US2248270A - Fire extinguishing method - Google Patents

Description

July 8, 1941 I E. GEERT 2.248.270

FIRE EXTINGUISHING METHOD Filed 001.151, 1939 by the smolderingfuel.

Water is an excellent. example of a medium which relies for its extinguishing eifect entirely Patented. July 8 1941 UNI D STATES PATENT OFF-ICE rum nx'rnvomsnmo METHOD .Eric Geertz, Glen Ellyn, 111., assignor to Cardox Corporation, Chicago, 111., a corporation of Illinols 1 Application October 31, 1939, Serial No. 302,239

9 Claims.

This invention relates to new and useful imnomena of the rapid chemical combination of oxygen with some combustible or burnable material. Before this chemical combination can take place at a rate rapid enough to support coml heat was so intense that the water particles were upon its ability absorb heat from and thereby cool the combustible material below its kindling point. However, there are numerous fires of record, for example, large lumber yard fires,

where the cooling efiect 'of ordinary hydrant water was insufilcient to overcome the great amountof heat produced by the fire. In those cases, the

vaporized and the resultant steam was carried up from the fire by the strong convection air currents. Water, also, is ineffective as an extinguishing medium for large unconfined or flowing oil fires. This is due to the fact that the oil mixture is raised to the kindling point by the application of heat from an extraneous source direct contact with fiame is not essential-burning will start. :The extraneous source of heat may be removed butthe fire will continue to burn because of its self-generated heat. If the temperature of the entire mass of fuel and all immediately adjacent masses of heat absorbing matter is lowered sufiiciently, burning will cease and the fire will be completely extinguished. If

the temperature of the fuel is lowered to a point below its kindling temperature, thefire will be extinguished. Rekindling will occur, however, if

sufllcient heat remains in immediately adjacent masses of material to again raise the temperature of the fuel, by conduction, etc., to its kin- I dling point. Rekindling also can take place when the temperature of the fuel is lowered to a point below that at which rapid burning will occur but not below its smoldering temperature. In such a case, the temperature again builds up to the rapid burningyalue by the heat generated tance above said surface.

floats on the top of the water and the oil vapors burn at a distance 'above the oil covering the water. It is impossible for the water to absorb .sufiicient heat from the oil vapors, through the superimposed layer of oil, to lower the temperature of the vapors below their ignition point because of the intense heat produced by this .type of fire.

Let us now consider a burning pool'of liquid, such as oil or gasoline. A careful inspection shows that the actual burning does not take place on the surface of the liquid but at a certain dis- This characteristic must be due to the fact that below 'the burning point the concentration of the fuel vapors is too high and the oxygen concentration is too low to support combustion. It cannot be due to absence ofsuificient heatin the body of liquid because the temperature of the liquid will be raised to its boiling point by the fire. if it is not extinguished in time to prevent such an action? Such a'liquid pool fire will cease to burn if inert gas in sufficient quantities is delivered to the zone of non-combustion, i. e., the zone between the surface of the liquid and the point at which the vapors burn. This inert gas dilutes the fuel vapors to such a low concentration that a burnable mixture does. not exist; Thus, it is seen that a proper concentration of fuel is needed or feeding of inert gas is stopped after 'fi're ceases to'exist but while the body of liquid and/or the adjacent heat absorbing masses still retain sufficient heat, the fire will rekindle. If the feeding of inert gas is continued long enough to lower the temperature of all involved matter below the ignition temperature of the fuel vapors, re-

kindling will not occur. This, of course, is turcharge as a cooling medium.

by completely isolating the same from the sur-.

rounding air by means of a blanketing medium which is itself combustible. Fabric blankets, quilts, and rugs frequently are employed to extinguish fires.

c. Solid and liquid combustible materials will cease to burn if the fire consuming the same is completely isolated from the surrounding atmosphere by a blanket of inert gas, chemical combinations which produce a foam, granular non-combustible materials, etc.

In each of these examples a, b, and c, the oxygen excluding medium will be materially assisted in extinguishing the fire by its ability to absorb heat from and thereby cool the combustible material. In example I), the combustible blanketing medium will be ineffective if the heat produced by the fire is sufficient to'raise the-temperature of the blanketing medium to its kindling temperature before the fire is extinguished. In such a case, the blanketing medium will ignite and add just so much more fuel to the fire.

It is clear from the above observations that all forms of fire extinguishment are either entirely dependent upon cooling the'combustible fuel and all involved adjacent masses of heat absorbing matter below the kindling'point of the fuel or they rely on the cooling action of the extinguishing medium in addition toits ability to lower the concentration of the fuel or the oxygen. With these points in mind, a careful study was made of the extinguishing method of my aforesaid patent to determine the reasons for its great effectiveness and to discover, if possible, ways of increasing its extinguishing powers.

In practicing my patented method, a cloud of carbon dioxide gas and snow is discharged at a high velocity and at a very rapid rate. The liquid from which this cloud is formed is maintained at a preselected subatmospheric temperature which more frequently than not is a subzero temperature. The temperature of the actual discharge, therefore, is extremely low and has a much greater cooling effect than any other commercially employed extinguishing medium. Actual comparative tests have proved that the cooling capacity of this extremely low temperature carbon dioxide discharge is 66% more eflective than a carbon dioxide discharge coming from a liquid source having a temperature which is ap- -proximately the same as normal atmospheric temperature, or 70 F. No question can be raised, therefore, regarding the superior effectiveness of this low temperature carbon dioxide (115-.

In applying this extinguishing medium to a fire, the carbon dioxidedischarge is directed at the burning material and at all adjacent heat absorbing matter. This discharged cloud has a three directional effect, for it travels around corners and into all cracks and crevices. It spreads out and settles down to form a veryeflective oxygen-excluding blanket over the fire. The

temperature of the burning fuel and all adjacent,

oxygen is excluded from. the fire. The fire then ceases to burn. By discharging the carbon dioxide cloud into the non-combustion zone of a gasoline or oil pool fire, the body of liquid and the vapors rising therefrom are rapidly cooled and the concentration of the'fuel vapors is greatly diluted. The fire is effectively extinguished.

Although the extinguishing medium made available by my patented process surpasses other mediums in its cooling action and is effective in lowering oxygen concentration and, if properly applied to appropriate fires, in lowering fuel con-. centration, there appeared to be room for improvement in one or more respects.

It was observed that in cooling off burning or heated objects having vertical and/or'underlying horizontal surfaces, to prevent rekindling and to extinguish the'fire, it was necessary to continue the discharge directly against such surfaces until the desired cooling had been completely accomplished. This was due to the weight of carbon dioxide gas and snow, as compared to air, which caused it to settle away from such surfaces, and the absence of any tendency for any portion of the medium to adhere to such surfaces. If this disadvantage could be overcome, it was decided that the, total cooling action of the discharge would be improved and less carbon dioxide would have to be used to efiect complete extinguishment and prevent rekindling for certain hazards.

Also, it was observed that the concentration of carbon dioxide gas in the discharge, although considerably lower, due to its higher percentage of snow, than with carbon dioxide discharges coming from sources of liquid at higher temperatures, definitely was a limiting factor in determining the distance to which the medium could be effectively expelled, and it lowered the effectiveness of the medium in penetrating to the seat of a fire against the updraft of heated air over the fire. If this concentration of gas could be lowered or the total weight of the cloud .could be increased,

it was decided that both the carrying and the penetrating action of the medium would be imbe increased.

Of course, the percentage oi yield of snow can be increased and the gas concentration lowered by reducing the temperature of the liquid source, but-this lowering of temperature is limited by the fact that carbon dioxide ceases to exist as a liquid at 69.9 F. and its corresponding vapor pressure of 75.1 lbs. per square inch, absolute.

It the temperature is brought too close to this critical condition, freezing will occur in the conduits, etc., through which the liquid must pass in reaching itspoint of discharge, Also, the carry-' ing and penetrating action of the medium may be improved by increasing the velocity oi. discharge, but the greater the velocity of discharg the greater the entrainment of air.

heated objects is very rapidly lowered to apoint below the kindling temperature of the fuel and Therefore, the primary object of this invention is to provide a method. which will result in improving the effectiveness of low temperature carbon dioxide to extinguish certain types of fires and thereby reduce the amount of. extinguishing medium required, and which will increase the carrying and penetrating character of low tem-- l perature carbon dioxide beyond any values which can be obtained by lowering the temperature of -the liquid source and will be apparent during the course of the following description- I have discovered that the desired improvements in the eilectiveness of low temperature carbon dioxide as a fire extinguishing medium can be obtained by discharging one or more small streams of water into the high velocity discharge of carbon dioxide gas and snow issuing from a suitable nozzle structure. In such a combined type of discharge the water is very finely atomized by the high velocity of the carbon dioxide discharge. The temperatureof the water is drastically reduced which causes the particles of the same to freeze. It has been determined that the water or water-ice particles entrained with the carbon ,dioxide will have the same three directional effect as occurs with the carbon dioxide. In other words, the water or water-ice 1 particles travel with the carbon dioxide around corners and into cracks and crevices.

The presence of the water and the water-ice particles will add materially to the cooling eifect of the carbon dioxide discharge and the water will dampen or wet down surfaces against which carbon dioxide cannot be maintained after direct impingement of the same thereagainst ceases. This wetting action materially increases the effectiveness of the combined discharge to prevent rekindling as the Water will cool glowing embers, etc. which are left after the direct-application of the extinguishing medium has ceased. Com-' plete extinguishment of a fire, therefore, can be accomplished with a smaller amount. of carbon dioxide and with a shorter discharge period. This combined type of discharge has been found to be particularly helpful on outdoor combustible material of the type designated as Class A fires, which consist of carbonaceous materials, such as wood, .paper, rags, excelsior, and the like.

It, also, will be obvious that this addition of water to the discharge will lower 'the concentraing rearwardly from thefiat rear wall 6 is a stem or shank I which is cored to provide an inlet passage 8 which'is closed at itsinner endbymeans of a conical projection 9 and is provided with internal threads 10 by means of which the nozzle may be attached toa suitable hose line, or the like, leading from a source of'low temperature, low pressure liquid carbon dioxide.

The conical projection 9 functions to split or deflect the stream of liquid carbon dioxide fiowing into and through the bore of the shank or stem 1. The liquid carbon' dioxide deflected by the conical projection I is caused to flow into the inlet ends ll of four ducts l2 which are of hook shape in longitudinal section and are formed by coring out the external ribs i3 and the internal tips ll. It will be noted that these four ducts extend radially outwardly of the inlet passage 8 and radially inwardly of the chamber'formed by the'peripheral and rear walls 5 and 6, respectively, of the main nozzle body. These ducts are arranged in diametrically opposed pairs with the result that the ducts of each pair and the two pairs of ducts oppose and counteract each other to dampen radial recoil resulting iromthe discharge of the carbon dioxide into the chamber of the main body. The liquid carbon dioxide remains as a liquid until it leaves the discharge ends l5 have a total or combined area which is tion of carbon dioxide gas in the total discharged cloud or jet' of extinguishing medium. The water-ice particles additionally will increase the total weight of the discharge. It has been determined that this combined type of discharge has an appreciably greater carrying range and is considerably more efiective in penetrating to the seat ofza fire against the strong convection air currents which rise from the fire.

In the accompanying drawing forming a. part of this specification and in whichlike numerals are employed to designate like parts throughout the same,

Figure 1 is a front elevational view of a. form of discharge 'nozzle which has been found to be particularly suitable for carrying out my novel fire extinguishing method when it is employed in conjunction with or as the discharge nozzle of the apparatus disclosed in my aforesaid Patent No.

2,143,311 for carrying out the method claimed therein,

Figure 2 is a rear elevational view of the nozzle" structure disclosed in Fig. 1, and V Figure 3 is a' transverse sectional view-taken on line 3-3 of-Fig..2.

In thedrawing, wherein for the purpose of illustration is shown the preferred embodiment of this invention, the low temperature carbon dioxide portion of the discharge nozzle includes a generally cylindrical main body portion which includes a peripheral wall 5 formed integrally with an imperforate, fiat rear closure wall 6. The

' outer side of this body is left entirely open, as

is clearly illustrated in Figs. 1 and 3. Project- I ends l5 of theseveral ducts. The carbon dioxide then expands in the chamber of the main body and is converted to ya mixture of gas and snow.

The combined area of all of the inlet ends ll of the four ducts preferably should equal the total area of the inlet passaget, although a lower combined inlet area for the several ducts may beemployed. The ducts areof gradually tapering formation from their inlet ends to their outlet ends with the result that the outlet or discharge less than the total or combined area of the inlet ends I4. For the most effective operation, it has been determined that the total area of the di'scharge ends of the ducts should be from 40% to 60% of the total area of the inlet ends or open- Centrally positioned in the discharge and expansion chamber of the main body, formed by the walls 5 and 6, is a bell-shaped diffuser it. This diffuser is detachably connected to the flat rear wall 6 by means of a threaded shank H, as is clearly illustrated in Fig. 3. Due to the detachable character of this connection, the difiuser may be replaced as desired or diffusers of difierent profile or contour may be employed. This interchangeability oi the difiuser is very important because the shape of the same determines the extent to which the discharged cloud or jet orcarbon dioxide gas and snow is caused to spread or expand radially.

eDischa'rge of the liquid carbon dioxide into the chamber of the main body, formed by the walls ,5 and 6, brings about impingement of the four streams of gas and snow upon the periphery of 'The means for introducing four jets of water individual weight than the carbon dioxide snow and gas.

, the spirit of .the invention or the subjoined claims.

into the discharged cloud or' stream of carbon dioxide gas and snow-is illustrated in the several figures of the drawing as consisting of four water nozzles l8 which are arranged at four equispaced points around the outside of the peripheral wall 5 and are located at angles of 45 with respect to the four carbon dioxide discharge tips l6. Fig. 3 discloses each'nozzle l8 as being formed with a passageway I9which terminates in a discharge end that is directed radially inwardly toward the zone of discharge of the This arrangement of the ends 20 of the passages causes the streams of. water to strike against the carbon dioxide 7 discharge. Asa result of the high velocity of this latter discharge, the jets of water are highly atomized and the water particles thoroughlymix with the carbon dioxide. Due to'the low temperature of the carbon dioxide discharge, -the water particles are frozen to Water-ice.

The various water nozzles 1'8 are spaced from the peripheral surface of the carbon dioxide nozzle body by means of heat insulating blocks 2|.

These blocks. prevent a too rapid absorption of heat from the water traveling through thewater nozzle passages l9 with the result that water ,icewill not be formed in the passages.

these several tubes 23 are connected by couplings 25 to a water distributing ring 26. A suitable shank or coupling nipple 21 is formed on the ring 26 and is .used for. attaching the ring to a hose line, or the like, leading from a source of water.

Fig. 2 discloses the water distributing ring 26 as being provided with a pair of diametrically arranged .lugs 28. These lugs engage the periphery of the shank or stem 1 of the carbon dioxide nozzle for assisting in supporting the water distributing ring 26. Fig. 2 also discloses the shank or stem 1 of the carbon dioxide nozzle as having a pair of tool engaging lugs 29 formed on the periphery thereof. These tool engaging I lugs function additionally to engage and support the water distributing ring 26 at points intermediate the supporting lugs 28.

It is to be "understood that the method of this invention herewith shown and described is to be taken as the preferred example of the same, and

' ing vapor pressure, to a point of discharge, per-' 2. 'A method of extinguishing a fire comprising conducting liquid carbon dioxide, having a subatmospheric temperature and its corresponding vapor pressure, to a point of discharge, permitting sudden expansion of the liquid to produce a mixture of gas and snow, projecting the mixture of gas and snow into the atmosphere in the form of a cloud or stream traveling at a high velocity, discharging into the projected mixture a plurality of jets of water which will be finely atomized by the velocity of the mixture, and so proportioning the water and mixture of snow and gas as well as so directing the streams of water into the mixture as to cause substantially all of the water to be entrained in the mixture.

3. A method of extinguishing a fire comprising conducting liquid carbon dioxide to a point of discharge, permitting sudden expansion of the liquid to produce a mixtureof gas and snow, projecting the mixture of gas and snow into the atmosphere in the form of a cloud or stream traveling at a high velocity, and discharging into the projected mixture a stream of liquid at an angle to the directionoftravel of the mixture which will cause the liquid to be finely atomized by the velocity of the mixture, the stream of liquid and the mixture of gas and snow being so proportioned and the angle of discharge oi the stream of liquid with respect to the direcmitting sudden expansion of the liquid to produce a mixture of gas and snow, projecting the a mixture of gas and snow into the atmosphere in the form of. a cloud or stream traveling at a high velocity,'and discharging into the projected mixture a plurality, of small ,streams'of liquid at an angle to the direction of travel of the mixture which will cause. the liquid to be finely atomized by the velocity of the mixture, "the streams of liquid and the mixture of gas and that various changes in the method steps and the shape, size, and arrangement of structural parts may be resorted to without departingirom scope of the Having thus described the invention, I claim:

1. A method of extinguishinga fire comprising conducting liquid carbon dioxide to a. point of discharge, permitting sudden expansion of theliquid to produce a mixture of gas and snow, projecting the mixture of gas'a'nd snow into'the traveling at a high velocity, and di'scharging a stream of liquid. against the periphery of the projected cloud or stream of mixed carbon dioxide gas and snow to cause the liquid stream to be broken up, the stream of liquid and the mixture of gas and snow being so proportioned and the angle or discharge of the stream relative to said periphery being such that substanatmosphere in the form of a cloud or stream traveling at a high velocity,.di scharging into the projected -mixture water which will be finely atomized by the velocity of the mixture, and so proportioning the water and mixture of snow and .gas as well as so directing the water into the tially all of the resultant liquid particles will be entrained in the cloud or stream and carried-to the point of application of the extinguishing medium by the velocity thereof.

6. Amethod of extinguishing a tire comprising conducting liquid carbon dioxide, having a subatmospheric temperature and its correspond ing. vapor pressure, to a point 01' discharge, permitting sudden expansion of the liquid to produce a mixture of gas and snow, projecting mixture of gas and snow into the atmosphere in the form of a cloud or stream traveling at a high Velocity, and discharging a plurality of small streams of liquid, having a higher freezing point than carbon dioxide, against the periphery of the projected cloud or stream of mixed carbon dioxide gas and snow to cause the liquid stream to be broken up, the streams of liquid and the mixture of gas and snow being so proportioned and the angles of discharge of the streams relative to said periphery being such that substantially all of the resultant liquid particles willbe entrained in the cloud or stream and carried to the point of application of the extinguishing medium by the velocity thereof.

7. A method of extinguishing a fire comprising conducting liquid carbon dioxide to a point of discharge, permitting sudden expansion of the liquid to produce a mixture of gas and fine snow particles, subjecting said gas and snow mixture to the shock of impingement to cause the line snow particles to unite to form larger snow flakes, projecting the mixture of gas and snow flakes into the atmosphere in the form of a cloud or stream traveling at a high velocity, and discharging a stream of liquid against the periphery of the projected cloud or stream of mixed carbon dioxide gas and snowflakes to cause theliquid vstream to be broken up, the stream of liquid and the mixture of gas and snow being so pro portioned and the angle of discharge of the stream relative to said periphery being such that substantially all of the resultant liquid particles will be entrained in the cloud or stream and carried to the point of application of the extinguishing medium by the velocity thereof.

8. A method of extinguishing a fire comprise ing conducting liquid carbon dioxide, having a subatmospherictemperature and its corresponding vapor pressure, to a point of discharge, per- 2,2 8,270 the mitting sudden expansion of the liquid to produce a mixture of gas and flne snow particles, subjecting said gas and snow mixture to the shock of impingement to cause the fine snow particles to unite to form larger snow flakes, projecting the mixture of gas and snow flakes into the atmosphere in the form of a cloud or stream traveling at a high velocity, and discharging a plurality of small streams oi liquid,

having a higher freezing point than carbon dioxide, against the periphery of the projected cloud or stream of mixed carbon dioxide gas and snow particles to cause the liquid stream to be broken up, the streams ofrliquid and the mixture of gas and snow being so proportioned and the angles of discharge of the streams relative to said periphery being such that substantially all of the resultant liquid particles will be entrained in the cloud or stream and car- A ried to the point of application of the extinguishing medium by the velocity thereof.

9, A method of extinguishing a fire and cooling the combustible material being consumed as well as heat absorbing objects positioned in' heat exchange relation to said combustile material to a temperature below that at which the material will rekindle, comprising delivering to the combustible material and the involved heat absorbing objects an extinguishing medium consisting entirely of a mixture of carbon dioxide gas and snow and water the gas and snow and water of said mixture being so proportioned and the entrainment of substantially all of the water with the gas and snow being so complete as to cause the delivery' characteristics of the mixture to possess the three-directional efi'ect of a carbon dioxide gas and snow discharge, and continuing said discharge until the mixture has cooled the material and objects to a temperature which will permit water to wet down the same.

ERIC 'GEERTZ.

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