Fireproof Container

Abstract

A container for protecting valuable items such as papers from exposure to fire or intense heat comprising an outer frame, an inner container, and a closure means or a lid. Between the outer frame and inner container, and within the lid, there are heat protection means, each comprising an outer portion of a heat resistant material such as ceramic fiber and an inner portion of an absorbent material such as glass paper which is soaked in water and encased in a water-impermeable jacket made of, for example, polyethylene, which is rupturable upon exposure to elevated temperatures. Typically, vents permit steam which is generated in the presence of intense heat in the inner portions of the heat protection means to pass into the interior of the container to further slow any rise in temperature therein by absorbing heat, and the vents also permit steam to slowly pass out of the container through the channel defined between the closure means and the container itself, thereby inhibiting the inward flow of heat through this channel. In a preferred embodiment, a water-soaked, elongated, fibrous, absorbent material, encased in an elongated water-impermeable jacket, is disposed between the outer frame and inner container at a location subject to high heat transfer rates, such as along the jamb between the outer frame and the inner container.

Parent Case Text

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of our copending and now abandoned application Ser. No. 702,307, filed on Feb. 1, 1968.

Description

BACKGROUND OF THE INVENTION

This invention relates to a lightweight container assembly which has the capability of protecting its contents from the effects of intense, long-lasting heat applied to the exterior of the container.

Most businesses have a vital interest in maintaining their records safe from fire, and thus many types of heat-resistant containers or safes have been available for years. Generally, these safes are extremely heavy, utilizing cement as the insulation against the external heat, and they have generally provided only a small storage volume since it has been impractical to provide large, fire-resistant containers of the types known to the prior art due to their great weight.

Another attempted solution to the problem is found in U.S. Pat. No. 2,586,873, which discloses a heat-resistant container using a water-soaked material encased in a water-impermeable jacket as an outside layer of insulation.

Such containers were never adopted into widespread use because they do not effectively protect their contents against fire unless thick, heavy, water-soaked insulation layers were used making the container assembly cumbersome and heavy. These water-soaked insulation layers would be relatively ineffective in the moderate thicknesses required for light containers because direct exposure to high temperatures causes the water to be rapidly boiled away, the steam being vented to the outside of the containers in accordance with the teachings of the patent. Following this rapid removal of the water, the temperature of the interior of the containers can quickly rise to the point where their contents can be damaged, as extreme heat can cause the dried absorbent material to degrade, resulting in a collapse in insulative properties in the containers.

The container of this invention is lightweight in comparison to the containers of the prior art, but it imparts good protection to its contents against intense heat for long periods of time.

DESCRIPTION OF THE INVENTION

In accordance with this invention a container assembly is provided which comprises an inner container and an outer frame which incloses a major portion of the assembly. A heat protective liner is interposed between the outer frame and inner container, the outer portion of this liner comprising a fibrous material having high temperature resistance and the inner portion comprising at least one porous carrier containing liquid water interspersed throughout the pores of the carrier, the carrier being enclosed in a water-impermeable casing which is rupturable upon exposure of the casing and carrier to elevated temperatures. The container also has a closure means for tight sealing of the container, which means preferably contains a similar protective liner having the same inner and outer portions.

The inner portions of both the preferred heat-protective liner of the closure means and the heat-protective liner located between the outer frame and inner container occupy from ten to fifty percent of the volume of each heat-protective liner. Typically, the inner portion is no more than three quarters of an inch thick.

The container assembly further includes means for securing the inner container to a fixed position within the outer frame, by use of a jamb which bridges the outer frame and the inner container.

Typically, vents are provided to permit any steam which is generated from the inner portions of the heat-protective liner between the inner container and outer frame to pass into the interior of the container by use of a venting system. Steam has a relatively high specific heat, and it therefore continues to absorb heat in the interior of the container, inhibiting the rise in temperature. The steam can also be permitted to seep out of the container via the channel formed between the jamb and the closure means when the closure means is in closing position. Steam flow outward through this channel effectively prevents the inflow of convection heat by this path.

At locations subject to high heat transfer rates, such as at the jamb which provides good metallic heat conduction from the high temperature exterior to the interior of the container, additional means are provided in the preferred embodiment to absorb the heat transmitted. Specifically, an elongated, heat-rupturable, water-impermeable casing is provided which contains a water-soaked, elongated, porous carrier and which lies alongside of the jamb, to provide substantial heat absorbing capacity at the locations most in need of such capacity without the addition of substantial weight. The elongated, porous carrier is preferably fibrous and may be rope-like in character, such as ceramic fiber strip or rope, or asbestos rope, or may be in the form of rolled up thin material such as glass paper rolled up on itself so that one dimension is substantially greater than the others.

FIG. 1 is a vertical sectional elevation of a container assembly in accordance with this invention;

FIG. 2 is a perspective view, partially broken, of a container assembly in accordance with the present invention without the closure means attached thereto;

FIG. 3 is a magnified portion of FIG. 1, showing in greater detail the area of the joint formed by the junction of the closure means with the rest of the assembly;

FIG. 4 is a perspective view, partly in section of an elongated heat-absorbent envelope comprising an elongated, water-soaked, fibrous absorbent material within an elongated heat-rupturable water-impermeable casing, suitable for placement in the container assembly of this invention at a location of high heat transmissivity;

FIG. 5 is a fragmentary vertical sectional elevation similar to FIG. 1, but showing an embodiment utilizing the elongated, heat-absorbent envelope of FIG. 4; and

FIG. 6 is a perspective view similar to FIG. 4, but drawn to another embodiment with respect to the nature of the fibrous absorbent material.

Referring to the drawings, a container assembly 10 is provided with feet 11, an outer frame 12, and an inner container 14. Interposed between the outer frame 12 and the inner container 14 is a heat-protective liner generally designated as 16. A jamb 18 is provided for bridging the outer frame 12 and the inner container 14. Typically, spot welds 19 are used to affix jamb 18 to the outer frame and inner container.

Vents 21 are formed in jamb 18 to allow any steam which is formed to pass from heat-protective liner 16 to space 23, from where the steam can flow both into the interior of the container and to the exterior of the container along the path or channel defined by the lid 20 and the other portions of the container assembly upon which the lid rests.

The lid 20 comprises an outer frame 22, an underframe 24, and an undersurface portion 26 bridging the outer frame 22 and the underframe 24. The heat-protective liner 25 for the lid is preferably identical in construction to heat protective liner 16. Typically the outer frame 22 can be affixed to the underframe 24 and the undersurface portion 26 by spot welds 29. The latter two parts are generally made from one stamped piece of sheet metal.

The lid 20 can contain an air space 27 above liner 25 if desired in order to provide a desired external configuration to the lid.

Undersurface portion 26 and jamb 18 are of such configuration that they fit closely to each other when lid 20 is closed, for the purpose of substantially sealing the interior of the container assembly from the air.

One or more hinges, shown at 28, can permit the lid 20 to be opened and closed by pivoting it in and out of engagement with the rest of the container assembly.

It is usually unnecessary to provide vents for the escape of steam from heat protective liner 25 in lid 20, since less moisture is generally present there than in liner 16, although vents, for example leading into space 23, can be provided if desired. Without such vents, steam can generally escape along the channel defined between outer frame 22 and undersurface portion 26, between the spot welds 29.

If desired, a locking means can be provided to lock the lid 20 in its closed position.

Heat-protective liners 16 and 25 each comprise an outer portion 30 and 32 which is made of a fibrous material having a high temperature resistance, positioned adjacent to the outer frames 12 and 22 respectively. Typically, this fibrous material having high temperature resistance is potassium titanate or ceramic fiber (e.g., ceramic fiber padding sold under the trade name of Johns-Manville Cerafelt, having a density of 12 pounds per cubic foot, or under the trade name of Babcock & Wilcox Kaowool, having a density of 3 to 8 pounds per cubic foot), but other fibrous materials having similar high temperature resistance can be used if desired.

In a preferred embodiment, outer portions 30 and 32 may comprise rigid fibrous boards in which the fibers of high temperature resistance are bonded to each other by inorganic binders. Boards suitable for use as the outer portions of the heat protective liners of this invention may be made of ceramic fibers, mineral wool, or mixtures of the two in any proportions, bonded together by colloidal silica. Optional components include potassium titanate, inert fillers such as alumina, and organic binders. Suitable boards for such use are disclosed in commonly owned application Ser. No. 821,065, filed May 1, 1969, now U.S. Pat. No. 3,629,116.

The heat protective liners 16 and 25 also contain inner portions 34 and 36. These portions contain envelopes (hereinafter called "liner envelopes") comprising porous carriers 35 containing liquid water interspersed throughout the pores of the carriers, the carriers being completely enclosed in a water-impermeable casing 37 which is rupturable upon exposure of the assembled casing and carrier to an elevated temperature, typically about 100.degree. C., through thermal degradation of the casing and pressure build-up inside of the casing caused by boiling of the water contained therein.

Typically, each liner envelope is relatively thin in comparison to its length and width and is sized so that only one such envelope is used on each face of the security container, for purposes of convenient installation of the envelopes into the container.

Any porous carrier which can absorb and hold water can be used as the inner portions 34 and 36, although it is preferred for the porous carrier to have a very low thermal conductivity and high temperature stability at temperatures up to at least 1000.degree. F. It is particularly desirable for the material used to have a thermal conductivity factor of less than 0.65 B.T.U. inches per square foot per degree Fahrenheit per hour when measured at 1000.degree. F. Many forms of fibrous glass paper and cloth, asbestos paper and cloth, and materials made of combined asbestos and glass fibers fulfil this requirement and are readily used as the porous carrier. Other materials which can be used as the porous carrier in less preferred embodiments are plastic foams such as polyurethane, epoxy, phenolic, or silicone resin foams or fibrous organic materials such as cardboard, cotton, or felt. In the embodiment shown, each porous carrier consists of four sheets of fibrous glass paper.

In the embodiment of FIGS. 4 and 5, elongated envelope 41 comprises an elongated water-impermeable casing 42 which is rupturable on exposure to elevated temperature, as is casing 37 of the liner envelope. Within the elongated envelope, porous carrier 43 is a strip of fibrous insulating material, such as ceramic fiber, having a length substantially in excess of its width and thickness. The fibrous insulating material is completely soaked in water so that all of the pores therein are water-filled.

In FIG. 5, there is an elongated envelope 41 between outer frame 12 and inner container 14 alongside of each of the four sides of jamb 18 and there is another set of elongated envelopes 41 around the periphery of lid 20 between outer frame 22 and underframe 24. If desired, other inorganic temperature resistant fibers, such as mineral wool or glass fibers may be used in place of ceramic fibers in the porous carriers, and the fibers may be in other elongated structures such as asbestos ropes or rolled up glass fiber papers. Other porous carriers which may be used include the plastic foams and fibrous organic materials discussed above as suitable for porous carrier 35 in the liner envelopes.

The length of the elongated envelopes may be varied as required depending on the jamb dimensions or the dimensions of whatever other site the envelopes are to be placed into. The width and thickness may also be varied as required, depending on the available space between the walls of the container, or within the lid, so that the cross-sectional shape of the envelope may be approximately square, or approximately rectangular, as required, or even circular, as is the case where the porous carrier is made of rolled-up glass fiber paper. In general, the length of the envelopes will be at least five times as great as any other dimension.

It will be noted that elongated envelopes 41 are substantially deformed when inserted into the positions shown in FIG. 5 so that the shape of the envelopes within the container assembly conforms closely to the interior surfaces of the jamb, or lid.

FIG. 6 is similar to FIG. 4, except that the porous carrier 43a is made of rolled-up glass paper, and the envelope (before any distortion) is of generally circular cross-section rather than rectangular, as in FIG. 4.

The elongated envelopes of FIGS. 4 and 6, appropriately dimensioned, may be used in other combinations than the container assembly of FIG. 1, wherever a localized concentration of heat is to be absorbed. Such elongated envelopes may, for example, be used within modular insulating wall members, such as those disclosed in commonly owned application Ser. No. 770,768, filed Oct. 25, 1968, at the location where one modular wall member is joined to another.

Since most water-impermeable films are somewhat permeable to water vapor, particularly when the films are thin, there is a tendency for the water in the liner envelopes and the elongated envelopes to evaporate slowly. Thus, over a long period the carriers may lose part of their water and part of their effectiveness as heat absorbers. To counteract this tendency, the porous carriers in a preferred embodiment also contain a humectant such as calcium chloride, ammonium chloride, calcium nitrate, glycerine, or silica gel in order to inhibit the loss of water from the porous carrier by means of evaporation.

A typical water-humectant solution for use in this invention might contain 16 weight percent of calcium chloride, based on the weight of the water present. This solution has a tendency to absorb water from the atmosphere, and thus the likelihood of the water solution evaporating away from the porous carriers is essentially eliminated.

A gelling agent such as methylcellulose, hydroxyethyl-cellulose, or vinylic polymers containing sufficient carboxylic acid groups to render the polymer water-soluble can be added to prevent the water from settling to the bottom of the porous carrier with a resulting scarcity of water at the top. A gelling agent also stiffens the composite of porous carriers and casing, permitting it to stand up more securely within the container walls. A type of the latter vinylic polymer is available under the trademark Carbopol from the B. F. Goodrich Co. This latter material can be used, for example, by dipping a porous carrier such as fibrous glass paper into a 1 weight percent aqueous solution of the vinylic polymer to saturate the paper with the solution. The paper is then dipped in or sprayed with an aqueous solution of ammonia to immediately cause gellation of the vinylic polymer within the pores of the glass fiber paper, entrapping the water contained therein.

In one preferred embodiment of this invention the gelling agent may be one which gels water in situ after a predetermined time lapse so that the water, before gelling, can penetrate the pores of the porous carrier. A suitable system for such in situ gellation is an aqueous solution of acrylamide and N,N'-methylenebisacrylamide to which is added a catalyst system comprising beta-dimethylaminopropionitrile, ammonium persulfate, and potassium ferricyanide.

The water-impermeable casings used herein are typically made from a thermoplastic film of polyethylene, poly(vinyl chloride-vinylidene chloride), sold under the trademark Saran, or laminated films containing a layer of each of the two previous materials which take advantage of both the good water impermeability of poly(vinyl chloride-vinylidene chloride) and the easy heat sealability of polyethylene.

In one suitable embodiment of the water-impermeable casing, at least the outer face of the liner envelope casing or at least a portion of the elongated envelope casing is an aluminum foil-paper laminate. The aluminum foil serves as a heat reflector, further increasing the heat resistance capacity of the container of this invention.

Other materials which are useable as the water-impermeable casing are thin films of butyl rubber, polybutadiene, and natural rubber. It is preferred to use a thermoplastic material which softens and weakens at a temperature in the vicinity of 100.degree. C. so that the water inside of the casing is released and permitted to vaporize before the temperature rises greatly over 100.degree. C.

The volume occupied by inner layers 34 and 36 should be from 10 to 50 percent of the volume occupied by insulating layers 16 and 25, but the best results are obtained when the volume occupied by each inner portion 34 and 36 is from 20 to 40 percent of the volume of each insulating layer respectively, typically about 30 percent.

The container of this invention achieves its superior heat resistance as follows: when external heat is generated due to a fire or some other reason near the container, the heat passes through the outer frames 12 and 22, which are generally made of steel sheeting. The first insulating action occurs in the outer portions 30 and 32, which can stand the intense heat without deterioration, providing continuing and undegrading insulation of the interior despite great extremes of heat. As the temperature of the inner portions 34 and 36 rises to about 100.degree. C. or slightly above, the water-impermeable casings rupture, and the water contained therein turns into steam, absorbing great amounts of heat due to the high latent heat of vaporization of water. The temperature of the inner portions 34 and 36 remains in the vicinity of 100.degree. C. until all of the water has vaporized. After this, the temperature in the inner portion can continue to rise, but the porous carriers of the inner portions 34 and 36 still provide insulating protection. When the porous carrier is a good high temperature insulating material, such as a glass fiber material or an asbestos fiber material, it can continue to provide insulating protection for an extended period while it, itself, is protected from degradation by the outer fibrous material.

The steam which is generated in the inner portion 34 can pass by means of vents through the jamb to air space 23. The steam can then pass from there to the interior of the container by path of flow 38 where it provides further heat-absorptive capability, and to the exterior of the container through the channel defined between jamb 18 and undersurface portion 26, impeding the flow of heat through the channel into the interior of the container assembly.

The invention of this application can also be embodied in other modifications such as fireproof side-opening containers, file drawers, and cabinets constructed in accordance with the above description.

If desired, additional layers of insulation can be provided in the containers of this invention to augment the insulation layers described above.

From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concept of the invention. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the invention.

Claims

What is claimed is:

1. A container assembly which comprises: an outer frame enclosing a major portion of the assembly; an inner container; a jamb bridging said outer frame and said inner container; heat protection means between said outer frame and said inner container, an outer portion of said heat protection means comprising fibrous material having high temperature resistance and an inner portion of said means comprising at least one porous carrier containing liquid water interspersed throughout the pores of said carrier, said carrier being enclosed in a water-impermeable casing carrying aluminum foil upon its outer surface which casing ruptures upon exposure of the inner portion to an elevated temperature, from 10 to 50 percent of the volume of said heat protection means being occupied by said inner portion; and closure means adapted for mating relationship with said jamb.

2. A container assembly which comprises: an outer frame enclosing a major portion of the assembly; an inner container; a jamb bridging said outer frame and said inner container; heat protection means between said outer frame and said inner container, an outer portion of said heat protection means comprising fibrous material having high temperature resistance and an inner portion of said means comprising at least one porous carrier containing liquid water interspersed throughout the pores of said carrier, said carrier being enclosed in a water-impermeable casing which casing ruptures upon exposure of the inner portion to an elevated temperature, from 10 to 50 percent of the volume of said heat protection means being occupied by said inner portion, closure means adapted for mating relationship with said jamb, and vents to provide access through said jamb to the channel which leads to the exterior of said container assembly defined between said jamb and the closure means, whereby steam which is generated in said heat protection means passes by way of said channel to the exterior of said container assembly, inhibiting the inflow of heat by way of said channel.

3. A container assembly which comprises: an outer frame enclosing a major portion or the assembly; an inner container; a jamb bridging said outer frame and said inner container; first heat protection means between said outer frame and said inner container, an outer portion of said first heat protection means comprising fibrous material having high temperature resistance and an inner portion of said means comprising at least one porous carrier containing liquid water interspersed throughout the pores of said carrier, said carrier being enclosed in a water-impermeable casing, which casing ruptures upon exposure of the inner portion to a temperature of about 100.degree. - 120.degree. C., from 10 to 50 percent of the volume of said first heat protection means being occupied by said inner portion; closure means adapted for mating relationship with said jamb, said closure means comprising an outer frame, an undersurface portion for mating with the jamb, an underframe, and second heat protection means interposed between said closure outer frame and said underframe, said latter means comprising an outer portion and an inner portion of types identical to said outer portion and inner portion of the first heat protection means, from 10 to 50 percent of the volume of said second heat protection means being occupied by said inner portion and vents to provide access from said first heat protection means through said jamb to the channel between said mated undersurface portion and jamb, whereby steam which is generated in said first heat protection means passes by way of said channel to the exterior of said container assembly, inhibiting the inflow of heat by way of said channel.

4. An insulating envelope suitable for use in fireproof containers comprising at least one porous carrier containing a liquid aqueous solution of a calcium chloride humectant in sufficient concentration to essentially eliminate evaporation of water from said solution, said carrier being enclosed in a water-impermeable casing, which casing ruptures upon exposure to an elevated temperature.

5. An insulating envelope suitable for use in fireproof containers comprising at least one porous carrier containing a liquid aqueous solution of calcium chloride humectant in sufficient concentration to essentially eliminate evaporation of water from said solution, said carrier being enclosed in a water-impermeable casing, which casing ruptures upon exposure to an elevated temperature, said casing being made from a material selected from the group consisting of polyethylene, poly(vinyl chloride-vinylidene chloride), and combinations thereof.

6. A container assembly which comprises: an outer frame enclosing a major portion of the assembly; an inner container; a jamb bridging said outer frame and said inner container; first heat protection means between said outer frame and said inner container, an outer portion of said first heat protection means comprising fibrous ceramic cloth having high temperature resistance and an inner portion of said means comprising fibrous glass paper containing liquid water interspersed throughout the pores of said paper, said paper being enclosed in a water-impermeable casing made of a thermoplastic film, which casing ruptures upon exposure of the inner portion to a temperature of about 100.degree.-120.degree. C., from 10 to 50 percent of the volume of said first heat protection means being occupied by said inner portion; closure means adapted for mating relationship with said jamb, said closure means comprising an outer frame, an undersurface portion for mating with the jamb, an underframe, and second heat protection means interposed between said closure outer frame and said underframe, said latter means comprising an outer portion and an inner portion of types identical to said outer portion and inner portion of the first heat protection means, from 10 to 50 percent of the volume of said second heat protection means being occupied by said inner portion.

7. An insulating envelope suitable for use in fireproof containers comprising at least one porous carrier containing a liquid aqueous solution of a humectant in sufficient concentration to essentially eliminate evaporation of water from said solution, said carrier being enclosed in a water-impermeable casing carrying aluminum foil upon its outer surface which casing ruptures upon exposure to an elevated temperature.

8. A container assembly which comprises: an outer frame enclosing a major portion of the assembly; an inner container; a jamb bridging said outer frame and said inner container; heat protection means between said outer frame and said inner container, said heat protection means comprising an elongated heat absorbent envelope comprising an elongated, water-impermeable casing having its long dimension adjacent to and parallel to the long dimension of said jamb, said casing being rupturable on exposure to elevated temperatures and an elongated porous carrier containing liquid water interspersed throughout its pores sealed within said casing; and closure means adapted for mating relationship with said jamb.

9. The container assembly of claim 8 wherein said closure means is hollow and contains within it at a location which mates with said jamb an elongated heat absorbent envelope comprising an elongated, water-impermeable casing having its long dimension parallel to an edge of said closure means, said casing being rupturable on exposure to elevated temperature and an elongated porous carrier containing liquid water interspersed throughout its pores sealed within said casing.

10. An insulating envelope suitable for use in fireproof containers comprising at least one porous carrier containing liquid water in gelled form interspersed throughout the pores of said carrier, said carrier being enclosed in a water-impermeable casing, which casing ruptures upon exposure to an elevated temperature.

11. The envelope of claim 10 in which the water-impermeable casing is made from a material selected from the group consisting of polyethylene, poly(vinyl chloride-vinylidene chloride), and combinations thereof.

12. The envelope of claim 10 in which the water-impermeable casing carries aluminum foil upon its outer surface.

13. The envelope of claim 10 which has dispersed therein at least one gelling agent selected from the group consisting of methylcellulose, hydroxyethylcellulose, and water-soluble vinylic polymers containing carboxylic acid groups.