US2829608A - Heat insulating enclosure - Google Patents

Description

April 8, 1958 www if A. R. BLACKBURN ET Al. I

HEAT INSULATING ENCLOSURE Filed Oct. 8. 1954 2 Sheets-Sheet l INVENTORS ATTORNEYS p'i 5, 1958 A. R. BLACKBURN ET AL 2,829,608

HEAT- INSULATING ENcLosuRE Filed Oct. 8. 1954 2 Sheets-Sheet 2 III,

ATTORNEYS United States Patent O HEAT INSULATING ENCLOSURE Andrew R. Blackburn, Westerville, and Richard E. Steele, Worthington, Ohio, assignors to Ram Incorporated, Columbus, Ohio, a corporation of Michigan Application October 8, 1954, Serial No. 461,082

Claims. (Cl. 109-33) This invention relates generally to a heat insulating wall structure for an enclosure. More particularly, the invention is directed to an enclosure wall structure having a layer of permeable material interposed between inner and outer walls of the enclosure with means for introducing a fluid into the permeable mass to maintain moisture therein so that upon exposure to flame or extreme heat the wall structure will not become unduly heated but will tend to dissipate the heat by vaporization of the fluid in the permeable mass.

Numerous previous attempts have been made to devise safes, file cabinets and other receptacles for containing or storing valuables of all kinds, as well as enclosure wall structures in general which will be resistant to and thereby protect the articles stored against damage by ame or extreme heat. In the majority of these receptacles or enclosures, the protection afforded the stored articles is secured by thermal insulation exteriorly of the inner storage space which will be effective for a predetermined period of time in preventing excess temperature rise within the receptacle due to high temperature existing exteriorly of the receptacle. Thus, the walls of the protective receptacle have been made of material of low heat conductivity or a thermal insulating material interposed between inner and outer walls of the protective container.

These previously designed receptacles or enclosures are effective only to the extent that the specially constructed walls thereof prevent conduction of heat inwardly to the articles contained therewithin. Although llames may be prevented from reaching the interior space or compartments, nevertheless suicient heat may be conducted through the walls of the container so that the objects or materials stored therein become scorched or otherwise damaged by the heat. Generally, the obvious approach to improve the fire or heat insulating qualities of the container is to increase the thickness of the container walls. Such an increase in thickness obviously not only increases the weight of the receptacle, but also reduces the effective storing capacity of the container for any particular set of outside dimensions.

Fire resistant receptacles, such as safes and tiling cabinets, are generally rated on an hourly basis as to the period they will be effective in preventing excessive temperature rise within the receptacle. In other words, a particular fire resistant receptacle is rated as to the period of time which it will restrict heat transfer to the interior of the receptacle which would raise the temperature within the cabinet to the ignition point to cause charring or burning of the articles contained within the receptacle.

Plaster, having a low heat transfer constant in the order of 0.4 B. t. u.s/sq. ft./hour/ F., has been used in many prior fire resistant structures. In such structures, plaster has been used not only because of its insulating properties but also because it has a characteristic of absorbing a substantial amount of heat causing the plaster to break down and dehydrate with the freed water, in turn, absorbing heat as it is changed into steam. This absorption of heat may run somewhere between 800 and 1000 2,829,608 Patented Apr. 8, 1958 fice B. t. u.s/lb. By maintaining the plaster in a moist state, exposure of the plaster to high temperatures will not result in dehydration and breaking down of the plaster. Accordingly, it will retain its heat insulating properties and continue to absorb heat as long as the moisture content is maintained within the plaster.

It is a principal object of this invention to provide a lire or heat insulating wall structure employing a permeable mass which may be internally subjected to fluid pressure so that the mass is maintained ina moist condition and thus relatively cool by evaporation of the uid from the permeable mass when exposed to high temperature conditions.

It is another object of this invention to provide a fire or heat insulating receptacle having inner and outer spaced walls and a permeable mass disposed intermediate said walls with passage means extending through said mass and communicating with a source of fluid pressure through a temperature responsive valve whereby upon exposure to excessive heat, said temperature responsive valve will admit fluid pressure to said passage to maintain a supply of fluid in said mass which is evaporated on exposure to heat to retain the receptacle in a relatively cool state.

It is a further object of this invention to provide a re or heat insulating receptacle having spaced walls with a permeable mass disposed therebetween, passage means formed in said mass to admit fluid pressure thereto and a fluid supply carried by said receptacle with means to pressurize said fluid supply upon the receptacles being exposed to excess heat whereby iluid will be forced through said passage means and into said permeable mass to cool said walls of said receptacle.

It will be evident from the description given hereinbelow of the specific embodiments of the invention illustrated, that the wall structure of the instant invention iS equally adaptable to and effective for use in the construction of stationary storage receptacles such as safes, filing cabinets and storage boxes of all kinds, as well as the walls of larger enclosures and rooms to produce a structure which will resist the destructive action of high heat or ame.

The above and other objects of the instant invention will become apparent from the following description of the specific embodiments illustrated on the accompanying drawings in which:

Figure 1 is a perspective view with parts thereof in section illustrating one application of the instant invention;

Figure 2 is a fragmentary sectional view taken on line 2 2 of Figure l;

Figure 3 is a partial perspective view illustrating the general formation of the conduit disposed interiorly of the walls of the cabinet of Figure l;

Figure 4 is a partial sectional view of a modified form of heat insulating receptacle.

Referring specifically to Figure 1 of the drawings, there is shown thereon a safe cabinet 10 constructed with the wall structure thereof embodying the features of the instant invention. The cabinet has a pair of doors 11 and 12 hingedly supported along the sides of the cabinet opening on hinges 13. A suitable latch 14 is provided to retain the doors in their closed position as desired and a combination lock 15 mounted to operate in conjunction with the latch 14 to lock the doors 11 and 12 in their closed position. In the illustrated embodiment a base 16 is provided to support the cabinet.

As illustrated by the sectionalzed portion of Figure 1, the cabinet doors 11 and 12 are formed with inner and outer spaced walls 17 and 18 with a heat insulating mass 19 disposed intermediate such walls and reinforced by wire mesh 20. On the drawings, the doors `11 and 12 have not been shown constructed to incorporate the permeable plastic mass and a passage for fluid therein which, as will become apparent from the description hereinbelow, is an important feature of the instant invention. The construction illustrated in Figure 1 for the doors 11 and 12 removes the necessity for providing exible connections to conduct the pressurized fluid to the hinged doors. However, it will be readily appreciated that Within the scope of the instant invention, the doors 11 and 12 may be so formed as to incorporate the features of the wall structure described hereinbelow with regard to the wall structure of the rest of cabinet 10.

Figure 2 most clearly illustrates the structural characteristics of the walls of cabinet 10. This wall structure is formed with an outer wall 25, which serves as the exterior wall of the cabinet, and an inner wall 26 spaced from the outer wall and defining an interior chamber or compartment which forms the storage space of the cabinet. The inner wall 26 is provided with a plurality of perforations 27 through "'hich vapors generated within the wall structure may flow into the storage compartment. It will be recognized that the safe is not pressure tight so that such vapor may seep out without there being a pressure build-up within the safe.

A mass or layer 28 of permeable material is disposed intermediate the Wall 26 and the outer wall 25 and is shown in Figures l and 2 as disposed in contact with the inner surface of outer wall 25. Preferably this permeable mass consists of a plaster such as disclosed and described in Patent 2,632,209. Such plaster has characteristics of permeability which permit a fluid to be expelled thereinto and thereby keep the plaster in a moist condition. A passage is formed within the mass as by a conduit 29 imbedded within such mass and extending back and forth within substantially the entire area of the cabinet wall structure covered by the layer of permeable material. Conduit 29 is perforated as shown at 30 on Figure 3 to permit fluid such as water to :be forced outwardly into the permeable mass 28. Subjecting the passages within the permeable mass to a pressurized fluid results in maintaining the mass in a moist state to preclude undue temperature rise upon exposure to extreme heat.

Conduit 29 extends outwardly through the outer wall 25 and is provided with a coupling 31 and a suitable temperature responsive valve 32, which valve in turn is connected to a supply pipe 33 leading to a source of uid under pressure (not shown). The temperature responsive valve 32 may be of any suitable construction and functions to normally maintain the pressure existent in pipe 33 out of communication with conduit 29. However, such valve is disposed outwardly of the cabinet and therefore upon being subjected to ame or extreme heat is actuated to connect conduit 29 with the fluid pressure in pipe 33. This valve actuation admits fluid into the conduit which flows outwardly into the permeable mass 28 to produce the protective moist condition within the mass to resist the destructive action of ame or extreme heat exteriorly of such cabinet.

Figure 4 illustrates a further embodiment of the instant invention employing a layer of permeable material between the spaced inner and outer walls. This embodiment has the additional advantage as compared with the embodiment described hereinabove in that it carries, as a self-contained part thereof, a readily available iluid supply and means for pressurizing such supply.

The receptacle shown in the fragmentary sectional view of Figure 4, has an outer wall 40 and an inner wall 41 spaced from said outer wall and defining an interior compartment for retaining articles to be stored. Intermediate the outer and inner walls 40 and 41 there is provided a mass or layer 42 of permeable material disposed in contacting relation with the outer surface of wall 41 and spaced from the outer wall by angular spacing members 43 secured at spaced positions to the outer wall. The permeable mass 42 has formed therein passages 44 which serve to conduct to the various points within the mass 42 the fluid which is to be expelled into such mass to maintain it in a moist state and thus perform the requisite cooling action. An aperture 45 is provided in the outer wall 40 to permit egress of the vapor from the receptacle which may be produced upon exposure of permeable mass 42 to high temperature condlitions.

As illustrated in the embodiment of Fig. 4, the receptacle has an open top and is provided with a cover or door 46 hinged as by hinges 47 to the side wall structure of the receptacle. Cover 46 is constructed in a manner similarly to the receptacle wall structure hereinabove described and thus has an outer wall 48, an inner wall 49 and a permeable mass 50 formed as a layery intermediate said walls. Such layer is in contact with the outer surface of the wall 49 and spaced from wall 418 by suitable angular members 51. A passage 52 is formed within the permeable mass to convey therethrough the fluid which is to be expelled outwardly into the mass. Such outer wall is also provided with an aperture 53 to permit vapor to flow out of the cover.

A flexible tube 54 is provided to couple the passage 52 in a door 46 with the passage 44 formed in the Wall structure of the receptacle. The slack in tube 54, as shown in Figure 4, permits opening of the cover or door 46 without breaking the communication between passage 52 and passage 44. As mentioned hereinabove, it will `be readily appreciated that the form of construction of door 46 in Figure 4 could be applied in the construction of doors 11 and 12 of the embodiment illustrated in Figures 1 through 3 so that such doors would be characterized by having a wall structure as incorporated into the walls of the cabinet 10.

The lower portion of inner wall 41 forms a sump or reservoir which retains a fluid F to be utilized in cooling the receptacle by its being expelled through permeable masses 42 and 50. A tube 61 extends through a seal 62 in the wall 41 to connect the passage 44 while its opposite end extends downwardly into the fluid supply F to a point near the bottom of the supply sump.

At a point on the wall 41 above the sump or reservoir 60, angles 65 are secured as by welding around the interior of wall 41. These angles support a plate 66 which separates the iluid reservoir or sump from a chamber C which is to serve as the article storing compartment of the receptacle. Plate 66 is secured to angles 65 by suitable bolts 67 with a gasket 68 interposed between the edge of the plate and the angles to seal the reservoir or sump from communication with the compartment C.

In view of the fact that the iluid F carried within the sump or reservoir 60 exists in such reservoir under atmospheric pressure, means must be provided to force such fluid outwardly through tube 61 and thence through passages 44 and 52 to be expelled into the permeable masses or layers 42 and 50. Such a pressurizing means is provided by a sealed cartridge 70 mounted within the reservoir on brackets 71 secured to the inner wall 41. Cartridge 70 may contain any suitable pressurized gas such as, for example, carbon dioxide.

To puncture cartridge 70 and thereby release the pressurized gas contained therein, a temperature responsive puncturing device 72 is mounted on the exterior wall 40. This device has a housing 73 with a puncturing pin 74 having an enlarged head 75 slidably received within such housing and a spring 76 continuously biasing pin 74 toward the cartridge 70. Pin 74 has a sharpened puncturing point 77 and extends inwardly through apertures provided in the outer and inner walls 40 and 41 to be disposed adjacent the cartridge 70. As illustrated, a suitable guide or bearing 78 is disposed adjacent the inner wall 41 within the permeable mass 42 to slidably support pin 74.

An annular body of material 79 is disposed within housing 73 to surround the pin 74 and retain it, against the biasing force of spring 76, outwardly away from contact with cartridge 70. Housing 73 is provided with an opening 80 adjacent the underside thereof. The material 79 is so selected as to have a melting point temperature approximately equal to the upper temperature at which it is desired that the receptacle be subjected to the cooling action provided by maintaining the permeable masses 42 and 50 in a moist state. Upon the temperature responsive device 72 being exposed to this temperature, the material 79 melts and flows out of housing 73 through opening 80. Under the urging of spring 76, pin 74 with its sharpened point 77 moves inwardly to puncture cartridge 70 and thus release the pressurized gas contained therewithin to subject fluid F to such pressure. In turn, the iiuid F is forced out through tube 61 into passages 44 and 52 and thence expelled into the permeable masses 42 and 50 which has a cooling effect on the wall structure so that the articles stored within the receptacle or container are protected from the extreme heat existent exteriorly of the receptacle.

ln actual applications of the instant invention, the pressure applied in forcing uid into the permeable mass may be in the order of 2() lbs./sq. in. It has been found that this pressure is adequate to keep water within the pores of the permeable mass and thereby keep the mass in a moist condition. In this condition breaking down and actual dehydration of the plaster will not start, or at least will only occur to a limited degree upon exposure of the wall structure to high temperatures. As heat is conducted through the permeable plaster mass tending to raise the temperature of such mass, the iiuid contained therewithin will be evaporated, absorbing the heat so that the temperature of the wall structure will not rise above 212 F. Thus the receptacle is maintained fireproof as the evaporated uid is replaced by fluid forced into the pores of the permeable mass.

Having thus described my invention, what we claim is:

l. A heat insulating receptacle comprising an inner wall defining an article storing compartment interiorly thereof, an outer wall surrounding said inner wall and spaced therefrom to provide a cavity intermediate said walls, a permeable mass disposed in said cavity, said mass having passage means formed therein, a cover for said receptacle having parallel walls and a layer of permeable material positioned intermediate said parallel walls, said layer having a passage therein, means for connecting said passage in said layer with said passage means in said permeable mass, a pressure tight liquid supply reservoir carried by said receptacle, tube means terminating within and adjacent the bottom of said reservoir and communicating with said passage means to conduct liquid from said reservoir to said passage means, a cartridge containing gas under pressure mounted within said reservoir, and temperature responsive puncturing means operatively associated with said cartridge to puncture said cartridge and release the gas pressure therein upon the occurrence of excessive temperature conditions adjacent said receptacle whereby liquid in said reservoir will be forced through said tube means to said passage means and said passage and into said permeable mass and permeable material to preclude the occurrence of excessive temperature conditions within said receptacle.

2. A heat insulating enclosure wall structure comprising a layer of permeable plaster material having a multitude of intercommunicating pores dispersed therethrough, said layer having a passage larger than said pores extending therethrough communicating at a plurality of points intermediate its ends with the pores of said material interiorly of said layer to conduct liquid directly to the pores within said plaster material, means connecting said passage with a liquid supply, and means responsive to excessive temperatures adjacent said wall structure to supply liquid from said liquid supply to said passage and intercommunicating pores in said plaster material so that internal dehydration of said plaster material is substantially precluded and heat transferred to said wall structure effects vaporization of moisture from the pores of said plaster material to lprevent undue temperature rise in said wall structure.

3. In a heat insulating receptacle, a wall structure having an inner wall defining an article retaining compartment and an outer wall surrounding and spaced from said inner wall, a layer of permeable plaster material disposed intermediate said inner and outer walls and having a multitude of intercommunicating pores dispersed therethrough, said layer having a passage larger than said pores extending therethrough communicating at a plurality of points intermediate its ends with the pores of said material interiorly of said layer to conduct liquid directly to the pores Within said plaster material, means connecting said passage with a liquid supply, and means responsive to excessive temperatures adjacent said wall structure to supply liquid from said liquid supply to said passage and intercommunicating pores in said plaster material so that internal dehydration of said plaster material is substantially precluded and heat transferred t0 said wall structure elfects vaporization of moisture from the pores of said plaster material to prevent undue temperature rise in said wall structure.

4. In a heat insulating receptacle, a wall structure having an inner wall defining an article containing compartment and an outer wall surrounding and spaced from said inner wall, a layer of permeable material disposed intermediate said inner and outer walls, said layer having a passage therein, means connecting said passage to a pressure tight liquid supply, a cartridge retaining a supply of gas under pressure and mounted to communicate said gas under pressure to said liquid supply, and temperature responsive means including a cartridge puncturing element mounted adjacent said cartridge to puncture said cartridge upon the occurrence of excessive temperature conditions to communicate said gas pressure to said liquid supply thereby forcing such liquid into said passage to maintain said layer of permeable material in a moist condition.

5. A heat insulating receptacle comprising an inner wall defining an article storing compartment interiorly thereof, an outer wall surrounding said inner wall and spaced therefrom to provide a cavity intermediate said walls, a permeable mass disposed in said cavity, said mass having passage means formed therein, a pressure tight liquid supply reservoir carried by said receptacle, tube means terminating within and adjacent the bottom of said reservoir and communicating with said passage means to conduct liquid from said reservoir to said passage means, a cartridge containing gas under pressure mounted within said reservoir, and temperature responsive puncturing means operatively associated with said cartridge to puncture said cartridge and release the gas pressure therein upon the occurrence of excessive temperature conditions adjacent said receptacle whereby liquid in said receptacle will be forced through said tube means to said passage means and into said permeable mass to maintain such mass moist and thereby prevent the occurrence of excessive temperature conditions within said receptacle.

References Cited in the le of this patent UNITED STATES PATENTS 5,582 Fitzgerald May 16, 1848 66,062 Ashcroft June 25, i867 86,356 Bryant Feb. 2, 1869 2,520,972 Siple Sept. 5, 1950 FOREIGN PATENTS 5,233 Great Britain Mar. 4, i907

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