GB2510717A

GB2510717A - Heat resistant casing

Info

Publication number: GB2510717A
Application number: GB1402271.9A
Authority: GB
Inventors: Daniel Hiscoke
Original assignee: Scolmore International Ltd
Current assignee: Scolmore International Ltd
Priority date: 2013-02-11
Filing date: 2014-02-10
Publication date: 2014-08-13
Anticipated expiration: 2034-02-10
Also published as: GB201402271D0; GB2510717B; GB201302348D0

Abstract

A heat resistant casing 10 comprises an outer housing 11 for locating relative to a support structure such as a ceiling, and an inner housing 12 for housing an electrical element such as a lighting element. The inner housing 12 is supported for at least one of pivotal and rotational movement relative to the outer housing 11. The outer surface of the inner housing 12 is spaced from the inner surface of the outer housing 11, and the space therebetween is occupied by an element 31 of fire resistant intumescent material which substantially wholly surrounds the inner housing 12 to inhibit passage of hot gas or flames through the casing via the space between the inner and outer housings.

Description

HEAT RESISTANT CASING

This invention relates to a heat resistant casing for use with an electrical fitting and in particular, though not exclusively, for use with a lighting element to inhibit the spread of fire.

The invention seeks in particular, though not exclusively, to provide an improved heat resistant casing suitable for use as the fire hood of a lighting element which is required to exhibit a swivel facility relative to the casing.

New building regulations require that down-lighters fitted into ceilings are to be provided with fire hoods to prevent or at least minimise the spread of fire.

Various types of fire hood have been proposed and which include a fire resistant intumescent material that upon excessive heating (e.g. in the event of a fire) expands to many times the original volume, thus forming a fire barrier to inhibit or prevent the spread of fire. Although known hoods have been successful in acting to minimise the spread of fire, that is sometimes at the expense of providing adequate ventilation to the electrical fitting to facilitate longevity and efficient operation. Furthermore in many cases the previously known fire hoods have not been as cost effective, compact or easy to install as desired.

The present invention seeks to provide a heat resistant casing suitable for use as a fire hood and in which at least some of the disadvantages of previously known fire hoods are mitigated or overcome.

In accordance with one aspect of the present invention there is provided a heat resistant casing comprising an outer housing for locating relative to a support structure such as a ceiling, and an inner casing for housing an electrical fitting such as a lighting element, the inner housing being supported for at least one of pivotal and rotational movement relative to the outer housing, the outer surface of the inner housing being spaced from the inner surface of the outer housing and the space therebetween being occupied by at least one element of fire resistant intumescent material which substantially wholly surrounds the inner housing thereby to inhibit passage of hot gas or flames through the casing via the space between the inner and outer housings.

The expression "heat resistant casing" as used herein is to be understood to include casings of the type which are non-combustible or fire resistant.

The outer housing may be of a substantially tubular shape and, for example, may comprise a section of cylindrical shape. The outer housing may be open at one end to facilitate insertion of the inner housing and/or an electrical fitting to be positioned and retained within the casing.

The outer housing may be of a tubular shape which has a major, longitudinal axis parallel with the length of the tubular housing. The inner housing may be pivotally mounted about an axis which is substantially perpendicular to said longitudinal axis. Additionally or alternatively the inner housing may be mounted for rotational movement about said longitudinal axis of the outer housing.

Each of the housings may have a circular shape in cross-section thereby to define an annular space therebetween and which may be occupied at least in part by a substantially circumferentially continuous element of fire resistant intumescent material, or sections of said material which combine to form a substantially circumferentially continuous element.

Pivot means such as one or more pivot devices may be provided whereby the inner housing is supported for pivotal movement relative to the outer housing.

Optionally said pivot means may comprise a pivot device which extends through an element of fire resistant intumescent material, or an annular element of intumescent material may lie at a position at which it is substantially adjacent the pivot device(s).

The pivot means may comprise two pivot devices located or acting at diametrically opposite positions of a circular section inner housing. Two annular elements or, for example, two semi-circular elements of intumescent material may be provided and each may be positioned to extend in a circumferential direction between two pivot devices. The elements of intumescent material may extend generally in a plane which is substantially perpendicular to the direction in which air might flow through the casing, between the housings, in the absence of the element(s) of intumescent material.

The outer housing may be of a substantially cylindrical shape and the inner housing may be of a part spherical shape. In that case the annular element of intumescent material may have an inner diameter corresponding substantially to the diameter of the outer surface of the spherical portion of the surface of the inner housing. Pivot means may extend through or be adjacent said element of intumescent material whereby the inner housing pivots about an axis which extends through the part spherical shape, for example, about an axis which extends through the centre of curvature of the part spherical shape.

The outer housing may comprise an inwardly extending abutment flange which in use restricts the range of pivotal or rotational movement of the inner housing.

An annular element of intumescent material may be provided at a position spaced from the axis about which an inner housing pivots relative to the outer housing such that the intumescent material fully occupies the radial space between the inner and outer housings, the intumescent material in this case necessarily being thicker than an annular element of intumescent material positioned aligned with the pivot axis if the outer housing is of a cylindrical or other shape for which the spacing from the inner housing varies along the length of the outer housing.

Although typically the inner and outer housings may be of a circular cross-sectional shape, as considered in a plane perpendicular to the direction in which air would flow between the housings in the absence of the element of intumescent material, other cross-sections such as square or rectangular cross-sections may be employed. In that case the element of intumescent material will not be of a circular, ring-like form and instead may be of, for example, a square or rectangular shape thereby to substantially wholly bridge a gap between the inner and outer housings. As in the case of a circular, ring-like element of intumescent material, an intumescent element of non-circular shape similarly may be aligned with or be spaced from an axis about which the inner housing may be pivotally supported relative to the outer housing.

Thus the present invention may be employed in a type of heat resistant casing in which the inner housing has a part cylindrical outer surface and in which the major, longitudinal axis of the inner housing is substantially perpendicular to the direction in which air might flow through the casing, between the housings, in the absence of the element(s) of intumescent material.

At least one of the inner surface of the outer housing or the outer surface of the inner housing may be provided with a recess or other form of retention means for location of intumescent material. A housing may be provided with a recess which is peripherally continuous as considered in a cross-sectional plane perpendicular to a longitudinal axis of the outer housing and in which a part of the thickness of the element of fire resistant intumescent material may be located. Additionally or alternatively the intumescent material may be secured in position by means of an adhesive.

In addition to providing fire resistance and acting as a barrier to through flow of flames and hot gases between the inner and outer housings the fire resistant intumescent material may be employed also to provide frictional resistance to pivotal and/or rotational movement of the inner housing relative to the outer housing.

Either of the housings may be provided with at least one recess or other form of retention means, such as adhesive, for location of two annular elements of intumescent material positioned at respective sides of an axis position about which the inner housing is intended to pivot relative to the outer housing and in which said elements of intumescent material are spaced apart, as considered in the direction of flow of air in the absence of the elements, thereby to serve as the pivot means and provide pivotal support of the inner housing relative to the outer housing.

Optionally the outer housing may be relatively closed at one end as compared to the other, open, end. However, in that case that region of the outer housing which is further from the open end of the housing than from the intumescent material between the housings may be provided with ventilation apertures for air cooling of an electrical fitting such as a transformer driver or lighting element contained within the inner housing. It may also be apertured for passage of electrical conductors to within the casing. The region of the inner housing which, for all relative positions of the housings, confronts an apertured region of the outer housing similarly may be provided with ventilation apertures.

Alternatively the outer housing may substantially open at both ends, thereby facilitating a good flow of air for cooling any heat sink or other component supported by the inner housing.

The inner housing or a component such as an electrical fitting within the inner housing preferably acts to inhibit airflow between the end regions of the inner housing.

One of the housings may be provided with a pair of spring-loaded type pivot devices which deflect for assembly of the casing, for example by deflection of pivot pins against a spring bias, but then each locate in a respective depression in the confronting surface of the other of the housings. Said depression may be peripherally continuous about one of the confronting surfaces and the pivots may be slidable within the depressions whereby in addition to pivotal movement the pivots allow relative rotational movement about a longitudinal axis extending, for example, between the open and substantially closed ends of the housing. As an alternative to spring-loaded type pivot devices other pivot devices such as rivets or screws may be employed.

The intumescent material may be based on graphite or other intumescent material(s) which expands in volume upon exposure to extreme heat. The thickness of the intumescent typically may be in the range 0.4mm to 6.0mm, more typically in the range 0.6mm to 2.0mm. An example of a graphite based material suitable for use in implementing the present invention is that supplied by Technical Fibre Products Limited under the name "Intumescent Material" and consisting of a high temperature Rockwool fibre mat containing easily dispersed foliating graphite bonded in acrylic.

Although some features of the present invention have been described in combination with other features of the present invention, it is to be understood that said features may be provided independently of one another or in combinations which differ from those specifically described.

Embodiments of the present 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, part cut away, of a light unit in accordance with a first embodiment of the present invention; Figure 2 is a longitudinal sectional view of the light unit of Figure 1; Figure 3 is a longitudinal sectional view of the light unit of Figure 1 in a plane perpendicular to that of Figure 2; Figure 4 is a perspective view, part cut away, of a light unit in accordance with another embodiment of the present invention, in combination with a driver and connector; Figure 5 is a longitudinal sectional view of the light unit of Figure 4, and Figure 6 is a perspective view of the inner housing of the light unit of Figures 4 and 5, A heat resistant, fire-rated swivel type LED light unit 10 (see Figures ito 3) for insetting into a plasterboard ceiling or wall comprises an outer housing ii and an inner housing 12.

The outer housing ii comprises a generally cylindrically shaped central body 13 which is open at one end 14 and relatively closed at the other end 15. The open end, in known manner, has secured thereto an outwardly extending flange 16. A pair of spring-loaded retention arms 17 extend from the body 13 whereby, in use, the arms bear against the normally hidden side of the plasterboard (not shown) and hold the flange 16 firmly against the other, visible side of the board. A band of intumescent material 18 extends around that end region of the central body 13 adjacent the flange so as to align with the aperture formed in the plasterboard for accommodating the light unit and thereby effect a fire barrier between the light unit and ceiling void.

The inner housing 12 is of a part-spherical shape and supports internally an electrical fitting in the form of an illumination unit 20 comprising an LED array 21, lenses 19 and a heat sink 22. The LED array is mounted adjacent a fire guard plate 24 whereby the lower end 23 of the inner housing 12 is effectively closed to prevent through-flow of air.

The inner housing 12 is pivotally supported relative to the outer housing 11 by means of a pair of spring-loaded pivot pins 25 (see Figures 1 and 3) positioned at diametrically opposite positions and mid-way between the ends of the housing. Each pin extends from a supporting barrel 26 which contains a spring 27 to urge the end of the pin outwards from the barrel. The barrel is located within a socket 28 formed in the housing wall and in the assembly as shown each pin extends into a blind bore cavity 29 formed in the outer housing. The inner housing is thereby pivotally mounted relative to the outer housing for pivotal movement about an axis of rotation which is perpendicular to the major] longitudinal axis of the cylindrical central body 13 of the outer housing.

At a position aligned with each blind bore cavity 29 the inner surface of the outer housing is formed with a circumferentially extending recess 30 (see Figure 2). A band 31 of fire resistant intumescent material of semicircular shape is located in each of the two semi-circular portions of the recess extending between the two cavities 29 such that they are able to provide a barrier to passage of hot gases or flames through the casing, via the spacing between the inner and outer housings.

That end region of the outer housing which is further from the flange 16 than the pivot pins 25 is provided with ventilation apertures 32. Similarly ventilation apertures 33 are provided in the region of the surface of the inner housing which at all times confronts said apertured end region of the outer housing.

That is, the ventilation apertures 33 of the inner housing are positioned such that for all swivel positions of the inner housing the inner housing ventilation apertures lie further from the flange 16 than the pivot pins 25 and the intumescent bands 31.

Accordingly, in conjunction with the external band 18 of intumescent material provided adjacent the flange, and the fire guard plate 24 in the lower end region of the inner casing, the aforementioned inner bands 31 advantageously assist in providing a fire-rated quality of casing. Furthermore that is achieved in a compact construction together with allowing for effective ventilation and air-cooling of heat generating components within the casing.

In the aforedescribed embodiment of the invention the outer housing 11 is relatively closed at the end 15 furthest from the open end 14. In contrast, in accordance with a second embodiment of the present invention (see Figures 4 to 6) a heat resistant fire rated swivel type LED light unit 40 comprises an outer housing 41 which is substantially open at each end.

The outer housing 41 comprises a generally cylindrically shaped central body 43 which is open at one end 44 from which an outwardly extending flange 46 extends. The other end 45 is integrally formed with a small radially inwardly extending flange 47 which assists in providing support for a pair of diametrically opposed support brackets 50 to which a pair of spring loaded retention arms 48 are secured in known manner. The brackets 47 also provide support for a mounting plate 53 to which a driver unit 54 is secured in a position which extends over and is spaced from the heat sink 52 of an illumination unit 51.

A band 49 of intumescent material extends around the central body 43 of the outer housing 41 An inner housing 42 is pivotally supported relative to the outer housing 41 by means of a pair of diametrically opposed pivot pins 55 which are secured to the outer housing and extend into the wall of the inner housing such that the inner housing pivots relative to the pins. The pins are located at diametrically opposite positions which lie on an axis which extends through the centre of curvature of the inner housing 42.

An annular band 58 of fire resistant intumescent material is provided between the inner and outer housings to encircle the inner housing at a position aligned with the major, maximum diameter of the inner housing as considered in a direction perpendicular to the cross section of Figure 5.

The band 58 is held in position by means of adhesive which secures it to the outer housing 41, around all of the inner periphery of the outer housing except at two diametrically opposite positions 59 aligned with the pivot pins 55. At each of these pivot positions 59 the band 58 is spaced locally from the outer housing by tabs 60 which extend from the main body 61 of the inner housing.

Each tab is provided with an aperture 62 that locates with a pivot pin 55 such that the housing is thereby pivotally secured relative to the housing.

The illumination unit 51 is of a kind corresponding to that described in respect of the first embodiment of the present invention.

Although in this second embodiment of the present invention the inner housing 42 has a part spherical shape which substantially wholly lies to one aside of the pivot pin axes, and only a short distance in the other direction, towards the end 45, the proximity of the inwardly extending flange 47 assists to ensure that the inner housing cannot be pivoted to a position at which the entire periphery of the inner housing ceases to be in contact with the annular band 58 of intumescent material.

Accordingly there results a more compact construction in which the heat sink 52 is exposed substantially wholly to the surrounding environment and thus is able readily to dissipate heat in an efficient manner.

Claims

Claims.1. A heat resistant casing comprises an outer housing for locating relative to a support structure such as a ceiling, and an inner casing for housing an electrical fitting such as a lighting element, the inner housing being supported for at least one of pivotal and rotational movement relative to the outer housing, the outer surface of the inner housing being spaced from the inner surface of the outer housing and the space therebetween being occupied by at least one element of fire resistant intumescent material which substantially wholly surrounds the inner housing thereby to inhibit passage of hot gas or flames through the casing via the space between the inner and outer housings.
2. A casing according to claim 1 wherein the outer housing is of a substantially tubular shape.
3. A casing according to claim 1 or claim 2 wherein the outer housing is open at one end to facilitate insertion of the inner housing and or an electrical fitting to be positioned and retained within the casing.
4. A casing according to any one of claims 1 to 3 wherein the outer housing is of a tubular shape having a major, longitudinal axis parallel with the length of the tubular housing and the inner housing is pivotally mounted about an axis which is substantially perpendicular to said longitudinal axis.
5. A casing according to any one of the preceding claims wherein the outer housing is of a tubular shape which has a major, longitudinal axis parallel with the length of the tubular housing and the inner housing is mounted for rotational movement about said longitudinal axis of the outer housing.
6. A casing according to any one of the preceding claims wherein the outer housing is open at one end and ventilation apertures are provided in a region of the outer housing which is further from said open end than intumescent material between the housings.
7. A casing according to claim 6 wherein that region of the inner housing which, for all relative positions of the housings, confronts an apertured region of the outer housing is provided with ventilation apertures.
8. A casing according to anyone of the preceding claims wherein the inner housing comprises a component, or is adapted to receive and locate a component which acts to inhibit air flow between the end regions of the inner housing.
9. A casing according to any one of the preceding claims wherein at least one of the inner surface of the outer housing and the outer surface of the inner housing is provided with retention means, such as a recess, for location of said intumescent material.
10. A casing according to claim 9 wherein at least one of said housings is provided with a recess which is peripherally continuous as considered in a cross-section plane perpendicular to a longitudinal axis of the outer housing, at least a part of the thickness of the element of fire resistant intumescent material being located in said recess.
11. A casing according to any one of the preceding claims wherein the fire resistant intumescent material provides frictional resistance to pivotal and for rotational movement of the inner housing relative to the outer housing.
12. A casing according to any one of the preceding claims and comprising at least one pivot device whereby the inner housing is supported for pivotal movement relative to the outer housing.
13. A casing according to claim 12 wherein said pivot device extends through an element of intumescent material.
14. A casing according to claim 12 or claim 13 wherein an element of intumescent material is positioned substantially adjacent the pivot device.
15. A casing according to any one of the preceding claims and comprising two pivot devices located or acting at diametrically opposite positions of a circular section inner housing.
16. A casing according at claim 15 and comprising two semi-circular elements of fire-resistant intumescent material each extending between the two pivot devices.
17. A casing according to any one of the preceding claims wherein the outer housing is of a substantially cylindrical shape and the inner housing is of a part-spherical shape.
18. A casing according to any one of the preceding claims wherein the outer housing is open at one end and said one end is provided with an outwardly extending flange for location against a support surface.
19. A casing according to claim 17 wherein an outer surface region of the outer housing adjacent said flange is provided with fire-resistant intumescent material.
20. A casing according to any one of the preceding claims wherein a said element of fire resistant intumescent material is held secured relative to one of the inner housing and outer housing by means of an adhesive.
21. A casing according to any one of the preceding claims wherein the outer housing comprises an inwardly extending abutment flange which in use restricts the range of pivotal or rotational movement of the inner housing.
22. A fire-rated element comprising a heat resistant casing according to any one of the preceding claims.
23. A casing substantially as hereinbefore described with reference to the accompanying drawings.