Abstract:
A dry refuge for a group of people in the event of a large fire front like a bush fire is a chamber with a roof, walls and doors made of a steel outer shell, a non-metal inner shell to accommodate people and a multi-layer ceramic fiber insulation layer between the shells capable of withstanding 1100EC difference in temperature. When the refuge is mobile in order to accompany firefighters into a fire zone, it is built as an insulated water tank with entry hatches for personnel and a quick release water valve for dumping water from the inner shell. The tanks may be on road going trailers in order to be transportable by the authorities to where they are needed. An air portable version is transportable by helicopter. All may have smoke proof seals on hatches and doors and internal air supply, sight glasses to view the outside, interior lighting and a radio.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 13/500,304, filed Apr. 4, 2012 and also titled “Fireproof Refuges”. The disclosure of said prior application and its entire file wrapper (including all prior art references cited therein) are hereby specifically and expressly incorporated by reference in their entirety as if set forth fully herein. 
    
    
     TECHNICAL FIELD 
     This invention concerns temporary refuges for personnel in the event of fire. These are classified as active safety measures. 
     BACKGROUND 
     Although fires in buildings consume the fuel inside the building and may persist until the fuel is exhausted or the fire is extinguished by firefighters, the behaviour of a bush fire is different in that a fire front forms and travels over the ground according to various conditions which determine direction and speed. 
     Sometimes firefighting vehicles become isolated then surrounded by fire and the crew have no means of escape. Residences which are reached by only one road in a rural setting may become similarly surrounded by fire leaving the occupants trapped. The building codes do not yet specify that residences shall have fireproof construction. Accordingly some householders rely on bunkers into which they retreat in the event of a bush fire. Unless these are purpose-built they may provide inadequate protection and death or injury results. 
     The heat of a bush fire can be high over a short period as the fire front advances, consumes oxygen and creates smoke. Any refuge must therefore offer effective heat insulation, a physical barrier to smoke, windblown debris and embers, and an air supply in the event that the design limit of the refuge is exceeded by crowding. 
     In U.S. Pat. No. 4,174,711 is a fireproof shelter for installation inside a building. The shelter&#39;s wall is 12-20 cm thick with chrome plating or gold finish. Crystal hydrates inside the shelter absorb incoming heat and the occupants spray themselves with water. While it may be possible to use such shelters within buildings, the design of shelters for bush fire resistance and for mobile use on roads or across country requires a different approach. 
     In my Australian Patent No. 567145 I set forth a mobile refuge in the form of a water tank which is heat insulated sufficiently to withstand a moving fire front with hatches for rapid entry of persons who dump the water in the tank through a rapid discharge valve as they enter and remain inside for the duration of the emergency. The requirements of a dry refuge to which a family may retreat introduces different requirements from the tank version which are addressed by this invention. 
     SUMMARY OF INVENTION 
     The first apparatus aspect of the invention provides a refuge for temporarily housing people in the event of fire, being a chamber with walls, a roof and a door constructed from an outer metal shell which is attachable to a fireproof base, and an inner shell which provide accommodation for people, the space between the shells being insulated with ceramic fibre. 
     Preferably the door is of like construction to a wall of the chamber. 
     The metal may be corrosion resistant alloy sheet 1-2 mm thick. This gives the chamber an outdoor life of at least 20 years. It is preferable that the inside face of the sheet be uncoated in order to avoid the generation of vapour or smoke which could adversely affect the occupants. The chamber may be cuboid and accommodate four or more persons. 
     The inner shell may be made of fibreglass and resin formed as a tank. Alternatively the inner shell may be a rotational moulding around which the metal shell is built. 
     The insulation may be applied to one or other of the shells in layers. The insulation may be in sheet form or as a flexible blanket. The inner or outer shells may have surface mounted spikes which pierce the insulation and keep it in position. 
     The chamber may have an external air duct which joins the chamber interior to a storage chamber capable of accommodating one or more oxygen/air bottles. The storage chamber walls and the duct preferably have walls built to the same standard of thermal insulation as the chamber. Alternatively, the chamber may have storage space for breathing apparatus. 
     The second aspect of the invention provides a water tank for a fire tanker which has multiple doors for admitting firefighters and a dump valve for releasing water rapidly, the tank being of the same construction as the chamber described above. The chamber may have an air duct which joins the interior to a storage chamber capable of accommodating a compressed air supply. Alternatively, the interior of the chamber may have waterproof breathing apparatus. 
     The chamber may be cuboid and large enough to house four six or eight persons. The doors may be in the top face of the chamber opening outwards. The doors may be insulated to the same standard and have door seals which cooperate with chamber seals effecting a double or labyrinth seal. The doors may have a convex exterior section. The interior may have baffles to quell water movement when the tank is full or partly full. The baffles may divide the interior into compartments for occupants. The interior may have lighting, a waterproof radio or phone, and an insulated aerial. A fire crew has six members. 
     The third aspect of the invention provides a trailer-mounted refuge for temporarily housing people in the event of fire, comprising a chamber with multiple doors securable to the floor of a road going trailer. The chamber having the same wall construction as described above. A storage chamber for the compressed air supply may be joined to the interior by a duct. The position of the doors may vary. 
     Such units would be brightly coloured for identification and have fluoro patches for detection from the air. These could be available from hire businesses or rural councils to be maintained and inspected while they wait to be used for fire protection. Here the protection of personnel is the aim rather than the dual function of water storage and personnel protection. 
     The fourth apparatus aspect of the invention provides a standalone refuge for temporarily housing people in the event of fire, comprising a chamber with multiple doors with a wall construction as described above and an optional water dump valve and lugs for slinging the refuge from a helicopter. 
     The chamber may contain a water pump facility for changing the interior with water from an external source. Preferably the chamber will have adjustable floor supports for resting the chamber on uneven ground. 
     The fifth apparatus aspect of the invention provides a dry refuge for housing people in the event of fire comprising a chamber, having one or two doors, walls and a roof and optionally a floor made of the same wall construction as described above. The floor may have adjustable supports to assist its placement on the ground. The chamber may be of modular construction with identical ends and intermediate modules so that the length was variable. The chamber may sit within an external frame in order to protect the roof from falling debris. The frame may have a lengthwise ridge member to withstand collapsing poles and the like. Lifting lugs allow placement by a crane. The roof profile may be arcuate. The modules may be rotational mouldings which are covered with insulation, joined together by connectors and placed within an outer steel shell. 
     If the refuge is designed to be fixed to a concrete base, the base frame need not be insulated like the other parts of the refuge. The base frame may be adapted to be picked up by a forklift. The refuge may have an external or internal air supply for the occupants. 
     Alternatively, the unit may have inner and outer like frames, one resting within the other, the inner being sheathed in plywood or plastic to which is attached the requisite insulation as described above, the outer frame being sheathed in sheet metal attached by fasteners. 
     The interior may have battery powered lights, peepholes, communication equipment and seating. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       One embodiment of the invention is now described with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective of a dry refuge for temporary or permanent ground installation in rural areas. 
         FIG. 2  is a perspective of the outer shell and the inner shell of the refuge of  FIG. 1 . 
         FIG. 3  is a cross section of the wall of the refuge of  FIG. 1 . 
         FIG. 4  is an end view of the nested frames of a variant dry refuge ready to be clad. 
         FIG. 5  is a perspective of the nested frames of  FIG. 11  with the inner frame clad with ply. 
         FIG. 6  is the same view as  FIG. 9  but with the ply sheath covered with insulation to the depth of the outer frame, ready to receive the steel sheet layer. 
         FIG. 7  is a fragmentary end section of the dry refuge shown in  FIGS. 4-6  standing on a slab with the insulation partially removed for clarity. 
         FIG. 8  is a side view of a firefighting, water carrying truck with an integral refuge for firefighting crew. 
         FIG. 9  is a perspective of the interior layout of the refuge in  FIG. 8 . 
         FIG. 10  is a perspective of a road trailer with a water tank which doubles as a fire refuge with an optional refuge as shown in  FIGS. 8 and 9 . 
         FIG. 11  is a section through the rectangular door shown in the end wall of the dry refuge in  FIG. 10 . 
         FIG. 12  is a perspective of a flap valve controlling water inflow. 
         FIG. 13  is a perspective of a drain valve. 
         FIG. 14  is a diagrammatic side view of the handle for operating the valve of  FIG. 13 . 
         FIG. 15  is a section through a hatch depicted in  FIG. 10 . 
         FIG. 16  is a perspective of a dry refuge which is intended to be carried to a site by helicopter to protect marooned firefighters. 
         FIG. 17  is a plan view of the base of the airborne refuge as shown in  FIG. 16 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Referring now to  FIGS. 1 and 2 , dry refuge  2  is 1800 mmW×2400 mmL×2000 mmH with an arcuate roof  4 , side walls  6  and end walls  8 . A door  10  opens outwards in each end wall  8 . Seats  12  accommodate six persons. 
       FIGS. 2 and 3  show the construction. Outer box shell  14  is made from 1.4 mm stainless steel sheet with a bolt on arcuate roof  4 . The roof has lifting lugs  16 . Inner shell  18  is a rotational moulding. Alternatively shell  18  is a fibreglass reinforced epoxy resin box laid on a mould and later joined to its floor. Brackets  20  bolt to the outer shell and assist placement or anchorage. The floor  22  of the inner shell is bored to receive rows of spacers  24  which lift the inner shell  18  off the floor  26  of the outer shell. A pad  28  of ceramic fibre insulation underlies the inner shell. In a variant, the shells are fixed to a rectangular steel frame which rests on the ground. 
     The inner shell is covered with a blanket  30  of the same ceramic fibre insulation to a sufficient depth to safely thermally insulate the inner shell even if the outer shell is exposed directly to the fire front. The insulation is supplied in rolls and can be laid over the inner shell as shown until the required depth is built up. The density of this fibre is important. Three layers of fibres are preferable, separated by intermediate adhered layers of aluminium foil  32 . The edges of the blankets are butted. The use of three layers allow the joins to be overlaid by the next layer. The fibre face slides over the foil face easily which assists in the cladding stage. 
     Door  10  is 900 mm wide and 1800 mm high and is mounted to open outwards. It is of the same insulated construction as the welds. Insulated duct  34  connects the interior of the inner shell to an insulated box  36  which houses gas bottles containing compressed air. A valve operable from the interior of the inner shell allows occupants an extra air supply. The volume of the inner shell is about 4200 l. Six persons may require 360 l/air per minute. As the percentage of carbon oxide in the air rises respiration rate also rises but is offset by the ingress of bottled air. The aim is to provide a refuge period of 20 minutes with the door closed. A sight glass  38  in the door allow the occupants to see outside and judge when it is safe to emerge. A tube carries an outer low expansion glass lens and an inner plain lens. 
     Refuges of this type of construction allow rises of less than one degree centigrade when exposed to a passing fire front. 
     An alternative construction is described in  FIGS. 4-6 . The refuge has an outer frame  200  with an arched roof made of metal bars  202  and a smaller inner frame  204  also made of metal bars nesting within the outer frame. Lifting lugs  206  allow the unit to be craned. 
     Each end wall  208  has a doorway  210 . Both frames are interconnected by ties  212 . Bending plywood  214  (see  FIG. 11 ) is screwed to the inner frame to form a cabin. Nails are driven through the ply from the interior towards the outer frame. These hold the insulation batts or blankets  230  referred to above. The end walls  208  are likewise sheathed and insulated. 
     The outer frame  200  is then sheathed in stainless steel sheet (not shown) which is rivetted to the bars. An insulated aerial  232  allows radio and phone reception despite the screening imposed by the metal sheet. The doors and door frame edges incorporate the double seal described above. 
     Referring now to  FIG. 7 , in this version the outer frame  200  consists of hoops  240  made of angle iron connected by horizontal tubular ties  242 . Inner frame  204  likewise consists of hoops made of angle iron  244  connected by horizontal tubular ties  246 . The ends of the two nesting frames are welded to inverted steel channel  248  which in turn is welded to rectangular base channel  250 . Concrete slab  252  may be in the garden of a house in a bush fire area. Aluminium bearers  254  support a pair of platforms made of particle board. These are carried through the door and placed on the slab  252 . The rectangular base  250  can be carried by a forklift. 
     Flexible plastic panels  256  are passed through the outer frame and screwed to ties  246  and to the flanges  258  of the hoops  244 . A multi-ply composite of plastic and aluminium sheets allow the inner shell to be curved by bending to allow other methods of fabrication. 
     The end walls are clad in the same way. Sealing tape is applied to the edges. The end walls have an edge flange which overlies the side walls. The seal lies between the wall and the flange. A shelter room  260  for the occupants with a pair of doors results. 
     Stainless steel panels  262  are next offered up to the hoops of the outer frame  200  and drilled to locate fixing sites in the angle iron  240 . The panels are then parked while the cladding ensues. 
     Panels  256  of the shelter room are drilled in a pattern in order to allow roofing nails  264  to be push fitted into the space  266  between the inner and outer frames. A roll of 160 kg/m 3  ceramic fibre (ISOWOOL)  30 A is laid over the panels  256 . A second layer  30 B of the same material increases the thickness followed by a third layer  30 C of 128 kg/m 3  of half the thickness. This produces a 62 mm layer of thermal insulation which entirely occupies space  266 . The nails are pushed outward to pierce the insulation layers. Adhesive applied to the nail head prevents its return. 
     The external faces of the hoops of the outer frame  200  and the ties  242  are covered with strips of sealing tape  268 . The steel panels  262  are then re-offered to the outer frame and attached by rivets  270 . 
     Referring to  FIGS. 8 and 9 , the cab  302  has exterior lights and speakers and a rear section  304  with its own doors  306  and interior seating (not shown) for fire crew. 
     Gap  308  separates the rear section  304  from the water tank  310  and houses shelter  312  and gate  314  giving access to shelter  312 . Into this gap  308  is fitted the cuboid refuge  316  shown in  FIG. 9 . This is 2500 mm long so as to fit within the trucks chassis width and the width is such as to accommodate a door  318  and interior seating  320 . Beneath seating  320  is the vehicle fuel tank  322  and 24v battery system  324 . These receive the same degree of heat insulation as the crew. In some vehicles the gap  308  may be smaller in which case the door  318  is in the end wall. 
     The construction of the refuge itself as described in relation to  FIGS. 1-3  with a fibreglass interior shell, a stainless steel exterior shell and 62 mm of ceramic fibre insulation. 
     Referring now to  FIG. 10 , the refuge is mounted on a trailer  326  having a single pair of wheels and an A-frame tow bar  328  which attaches to the truck via a RINGFEDER® hitch  330 . 
     The main part of the trailer supports a 2500 l water storage tank  332  of the type used by rural property owners where mains water is not available. If a source of bulk water such as a swimming pool is not available, a tank on a trailer can be filled at a pump station and kept for firefighting duty. 
     The dry refuge  316  with walls, roof and floor is insulated with ceramic fibre. Tow bar  328  permits mobile deployment and typically it would have dual use, primarily as a permanent source of hose water, but secondarily as a fireproof refuge for the rural residents. 
     Persons wishing to use the trailer refuge can mount the steps  336  and  338  to open hatches  340  in order to release the tank water through duct  342 . The hatches  340  give access to the operating rod and dump valve shown in  FIGS. 12-14 . 
     The door shown in  FIG. 11  hangs by four hinges  272  from the refuge wall. The door is made from outer and inner panels  274 ,  276  with insulation layers  30 A,  30 B and  30 C between the panels. 
     The doors have the same paired smoke proof seals  54 ,  58 ,  68 ,  70  as used in the tank hatches in  FIG. 15 . A solar panel may trickle charge a battery inside the refuge to provide power for LED lighting and radio communication. 
     Referring now to  FIG. 12 , the incoming port is a double port having two pipes  84  leading from the interior to an external plenum chamber (not shown) outside the outer shell. The pipes terminate in hose fittings inside duct  42  to which fire hoses are attachable. If the hoses dry and burn the hinged flap  86  can be closed by stainless wire line  88  acting on actuating lever  90 . The tank is filled from an external pump. The inner shell is accordingly constructed as a tank and the hatches are operable from inside and outside. 
     In  FIG. 13 , the drain is a flap valve  92  pivoted to the inner shell  18  by hinges  94 . The rise and fall operating rod  96  acts on double bracket  98 . A locking tongue  100  engages a detent  101  extending from the face of the inner shell urged by a rat trap spring. When the rod falls the operating rod  96  is operated from within the interior by manual movement of a first lever  102  (see  FIG. 14 ) pivoted to a fulcrum  104  on the inner shell using handle  106  from outside the unit by operation of a second lever acting on an extension of the first lever  102 . As the rod  96  falls, finger  106  rotates tongue  100  which unlatches from detent  101  against spring tension and further fall pulls flap  92  away from aperture  108 . 
     The hatch construction is shown in  FIG. 15 . The top wall  50  of the refuge has an aperture  52  for each hatch and the edge defining the aperture has a rebate  54  which is surrounded by an upstanding circular flange  56 . The rebate is annular and acts as a seat for a braided resilient seal  58 . Insulation  30  fills the gap between the outer steel shell and the inner polymeric shell. 
     The underside of the inner shell has a pivot  60  which supports hatch swing arm  62 . The hatch is made of a steel pan  64  covered by a convex steel cover  66  with insulation between. The pan has an annular seat  68  for a circular braided seal  70  like seal  58  but softer. Similarly the hatch has a downwardly depended circular flange  72  which engages seal  58 . Thus the flanges establish a labyrinth seal at aperture  52 . 
     Referring now to  FIGS. 16 and 17 , the unit is intended to be airlifted into fire threatened sites. The refuge has metal bearers  350  arranged as a cross. The rest of coil springs  352  which surround steel plunges  354  capped by domes  356 . The refuge is rendered mobile by activating wind down jockey wheels  358  at the ends of the bearers  350 . 
     A stainless steel cuboid box  360  forms the outer shell 1900×1900 mm and 2000 mm high. The box is attached to the bearers via by high tensile bolts  362  which pass through spacers  364 . The outer shell is 1.6 mm 304 stainless steel. One wall has four stainless steel hinges  366  which support the door shown in  FIG. 11 . The same wall contains a flameproof optical viewer  368 . The inner shell is made of fibreglass and the space between the shells is filled with 65 mm of fibre insulation as discussed in previous embodiments. 
     The floor  370  is made of layers of plywood in order to take the weight of the occupants. 
     The four upper corners of the box each have a stainless steel eye fitting  372  for holding angled tubes  374 . These act as guides for two steel cables  376 , each of which is attached to the end of a bearer  350  by a steel shackle  378 . The two cables meet and cross at swivel eye  380  intended to receive the suspension hook of a helicopter. A foam ball  382  in a net is fixed beneath the swivel eye  380  to absorb impact when the eye detaches from the helicopter hook and falls on top of the box. Viewing port  368  allows the occupants to see the surroundings. 
     It is to be understood that the word “comprising” as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word “comprising” does not exclude the addition of other elements. 
     It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications and/or additions are therefore considered to fall within the scope of the invention.