0 17.6 Pass Pass 17 hrs. (11
.times. 7 Peanut Oil 24 min. in.) 12 Extin- 32.degree. 30 Dutch
Oven 1/4in. 33.6 41.0 Pass Pass guish 11 hrs. (11 .times. 7 Peanut
Oil 18 min. in.) 13 Extin- 86.degree. 24 Steel Skil- Peanut Oil
34.0 35.2 Pass Pass guish let (10 .times. (0.7 lb.) 16 min. 2 in.)
14 Extin- 80.degree. 24 Steel Skil- Peanut Oil 46.0 47.1 Pass Pass
guish let (10 .times. (0.7 lb.) 16 min. 2 min.) 15 Extin-
86.degree. 24 Steel Skil- Peanut Oil 41.0 42.2 Pass Pass guish let
(10 .times. (0.7 lb.) 14 min. 2 in.) 16 Extin- 87.degree. 24 Steel
Skil- Peanut Oil 42.0 43.1 Pass Pass guish let (10 .times. (0.7
lb.) 15 min. 2 in.) 17 Extin- 81.degree. 24 Steel Skil- Peanut Oil
62.0 63.2 Pass Pass guish let (10 .times. (0.8 lb.) 16 min. 2 in.)
18 Extin- 79.degree. 24 Steel Seven 37.0 38.2 Pass Pass guish
Skillet strips 20 min. (10 .times. 2 bacon in.) 19 Extin-
79.degree. 24 Cast Iron 15 strips 47.0 48.3 Pass Pass guish Skillet
bacon 20 min. (13 1/4 .times. (0.38 in. 2 in.) grease) 20 Extin-
65.degree. 24 Steel Pan 0.28 in. 28.0 29.2 Pass Pass guish (24
.times. 30 .times. Peanut Oil 43 min. 3 in.) (4.4 lb.) 21 Extin-
65.degree. 24 Steel 0.40 in. 36.0 37.1 Pass Pass guish Skillet Corn
Oil 15 min. (10 .times. 2 (1/2 lb.) in.) 22 Extin- 74.degree. 24
Steel Safflower 48.0 49.0 Pass Pass guish Skillet Oil (1/2 13 min.
( .times. 2 lb.) in.) 23 Splash 120.degree. 20 Cast Iron 0.20 in.
Pea- -- -- -- No Skillet nut Oil (40 Splash (6 .times. 1 in.) g.)
24 Extin- 32.degree. 30 Steel Pan 0.25 in. 15.8 17.0 Pass Pass
guish (42 .times. 24 .times. Peanut Oil 20 min. 3 in.) (2800 g.) 25
Extin- 32.degree. 20 Steel Pan 0.25 in. 16.3 20.0 Pass Pass guish
(42 .times. 24 .times. Peanut Oil 10 min. 3 in.) (2800 g.)
__________________________________________________________________________
Tests were also conducted to determine the actual pressure
developed in the canister and the amount of chemical discharged.
The results of these tests are set forth in Table 4 below. Except
where indicated, the pressure was measured by a pressure transducer
and recorded by a chart recorder.
TABLE 4
__________________________________________________________________________
PROTOTYPE UNITS Conditioning Maximum Dry Chemical Dry Chemical
Collected Temperature, Pressure, Discharged, From Nozzle, G Degrees
F PSIG G Per Cent 1 2 3 4
__________________________________________________________________________
32 70*** 737 (92.1) 200 170 173 216 70 110*** 729 (91.3) 215 180
127* 191 120 100*** 712 (89.0) 169 180 183 206 PRODUCTION UNITS 32
80*** 874 (92.0) 212 227 241 195 70 90*** 844 (88.8) 192 236 227
190 120 90*** 889 (93.6) 202 231 229 222 70 58 893 (94.0) 70 38 719
(75.7) 70 47 719 (75.7) 70 39 794 (83.6) 70 52 868 (91.4) 70 43 794
(83.6) Avg.=46 70** 86 893 (94.0) 70** 69 889 (93.6) 120** 36 753
(79.2) 120** 88 913 (96.1) 120 2,016 (96.2) (24 Hrs.) (lb.) 70 (24
Hrs.) 2,023 (96.6) (lb.)
__________________________________________________________________________
*Some dry chemical spilled from bag. **Two frangible discs at each
location ***Pressure measured using pressure gauge (0-1000 psi)
In addition to the test results given above, the system was
subjected to a number of other rather stringent tests.
The body of the unit was subjected to air-oven aging for 17 days at
212.degree.F and 75 days at 212.degree.F. After the aging period,
the units were examined for cracking, pitting, deformation and
other signs of deterioration. Rings (1 in. wide) were also cut from
several aged samples and subjected to a crush test. A crosshead
speed of 0.5 inch per minute was used in an Instron Testing
machine. The components of the unit showed no signs of cracking,
pitting, deformation or deterioration under the test conditions. In
the ring crush tests, a minimum of 95 pounds was determined with an
average of about 105.9 pounds for the tests. In another series of
tests, the average yield strength (considered to be the first
significant deflection of the load-deformation curve) averaged
112.4 pounds.
Sections of the canister were also exposed to ultraviolet light
from two single enclosed carbon arc lamps. Water was automatically
sprayed into the specimen at predetermined intervals. The arc was
formed between one upper electrode and two lower, vertical
electrodes held in a solenoid-actuated speed mechanism. All
electrodes were of carbon, 1/2 inch in diameter, the upper
electrode being of the solid type and the lower electrodes being of
the neutral- cored type, or vice versa. The potential across the
arc was 120 to 145 volts AC at an operating current of about 15 to
17 amps. Water, at room temperature, was sprayed horizontally onto
the samples at about 12 psig. During each operating cycle (about
120 min.), each specimen was exposed to ultraviolet light from the
carbon arc for 102 minutes and the ultraviolet light and water for
18 minutes. The test was continued until the samples had been
exposed to ultraviolet light for a total of 612 hours and
ultraviolet light and water for a total of 108 hours. The samples
showed no cracking, crazing, distortion or other signs of
deterioration as a result of this exposure.
Hydrostatic pressure tests were also conducted on sample units. The
extinguishing unit assemblies (less piston actuator plate and
nozzles) was fitted with an adaptor, filled with water and
connected to a source of hydrostatic pressure in a manner which
excluded all air from the enclosed volume. The pressure was
gradually increased at a rate of approximately 300 psi per minute
until failure occurred. It was expected that the unit would be able
to withstand a minimum of 4 times the average working pressure (4
.times. 46 = 184 psi.) without rupture. As a result of these tests,
a minimum rupture strength of about 220 pounds per square inch and
a minimum of 400 pounds per square inch were measured.
While specific structures and variations of the same have been
shown and described herein for purposes of illustration, it is to
be understood that various modifications and equivalents of such
structures will be apparent to one skilled in the art. Accordingly,
the present invention includes such modifications and equivalents
and is to be limited only in accordance with the appended
Claims.
* * * * *