GB1600236A

GB1600236A - Fire resistant structures

Info

Publication number: GB1600236A
Application number: GB3002576A
Authority: GB
Original assignee: Ameeca Ltd
Current assignee: Ameeca Ltd
Priority date: 1977-10-07
Filing date: 1977-10-07
Publication date: 1981-10-14

Description

(54) IMPROVEMENTS IN OR RELATING TO FIRE RESISTANT STRUCTURES (71) We, AMEECO LIMITED, a British Company of Clock House, Laindon Centre, Basildon, Essex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to fire resistant enclosures such as cupboards, cabinets or lidded-containers in which highly inflammable liquids may be kept or stored.

In the United Kingdom and in many other countries, stringent regulations have to be met by structures which are to be used to store highly inflammable liquids. The main requirement of such structures is that they be free from collapse and resistant to the passage of flame in the event of a fire, either internal or external, for a period of, for instance, half an hour. One way of achieving this object is to make the body of the structure and its door or lid from metal thick enough to comply with the regulations but this makes the structure prohibitively expensive and unduly heavy.

According to the invention there is provided a fire-resistant enclosure comprising: a wall or walls having a relatively thin sheet metal (as herein defined) outer skin and an inner skin spaced therefrom; an access opening for gaining access to the interior of the enclosure; a door movable between an open position in which access may be had to the interior of the enclosure via the access opening and a closed position in which the door closes the access opening; latch means having a retracted position in which the door can be moved out of the closed position and an extended position in which the door is held in the closed position; and interlock means automatically operable when the door is in any position other than its closed position to prevent the latch means from being moved from the retracted position to the extended position.

The design of the latch means eliminates the risk of sparks being produced during closing of the door due to some part of the latch striking the adjacent part of the enclosure.

Preferably the enclosure includes a double skinned top and bottom whose outer skin is made of a relatively thin sheet metal, the inner skin being spaced therefrom although an enclosure of the invention could provide no bottom, top or back or any combination thereof so that it could be fitted into a space already providing a fire-resistant top, bottom or back for the enclosure.

Conveniently, the inner skin of the double skinned bottom is attached to the or each wall to provide a leak proof tray in the bottom of the enclosure, the outer wall being of a relatively thin sheet metal and secured to the or each outer wall of the enclosure.

Preferably the or each inner skin is spaced from its adjacent outer skin to leave an air gap therebetween, conveniently between 1" and 3", but this space may be filled with a heat-resistant material such as Vermiculite, Mineral Wool or Asbestos Plaster if desired.

Alternatively, or additionally a reflective interlayer material may be used.

The enclosure may be provided with one or more doors, each of which is preferably double skinned with a thin sheet metal outer skin and an inner skin spaced therefrom.

In a preferred embodiment the or each door has a self-closing mechanism associated therewith whereby the or each door is automatically closed within a predetermined period of time after it has been opened.

Throughout the specification and claims, the expression "relatively thin sheet metal" is intended to be restricted to sheet metal of a thickness in the range between 1 20 Standard Wire Gauge, i.e. between 0.064" and 0.036" (0.75 mm- 1.5 mm).

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a perspective view of a preferred enclosure of the invention, in this case a cabinet; Figure 2 is a plan view showing the door closing mechanism for the cabinet of Figure 1; Figure 3 shows the door locking mechanism for the cabinet of Figure 1; and Figure 4 shows the door latch retaining and releasing mechanism of the cabinet of Figure 1.

Referring to the drawings, there is shown a fire resistant enclosure or cabinet 1 comprising a body 2, a shelf 3 and securable closure means in the form of a door 4. The door includes a self closing and restraining mechanism 5, illustrated in more detail in Figure 2, which is housed, when the door is closed, in a separate space 6 at the top of the cabinet, this space 6 being separated from the interior of the cabinet by a wall or partition 7 which may be fire resistant. The door 4 is provided with a locking mechanism 8 illustrated in more detail in Figures 3 and 4.

All the walls of the cabinet are double skinned. As can be seen more clearly from Figure 2, each wall comprises an outer skin 2a to the inner face of which is attached an inner skin 2b by means of supports 2c.

Conveniently, the supports are spot welded to both the inner and outer skins, the joints between the abutting edges of each inner skin also being welded together to render the joints flame proof.

An air space (conveniently about 1+") is left between the inner and outer skins 2a, 2b although the exact spacing depends on the dimensions of the cabinet. If desired the space between the wall skins may be filled with Vermiculite, Mineral Wool, Asbestos Plaster or some other heat resistant material which may be reflective. An advantage of the double skinned cabinet construction is that not only is it fire resistant but its strength is also increased without unduly adding to its overall weight.

The outer and inner skins in the illustrated cabinet as well as the partition 7 and tray 2d are all made of 1620 gauge (SWG) mild steel sheet. However, if desired the inner skins can be made of asbestos sheets for instance attached in a convenient manner to the outer skin in spaced relationship therewith.

The top of the cabinet is double skinned by virtue of the partition 7 whereas the bottom is rendered double.skinned by virtue of tray 2d having upstanding side walls 2e which are attached, preferably by welding, to the inner skins 2b so that the tray 2d is spaced above the outer bottom skin of the cabinet.

This is an important feature of the cabinet as the tray 2d renders the bottom of the cabinet leak proof so that if highly inflammable liquids are accidentally upset or spilled in the cabinet, they cannot leak out.

Referring now to Figure 2 there is shown the door closing and restraining arrangement 5 shown in Figure 1. As can be seen, this comprises a damper 8, one end of which is pivotally attached at 9 to one end of a flange 11 on the door 4, the other end being pivotally secured to the cabinet at 10. A spring 13 is also attached at 12 to the flange 11, the other end being attached at 14 to the cabinet, the purpose of the spring being to normally bias the door to its closed position so that it is closed automatically after being opened. A strut 15 with an upstanding foot 15' is slidable in guide 16 and is also attached to the door 4 to act as a stop to limit the opening of the door 4 when foot 15' abuts guide 16.

Under the action of the spring 13, the door is automatically closed, the speed of closing of the door being restricted by the damper 8 which comprises a piston working in a cylinder with fluid on either side of the piston which has a valve within it to permit the fluid to flow freely from the outer to the inner end of the cylinder but restricts the flow in the opposite direction. Thus there is no interference with the opening of the door but sudden closure is prevented. In fact the fluid transfer valve could be adjustable such that the time taken for the door to travel from fully open to closed can be varied from a few seconds to approximately two minutes. The minimum time would be sufficient to prevent slamming of the door and, with it, the risk of injury to a users hands.The maximum time would be sufficient to allow access for placing or removing any item which may have to be stored in the cabinet but would not prevent automatic closure of the door.

If desired, the door closing arrangement 5 can be operable to normally keep the door open at all times, the arrangement 5 including a fusible link (not shown) which melts when a predetermined threshold temperature is reached to permit automatic closing of the door.

The latch mechanism which secures the door is designed to avoid any possibility of sparks being generated during closing of the door is illustrated in Figures 3 and 4 and comprises a pair of bolts or levers 17, 18 pivotally attached to a pivoted member 20.

The levers 17, 18 are slidable under the action of biassing means in the form of spring 19 in respective guides 17', 18' attached to the front skin of the door 4, nose portions 21, 22 being movable out of the interior of the door through slots 21a therein into slots 21b in the inner skin of the top of the cabinet to effect locking of the door.

Locking and unlocking of the door is achieved as illustrated in Figure 3. It will be appreciated that although the guides 17' and 18' are shown in Figure 4 as attached to the front (outer) skin of the door, they could be attached to any other suitable part of the door.

As already mentioned, the latch mechanism also includes an anti-spark device which will now be described with reference to Figure 4. The spring 19 is offset to one side so that when the lever 18 is in its unlocked position (illustrated in dotted line) it is inside the door 4 and pulled to one side of the slot 21a. A pin 26 is slidably mounted in a bush 27 mounted on the inside skin of the door 4, its end 30 co-operating with an abutment surface in the form of head 35 of bolt 28 supported from bracket 29 attached to the underside of the inner skin of the top wall of the cabinet when the door is closed to deflect the lever 18 from its closed position within the door to a position where it can slide out of the slot 21 a under the action of the spring 19 to engage in slot 21b in the cabinet partition 7.It will be seen therefore that with this arrangement because the levers 17, 18 are withdrawn completely within the double skinned door 4 until moved to their locked position, there can be no risk of the nose portions 21, 22 coming into sliding or glancing contact with the cabinet during closing so the risk of spark generation is substantially reduced. As can be seen from Figure 4, the position of the head 35 of the bolt 28 relative to the door 4 is adjustable by screwing it into or out of captive nut 31 secured to the bracket 29, a lock nut 32 fixing the selected position.

Other features of the illustrated cabinet which contribute to its suitability for storing highly inflammable liquids are the vent openings 41, 42 which are each fitted with flash arrester gauzes.

An earthing point 43 is also provided so that the cabinet may be earthed by the attachement of a suitable cable (not shown).

A drain plug (not shown) may also be provided in the bottom of the cabinet if desired.

It will be appreciated that although we have described a cabinet enclosure to illustrate the features of the invention the enclosure of the invention could equally well be a cupboard with double doors or containers provided with a lid.

WHAT WE CLAIM IS: 1. A fire resistant enclosure comprising: a wall or walls having a relatively thin sheet metal (as herein defined) outer skin and an inner skin spaced therefrom; an access opening for gaining access to the interior of the enclosure; a door movable between an open position in which access may be had to the interior of the enclosure via the access opening and a closed position in which the door closes the access opening; latch means having a retracted position in which the door can be moved out of the closed position and an extended position in which the door is held in the closed position; and interlock means automatically operable when-the door is in any position other than its closed position to prevent the latch means from being moved from the retracted position to the extended position.

2. An enclosure as claimed in claim 1 wherein the door is a double skinned door, the outer skin of which is made of said relatively thin sheet metal and spaced from the inner skin.

3. An enclosure as claimed in claim 1 or claim 2 wherein the door has a self-closing mechanism associated therewith whereby the door is automatically closed within a predetermined period of time after it has been opened.

4. An enclosure as claimed in any preceding claim wherein the latch means comprises a bolt mounted on the door and which, in the extended position, is located in aligned apertures on the enclosure and on the door, the bolt being deflectably mounted relative to its associated door aperture; and wherein the interlock means comprises means biasing the bolt out of axis alignment with its associated door aperture, and release means engageable with the bolt when the door is closed to deflect the bolt into a position in which it is axially aligned with its associated door aperture so that the bolt may be slid into its associated door and enclosure apertures to secure the door.

5. An enclosure as claimed in claim 4 wherein the biasing means comprises a spring.

6. An enclosure as claimed in claim 4 or claim 5 wherein a further bolt is provided connected to the first mentioned bolt so as to be operable simultaneously therewith, one of said bolts being locatable in an associated aperture adjacent the top of the door and the other being locatable in an associated aperture adjacent the bottom of the door.

7. An enclosure as claimed in any of claims 4 to 6 wherein the release means is adjustable to vary the degree of deflection of the bolt as the door is closed.

8. An enclosure as claimed in any of claims 4 to 7 wherein the release means comprises a pin slidably mounted on the door, one end of which engages an abutment surface on the enclosure when the door is closed and the other end of which engages the bolt to deflect it into alignment with its associated door aperture.

9. A fire resistant enclosure, substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. appreciated that although the guides 17' and 18' are shown in Figure 4 as attached to the front (outer) skin of the door, they could be attached to any other suitable part of the door. As already mentioned, the latch mechanism also includes an anti-spark device which will now be described with reference to Figure 4. The spring 19 is offset to one side so that when the lever 18 is in its unlocked position (illustrated in dotted line) it is inside the door 4 and pulled to one side of the slot 21a. A pin 26 is slidably mounted in a bush 27 mounted on the inside skin of the door 4, its end 30 co-operating with an abutment surface in the form of head 35 of bolt 28 supported from bracket 29 attached to the underside of the inner skin of the top wall of the cabinet when the door is closed to deflect the lever 18 from its closed position within the door to a position where it can slide out of the slot 21 a under the action of the spring 19 to engage in slot 21b in the cabinet partition 7.It will be seen therefore that with this arrangement because the levers 17, 18 are withdrawn completely within the double skinned door 4 until moved to their locked position, there can be no risk of the nose portions 21, 22 coming into sliding or glancing contact with the cabinet during closing so the risk of spark generation is substantially reduced. As can be seen from Figure 4, the position of the head 35 of the bolt 28 relative to the door 4 is adjustable by screwing it into or out of captive nut 31 secured to the bracket 29, a lock nut 32 fixing the selected position. Other features of the illustrated cabinet which contribute to its suitability for storing highly inflammable liquids are the vent openings 41, 42 which are each fitted with flash arrester gauzes. An earthing point 43 is also provided so that the cabinet may be earthed by the attachement of a suitable cable (not shown). A drain plug (not shown) may also be provided in the bottom of the cabinet if desired. It will be appreciated that although we have described a cabinet enclosure to illustrate the features of the invention the enclosure of the invention could equally well be a cupboard with double doors or containers provided with a lid. WHAT WE CLAIM IS:

1. A fire resistant enclosure comprising: a wall or walls having a relatively thin sheet metal (as herein defined) outer skin and an inner skin spaced therefrom; an access opening for gaining access to the interior of the enclosure; a door movable between an open position in which access may be had to the interior of the enclosure via the access opening and a closed position in which the door closes the access opening; latch means having a retracted position in which the door can be moved out of the closed position and an extended position in which the door is held in the closed position; and interlock means automatically operable when-the door is in any position other than its closed position to prevent the latch means from being moved from the retracted position to the extended position.