GB2581201A

GB2581201A - Improvements in or relating to fire-rated door sets

Info

Publication number: GB2581201A
Application number: GB1901812.6A
Authority: GB
Inventors: Hughes Ian
Original assignee: Rutland Trading Co Ltd
Current assignee: Rutland Trading Co Ltd
Priority date: 2019-02-11
Filing date: 2019-02-11
Publication date: 2020-08-12
Also published as: GB201901812D0

Abstract

The door 3 comprises a base 43 in which the base comprises an intumescent material 44. The base of the door may comprise a recess 42 in which the intumescent material is provided. The intumescent material may be provided in a strip which is arranged within the recess. The strip may be equal in length to the length of the base and span the entire length of the base and the recess may extend along the entire length of the door. The intumescent material may be adhered to the base of the door and the intumescent material may comprise graphite. The door may be comprised within a door set which also comprises a metal sill or threshold. Also disclosed is a door jamb comprising at least two different intumescent materials, a first material having a higher response temperature than a second material.

Description

Improvements in or relating to Fire-Rated Door Sets Technical Field of the Invention The present invention relates to improvements in or relating to fire-rated door sets.

Background to the Invention

Fire-rated door sets (or "fire doors" as they are colloquially known) are provided to compartmentalise buildings and form barriers to stop the spread of fires within a building. One very common application of fire-rated door sets is as front doors of apartments within apartment buildings, separating apartments from communal corridors, with the aim of hindering the spread of fire from an apartment to the communal corridor (and on to other apartments).

In the UK, fire-rated door sets are assessed in test procedures as specified in BS 476-22:1987 or BS EN 1634-1:2014 and rated as FD30 if capable of resisting fire for 30 minutes or FD60 if capable of resisting fire for an hour.

Tests are made on complete door sets, i.e. the fire door and door frame with all the requisite hardware (e.g. locks, latches, hinges, etc). The test procedure involves exposing one face of the door set to the heat conditions anticipated in a fire while observing the door set for stability and integrity.

The side exposed to the fire is normally that side which will, when mounted as a front door, face the inside of an apartment. However, it is considered beneficial for a fire door to be similarly capable of resisting fire from the opposite side -i.e. to hinder fire which has spread to a communal corridor from entering apartments. For various reasons, it is not always the case that fire-rated door sets are equally capable of resisting fire from both sides.

Aspects of the present invention seek to provide improvements that may be of particular use in resisting fire spreading from a communal corridor to an apartment -the characteristics of such fires can differ from fires spreading from an apartment to a corridor.

Other aspects of the invention seek to allow cheaper (but more flammable) materials to be used in fire-rated door sets. In particular, aspects of the invention seek to allow for the use of door frames comprising, or formed predominantly from plastics such as PVCu, for example having a profile formed from PVCu with a plywood core.

Of course, the improvements may also find use in doors or door sets that are not fire-rated

Summary of the Invention

According to a first aspect of the invention there is provided a spyhole, the spyhole comprising a hollow body having a viewing bore therethrough, wherein an aperture extends from an external surface of the hollow body to the viewing bore.

The aperture from the external surface of the hollow body to the viewing bore allows an intumescent material located around the external surface of the hollow body to expand through the aperture and block the viewing bore.

This can improve the fire resistance of a door comprising such a spyhole by preventing fire from passing through the viewing bore. This could otherwise occur when lenses fail -such lenses which are typically found in spyhol es provide a physical barrier to flames passing through the viewing bore until (and unless) they fail The aperture may be at least 2mm in diameter, e.g. between 2mm and 5mm in diameter, for example about 4mm in diameter. This has been found adequate to allow a sufficient amount of intumescent material to pass through a body and close off a viewing bore of 12.5mm -which is of the order typical in spyholes.

The spyhole may comprise an intumescent material provided on the external surface. Alternatively, the intumescent material could be supplied separately and attached by an installer.

The intumescent material may be provided so as to cover the aperture. This will ensure that when activated, the intumescent material expands and is forced through the aperture into the viewing bore.

The intumescent material may be provided around the external surface.

The body may be a cylindrical tube, having a circumferential outer surface and a circumferential inner surface defined by the viewing bore The intumescent material may extend around, or extend substantially around the circumferential outer surface. This ensures that when activated the intumescent material seals between the outer circumferential surface and a bore in the door, in which the spyhole is installed, as well as sealing the viewing bore through the spy hole. This can prevent fire passing through any gap between the spyhole and the bore in the door in which it is installed.

The body may be a barrel. One end of the barrel may be threaded and arranged to engage with a threaded core. The barrel may be partially threaded and partially plain, I 0 with the core arranged to engage with the threaded region and the aperture arranged in the plain region The core may be externally threaded and the barrel may be internally threaded. The barrel may be provided with a flange. The core may be provided with a flange. This allows for the core and the barrel to be arranged on opposite sides of the door, and for the core to be screwed into the barrel, until the flanges abut respective sides of the door.

One of the barrel and the core (e.g. the barrel) may be provided with a privacy cover attached to the flange. The other of the barrel and the core (e.g, the core) may be provided with an external lens, which may be a magnification lens, optionally a lens cap arranged to sandwich the lens between the flange and the cap, optionally sandwiching a washer between the external lens and the flange; one or more magnification lenses or other lenses and optionally an inner tube. For example, the core may comprise an assembly comprising an inner lens, arranged closest to the privacy cover of the barrel, an inner tube extending away from the inner lens towards the flange of the core and a pair of magnification lenses furthest from the privacy cover.

The intumescent material may comprise graphite. The intumescent material may be provided as a strip. It may be wrapped around the body. It may adhered to the body, For example it may be taped to the body, for example by double sided tape.

This aspect of the invention also extends to a door comprising the spyhole.

The door may be a solid-core door (this improves the effectiveness of the intumescent blocking effect, as it is squeezed against the solid core and into the aperture), for example a door with a core of plywood and a coating of PVCu.

The invention further extends to a door set comprising a door frame and a door, the door comprising the spyhole.

The door may be a fire door and the door set may be a fire-rated door set A second aspect of the invention provides a door hinge comprising a plurality of leaves, each leaf comprising an interior surface and an exterior surface, wherein, with the hinge closed, the exterior surfaces face away from each other and the interior surfaces of the leaves face towards one another and wherein, an intumescent material is provided on at least one of the interior surfaces.

Those skilled in the art will have no trouble determining the interior and exterior surfaces of a hinge, but for clarity, the interior and exterior surfaces may be determined based on one of more of the following definitions: IS The hinge may comprise knuckles and a pin, and before installation, edges of the interior surfaces distal from the pin may be capable of facing and abutting one another, whilst the knuckles may prevent edges of the exterior surfaces distal from the pin from facing and abutting one another.

The exterior surface of one leaf may be configured to face a door in use and the exterior surface of the other leaf may be configured to face a doorframe.

The leaves may be provided with apertures to receive fasteners (such as screws) for fastening the hinge and the apertures may be counterbored with the counterbored apertures having a greater diameter at the interior surfaces than the exterior surfaces. This means that the head of the fastener can received in the counterbore, optionally flush with the interior surfaces.

This can improve the fire resistance of a door set comprising such a hinge. Notably, doors and door frames are frequently recessed to receive a hinge, and in the event that the door or frame is provided with a strip of intumescent material extending along facing edges of the frame and the door, the strip may be removed in the region of the hinge as a result of the recessing. This would create a gap through which flames could potentially pass -the provision of an intumescent in the hinge can improve fire resistance in this situation.

Moreover, even if no intumescent is removed as a result of recessing, a small gap may be provided between the two leaves, in use, through which flame can pass and, since hinges are typically metal, heat can very easily pass through the hinge. The intumescent on one or more for the interior surfaces can be activated by the heat passing through the hinge, expand and seal any gap and/or reduce the heat-conductivity of the hinge.

Each of the leaves may have a length. The intumescent may extend along substantially all of the length of the (or each) leaf on which it is provided.

The intumescent material may comprise graphite. The intumescent material may be provided as a strip. It may adhered to the or each leaf For example it may be taped to the body, for example by double sided tape In light of this description, those skilled in the art will be capable of determining suitable intumescents, and suitable dimensions thereof by trial and error, but, for example, for a hinge having leaves with a length of 10cm and a width of 3cm, a strip of graphite intumescent having a length of 10cm and a width of 2cm has been found sufficient.

The invention extends to a kit of parts for forming a hinge according to this aspect of the invention. In particular to a kit of parts comprising a door hinge comprising a plurality of leaves, each leaf comprising an interior surface and an exterior surface, wherein, with the hinge closed, the exterior surfaces face away from each other and the interior surfaces of the leaves face towards one another; and an intumescent material arranged to be provided on at least one of the interior surfaces.

The kit of parts may further comprise fasteners arranged to fasten the hinge to a door and a door frame The intumescent material may be provided as a strip of substantially equal length to the length of one or both leaves. The intumescent material may be provided with an adhesive backing and optionally a release panel (e.g. of release paper), alternatively the kit may further comprise adhesive.

The kit of parts may comprise instructions instructing a user to apply the intumescent material to an interior surface of one or both leaves The instructions may instruct the user to apply the intumescent material after fastening a leaf to a door or door frame.

This aspect of the invention also extends to a door comprising the hinge, a doorframe comprising the hinge, or a door set comprising a doorframe and a door joined by the hinge. The door may be a fire door and the door set may be a fire-rated door set.

Of course, the invention further extends to a door or door set comprising a hinge according to the second aspect of the invention (optionally including any optional features) and a spyhole according to the first aspect of the invention (optionally including any optional features).

According to a third aspect of the invention there is provided a door, the door having a base and the base comprising an intumescent material.

The door may be cuboid, as is typical, with a top opposing the base, a front, a rear, and two edges One edge may be hingedly connected (or intended to be hingedly connected) to a doorframe and the other provided with (or intended to be provided with) a closure mechanism, such as a latch.

In fire-rated door sets, intumescent materials are typically provided on the frame, rather than the door -this may be for various reasons, for example, aesthetics (in terms of keeping the intumescent out of sight) and avoidance of wear (by placing the intumescent on the non-moving part) However, the inventors have determined that at the bottom of the door, the intumescent may be better placed on the door itself, which will not be walked on in-use (unlike the sill at the bottom of the frame).

The base of the door may be provided with a recess and the intumescent material may be provided in the recess. The recess may be a groove. This reduces the likelihood of damage to the intumescent and improves the appearance.

The intumescent material may be provided as a strip. The strip may be arranged in the recess. The strip may be equal in length to the length of the base (i.e. the distance from one edge of the door to the other), and may span the entire length of the base. Correspondingly, the recess, or groove may extend along the entire length of the base (i.e. the width of the door) from one edge to the other.

The intumescent material may be adhered or otherwise connected to the base of the door. The intumescent material may comprise graphite.

This aspect of the invention extends to a door set comprising a door frame and the door (optionally including any of the optional features) The door frame may comprise a metal sill or threshold. The metal sill or threshold may be aluminium.

The door frame may comprise plastic, for example, PVCu and may be formed predominantly from plastic, for example PVCu. In particular, the door jambs (including door posts and a head jamb) may be formed of plastic, such as PVCu, (optionally with an internal reinforcement, such as plywood).

The provision of an intumescent material at the base of the door is especially useful in terms of improving fire resistance when the sill or threshold is metal. In these circumstances, the sill or threshold may typically be fire resistant in its own right. It may be raised on one side (the side opposite to the direction in which the door opens (i.e, normally the outside)) and may have one or more smoke seals. A smoke seal may be provided on the raised part. A smoke seal may be provided opposite the intumescent material.

In the event of an internal fire, this raised part and the smoke seals will normally be sufficient to prevent fire from passing beneath the door. Since it is not normally especially hot at the bottom, the smoke seal on the raised part at the exterior will normally withstand the temperature and be sufficient to prevent fire passing under the door. However, in the event of a fire on the external side, this smoke seal on the raised part may be subject to much greater temperature since the fire would not be separated from it by the door and may fail. In this circumstance, the underneath of the door is likely to be subject to a much higher temperature, since the metal sill/threshold will heat up, and that temperature will be sufficient to cause the intumescent material to expand and close the gap.

Of course, this aspect of the invention also extends to a door comprising the hinge of the second aspect of the invention (optionally including any optional features) or a door set comprising a doorframe and a door joined by the hinge of the second aspect of the invention (optionally including any optional features) Moreover, the invention further extends to a door or door set according to the third aspect (optionally comprising a hinge according to the second aspect of the invention (optionally including any optional features)), wherein the door comprises a spyhole according to the first aspect of the invention (optionally including any optional features).

The door may be a fire door and the door set may be a fire-rated door set.

According to a fourth aspect of the invention there is provided a door jamb comprising at least two different intumescent materials, a first intumescent material having a higher response temperature than a second intumescent material.

As mentioned above, the characteristics of a fire one side of a door can be different from a fire on the other side of a door (e.g. as between a fire inside an apartment and a fire in a corridor). Providing two different intumescent materials can tailor the response based on the likely characteristics.

For example, a first intumescent material may comprise (or consist of) graphite.

Graphite typically has a response temperature (the temperature at which it expands) of at least 180 degrees C (see: m i sec tip! Cfrad C. pd 0. The first intumescent material may have a response temperature of at least 150 degrees C, at least 180 degrees C or at least 200 degrees C. A second intumescent material may comprise or consist of a silicate, for example Palusol 0 available from BASF 0. These materials typically have a lower response temperature, starting to expand at just 100°C and developing a significant expansion pressure of up to 1.60 Nimm2 at 120°C (see.

daSEICS'Or.euwaln a rics Ub B SII/C ontmon o orocnt:i '). The second intumescent material may have a response temperature of less than 180 degrees C, less than 150 degrees C or less than 120 degrees C (e.g. about 100 degrees C).

The intumescent materials may be provided as strips.

The door jamb may comprise plastic, for example, PVCu and may be formed predominantly from plastic, for example PVCu In particular, the door jamb may be formed of plastic, such as PVCu, (optionally with an internal reinforcement, such as plywood).

The door jamb may comprise a rebate. The rebate may comprise a first surface arranged to face an edge of the door and a second surface arranged to face a front of a door. The first surface may be formed on a body of the door jamb and the second surface may be formed on an extension extending therefrom. A smoke seal may be provided on the second surface.

The intumescent materials may be provided on the first surface of the doorjamb The intumescent materials may extend along the length of the door jamb (i.e. the height of a door post or the width of a head jamb) The intumescent materials may extend along substantially the entire length of the doorjamb, They may be continuous, or may extend over at least 80 or 90% of the length (e.g. only broken to allow for hinges to be attached -ideally hinges according to the second aspect of the invention, ideally also comprising at least two different intumescent materials).

The first intumescent material may be provided further from the second surface of the rebate than the second intumescent material.

A smoke seal may be provided on one or both of the intumescent materials. In particular, a smoke seal may be provided on the second intumescent material.

The door jamb may be a door post or a head jamb The invention extends to a door frame comprising a plurality of door jambs, for example two door posts and a head jamb, in which one or more or each is a door jamb according to the fourth aspect of the invention In one particular embodiment, door frame comprises three PVCu door jambs being two door posts and a head jamb, wherein each comprises at least two different intumescent materials, a first intumescent material having a higher response temperature than a second intumescent material; the intumescent materials being provided as strips extending along the length of the first surface of the body of each doorjamb, wherein a second surface is formed on an extension extending from the door jamb, wherein smoke seals are provided on the second intumescent material and the second surface, and wherein the first intumescent material is provided further from the second surface of the rebate than the second intumescent material Such an embodiment can be used as the frame of a front door of an apartment, separating the apartment from a corridor. In these circumstances, with a fire in the apartment, the fire door will act much as a standard fire door; the fire will, to an extent, be contained on the inside by the smoke seals on the intumescent and the second surface, and by the time it is necessary for the first intumescent material to deploy, a high enough temperature will be reached to activate it. On the other hand, with a fire in the corridor, because the door jambs are formed of PVCu, they will burn quite rapidly, stripping off the extension on which the second surface is formed, and which carries a smoke seal, rendering that smoke seal ineffective and relatively quickly burning the smoke seal provided on the second intumescent. All this can happen before the fire reaches a temperature hot enough to activate the first intumescent. However, because the second intumescent has a lower response temperature, it will expand and prevent flames from passing the first intumescent, breaching the fire door.

The door set may be a fire-rated door set The invention extends to a door frame comprising a door jamb according to the fourth aspect of the invention in combination with a door according to the third aspect of the invention; and/or a door hinge according to the second aspect of the invention (in particular a hinge comprising an intumescent material arranged in alignment with at least one of the intumescent materials on the doorjamb); and/or a door having a spyhole according to the first aspect of the invention, in each case optionally including any optional features.

Detailed Description of the Invention Ii

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a rear view of a door set; Figure 2 is an exploded perspective view of the spy hole of the door set of figure 1; Figure 3 is an exploded side view of the spy hole of figure 2; Figure 4 is a schematic cross-sectional view of the spy hole of figures 2 and 3 in the door of figure 1; Figure 5 is a perspective view of a hinge of the door set of figure 1; Figure 6 is a cross sectional view (looking upwards) of a slice through part of the door set of figure 1 in the region of a hinge Figure 7 is a cross sectional view (looking left) of a slice through part of the door set of figure 1 in the region of the bottom of the door; and Figure 8 is a cross sectional view (looking left) of a slice through part of the door set of figure 1 in the region of the top of the door.

Referring to figure 1, a fire rated door set 1 is shown. The door set comprises a door frame 2 and a door leaf, or door, 3. The door set 1 is also provided with certain typical door furniture, including a handle 4 associated with a latch (not shown); a letterbox 5 and a door closer 6.

The door 3 of this embodiment is a fire door and has a plywood core with a PVCu coating. The door comprises two decorative panels 7 in the lower half and a large lite 8 in the top half, formed of fire resistant glass A spy hole 9 (described in detail below with reference to figures 2-4) is provided in the door 3 and the door 3 is hung on the door frame 2 by hinges 10 (described in detail below with reference to figures 5 and 6) attached to one edge of the door 3 In this case there are four hinges 10, but of course more or fewer could be used (depending on factors such as the weight of the door 3 and the strength of the hinges 10).

The door 3 of this embodiment is generally cuboid, with a height of approximately 2 metres, a width of approximately 1 metre and a depth of approximately 5cm. The door 3 is cuboid (albeit relatively thin in one dimension), as is typical, with a top opposing a base, a front, a rear, and two edges. One edge is hingedly connected (or intended to be hingedly connected) to a doorframe and the other provided with (or intended to be provided with) a closure mechanism, such as a latch.

The view of figure 1 shows the rear of the door 3, which is used as the front door of an apartment, so the view is from inside the apartment towards an external corridor.

Referring to figures 2-4, the spyhole 9 is largely comprised of conventional parts. In particular, the spyhole 9 comprises two hollow bodies in the form of a tubular cylindrical barrel 11 and a tubular cylindrical core 12. Both of these bodies 11, 12 are in this embodiment formed of metal, in this case brass.

The core 12 is sized to screw into the barrel 11 via a thread 13 on the external surface of the core 12 and a corresponding thread 14 on the internal surface of the barrel H. The barrel 11 is only threaded along approximately 1 cm from one end and the remainder of the bore therethrough is plain.

At the opposite end from the thread 13, the core 12 is provided with a flange 15, which in turn is externally threaded. Likewise, at the opposite end from the thread 14, the barrel 11 is provided with a flange 16. Pivotally connected to the flange 16 of the barrel 11 is a privacy cover 17. The privacy cover 17 is arranged, in use, on the internal side of the door 3 and covers a viewing bore defined by the adjoining cavities through the hollow barrel 11 and hollow core 12.

Within the viewing bore, specifically, within the cavity through the core 12, in a conventional manner, is an assembly comprising an inner lens 18, arranged closest to the privacy cover of the barrel 11, an inner tube 19 extending away from the inner lens 18 towards the flange 15 of the core and a pair of magnification lenses 20 furthest from the privacy cover 17.

An external lens 22 is mounted on the flange 15 separated therefrom by a plastic washer 22, and held in place by a (brass) lens cap 23 screwed onto the thread on the flange 15.

Importantly, one of the hollow bodies 11, 12, in this case the barrel H has an aperture 24 extending from its circumferential external surface to the circumferential inner surface of the barrel, which defines part of the viewing bore. In this embodiment, where the viewing bore through the hollow barrel 11 is 12.5mm, the aperture is 4mm in diameter. The aperture 24 is arranged in the plain region of the barrel 11, into which the core 12 will not extend, when they are screwed together. In particular, it is arranged in proximity to the flange 16, approximately lOmm therefrom.

A strip 25 of intumescent material, in this case graphite, is wrapped around the outer circumferential surface of the hollow bodies of the spyhole 9, forming a tube extending around the barrel 11 and arranged so as to cover the aperture 24 therethrough.

The strip 25 of intumescent material is adhered to the barrel 11 for example by double sided tape (not shown) To assemble the spyhole 9, an appropriately sized hole is drilled through the door 3. The core 12, containing the lens assembly is introduced from the external side of the door 3, such that its flange 15 faces the external surface of the door 3. The barrel 11, with the strip 25 of intumescent material wrapped around it is introduced from the opposite, internal, side of the door and the core 12 is screwed into the barrel 11 until the two flanges 15, 16 abut respective external and internal surfaces of the door 3. The barrel is arranged with the pivot from which the privacy cover 17 pivots at the top and the washer and external lens 21 are arranged in position and the lens cap is screwed onto the flange 15 In the event of a fire, which breaks the lenses, allowing flame to extend through the viewing bore, the intumescent material is heated up and activated When activated, the intumescent material expands and seals between the outer circumferential surface of the hollow bodies 11, 12 and the hole in which they are installed. Moreover, the intumescent material is forced through the aperture 24 blocking and sealing the viewing bore through the spy hole 9.

This improves the fire resistance of the door 3 comprising the spyhole 9 by preventing fire from passing through the viewing bore.

Another aspect of the invention that improves the fire resistance of the fire rated door set 1 is the construction of each hinge 10, as now described with reference to figures 5 and 6 The door hinge 10 comprises a first leaf 30, intended to be attached to a door jamb of the door frame 2 (in particular to a door post) and a second leaf 31.

The leaves 30, 31 are provided with knuckles 32, through which a pin 33 extends to hold the leaves 30, 31 together, inside the knuckle 32 and define the axis of 10 rotation.

As is typical, the knuckles 32 are offset from the plane of the leaves 30, 31, so as to allow interior surfaces 34, 35 of the leaves 30, 31 to face each other whilst the leaves are parallel, as shown in figure 6, whilst they would prevent the external surfaces from facing each other whilst the leaves are parallel. Likewise, before installation, edges of the interior surfaces 34, 35 distal from the pin 33 would be capable of facing and abutting one another, whilst the knuckles prevent edges of the exterior surfaces distal from the pin 33 from facing and abutting one another.

With the hinge closed, as shown in figure 6, the exterior surfaces face away from each other and the interior surfaces 34, 35 of the leaves 30, 31 face towards one 20 another, Each of the leaves 30, 31 is provided with apertures 37 to receive screws 38 which fasten the hinge 10 to the door 3 and the frame 2. In this embodiment each leaf 30, 31 comprises five apertures and each aperture is counterbored with the counterbored apertures having a greater diameter at the interior surfaces than the exterior surfaces.

This means that the head of each screw 38 can received in the counterbore, flush with the interior surfaces As shown part-cutaway, a strip of intumescent material 36 (graphite) is adhered by double sided tape (not shown) to the interior surface 34 of the leaf 30 which is attached to the door frame 2 The strip of intumescent material 36 extends along the entire length of the leaf 30.

IS

In this particular embodiment, the leaves 30, 31 have a length of about 10cm and a width of about 3cm. The strip of graphite intumescent material 36 has the same length (of about 10cm) and has a width of about 2cm.

Figure 8 shows a cross sectional view (looking left) of a slice through part of the door set 1 in the region of the top of the door 3. In particular, it shows a the profile of the header jamb 50, which is extruded from PVCu and contains a reinforcing core 51, which in this embodiment is formed of plywood. However, all the door jambs are formed from the same extrusion process, so the profile of the header jamb 50 is the same as the door posts 40.

Comparison of figure 8 with figure 6 will reveal that in the region of the hinges 10, the door posts are recessed; in particular, part of two protrusions which define a channel 52 at the internal side of the door are removed, as is part of a first strip of intumescent material 53 and part of a rib 54 which separates the first strip of intumescent material 53 from a second strip of intumescent material 55 In practice, the intumescent strip 36 is provided with an adhesive backing (not shown) and release tape (not shown) for application to the hinge 10 after installation. A set of instructions (not shown) would also be provided, instructing a user to apply the intumescent material to an interior surface of the leaf 30 after attaching that leaf to the door frame 2.

The hinge 10 is then attached to the door 3 and doorpost 40 in the usual way, screwing the screws 38 through the apertures 37 in the second leaf and into the door 3, and screwing the fasteners 38 through the apertures 37 in the first leaf 30 and into the recess in the door post 40. Then, the release tape is removed from the strip 36 and it is applied to the hinge to close the gap in the first strip of intumescent material 53 on the door post 40.

This improves the fire resistance of the door set as it closes a gap in the first intumescent strip 53 through which flames could potentially pass.

Moreover, even if no intumescent was removed as a result of recessing, a small gap may be provided between the internal surfaces 34, 35 of the two leaves 30, 31, in use, through which flame could pass and, since the hinges 10 are formed of metal (e.g. steel), heat could otherwise very easily pass through the hinge. The intumescent on the interior surface 30 will be activated by the heat passing through the hinge, expand and seal the gap and reduce the heat-conductivity of the hinge.

A further aspect of this invention that improves the fire resistance of the fire rated door set 1 concerns the base of the door 2 and is now described with reference to figure 7 Briefly, this aspect of the invention involves the provision of a recess in the form of a groove 42 in the base (i.e. the bottom surface) 43 of the door 3, in which a strip of intumescent material 44 is provided.

The groove 42 extends along the entire length of the base 43 (i.e. the entire width of the door from one edge to the other edge). It is centrally aligned, between the front surface 45 and the rear surface 46 of the door, and has a rectangular cross section and with a width of about 3cm and a depth (upwards into the door) of about 3mm The strip of intumescent material 44 in this embodiment is graphite and has a length equal to that of the groove (i.e. the same as the width of the door 3), which is approximately 1 metre, a width of about 2 5cm and a depth of about 2mm, such that it fits completely within the recess 42 when adhered therein (by double-sided tape).

Whereas, as mentioned above, the door jambs (door posts 40 and header jamb 50) of this embodiment are extruded from PVCu and provided with a plywood core 51, the threshold (or sill) 41 of the door set 1_ is extruded from metal, in this embodiment aluminium.

The threshold 41 has a raised portion, or stop 47 on the side opposite to the direction in which the door opens (i.e. towards the outside) and the stop supports a first smoke seal 48 in a channel in the stop, which first smoke seal 48 abuts the front surface 45 of the door 3. From the base of the raised portion, the threshold slopes gently upwards and rearward and, towards its rear it has another channel, in its upper surface, in which a second smoke seal 49 is provided. Both of the smoke seals 48, 49 extend along the entire length of the threshold 41, which is to say, along the entire width of the opening in which the door is arranged. The second smoke seal 49 is positioned opposite the strip of intumescent material 44 that is arranged in the groove 42 in the base of the door 3 As set out in the introduction, in the event of an internal fire (i.e. a fire on the side of the rear surface 46 of the door 3, the raised stop 47 and in particular the smoke seals 48, 49 will normally be sufficient to prevent fire from passing beneath the door to the outside (i.e. the side in front of the front surface 45). Since it is not normally especially hot at the bottom, the smoke seal 48 on the raised part at the exterior, at least, will normally withstand the temperature and be sufficient to prevent fire passing under the door.

However, in the event of a fire on the external side (i.e. outside the front surface of the door), this first smoke seal 48 on the raised part may be subject to much greater temperature since the fire would not be separated from it by the door 3 and may fail, burning or melting away. In this circumstance, the underneath of the door is likely to be subject to a much higher temperature, since the metal threshold 41 will heat up.

However, this aspect of the invention operates on the (proven) principle that the increased temperature of the threshold will be sufficient to cause the intumescent material to expand and close the gap between the base 43 of the door 3 and the threshold 41, blocking fire from passing beneath the door 3.

Yet another aspect of this invention that improves the fire resistance of the fire rated door set 1 is concerned with the door jambs and was mentioned briefly above with reference to figure 8, which is a cross section through the header jamb 50, but equally represents a cross section through the door posts 50, which are made from the same PVCu extrusion, with a plywood core.

These door jambs are described in more detail below with reference to figure 8, but arguably the most important feature of the door jambs 40,50 is the provision of the two strips of intumescent material, 53, 55 and in particular the fact that the first intumescent material 53 has a higher response temperature than a second intumescent material 55. In particular, in the embodiment, the first strip of intumescent material 53 consists of graphite (which typically has a response temperature (the temperature at which it expands) of at least 180 degrees C), whilst the second strip of intumescent material 55 consists of Palusol ® available from BASF ®, which has a lower response temperature, starting to expand at just 100°C and developing a significant expansion pressure of up to 1.60 24/mm2 at 120°C.

Whilst the door jambs are predominantly formed of PVCu, the PVCu extrusion, as mentioned before, receives a bar of plywood 51 as a core to reinforce the PVCu and to receive the fasteners which attach the hinges 10 (and other furniture) to the door frame 2.

The plywood core 51 has a square cross section and is received in a central cavity 56 through the PVCu extrusion, which also has a generally square cross section. The orientation of the generally square central cavity 56 is aligned with that of the door 3 (when closed). Hence, it has front and rear walls 57, 58 which are parallel with the front and rear surfaces 45, 46 of the door (when closed).

Layers of intumescent material 59 (graphite strips in this embodiment) are sandwiched between the front and rear of plywood core and respective front and rear walls 57, 58 This can be achieved by applying the strips to the plywood core 51 before inserting it into the central cavity 56 The outer wall 61 of the central cavity 56 furthest from the top (or in the case of a door post the edge) of the door 3 is flat and simply receives the edge of the plywood core 51 in abutment against it. On the other hand, the inner wall 62 of the central cavity closest to the top (or in the case of a door post the edge) of the door 3 is provided with a pair of internally extending bumpers 60. These bumpers 60 are longitudinally extending projections of hollow circular cross-section and serve to urge the plywood core 51 against the opposing flat outer wall 61 of the central cavity 56, keeping it in position and accommodating small variations in cross section of the plywood core 51.

The outer and inner walls 61, 62 of the central cavity extend rearward of the central cavity 56, forming a further two cavities 63, 64, which are separated by a strengthening web 65 and space the rear wall 58 of the central cavity from a rear wall 66 of the PVCu extrusion, which forms the rear wall of the door frame and (in this embodiment) is aligned with the plane of the rear surface 46 of the door 3.

Further protrusions, one formed by the inner edge of the rear wall 66 define a channel 52 which could hold an optional brush seal, but does not in this embodiment, to ensure that it does not prevent the door from closing. Another protrusion 67 is provided at the outer edge of the rear wall 66.

Two protrusions with mushroom-shaped profiles 68 roughly in line with the front and rear walls 57, 58 and extending away from the top of the door (or in the case of a door post away from the door's edge) beyond the outer wall 61 of the cavity 56 define a channel in which a further strip of graphite intumescent 70 is arranged. In the event that the PVCu extrusion bums away, this intumescent 70 can close the gap between the plywood core 70 (and its associated intumescent strips 59) and the opening in which the door set is installed.

In something of a mirror image of the cavities 63, 64 to the rear of the rear wall 58 of the central cavity 56, another set of cavities 71, 72, 73 are provided forward of the front wall 57 of the central cavity. An outermost cavity 71 is defined by the front wall of the central cavity 56, a continuation of the outer wall 61, a strengthening web 74 and a front wall 75 of the PVCu extrusion, which forms the front wall of the door frame 2 and is located forward of the door 3 when closed.

Mirroring the protrusion 67 at the outer edge of the rear wall 66 of the PVCu extrusion, another protrusion 76 is provided at the outer edge of the front wall 75 of the PVCu extrusion, which rests against the construction opening in the wall in which the door set is installed.

The cavity 72 is provided between the front wall 57 of the central cavity, the front wall 75 of the PVCu extrusion, the aforementioned web 74 and a further strengthening web 77 arranged slightly radially inward of the inner wall 62 of the central cavity.

The cavity 71, is provided in an extension 78 of generally triangular cross section which extends from the body of the PVCu extrusion in front of the front surface of the closed door, in use.

This extension 78 forms the rebate into which the door 3 is closed -a familiar feature of door frames.

In particular, the rebate comprises a first surface defined, broadly speaking, by the inner surface of the inner wall 62 which faces the top (or an edge) of the door and a second surface defined, broadly speaking, but the surface of the extension 78 which faces the front of the door 3 A channel 79 is formed in the extension open at the surface which faces the front of the door 3 in order to receive a smoke seal 80, which seals against the front of the door 3.

The first and second strips of intumescent material 53, 55 mentioned above are provided on the first surface of the door jamb and extend along the entire length of the door jamb (i.e. the height of a door post 40 or the width of a head jamb 50).

The second strip of intumescent material 55 is continuous, and the first strip of intumescent material 53 extends continuously along the width of the head jamb, and substantially continuously along the door posts, interrupted only by the hinges 10 on the side where the door is attached, or for example a slot (not shown) for the latch associated with the handle 4.

The first strip of intumescent material 53 is provided further from the second surface of the rebate than the second strip of intumescent material 55 (i.e. the second strip 55 is closest to the front and the extension 78 The second strip 55 is provided with a smoke seal 81 in the form of a pair of fins extending from the centre of the second strip in a v-shape. The ends of the fins distal from the second strip 55 seal against the top of the door 3 (or edge in respect of a door post 40), towards the front Providing the smoke seal 81 on the second strip is advantageous for several reasons, for example, the second strip is positioned closest to the extension, and less likely to be cut out to accommodate hinges or other furniture, it is therefore continuous, so there is no break in the smoke seal.

When the embodiment is used as the frame of a front door of an apartment, separating the apartment from a corridor. In these circumstances, with a fire in the apartment, the fire door will act much as a standard fire door; the fire will, to an extent, be contained on the inside by the smoke seals 80, 81 on the second strip of intumescent material 55 and the second surface, and by the time it is necessary for the first intumescent material 53 to deploy, a high enough temperature will be reached to activate it On the other hand, an important feature of this aspect of the invention is that with a fire in the corridor, because the door jambs 40, 50 are formed (predominantly) of PVCu, they will burn quite rapidly, stripping off the extension 78 on which the second surface is formed, and which carries a smoke seal 80, rendering that smoke seal ineffective and relatively quickly burning the smoke seal 81 provided on the second intumescent. All this can happen before the fire reaches a temperature hot enough to activate the first intumescent strip 53. However, because the second intumescent strip 55 has a lower response temperature, it will expand and prevent flames from passing the first intumescent 53, breaching the fire rated door set.

Notably, a door set with all the aspects mentioned above can pass the UK FD30 regulations when tested from both sides, even when formed predominantly from PVCu -this allows for a fire rated door set to be manufactured at a substantially cheaper cost than normal, with all the other benefits of PVCu, a material not normally considered suitable for fire rated door sets.

It is considered that a door set with these aspects may well also pass the more rigorous FD60 tests against fires from either side and it is also considered that the various aspects alone may offer useful improvements in fire resistance, or allow for material changes in other fire rated door sets whilst keeping the fire rating The one or more embodiments are described above by way of example only.

Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMSA door, the door having abase and the base comprising an intumescent material.
2. A door according to claim I wherein the base of the door is provided with a recess and the intumescent material may be provided in the recess.
3. A door according to claim 2 wherein the recess is a groove.
A door according to any preceding claim wherein the intumescent material is provided as a strip.
5. A door according to claim 4 when dependent on claim 2 or 3 wherein the strip is arranged in the recess.
6. A door according to claim 5 wherein the strip is equal in length to the length of the base and spans the entire length of the base, and wherein the recess extends along the entire length of the base.
7. A door according to any preceding claim wherein the intumescent material is adhered to the base of the door.
IS 8. A door according to any preceding claim wherein the intumescent material comprises graphite.
9. A door set comprising a door frame and the door according to any of claims 1 to 8, wherein the door frame comprises a metal sill or threshold.
10. A door set according to claim 9 wherein the door jambs are formed of plastic, such as PVCu.
11. A door set according to claim 9 or 10 wherein the sill or threshold is raised on one side and has one or more smoke seals provided on the raised part.
12. A door set according to any of claims 9 to 11 wherein a smoke seal is provided on the sill or threshold opposite the intumescent material.
13. A door jamb comprising at least two different intumescent materials, a first intumescent material having a higher response temperature than a second intumescent material.
14. A door jamb according to claim 13 wherein the first intumescent material comprises graphite.
15. A door jamb according to claim 13 or 14 wherein the first intumescent material has a response temperature of at least 150 degrees C.
16. A door jamb according to any of claims 13 to 15 wherein the second intumescent material comprises a silicate
17. A door jamb according to any of claims 13 to 16 wherein the second intumescent material has a response temperature of less than 150 degrees C.
18. A door jamb according to any of claims 13 to 17 wherein the intumescent materials are provided as strips extending along substantially the entire length of the doorjamb.
19. A door jamb according to any of claims 13 to 18 formed predominantly from PVCu.
20. A door jamb according to any of claims 13 to 19 comprising a rebate, the rebate comprising a first surface arranged to face an edge of the door and a second surface arranged to face a front of a door, wherein the intumescent materials are provided on the first surface of the doorjamb.
21. A door jamb according to claim 20 wherein the first surface is formed on a body of the door jamb and the second surface formed on an extension extending therefrom and wherein a smoke seal is provided on the second surface.
22. A door jamb according to claim 20 or 21 wherein the first intumescent material is provided further from the second surface of the rebate than the second intumescent material.
23. A door jamb according to any of claims 13 to 22 wherein a smoke seal is provided on the second intumescent material.
24. A door frame comprising three PVCu door jambs according to any of claims 13 to 23, being two door posts and a head jamb, wherein each comprises at least two different intumescent materials, a first intumescent material having a higher response temperature than a second intumescent material; the intumescent materials being provided as strips extending along the length of the first surface of the body of each door jamb, wherein a second surface is formed on an extension extending from the doorjamb, wherein smoke seals are provided on the second intumescent material and the second surface, and wherein the first intumescent material is provided further from the second surface of the rebate than the second intumescent material.
25. A door set comprising a door frame comprising a door jamb according to any of claims 13 to 23 the frame having a metal sill or threshold, and a door according to any of claims 1 to 12.