IE57191B1 - Fire door - Google Patents

Abstract

The fire door includes an internal core and an internal surrounding framework of fibreboard replacing the conventional hardwood frame with an economical and consistent medium. Two stiles and two rails, of laminated fibreboard, end sections facing the planar surfaces of the door so as to be more resistant to fire, make up the framework. The core comprises three sheets of chipboard, and is faced with plywood.

Description

The present invention relates to fire doors· It is known to inake fire doors in which the door panel comprises one or more sheets of chipboard.

Chipboard is a satisfactory fire retardant· Chipboard cannot, however, retain the screws of door hinges for jt' example. Furthermore, the appearance of chipboard is generally undesirable. Accordingly it has been the practice to surround the edge of the chipboard sheets by a hardwood frame to which may be fitted any hinges or other necessary attachments, and which give the door a more pleasing appearance. The faces of the chipboard sheets are finished in plywood to improve the appearance of the door.

A disadvantage with the above described construction of door is that hardwood is very expensive.

A further disadvantage with using hardwood is that hardwood is not of a uniform consistent quality and each individual door containing hardwood would react differently in a fire.

It is an object of the present invention to provide a fire door which is economical to manufacture and effective in use.

The invention provides a fire door including an t fr internal core and an internal supporting framework surrounding said internal core, the internal supporting framework comprising at least two vertical stiles and two horizontal rails of elongate members of fibreboard, the outer face of each of said stiles and rails being covered and protected by an elongate hardwood member, whereby the least fire resistant faces of the elongate fibreboard members are protected by the hardwood members and the overall fire-rating of the door is enhanced.

Conveniently, the elongate members of fibreboard of the 10 vertical stiles comprise at least two elongate fibreboard elements laminated together.

Preferably, the fibreboard is a medium density fibreboard.

Advantageously, a strip of intumescent material is provided between at least one elongate hardwood member and a 15 juxtaposed elongate fibreboard member.

The invention will now be described more particularly with reference to the accompanying drawings which show, by way of example only, one embodiment of a fire door according to the invention. In the drawings; Figure 1 is a front elevational view of a double fire door; Figure 2 is a sectional plan view of II-II of Figure 1; and Figure 3 is a sectional elevation view on III-III of 25 Figure 1.

Referring to Figure 1, the fire door comprises a double door la, lb mounted by means of hinges 2a, 2b - 3 anti floor springs 3a, 3b in a doorway frame 4.

Figure 2 shows a doorway frame jamb 4a and doorway saddle 4b underneath the doors la and lb.

Included on the door la is a hardwood edging lip 5a facing the doorway frame jamb 4a, the lip consisting of cambered a Sapele hardwood having a maximum thickness of 10mm. Next to the lip 5a is a concealed strip of intumscent material 21 after which is a stile 16 comprising a pair of elongate medium density fibreboard elements 6a laminated together paving cross sectional dimensions of 43 mm by 50. mm and an approximate density of 720 kg per cubic metre· The core 7 of the door comprises three sheets of chipboard 7a, 7b and 7c which are 18 mm, 12 mm and 18 mm in thickness respectively, laminated together by glue. Stile 26, comprising a further pair of elongate medium density fibreboard elements 6b laminated together, faces the other door lb of the double door. The face of the outer element 6b is covered by a hardwood lip 5b facing the edge of the door lb. A strip 8a of intumescent material is disposed in a groove in the lip 5b, and a pair of strips 8c are provided on the corresponding lip of the door lb.

The function of the strips of the intumescent material 21 is to expand when heated by a fire and thereby seal the space adjacent the strip. A suitable intumescent material is the one sold under the trade mark PALOSOL 100 P. f V I t 25 / Figure 3 illustrates the horizontal member 4c of the door support frame 4, intumescent strip 8b, horizontal rail 6c and the core 7 of the door. Also shown is a hardwood rail 10 which protects the face of the horizontal rail 6c manufactured from medium density fibreboard.

A hardwood protective rail member is also provided along the bottom edge of the door la. Thus it will be appreciated that the hardwood used in the fire door described consists of one rail 10 along the top edge of the door and a further rail along the bottom edge of the door and a lip 5a,5b along each of the two vertical edges. The reduced use of expensive hardwood makes the doors much less expensive.

Fibreboard when being manufactured is made up of layers which are then compressed to produce a sheet of material. The face of the fibreboard produced is coplanar with the layers and will burn very easily when exposed to fire as the layers simply peel off when burned. The end section and side section of a length of fibreboard are considerably more resistant to fire than the face. Therefore, when the face of a length of fibreboard is protected as in the described embodiment, the disadvantage of the material is overcome while allowing the internal frame of the door to be manufactured from a material which is a fraction of the cost of hardwood, yet can take - 5 screws, locks and hinges, supports the internal core of . the door and is not susceptible to warping.

It will also be. noted that the vertical stiles 16 and 26 are laminiated. Such a construction provides a stile of greater density than a stile produced from one Λ length of medium density fibreboard.

To illustrate the effectiveness of a fire door according to the inventiion, reference will now be made to a fire resistance test performed by the Timber Research and Development Association (TRADA) of High Wycombe, England.

The test was performed to determine the fire resistance performance of a double leaf, single action doorset with overpanel when tested in accordance with the conditions specified in British Standard BS476: Part 8: 1972. The doorset was mounted in a plasterboard clad, timber stud partition forming one side of the test furnace. It was hung to open towards the furnace as this was considered the weaker direction.

The procedures adopted during the test followed the resolutions of the Fire Test Study Group, where appropriate. These resolutions provide the basis of common agreements between the consultant fire test laboratories in the UK on areas of the test specification which may be ambiguous or open to interpretation. t V The doorsets were manufctured in accordance with the invention. The frame, ironmongery and intumeecent material were supplied and fitted by TRADA.

Each leaf was of-overall size 2095mm high by “ 5 920mm wide by 57mm thick and consisted of a high density chipboard core with a medium density fibreboard framing j faced with mahogany veneered Lauan plywood and lipped on all edges with Utile mahogany. The doorset included an overpanel of overall size 680mm high by 1837mm wide by 57mm thick of similar construction.

The door leaf consisted of three layers of laminated chipboards (stated density 720kg/m3) within a j frame comprised of members each formed from two pieces of medium density fibreboard (stated density 720kg3/m3) continuously glued to form stiles and rails of 48mm width hanging edge, 42mm width meeting edge, base rail 47mm width and head rail 33mm width, the base rail being a combination of a strip of medium density fibreboard and a strip of Brazilian mahogany (nominal density 540kg/m3).

The core was faced on either side with nominal 3.2mm thick three-ply Lauan type plywood. The leaf was lipped on the bottom and hanging edges with 10mm thick Utile mahogany (nominal density 660kg/m3), along the head with i7mm thick Utile mahogany rebated to a depth of 13mm by 29mra wide and Ϋ on the meeting edge with 24mm thick Utile mahogany rebated X 5i - 7 to a depth of 12.5mm by 29mm wide· The leaf was hung in a 39mm by 91.5mm Utile mahogany frame with a 13mm Utile mahogany planted stop on Steep butt hinges. No latch was fitted, closing being effected by overhead closers fixed to the exposed eurfce G of each leaf· The overpanel was of similar construction to each leaf.

A 20mm wide by 3mm thick strip of Mann McGowan 10 Pyrostrip 100P intumescent material was fitted centrally along the frame head and each frame jamb and to the rebate in both overpanel lower edge and door head. Where this intumescent was interrupted at the hinge positions, additional 10am wide stripe were run along the edges of the hinges placed between the hinges and doorstop. A 15mm wide by 3am thick strip of Mann McGowan Pyrostrip 100P intumescent material was fitted in the rebate of the vertical meeting edge' of eabh leaf. A non-combustible threshold completed the construction.

TEST PROCEDURE Before the test, the satisfactory operation of the doorset was checked and the gaps between the doors and frames recorded. The moisture content of the doors and frames was measured with a Protimeter. That of the door Ca leaves and overpanel was found to be not practical to I - 8 measure and that of the frames was 11%.

The moment required to overcome the force of the door closers was checked and was found to be 45Nm for the left hand door and 39Nm for the right hand door. * 5 Thermocouples were fitted in accordance with BS476: Part 8: 1972. Six suitably distributed J 5 thermocouples monitored the furnace temperature and five disc type surface thermocouples were fixed to the unexposed face of each door to monitor the insulatioin performance.

The furnace was operated to follow as closely as practical the time/temperature relationship specified in BS476: Part 8$ 1972.

The furnace pressure was measured 200mm from the 15 top of the furnace and was controlled after the first five minutes to provide a positive pressure of approximately 1.5mm watergauge for the duration of the test. This represents a pressure of approximately 1.0mm watergauge at the head of the doors.

At the conclusion of the test the furnace was shut down and the specimens hosed with water.

The observations which were made during the test are as follows: Ί1 OBSERVATIONS Time (min/sec) 00.00 04.00 07.00 Comment (mm Test started Smoke from top third of all the door gaps - stopped in approximately 20 seconds Slight smoke across both heads Pressure watergauge) 10.00 Slight smoke from both top corners. Cracking sounds from both leaves 1.0 11.00 Smoke from both top hinge positions 14.30 Right hand leaf bowed in 1mm compared with left hand leaf 19.00 Meeting edge gap closing at top, opening at bottom (1.5mm at top and 5mm at bottom) 20.00 Both closers still in place 28.00 Both closers still in place 1.5 29.00 Slight smoke from one third of way up meeting edge. 33.00 Both closers fallen 35.00 Top meeting edges both in 5mm 1.5 42.00 Glow at bottom meeting edge. 49.00 Slight smoke from between top meeting edge and overpanel 51.00 Glow 400mm up meeting edge 52.00 Slight glow at very top of meeting edge (between top meeting edge and overpanel) 53.30 Glow at top meeting edge enlarging LO 54.30 Burn hand through at lipping on bottom left leaf, 400mm from meeting edge 55.00 Burn hand through at lipping bottom right leaf, 100mm from heel. 5 56.00 Burn hand through at lipping bottom left leaf, 100mm from meeting edge - all burn throughs enlarging· 57.00 Scorch mark at overpanel, 100mm from bottom, 200mm to right of centre 1.5 59.00 Cotton pad integrity test performed at top meeting edge - no failure 60.00 Glow spreading up two thirds of meeting edge. 60.30 Intermittent flaming at top meeting edge. 61.14 Cotton pad integrity test performed at top meeting edge - failure. 61.46 Continuous flaming at top meeting edge 62.00 Glow on left hand leaf at centre hinge position 62.30 Several scorch marks on both leaves and overpanel, intermittent flaming at top right hand corner 1·5 63.34 Pin prick glows and scorch marks on overpanel 65.00 Test terminated· The doorset failed integrity at 61 minutes when hot gases and intermittent flaming from the top of the meeting stiles /frame junction ignited a cotton pad. Insulation failure was deemed to have occurred simultaneously. The maximum temperature recorded by any fixed unexposed face thermocouple wae 115 degrees C at 65 minutes· The dooreet remained in position and satisfied the stability criterion for the 65 minutes duration of test.

After cooling an attempt was made to open the doors. Both opened and fell from the frame; the hinge fixings being retained only in char· Analysis of the remains revealed that the 10 internal frame of the door had charred to a residual thickness of approximately 20mm. Joints between framing members had opened and locally the core of the door had charred completely, as evidenced by scorching on the unexposed face towards the end of the test.

When tested in accordance with the provisions of BS476: Part 8: 1972, the double leaf, single action doorset with overpanel of the invention achieved the following fire resistance performance ratings: Stability : 65 minutes 20 Integrity : 61 minutes Insulation: 61 minutes and thus was certified as satisfying the criteria specified in the above mentioned British Standard.

Claims (5)

1. A fire door including an internal core and an internal supporting framework surrounding said internal core, the internal supporting framework comprising at least two vertical 5 stiles and two horizontal rails of elongate members of fibreboard, the outer faces of said stiles and rails being j covered and protected by an elongate hardwood member, whereby the least fire resistant faces of the elongate fibreboard members are protected by the hardwood members and the overall 10 fire-rating of the door is enhanced.

2. A fire door as claimed in Claim 1, in which the elongate members of fibreboard of the vertical stiles comprise at least two elongate fibreboard elements laminated together.

3. A fire door as claimed in any one of preceding Claims in 15 which the fibreboard is a medium density fibreboard.

4. A fire door as claimed in any one of the preceding claims in which a strip of intumescent material is provided between at least one elongate hardwood member and a juxtaposed elongate fibreboard member. 20

5. A fire door substantially as herein described with reference to and as shown in the accompanying drawings.