IE83305B1 - Fire retardant doors - Google Patents

Description

Title Fire retardant doors Field of the Invention The invention relates to doors which may be used to restrict the passage of fire and smoke between rooms within a building, and which are known as “fire retardant doors” or “fire resistant doors”, and are herinafter referred to as “fire doors”. The invention also relates to fire door set, which is a term used to described a fire door and related door frames.

Background Art One of the greatest problems associated with fire is the speed at which a fire can move through a building. Many buildings incorporate fire doors so as to slow the spread of fire throughout the building. A properly installed fire door can contain the fire within a specific room, thus allowing people to escape from the danger areas and increase the response time allowable for emergency services to contain the fire. Alternatively a particular room may house important documents/ goods and or dangerous substances. To protect these in the event of a fire, a fire door may be installed. Fire doors are built to specific engineering and architectural specifications and are tested for an hourly rating. In domestic situations most fire doors have an hourly rating of approximately one to two hours.

It is known to construct fire doors from mild steel sheets bonded to a honeycomb mineral fibre core. The known doors are rectangular in section and are designed to fit within a frame of single or double rebate section. Such doors include those described in British Patent appliction GB 2 051 192 A and European patent EP 0 001 828. These steel fire doors are constructed with external seams and welds which are not aesthetically attractive, and are immediately identifiable as a steel door. Furthermore the rigid nature "" 83305 of the seams does not allow the door to flex and expand on the application of heat. Such doors do not offer a high level of fire resistant integrity.

Doors have been developed, for specific industrial situations, which can retain their fire resitant integrity for up to four hours. These doors tend, however, to be very heavy in construction. There is a need within the industry for a fire door of improved rating, i.e. a door that will withstand fire for a longer period of time while at the same time not requiring the heavy construction already known. Any extra time in improved fire integrity is significant for the purposes of insurance companies and underwriters when they are considering the risk involved in insuring valuable documents, components or equipment from smoke/ fire damage.

There is therefore a requirement for a fire door of improved performance which does not incorporate aesthetic or technical disadvantages that are present in existing doors.

Object of the Invention The object of the invention is to provide a fire door, for incorporation within a door frame, with an improved resistance to fire and smoke, and which does not incorporate the features of external seams or welds which identify existing doors as being manufactured from steel.

Summai_'y of the Invention According to a first embodiment the invention provides a door set incorporating a door and a door frame , the door adapted for mounting on and opening out from the door frame, the door comprising two spaced substantially parallel door panels which define between them an inner space, and wherein a) the first panel has a substantially planar portion which extends to form one face of the door, a bottom portion being folded perpendicularly to the planar portion forming a planar bottom edge, and having an inner part which extends upwardly defining an upwardly extending flange, a top portion of the panel being folded perpendicularly about a comer so as to form a horizontal planar top edge, and having an end part of portion being folded perpendicularly and downwardly about corner so as to form a vertical flange, and b) the second panel has a substantially planar portion which extends to form a second face of the door, a lower part of the portion being folded about comer and extending upwardly before being folded about itself in substantially inverted U-shape at comer so as to form a receiver about flange, a top portion of portion being folded perpendicularly about corner so as to form a horizontal top planar surface which folds perpendicularly downwardly at corner so as to form a downwardly directing planar surface which projects past corner before folding back upon itself to form a predominantly U-shaped structure; and wherein the folding and engagement of the edge portions of the panels with each other forms a non-static, non-rigidjoint, the folding of planar portions about corner and planar portion about corner and corner forms a rebate, the shape of which is maintained due to the tension resulting from the folding of the two panels, the rebate extending around at least three edges of the door, such that when the door is closed an inner portion of the door is enclosed within the door frame and an outer portion of the door covers thejoint on at least three sides between the door and the door frame.

The frame may be inserted into an opening on a supporting structure and includes a means to plumb the door frame on two axes, said means optionally comprising a jacking bolt, which can be altered so as to vary the tension on the door frame.

The folding and engagement of edge portions of the panels with each other provides a double seam which allows the door to expand and be flexible with increased heating. 3A ln an alternative embodiment the invention provides a door set incorporating a door and a door frame, the door adapted for mounting on and opening out from the door frame, the door comprising two spaced substantially parallel door panels which define between them an inner space, and wherein a) the first panel has a substantially planar portion which folds perpendicularly about a comer so as to form a top planar surface which folds about comer so as to form a planar surface projecting downwardly and about corner so as to form a receiver, b) the second sheet has atop portion being folded perpendicularly about corner so as to form a horizontal top planar surface, which is folded perpendicularly downwardly at comer to form a downwardly directing planar surface 6 extending past corner so as to form a flange which is contained within the receiver; and wherein the folding and engagement of the edge portions of the panels with each other forms a non—static, non—rigid joint, the folding of planar portions about corner and planar portion about comer and comer forms a rebate, the shape of which is maintained due to the tension resulting from the folding of the two panels, the rebate extending around at least three edges of the door, such that when the door is closed an inner portion of the door is enclosed within the door frame and an outer portion of the door covers the joint on at least three sides between the door and the door frame.

Preferably, the inner space of the door contains an insulation core.

Preferably, when the door is closed within the door frame the rebate of the door abuts the door frame, and the inner portion of the door abuts a rubber seal which is provided within a lip of the frame.

Brief Description of the Drawings Figure 1 shows a View from the front of a door, in accordance with the invention, Figure 2 is an isometric elevation of the door, as shown in Figure 1, Figure 3 is a section along line B-B, showing one embodiment of the top and bottom seam, Figure 4 is a section along line B-B, showing a second embodiment of the top seam, Figure 5 is a section along line A-A, showing a side seam and lip detail, Figure 6a shows a jacking bolt, Figure 6b is a view along line A-A’ of Figure 6a, Figure 6b is a section through line A-A’ of Figure 6a, Figure 7 shows a door according to the invention, mounted on a door frame, Figure 8 is a section through line B-B of Figure 7, and Figure 9 is a section through line A-A of Figure 7 Figure 10 is a perspective view of a comer of a door, with a portion cut away, so as to show the internal structure of the door, Figure 11 is the same perspective view shown in Figure 10, but with no portion cut away, Figure 12 is a view from the front of a modification of the fire door, with a portion cut away so as to show the internal structure.

Detailed Description of the Drawings Figures 1 and 2 show a fire-door l in accordance with the invention. The door 1 is substantially rectangnilar in shape, being substantially shorter in dimension across the top 3 than the side 4. A seamed lip or rebate 2 extends substantially along the top 3 and side 4 of the door 1. The door has a back 20 and a front 21, which correspond to the inner and outer portions of the door when the door is fitted to a door frame.

Figure 3 is a section along line B-B of Figure 1, showing the structure of the door in vertical section.The door is preferably made from two rectangular cold rolled mild steel panels or sheets 7,8 which are bent and folded together so as to form an outer casing which contains an inner insulating core, suitably made from a mineral wool core, and which is bonded to the outer sheets. The bonding may be achieved using an adhesive such as that manufactured by the Carborundum Company, and sold under the trade name “Fraxbond 715”.

The sheet 7 has a substantially planar portion 60 which extends to form one face of the door. A bottom portion 61 of the sheet 7 is folded perpendicularly to the portion 60 so as to form a planar bottom edge 12 of the door. An inner part 14 of the portion 61 is turned upwards at right angles to define a upwardly extending vertical flange 63.

A top portion 62 of the sheet 7 is folded perpendicularly about comer 10 so as to form a horizontal planar top edge 5. An end part of portion 62 is folded perpendicularly and downwardly about comer 9 so as to form a vertical flange 64.

The sheet 8 also has a substantially planar portion 65 which extends to form a second face of the door. A lower part of the portion 65 is folded about corner 13 and extends upwardly before it is folded about itself, in substantially inverted U-shape, at corner 66 so as to form a receiver 67 about flange 63.

A top portion 68 of portion 65 is folded perpendicularly about comer 69 so as to form a horizontal top planar surface 70. This then folds perpendicularly downwardly at comer 1 1 to form a downwardly directing planar surface 6, which projects passed comer before folding back upon itself to form a predominately U shaped structure 71.

Although surfaces 5 and 6 abut at comer 9 there is no physical bond or connection between the two surfaces at this comer, and the abutment is a non—static, non-rigid joint.

Due to the folding of planar portion 60 about corner 10 and planar portion 65 about comers 69 and 11 a step like structure or rebate 2 is formed. The tension that results from the folding of sheet 7 and sheet 8 maintains the shape of this rebate 2, even though there is no physical bond between the two sheets in this region. The absence of a physical join allows the sheets 7 and 8 to move relative to each other while maintaining the same outline shape. On heating, the door may expand and this arrangement allows for the expansion and also allows the door to be a flexible structure, reducing the possibility of warping or breaking. The front and back of the door incorporate the top and bottom as illustrated in figure 3 Figure 4 shows an alternative arrangement for the formation of the rebate 2 than that illustrated in Figure 3. In this embodiment, the formation of the bottom edge 12 is the same as described with reference to Figure 3 and like reference numerals denote like parts. The rebate 2 formed in this embodiment is the same as that described in Figure 3, the difference is in the formation of the rebate. The planar portion 60 still folds perpendicularly about corner 10 so as to form top planar surface 5 which folds about comer 9. However, whereas in Figure 3 a downwardly directing vertical flange 63 was formed, in Figure 4 a planar surface 72 is formed, which extends vertically downwardly to comer 73. It then folds back upon itself, so as to form a receiver 16. Whereas in the first embodiment planar surface 6 folded back upon itself at comer 9, in this embodiment it extends vertically past comer 9 so as to form a flange 74 which is contained within the receiver 16. There is no physical bond formed between the sheet 7 and sheet 8.

Figure 5 is a view taken from the right hand side along line A-A, shown in Figure 1. The view from left hand side is similar. The back 20, front 21 and side 4 of the door 1 are shown. The back 20 and front 21 of the door are made from pieces of sheet metal 7, 8 respectively, and have planar portions 60,65. Planar portion 60 folds perpendicularly and inwardly about corner 75 so as to form a side planar portion 76. At corner 77 this then folds perpendicularly and inwardly so as to form an inner planar portion 78 which folds about itself at comer 26 so as to form a predominately U—shaped structure 79. In a similar manner planar portion 65 folds perpendicularly about corners 80 to form a planar portion 17 and then about comers 81 and 27 so as to form a U shaped receiver 82. The intersection of U-shaped receivers 79,82 maintains a flexible join between the sheets 7,8.

Research into the operation of fire doors has shown that the performance of a fire door is very much dependant on the size tolerance of the structural ope in which the door is fitted. When hanging the door on the door frame it is necessary to use the hinges to adjust the distance between the door and the door frame. However, a common problem in every day construction is the occurrence of irregularities that may occur in the construction of a uniform ope to take the door frame.

Figure 6 shows a jacking bolt 30, which may be used with the fire door of the present invention to compensate for any irregularities which occur in structual openings.

The bolt arrangement comprises a nut 31 and a locking bolt 33, which are used in conjunction with each other to ensure that the frame may be plumbed/levelled in the structural ope. The nut 31 is attached to the door frame 40, by weldin g or some other suitable manner. The bolt 33 is threaded through the nut 31, such that the head 32 of the bolt on the side of the frame facing the structural opening (not shown). Figmre 6b is a view through the bolt arrangement, along the line A’-A, shown in figure 6a. Figure 6c is a cross section through the bolt arrangement 30. The jacking bolt has a hollow central bore 34 which allows for a primary fixing screw (not shown) to pass through, and into the supporting structure. In use the bolt 33 is threaded through the nut, until the head 32 abuts the supporting structure. This allows for the frame to be securely jacked between itself and the supporting structure. Each door preferably has three jacking bolts supplied on each vertical side of the frame and one on the horizontal head of the frame. By using the fixing screw correctly, it is possible to secure the frame properly through the central bore of the bolt, using the fixing screw. The varying of tension on the fixing screw allows the frame to be adjusted, so as to compensate for any irregularities in the structural ope.

Figure 7 shows a fire door 1 according to the invention mounted in a door frame 40. The door has a handle 41 and three hinges 42. The hinges allow the door to be hung on the door frame preferably using a three axis: up/down, in/out, back/forward, hinging arrangement such as that manufactured by the Simonswerk company of Germany. The handle is preferably made from east aluminium, such as those supplied by the Hoppe company. The locking arrangement ( not shown) is preferably manufactured from a phosphate coated mild steel, an example of which is the “Ferco 13774” supplied by the Hoppe company.

As a result of the method hereinbefore described to form the outer layer of the door when the door is closed, i.e. intersecting with the frame, a mechanical seal is formed. When the door is in a closed position there are no visible door seams or joints.

Figure 8 shows the door 1, a supporting structure 50 and the door frame 40. The frame is attached to the structure by drilling a hole in the structure. The drill bit (not shown) passes through a jacking bolt 30, and a fixing screw (not shown) is fitted into the hole formed by the drill. This secures the frame 40 to the structure. The jacking bolt is attached to the frame by means of the nut on the jacking bolt, by welding or some similar manner.

Within the door 1 is provided a core 51, preferably made from a fire retardant material such as a rock fibre insulation quilt provided by the Rockwool company under their reference “Rockwool RW3”. Jacking bolts are provided in the head and sides of the door frame. When the door is closed, as is seen in this figure, the top rebate 2 of the door 1 intersects with the frame 40. The back 20 of the door 1 abuts a gasket 52 that is provided within a lip 53 of the frame 40. At the foot of the door the door 1 rests against a saddle board 54, which is also provided with a gasket 55. The gasket 52, 55 is preferably manufactured from a PVC resin with plasticizer, such as that supplied by Medinagen Gesselchaft Mbh., of Germany. The saddle board 54 and frame 40 are preferably manufactured from galvinised steel. By adjusting the bolt it is possible to vary the tension on the door frame, thereby altering the distance between the structural ope and the frame, so that when the door is in a closed position the rebate 2 intersects closely with the frame 40, the back 20 abuts the gasket 52, 55 firmly, and there is no opening between the frame and the supporting ope.

Figure 9 shows a section along line A-A of Figure 7. In a similar manner to that described with reference to the head of the door, the rebate 25 of the door intersects the door frame 40 and the back 20 of the door abuts a rubber seal 52, which is provided within a lip 53 of the frame 40. The level of interaction between the ope and frame is adjusted using the jacking bolts 30.

In the occurrence of a fire the sheets 7,8 that make up the outer panel of door 1 will expand with increased heat, thus improving the mechanical seal between the door and frame. Due to the non rigid nature of the interaction between the front and back sheets that make up the door, there is room for this expansion and the door will not shatter or break. The rubber seal or gaskets 52, 55 will also melt and as such prevent smoke from passing from one side of the door to the other. The provision of a double seal creates a smaller gap than is provided for in conventional fire doors.

Figures 10 and 11 show a preferred corner arrangement. Figure 10 is a section through a corner piece of the door previously described with reference to Figures 3 and 5, showing the intersection of the front and back 7, 8 of the door. Figure 11 is a perspective view of the comer piece of figure 10, but not cut away. It shows the intersection between the two rebates 2, 25 and the formation of a step between sheets 7,8.

Figure 12 is a view from the front of a further modification to the door hereinbefore described. A door brace 83 is incorporated within the door frame to strengthen the door. The brace is preferably positioned within the outer sheets, such that the brace is only visible if the outer sheet 8 of the door are cut away. Preferably comprising two horizontal struts 84, 85 which traverse the width of the door and are positioned approximately one sixth the distance from the top and bottom of the door respectively. These struts are preferably linked by two longer struts 86, 87 which are linked to opposite ends of upper and lower horizontal struts such that the two longer struts cross over in the middle of the door. The core 51 may optionally be bonded to the brace. This brace is preferably manufactured from a material such as zintec steel.

Fire Testing Results A fire door as described hereinbefore was tested at the Warrington Fire Research Facility, in accordance with Clause 8 of the British Standard 476 Part 2: 1987. The doorset had overall nominal dimensions of 2165 mm high by 1030 mm wide, and incorporated a door leaf of ovreall dimensions 2120 mm high by 980 mm wide by 51 mm thick. The doorset was mounted within a masonry wall construction such that the leaf opened away from the furnace, and the performance of the door was judged against the performance criteria specified in Clause 8 of BS 476 Part 22: 1987. The results obtained were as follows: Integrity: 296 minutes Failure of the door at 296 minutes was deemed attributable to the fact that the concrete lintel above the door set cracked during the test causing radiant heat to be directed at the door closer which in turn flamed, causing the doorset to fail the integrity criteria through sustained flaming. The fire report concluded that if the lintel had not exhibited cracking, the expected performance of the doorset would have been in excess of minutes. The test was discontinued after a period of 300 minutes.

In a similar air leakage text utilising the general principle of BS476:Part 31, Section 31.1.1983 wherein ‘A fire door required to resist the passage of smoke at ambient temperature conditions should, when tested in accordance with BS 476:Section 31.1 with the threshold taped and subjected to a pressure of 25 Pa, have a leakage not exceeding 3 m3/m/h’, the results obtained were as follows: Rig under positive presure (25 Pa) : 1.18 m3/m/h Rig under negative pressure (25 Pa) : 1.08m3/m/h

Claims (7)

Claims

1. A door set incorporating a door (1) and a door frame (46), the door adapted for mounting on and opening out from the door frame (46), the door comprising two spaced substantially parallel door panels (7, 8) which define between them an inner space, and wherein a) the first panel (7) has a substantially planar portion (60) which extends to form one face of the door, a bottom portion (61) being folded perpendicularly to the planar portion (60) forming a planar bottom edge (12), and having an inner part (14) which extends upwardly defining an upwardly extending flange (63), atop portion (62) of the panel (7) being folded perpendicularly about a comer (10) so as to form a horizontal planar top edge (5), and having an end part of portion (62) being folded perpendicularly and downwardly about corner (9) so as to form a vertical flange (64), and b) the second panel (8) has a substantially planar portion (65) which extends to form a second face of the door, a lower part of the portion (65) being folded about corner (13) and extending upwardly before being folded about itself in substantially inverted U-shape at corner (66) so as to form a receiver (67) about flange (63), a top portion (68) of portion (65) being folded perpendicularly about corner (69) so as to form a horizontal top planar surface (70) which folds perpendicularly downwardly at corner (11) so as to form a downwardly directing planar surface (6) which projects past corner (9) before folding back upon itself to form a predominantly U—shaped structure (71); and wherein the folding and engagement of the edge portions of the panels with each other forms a non-static, non-rigid joint, the folding of planar portions (60) about corner (10) and planar portion (65) about comer (69) and corner (1 1) forms a rebate (2), the shape of which is maintained due to the tension resulting from the folding of the two panels (7, 8), the rebate extending around at least three edges of the door, such that when the door is closed an inner portion of the door (1) is enclosed within the door frame (46) and an outer portion of the door covers the joint on at least three sides between the door and the door frame.

2. The door set as claimed in claim 1, wherein the frame is inserted into an opening on a supporting structure and includes a means (30) to plumb the door frame on two axes, said means optionally comprising a jacking bolt (32, 33), which can be altered so as to vary the tension on the door frame.

. The door set as claimed in any preceding claim wherein the folding and engagement of edge portions of the panels with each other provides a double seam which allows the door to expand and be flexible with increased heating.

. A door set incorporating a door (1) and a door frame (46), the door adapted for mounting on and opening out from the door frame (46), the door comprising two spaced substantially parallel door panels (7, 8) which define between them an inner space, and wherein a) the first panel (7) has a substantially planar portion (60) which folds perpendicularly about a corner (10) so as to form a top planar surface (5) which folds about corner (9) so as to form a planar surface (72) projecting downwardly and about comer (73) so as to form a receiver (16), b) the second sheet has a top portion (68) being folded perpendicularly about corner (69) so as to form a horizontal top planar surface (70), which is folded perpendicularly downwardly at corner (11) to form a downwardly directing planar surface 6 extending past corner (9) so as to form a flange (74) which is contained within the receiver (16); and wherein the folding and engagement of the edge portions of the panels with each other forms a non-static, non-rigid joint, the folding of planar portions (60) about corner (10) and planar portion (65) about corner (69) and corner (11) forms a rebate (2), the shape of which is maintained due to the tension resulting from the folding of the two panels (7, 8), the rebate extending around at least three edges of the door, such that when the door is closed an inner portion of the door (1) is enclosed within the door frame (46) and an outer portion of the door covers the joint on at least three sides between the door and the door frame.

5. A door set as claimed in any preceding claim wherein the inner space of the door contains an insulation core.

6. A door set as claimed in any of claims 2 to 5 wherein when the door is closed within the door frame the rebate of the door abuts the door frame, and an inner portion of the door abuts a rubber seal which is provided within a lip of the frame.

7. A door set substantially as hereinbefore described with reference to, and or as illustrated in