GB2475258A - Ventilator grille - Google Patents

Abstract

A ventilator grille comprises at least a first and second array of spaced apart parallel wires mounted in a frame, the wires of the first array or wires being parallel to the wires of the second array of wires, and the wires being coated with an intumescent paint such that the ventilator grille is sealed by the intumescent paint after expansion on exposure to heat. The first array of wires may be staggered relative to the wires of the second array of wires when viewed perpendicularly to the plane of the array of wires. A third array of spaced apart parallel wines may be used with one array of the wires being staggered relative to the wires of each adjacent array of wires. The first array of wires may be in-line with a respective wire of the second array of wires. The parallel wires may form a mesh.

Description

Ventilator Grille The present invention relates to ventilator grilles and, in particular, grilles which incorporate an intumescent paint which on exposure to heat expands to close the grille to prevent hot gas and fire passing through the grille.

One known approach is to place a metal honeycomb structure within a frame of the grille so as to present an array of square cross-section tubes through which air can flow for ventilation. The planar sides of the honeycomb are coated with an intumescent paint such that the honeycomb tubes are closed when the paint expands on exposure to heat.

A potential failure point in such known grilles is that after the paint swells from the sides of each tube a central through hole can be left which means the grille is not fully sealed.

The present invention is a ventilator grille which comprises a frame, at least a first and a second array of spaced-apart parallel wires spanning the frame, the wires of the first array of wires being parallel to the wires of the second array of wires, and in which the wires are coated with an intumescent paint and the spacing of the adjacent wires of the two arrays and the thickness of the coating of the intumescent paint is such that the ventilator grille is sealed by the intumescent paint after expansion on exposure to heat. The invention may take at least the following two forms.

A first arrangement is a grille in which the wires of first array of wires are located in staggered positions relative to the wires of the second array of wires when viewed in a direction perpendicular to the planes of the arrays of wires. The wires are individually coated with intumescent paint. The wires may be spaced apart such that the paint on the wires in the same array does not expand sufficiently to bridge the gap between those wires but wires of the other array being positioned such that the paint of these nearby staggered wires of the other array expanding to flU the gap that would otherwise be present if only the wires of the first array were present.

Such a ventilator grille may include a third array of spaced-apart parallel wires spanning the frame in which the wires of one array of wires are located in staggered positions relative to wires of each adjacent array of wires when viewed in a direction perpendicular to the planes of the arrays of wires.

In a second arrangement is a ventilator grille in which the wires of the first array of wires are located in-line with a respective wire of the second array of wires when viewed in a direction perpendicular to the planes of the arrays of wires and the intumescent paint coating occludes the gap between each of the pairs of wires of the respective arrays of wires which are in-line with each other. This provides that each pair of wires can support a large volume of intumescent paint in their shared coating allowing a larger inter-wire gap to be sealed than would be possible if the wires were individually coated in intumescent paint with none bridging the inter-wire gaps.

Conveniently, the parallel wires of each array of wires of the ventilator grille of the present invention are wires of a respective mesh.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures.

Figure 1 shows a frame A in which steel wires B are held, preferably 1.5mm steel wires at 1 2mm intervals.

Figure 1 b shows the end of one of the 1.5mm steel wires of Figure 1 with the end bent at 90 degrees.

Figure 1 c shows an exploded part view of the frame of Figure 1 showing how the wires are held in place by frame members. Wire end E fits into slot F and is encapsulated by riveting sheet metal part H to sheet metal part I with rivets through holes G. Figure 2 shows the wires and frame of Figure 1 after it is assembled.

Figure 3 shows an exploded view of a embodiment of the invention having a housing A which has steel tubes D welded into its inner side and which locate wire grille Band E via holes C in the frames holding the wires.. The grille panels are fixed inside the housing with circular spring retaining washer fitted over tube D. Holes C in the wire panel frames are positioned so that the wires of each grille overlap the gaps of the other (see figure 5).

Figures 4a and 4b show the front and rear of the grille of Figure 3 when assembled.

Figure 4c is a close up view of a corner of the grille as shown in Figure 4b showing the steel tube D over which the spring retaining washer is placed to keep wire panels C in place.

Steel tubes D also act to guide fixing screws that will hold the frame in place when fixed to a wall.

Once frames holding the wires panels have been made as in Figure 1 a layer of polythene is laid onto a bench and Thermo Guard W intumescing paint (other intumescing paint may be used) suitable is pored into a pool on it. This is a viscous paint and is spread to a depth of approximately 20mm to an area larger than each individual wire panel. Each wire panel is then placed onto the paint and pushed so to allow the paint to cover it completely. The paint is then smoothed over the surface to leave a depth of at least 3mm over the wires, in this embodiment. The coated wire panel is then peeled out of the paint from one corner. The polythene acts to pull the paint out of the gaps between the wires leaving an even coating on the wires. After this the wire panels are put on a rack to dry.

After the wire panels have been coated and dried they are assembled into the grille frame as previously described.

Figure 5 is a diagram showing an example of spacing of the wires on fitting into the grille frame the gap between wires of a given array of wires being 10mm and the pitch of the wires being 1 2mm. In this case each wire A has approximately 0.25mm coating of intumescing paint on it as shown as E giving the coated wire an overall diameter of 2mm.

The free vent area (FVA) of each single wire panel is 83%. In order to maintain this high FVA the combined distance between wire A and C and Band C should equal or exceed the distance between A and B. In order for the intumescing paint expansion to fully fill the gaps between the wires during the exposure to heat it is necessary for the wire panels to be as close to each other as possible hence this configuration of 1.5mm wires at 1 2mm spacing with 0.25 mm of paint on them whilst maintaining the FVA of a single wire set is 4mm as shown in figure 5.

Figure 6 shows the expanded coating of each wire P of the embodiment of Figure 5 intersecting and sealing gaps R. Q represents the gaps that would be left if only one wire set was used. It is not preferable simply to put more paint on each wire since this will lead to a decrease in the FVA of the grille in non-fire conditions plus the fact that the paint coating is not mechanically durable in thicker coatings.

Figure 7 shows a double wire embodiment of the present invention. Two wire panels A and B are fixed together but separated by space strip C to form the grille of Figure 8a, a corner of this grille being shown in detail at Figure 8b. This is done before the panels are coated.

Figure 9 is a part cross section of embodiment of Figure 8a showing the wires, only, each wire of the pairs of wires being 1.5mm in diameter and wire B being adjacent C and spaced from each other by the 1.5mm thick sheet spacer.

When assembled this double wire set is dipped as previously described in intumescing paint.

Figure 9b shows that the gap between double wires D is filled with paint to a thickness of 1.5 to 2mm. This is considerably more volume of paint than can be successfully held on the two single wire alone. Since it is achieved with a single dip in the coating and due to it being held between 2 steel wires is substantially reinforced. The thickness of this double wire pairs in the direction of air flow is the same as a single wire, ie 2mm (and indicated by ID) so a significant increase of intumescing properties is achieved without encroaching on the FVA of the unit. The gap between adjacent pairs of coated wires is 1 0mm as in a single wire arrangement of Figure 5.

Figure 10 shows 2 sets of double wires which are inline. Since there is such a larger increase in intumescing volume properties with this method it negates the need to stagger single wire panels as previously described whilst greatly improving its thermally insulating properties when the intumescent paint has expanded.

Figure 11 shows 2 panels of wire mesh wires. Wire meshes with horizontal or vertical wires only as shown in figure 1 through to 10 are not practical for a grille of over 300mm square since even if in a frame the wires are difficult to hold straight and parallel and in the vertical arrangement are likely to sag. Also the frame that holds the wires is complicated and labour intensive to assemble. It is therefore far more practical to use a wire mesh since these are widely available and are more rigid due to both vertical and horizontal wires being welded to each other.

The mesh shown in Figure lila and ii b (in exploded and assembled condition,respectively} is of 1.5mm steel wireswith 1 2mm x 25mm spacing. To make a double wire panel all that is needed is to either spot weld two mesh sheets together in just a few places or to wire them together so that the wires of each mesh panel are inline with each other. This double mesh panel is then dipped in intumescing coating as previously described.

Figure 1 2 shows that due to the wires being 1.5mm diameter they effectively hold there corresponding wires 1.5mm apart therefore doing away with the need for a separate spacer.

When the double mesh panels are coated and dry they are located into the grille frame by locating the holes in the mesh over the steel fixing screw' tubes that are welded into the grille frame.

Figure 1 3 shows, in an exploded view, mesh panels E and F which are inserted into grille housing A and located via mesh holes B fitting over steel tubes D. sheet metal angles C are then placed into the frame over the mesh and located over the steel fixing screw' tubes D and held into place with steel spring retaining washers.

Even though the performance of each grille is adequate for added insulation integrity each double panel can also be located over the next so that the wires of one panel intersect the gaps in the next. This can be easily achieved by making the distance between the steel tubes in the grille frame used to locate the mesh out of sync with the mesh panels. One panel is then fitted into the frame by putting the top set of holes in the mesh over the tubes and cutting out the wires that interfere with the bottom tubes as indicated by G in figure 1 3.

By doing the opposite for the next panel, locating the holes in the bottom of the grille over the bottom steel tubes and cutting the wires that interfere with the top tubes one effectively stagers each panel so the wires of one intersect the gaps of the other.

In order to increase insulating values of each grille subsequent layers of mesh panels can be added to each grille.

Claims (5)

1. CLAIMS1. A ventilator grille including: a frame: at least a first and a second array of spaced-apart parallel wires spanning the frame, the wires of the first array of wires being parallel to the wires of the second array of wires; and in which; the wires are coated with an intumescent paint; and the spacing of the adjacent wires of the two arrays and the thickness of the coating of the intumescent paint is such that the ventilator grille is sealed by the intumescent paint after expansion on exposure to heat.
2. 2. A ventilator grille as claimed in claim 1, in which the wires of first array of wires are located in staggered positions relative to the wires of the second array of wires when viewed in a direction perpendicular to the planes of the arrays of wires.
3. 3. A ventilator grille as claimed in claim 2, including a third array of spaced-apart parallel wires spanning the frame in which the wires of one array of wires are located in staggered positions relative to wires of each adjacent array of wires when viewed in a direction perpendicular to the planes of the arrays of wires.
4. 4. A ventilator grille as claimed in claim 1 in which the wires of the first array of wires are located in-line with a respective wire of the second array of wires when viewed in a direction perpendicular to the planes of the arrays of wires and the intumescent paint occludes the gap between each of the pairs of wires of the respective arrays of wires which are in-line with each other.
5. 5. A ventilator grille as claimed in any preceding claim, in which the parallel wires of each array are wires of a respective mesh.