WO2019036755A1

WO2019036755A1 - Improvements in and for fire protection

Info

Publication number: WO2019036755A1
Application number: PCT/AU2018/050885
Authority: WO
Inventors: David Mann
Original assignee: AAA R & D Pty Ltd
Priority date: 2017-08-21
Filing date: 2018-08-21
Publication date: 2019-02-28

Abstract

A web for insulating vulnerable material from fire. The web includes intumescent material and mesh. The intumescent material is configured to activate, to form activated material, in response to fire. The mesh is capable of remaining intact to support the activated material.

Description

IMPROVEMENTS IN AND FOR FIRE PROTECTION

FIELD

The invention relates to fire protection. BACKGROUND It is desirable to protect elements of buildings and vulnerable materials from fire, e.g. to minimise damage to the structure or at least delay structural collapse to give occupants more time to escape.

Vulnerable elements can be protected by the addition of one or more insulating layers. Intumescent coatings are often specified to protect structural steel such as I- beams and hollow sections because of their attractive, paint-like appearance. The thin, aesthetically attractive, layer of intumescent material is activated by the heat of fire to swell to form activated material frequently referred to as 'char'. The activated material is much thicker than the original paint-like layer and provides a high degree of insulation. On the other hand, the application of intumescent coatings is typically expensive.

Usually the steel must first be shot blasted and cleaned, and then primed. The primer typically takes about 48 hours to dry before a first coat of intumescent material can be applied. Typical intumescent coatings are relatively flowable so that, at most, about 1000 pm of material can be applied in each coat. 1000 pm of coating typically dries to about 600 m thick over a period of about 48 hours before the next coat can be applied. As such, five or six coats of intumescent materials can be required to build up, say 3 or 4 mm of material to protect a steel column. This can take weeks and many man hours. For each coat, the application equipment must be set up, the coating applied, and then the equipment cleaned and packed away. Activated intumescent materials are not as mechanically robust as some other insulators. Robust insulators are required to protect vulnerable materials at risk of exposure to energetic jet fires to minimise the risk of the insulator being blown away, leaving the vulnerable material unprotected.

Many buildings carry ducts for heating and/or ventilation and/or air conditioning, etc (hereinafter HVAC ducts). It is important to protect such ducts from fire so that fire is not allowed to enter the ducts and therethrough propagate throughout the building.

One approach to the protection of HVAC ducts involves the application of vermiculite. Typically mesh is first pinned to the exterior of duct work to give purchase to the vermiculite when it is applied by spraying.

Another approach to protecting HVAC ducts involves the application of suitable insulating blankets, e.g. ceramic wool blankets. Typically the blankets are held in place with suitable strapping and/or pinned to the exterior of the ducts.

Both of these existing approaches are slow and laborious and thus expensive.

Figure 1 illustrates a joint J between the end Ei of a duct section and the end E2 of another duct section. The ends Ei, E2 each incorporate flanges F. A gasket G is clamped between the two flanges and hardware H clamps the two flanges together to complete the joint J.

The illustrated duct sections have a rectangular profile. For the avoidance of doubt, as the wording is used herein, a square is an example of a rectangle.

HVAC duct systems often incorporate fan-and-motor units for moving air along the ducts. Such units are sources of vibration. Figure 2 illustrates a flexible portion FP for carrying fluid between two fluid-carrying portions of a duct system, e.g. from a fan- and-motor unit to a duct section. Such flexible portions are sometimes known as 'duct vibration dampeners' or 'duct vibration isolators'.

Concrete, such as the structural linings used in vehicular tunnels, is also vulnerable to fire. Typically, such concrete is reinforced by steel reinforcing bars and has some moisture content even years after the concrete has cured. When exposed to the extremes of fire, the expanding moisture content can fracture the concrete causing portions to fall away leaving the steel reinforcement exposed. With ongoing heating the reinforcement loses its strength whereupon the tunnel lining may collapse.

An existing approach to protecting the structural linings of tunnels entails the addition of further cementitious material. First a mesh is fixed to the structural concrete to support the further material and then the further material is sprayed on through a process known as 'shotcreting'. The material is then trowelled-off by hand.

The present inventor has recognised that this process is slow and laborious and that a relatively thick layer of further material is required to insulate the structural lining. Furthermore, the present inventor has recognised that this additional thickness is relatively costly in that it necessitates a relatively larger hole being bored to form the tunnel.

US patent no. 8,444,790 discloses an intumescent fire protection barrier in the form of an adhesive sheet or continuous roll of tape. The barrier comprises intumescent material, a reinforcing matrix, a pressure-sensitive adhesive and a release liner. The barrier is adhesively applicable and can be applied in multiple layers.

The present invention aims to provide improvements in and for fire protection, or at least to provide alternatives for those concerned with fire protection.

SUMMARY

One aspect of the invention provides a web, for insulating vulnerable material from fire, including intumescent material configured to activate, to form activated material, in response to fire; and mesh capable of remaining intact to support the activated material.

Preferably at least most of the mesh is bracketed by the intumescent material. Most preferably at least most of the mesh is within a middle 20% of a thickness of the intumescent material. The mesh may be carbon fibre mesh. Another aspect of the invention provides a web, for insulating vulnerable material from fire, including intumescent material configured to activate, to form activated material, in response to fire; and insulation positionable between the vulnerable material and the intumescent material to insulate the vulnerable material until the intumescent material has activated.

The insulation may be non-intumescent insulation, and preferably has an R value of at least 1 .0, e.g. at least 1 .5. The insulation may be composite-ceramic insulation.

The web may include adhesive, e.g. pressure-sensitive adhesive, to adhere the web relative to the vulnerable material. The web may include a backing removable to expose the adhesive.

The web may include a shield for shielding the intumescent material from water. The shield may be metallic.

Another aspect of the invention provides a web, for insulating vulnerable material from fire, including intumescent material; and being a panel having a first edge and a second edge; the second edge being shaped to co-operate with a first edge of an adjacent panel identical to the panel to form an overlapping point. The web may have a third edge and a fourth edge; the fourth edge being shaped to co-operate with a third edge of an adjacent panel identical to the panel to form an overlapping point.

Preferably the web is a flexible web. Most preferably the intumescent material provides at least most of a capacity of the web to insulate against fire. Another aspect of the invention provides a method, of insulating vulnerable material against fire, including placing the web over the vulnerable material. The method may include adhering the web to the vulnerable material and/or applying mechanical fasteners to fasten the web to the vulnerable material. Another aspect of the invention provides a method, of insulating vulnerable material against fire, including placing the web over the vulnerable material; and passing at least one mechanical fastening portion through the mesh of the web to keep the activated material in place.

Optionally the vulnerable material is one of an HVAC duct, structural steel, and a concrete interior of a vehicular tunnel.

Another aspect of the invention provides a prefabricated HVAC duct section including walls insulated by one or more of the webs.

Another aspect of the invention provides a fire-resistant vibration-isolating joint for a duct system; the duct system including a first fluid-carrying portion having an interior for carrying fluid; and a second air-carrying portion having an interior for carrying the fluid; the joint being for connecting the first fluid-carrying portion to the second fluid- carrying portion and including a flexible portion for carrying the fluid; vibration-transmitting material and intumescent material defining a vibration- isolating gap isolating the first fluid-carrying portion from the second fluid- carrying portion; the intumescent material being arranged to, when exposed to fire, close the gap to seal the duct system against the ingress of fire via the joint.

Preferably the flexible portion is arranged within the duct system to be protected from fire by the vibration-transmitting material and the intumescent material. The vibration- transmitting material may define opposed surfaces bracketing the gap. The vibration- transmitting material may be metallic.

Preferably the first air-carrying portion is a fan-and-motor unit. The second air- carrying portion may be a sheet metal duct section.

Preferably the duct system is an HVAC duct system. Another aspect of the invention provides a fire-resistant HVAC duct including an end of a first duct section; an end of a second duct section fastened to the end of the first duct section to form a joint; and intumescent material overlying the joint. The intumescent material may be adhesively applied intumescent sheet. The end of the first duct section and the end of the second duct section may be flanged ends. The duct may have a rectangular profile.

Another aspect of the invention provides a fire-resistant fan-and-motor arrangement, for an HVAC duct system, including a first duct portion; a second duct portion; a fan-and-motor unit between the first duct portion and the second duct portion for moving air along the arrangement; a first flexible portion for carrying the air from the first duct portion to the fan-and- motor unit; a second flexible portion for carrying the air from the fan-and-motor unit to the second duct second; and a fire-resistant enclosure coupled, to the first duct portion and to the second duct portion, to enclose the fan-and-motor unit.

Preferably the enclosure is formed of sheet material at least most, and more preferably substantially all, of which is covered by intumescent material. Preferably the first duct portion and the second duct portion are formed of sheet material at least most of which is covered by intumescent material. The intumescent material may be adhesively applied intumescent sheet.

Another aspect of the invention provides a fire-resistant HVAC duct portion including a tubular portion; and intumescent sheet material adhered to the tubular portion. Preferably the tubular portion is metallic. The duct portion may have a rectangular profile.

Another aspect of the invention provides a fire-resistant HVAC duct portion including an interior along which air is conveyable; a wall; a opening through the wall and via which the interior is accessible; a panel for closing the opening; and intumescent material spanning at least most, and preferably substantially all, of the panel. The duct portion may include a tubular portion for holding the panel a stand-off distance out from the wall; and intumescent material arranged around the opening to expand across the stand-off distance when exposed to fire. Another aspect of the invention provides a fire-resistant HVAC duct portion including an interior along which air is conveyable; a wall; a opening through the wall and via which the interior is accessible; a panel for closing the opening; a tubular portion for holding the panel a stand-off distance out from the wall; and intumescent material arranged around the opening to expand across the stand-off distance when exposed to fire.

Another aspect of the invention provides a HVAC system including one or more, or preferably two or more, of the joint, the duct, the fire-resistant fan-and-motor arrangement, the duct portion with intumescent sheet, and the accessible duct portion.

Another aspect of the invention provides a method, of providing a fire-resistant element to a work site, including applying intumescent material to the element; then transporting the element to the work site.

The element may be a structural element for a building. The element may be hollow. The element may be an HVAC duct section. The element may be metallic. Preferably the applying is adhesively applying. Most preferably the intumescent material includes sheet material.

The transporting may be transporting at least 5 kilometers (3.1 miles). The transporting preferably includes transporting by road. Another aspect of the invention provides a method, of installing a fire-resistant HVAC duct, including mutually joining a first fire-resistant HVAC duct section and a second fire-resistant HVAC duct section to form a joint; and adding fire protection to the joint. Preferably the adding includes adhesively applying intumescent sheet material.

Preferably the duct sections are prefabricated.

Another aspect of the invention provides a panel, for insulating a surface (e.g. the concrete interior of a tunnel) from fire, comprising holes to carry water through the panel; and intumescent material arranged to close the holes when the panel is exposed to fire.

The panel preferably has at least 9, or more preferably at least 25, of the holes per square meter of frontal area of the panel. Preferably each of the holes has a cross- sectional area of not more than 320 mm². Most preferably each of the holes has a cross-sectional area of at least 3 mm².

Another aspect of the invention provides a panel attachable to a surface to insulate the surface from fire and having a total-thickness of intumescent material of at least 3 mm. The panel preferably has a total-thickness of the intumescent material of at least 8 mm. The panel is preferably no more than 25 mm thick, e.g. is about 12 mm thick. The intumescent material spans substantially all of the panel.

The panel is preferably deformable to a radius smaller than 6 m.

Another aspect of the invention provides a method of insulating an interior surface of a tunnel against fire; the tunnel being for carrying vehicles; the method including applying panels to the surface; the panels comprising intumescent material and having a capacity to insulate against fire; and at least most of the capacity being provided by the intumescent material.

The applying may comprise adhesively applying. It may also comprise depositing adhesive. The depositing may be depositing on rears of the panels. The applying may include mechanical-fastening, e.g. to hold the panel in place until the adhesive has cured. Another aspect of the invention provides a method, of insulating a surface against fire, including: applying panels to the surface; the panels comprising intumescent material and having a capacity to insulate against fire; at least most of the capacity being provided by the intumescent material; and the applying comprising adhesively applying. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a perspective view of a joint;

Figure 2 is a perspective view of a flexible portion;

Figure 3 is an expanded cross-section view of a web of material; Figure 4 is a cross-section view of an I-beam;

Figure 4a is a cross-section view of an I-beam;

Figure 4b is a perspective view of the I-beam of Figure 4a;

Figure 5 is a cross-section view of an I-beam;

Figure 6 is a transverse cross-section view of a portion of a duct; Figure 7 is a longitudinal cross-section view of a portion of a duct;

Figure 8 is a cross-section view of a hatch;

Figure 9 is a cross-section view of another hatch;

Figure 10 is a front view of the hatch of Figure 9;

Figure 1 1 is a cross-section view of a portion of a duct system; Figure 12 is a cross-section view of a portion of a duct system;

Figure 13 is a cross-section view of a portion of a duct system;

Figure 14 is a cross-section view of a tunnel lining;

Figure 15 illustrates a panel-application process;

Figure 16a is a cross-section view of an overlapping joint; and Figure 16b is a cross-section view of another overlapping joint. DESCRIPTION OF EMBODIMENTS

The following examples are intended to illustrate to enable reproduction and comparison. They are not intended to limit the scope of the disclosure in any way. The present inventor has recognised that the cost associated with applying intumescent paint can be avoided by adhesively applying a web of material.

Accordingly, intumescent sheet material is proposed. Some forms of the sheet material include gauze (or other suitable reinforcement) to which intumescent material is applied and allowed to set. The material can be applied whilst the vulnerable material is at a convenient working height and orientation and thereby applied more efficiently than on the work site. As such, sheets in the vicinity of 1 mm thick are contemplated. Sheets may be provided in a range of thicknesses, say 0.5 mm, 1 .0 mm and 1.5 mm thick, that can be layered to achieve the desired degree of fire protection. The following proprietary liquids are suitable: Chartek 7E, Chartek 8E, Chartek 7+, Chartek 1620CSP, Chartek 1709, Chartek 2218, Aithon A90H, Jotachar 1709, Nullifire SC902, Nullifire System S, ECT, PPG Pitt-Char XP and PG Pitt-Char NX. Other intumescent materials are possible although preferably the material is water resistant. Epoxy based intumescent materials are typically water resistant. If a non- water-resistant intumescent material is used, preferably it is encapsulated (e.g. with the aid of a sealant) to protect it from water.

Preferred forms of the sheet material are provided with a shield in the form of foil (or other water-resistant) outer layer to protect the intumescent material from water damage. Figure 3 is an exploded cross-section view of a preferred insulating web 1 a well adapted to insulating HVAC ducts such as the duct work of Figure 1.

The web 1 a includes an adhesive backing 3, ceramic layer 5, an intumescent core 7 and a foil shield 9. The core 7 is preferably made up of an epoxy-silicon-based flexible intumescent such as PPG's Pitt-Char XP, along with a structural mesh to support the intumescent material. Preferably the mesh is configured to remain intact when the web 1 a is exposed to fire, to continue supporting the activated intumescent material. Preferably the mesh is formed of carbon fibre.

The mesh is preferably about 5 mm x 5 mm x 1 mm mesh. Carbon fibre is a preferred material, although other fire-resistant materials (e.g. fibreglass) are possible. The mesh is configured to remain intact to support the activated material at least for the desired fire protection level of the web. The web 1 a preferably has a fire protection level of at least 60/60/60 (one hour structural adequacy/integrity/insulation). A fire protection level in the vicinity of 240/240/240 (four hours) is also contemplated for some applications. Preferably the bare mesh per se is capable of maintaining integrity sufficient to support activated material after exposure for at least one hour, or more preferably at least four hours, to a jet fire for tunnels in accordance with ISO 22899-1 :2007 wherein the temperature rises from ambient to 1093°C within five minutes.

One approach to constructing the core 7 entails laying down a first portion of the liquid intumescent material, e.g. spreading half of the material across a suitable pan, and laying down the carbon fibre mesh before laying down the remaining

intumescent material. This combination of ingredients can then be allowed to set.

The inventor has found that the intumescent material is thick enough that the mesh neither sinks nor floats to any appreciable extent, whereby the mesh remains within the middle of the intumescent material whereat it is bracketed by layers of

intumescent material. Those bracketing layers are above and below the mesh when the core is formed in this way, and correspond to inner and outer layers of

intumescent material when the web 1 a is applied in use.

Other modes of production are possible. By way of example, the inner and outer layers of solid intumescent material may be separately produced, and these layers and the carbon fibre mesh brought together along with a suitable adhesive in a single operation. The outer layer 9 is a shielding layer to shield the intumescent material from water. A metallic construction such as foil (e.g. aluminium foil) or metallised plastic is preferred.

The ceramic layer 5 is formed of composite ceramic material, most preferably Mascoat Delta DTI. Other materials are possible, e.g. high temperature silicone would also be convenient.

The present inventor has recognised that intumescent materials, such as the intumescent core 7, take time to react. In the context of protecting vulnerable materials having limited thermal inertia, such as sheet metal duct work, and fires that start very aggressively, the vulnerable material can overheat before the intumescent material has reacted. By way of example, various test standards specify numerous temperature sensors spread across the sample of vulnerable material and dictate that an insulator fails if any one sensor reaches 180°C or an average across the sensors reaches 140°C at any point over a test period. Typically the test period is in the range of 60 minutes to 240 minutes, depending on the requisite fire protection level.

The ceramic layer 5 provides instantaneous protection when a fire starts, to preserve the vulnerable material whilst the intumescent core 7 is activated. Other forms of insulating layer may be employed for this purpose. Preferably the insulating layer is a non-intumescent insulating layer to provide instantaneous protection, although in principle a layer of intumescent material that reacts at a lower temperature and/or faster than the core 7 may also be advantageous.

Preferably the mesh and the ceramic layer each span substantially all of an area of the web whereby the web has a substantially uniform construction across its entire area. Alternatively one or both of the web and the ceramic layer 5 may be portions selectively located e.g. a version of the web might be constructed to suit a particular application and have additional insulation and/or reinforcement in specific areas where it is needed. The insulating layer limits the flow of heat from the intumescent material to the vulnerable element. This limiting not only protects the vulnerable element but also expedites the heating, and thus activation, of the intumescent material by limiting the rate at which the vulnerable material cools the intumescent material. The adhesive backing preferably includes two sub-layers: a pressure-sensitive adhesive fixed to the side surface of the ceramic coating 5, and a backing sheet removable to expose the pressure-sensitive adhesive.

The core is preferably in the range of 4 mm to 8 mm thick. The ceramic coating is preferably in the range of 1 mm to 2 mm thick. A 2 mm thick layer of Mascoat Delta DTI has an R value of approximately 1 .8.

The inventor has found the intumescent sheet material formed by this method to be sufficiently pliable (e.g. can bend to an inner radius in the vicinity of 5 mm) to be conformably applied to the exterior of structural members such as the I-beam IB illustrated in Figure 4. Another approach to protecting an I-beam is illustrated in Figure 5 wherein, instead of conformably wrapping the I-beam, the I-beam is boxed in, e.g. with 0.3 mm thick sheet metal, to which the intumescent sheet 1 is adhesively applied.

Figure 4a and 4b schematically illustrate a preferred wrapping pattern in more detail utilising a variant of the web 1 a, without the insulation 5, to protect structural steel in the form of an I beam 1 b.

To apply the web 1 a, a portion of the backing sheet is removed to expose the pressure-sensitive adhesive in the vicinity of the edge 1 b and that edge of the web is then pressed into place along one edge of the I-beam IB. The backing sheet is then peeled away and the subsequently exposed adhesive continuously pressed onto the I-beam until the worker has worked all about the periphery of the I-beam until a tail 1 c of the web is left overlying the start 1 b. The backing layer is fully removed and the tail 1 c is adhered to the start 1 b in an overlapping arrangement, e.g. an about 50 mm wide overlap. Figures 4a and 4b illustrate a physical separation between the overlapping portions. This is merely for illustration. In practice, they are adhered together.

Suitable mechanical fasteners 4 are the applied to secure the web to the I-beam IB. In this example, the mechanical fasteners take the form of elongate elements (e.g. capacitor discharge pins) which are pressed through the overlapping layers of web 1 a and welded to the I-beam IB. The fasteners may be applied at about 200 mm centres along the beam.

The mechanical fasteners 4 help to keep the web 1 a in place when exposed to fire. In particular, it is not critical that the adhesive be fire-resistant. As such, relatively inexpensive adhesives that are safe and easy to work with can be employed. The shaft of the discharge pins pass through the carbon fibre mesh to co-operate with the mesh to keep it in place as the intumescent material expands. This and other similar forms of mechanical interlocking are simple, convenient and reliable modes of retention. Furthermore, the intumescent material is intimately interlocked with the mesh, whereby the mesh helps to retain the activated material when exposed to more energetic fires. In particular, the risk of large chunks of activated material being blown away is reduced and some of the activated material tends to be retained within the mesh even if the activated material is broken up. Whilst a preferred mode of application has been described, that mode is not the only option; e.g. whilst preferably the intumescent sheet material carries suitable adhesive and a backing removable to expose the adhesive (to enable the simple and convenient peel-and-stick application of the material), the sheet material may be adhesively applied with a silicone-based high-temperature adhesive. HTA (TUNNEL) ADHESIVE™ (CAS no. 1344-09-8; EINECS no 215-687-4) sold by High

Temperature Adhesive Limited is suitable. "Silicate 1200°C KLEJ TERMICZNY" sold under TECHNICQLL™ is also suitable. Preferably the adhesive is rated to at least 1 ,080°C, or more preferably to at least 1 ,200°C. The present inventor has also recognised that significant cost savings can be realised by the provision of prefabricated fire-resistant elements. By way of example, by applying the sheet 1 to the I-beam IB at one location (e.g. in a factory where the beam is at a convenient working height and orientation) and then transporting the beam to a work site, the expense of the on-site application of fire-protective material can be avoided. Of course, often such beams are installed in difficult to access locations once on-site. Accordingly, a range of prefabricated fire-resistant elements such as I-beams, hollow structural sections, steel members and HVAC ducts are contemplated. Whilst these elements preferably have intumescent fire protection, other forms of fire protection may also be applied off-site.

Figure 6 is a transverse cross-section view of a corner of a duct section DS. Separate pieces of the intumescent sheet material 1 are applied to the top and side portions of the duct section DS. Preferably most, or more preferably substantially all, of an exterior of the duct section is covered by the intumescent material. The duct section DS may have flanged ends.

Preferably portions of the applied intumescent material vulnerable to water are suitably sealed. In this example, the corner is sealed by the addition of a foil strip 1 1 . The foil 1 1 may be added off-site and as such form part of the prefabricated duct section. The method of installing the element may entail post-installation sealing of any exposed intumescent material. By way of example, if any of the foil of the layers 1 illustrated in Figure 6 is damaged in transit or during installation, it may be patched with suitable foil patches after the duct section DS has been installed.

Figure 7 illustrates a joint J between two duct sections DSi, DS2. The duct sections are protected by intumescent sheet material 1 and include end flanges F which are suitably fastened on the work site. The joint J further includes a strip 16 of

intumescent sheet material adhesively applied to run about and overlie the joint J.

It is contemplated that the duct sections DSi, DS2 arrive on-site with substantially all of their walls covered by intumescent material whilst their mounting flanges remain exposed to enable the duct sections to be joined in conventional fashion. Preferably the strip 13 is applied on the work site when the duct sections are in their final installed position.

HVAC ducts may be provided with access panels via which their interiors may be accessed. Figure 8 illustrates the wall W of a duct to which a conventional access panel AP is fitted. The access panel AP sits in an opening in the wall W and is removable to permit access to the interior I. In this example, that opening is also closed by a secondary panel 15 formed of sheet metal 17 carrying a layer of the intumescent material 1. The opening O is surrounded by Z-profiles 19 which support the panel 15 a stand-off distance SD away from the wall W. The wall W and wall- facing portions of the Z-profiles 19 both carry intumescent material configured to expand to close the stand-off distance SD when exposed to fire.

Figures 9 and 10 illustrate the preferred mounting arrangement for an access panel 13. According to this arrangement, the panel 13 is mounted to pivot substantially in its own plane relative to the wall W and about pivotal mounting point 21 . The panel 13 is approximately square and the pivotal mounting point 21 is in the vicinity of a corner of the square. One of the stand-off profiles 19a incorporates an oblique return fold 19b in which an edge of the panel 13 spaced from the pivot 21 is captured when the panel 13 is in its closed position. In this position, a locking pin 23 is placeable through suitable apertures in the vicinity of a corner of the panel 13 spaced from the fold 19b and the pivot 21 to hold the panel 13 in the selected position.

Figure 1 1 illustrates a trio of air-carrying portions 17, 18, 21 connected in series. In this example, the air-carrying portions 17, 21 are duct sections and the air-carrying portion 18 is a fan-and-motor unit. The portions 17, 18 are mutually connected by a flexible portion 23 whilst the portions 18, 21 are mutually connected by a flexible portion 25.

The portions 17, 18, 21 are protected by intumescent material which is preferably applied away from the work site as previously described. Intumescent material is also arranged to prevent fire entering the duct system via the flexible portions 23, 25. The portions 17, 18 carry a complementary pair of Z-profiles 17a, 18a defining a pair of opposing surfaces on either side of a vibration-isolating gap G. The Z-profiles 17a, 18a are formed of galvanised steel. Galvanised steel is an example of vibration-transmitting material. 'Vibration-transmitting material', and similar terminology, is used herein in contrast to the vibration-isolating material of the flexible portions 23, 25.

The opposing faces are approximately parallel to the direction of air flow whereby the gap G occupies a short, tubular region of space. The profile 17a carries a 2 mm thick layer of intumescent material. The gap G is about 30 to 35 mm thick, allowing for 20 mm of relative vibration between the portions 17, 18 and about 10 to 15 mm of clearance.

Typical intumescent material expands in thickness by a factor of at least 10 when exposed to fire. The preferred intumescent materials expand in thickness by a factor of 20 or more, whereby the 2 mm thick layer carried by the profile 17a closes the tubular gap G to prevent the ingress of fire to the interior of the duct work via the joint between the portions 17, 18. Most preferably the intumescent material is configured to expand by a factor of at least 30.

In this example, the gap G is external to the flexible portion 23 whereby the flexible portion 23 is to some degree protected from fire, although it is also plausible that the gap G could be arranged internally to the flexible portion 23.

In the variant of Figure 12, the Z-profiles 17a, 18a are replaced by right-angled profiles defining a pair of opposing faces perpendicular to the direction of air flow and defining the gap G. In this example, both of the opposing faces carry gap-closing intumescent material. The orientation of the opposing faces is not critical, although preferably the gap is defined by a pair of faces as opposed to, for example, a face and an edge. In the variant of Figure 12, the joint between the portions 17, 18 is also enclosed by flexible intumescent material 27. In the examples of Figures 1 1 and 12, the flexible portion 23 sits in axial register with the gap G. In other examples, these features may be axially offset.

Figure 13 illustrates an alternative approach to protecting the fan-and-motor unit 18 from fire. The unit 18 is boxed in in tubular enclosure 29. The enclosure 29 is connected to each of the units 17, 21 . Preferably the enclosure is formed of sheet metal protected by intumescent material. Advantageously, strips 16a of flexible intumescent material, akin to the strip 16 in Figure 7, may be applied to protect at the junctures between the units 17, 29 and the juncture between the units 21 , 29.

The enclosure 29 may be equipped with an access panel 33 or other suitable access panel.

As noted, the web 1 a of Figure 3 is well adapted to protect lightweight structures such as HVAC ducts, and a variant of that web without the ceramic coating layer 5 is well adapted to protect heavier structures such as I-beams and other forms of structural steel. To protect the concrete linings CL of vehicular tunnels as shown in Figure 14, the inventor proposes panels 107 akin to the intumescent core 7 (i.e. panels at least predominantly consisting of intumescent material and suitable reinforcing mesh within that material) although other modes of construction are also possible. The panels may be in the vicinity of 10 mm to 20 mm thick. The panel is preferably dimensioned for convenient handling by human operators. 1 .2 m x 1 m is a convenient size. Preferably the panel has a length in the range of 1 m to 3 m and a width in the range of 0.5 m to 1 .5 m.

Each panel may be penetrated by holes, e.g. a rectangular array of holes, to prevent water pressure building up behind the panel and driving the panel away from the surface it is meant to protect. The seepage of significant volumes of water through a tunnel's linings is commonplace.

The holes may be spaced at a density approximately equivalent to a density of a regular rectangular array of holes at about 150 mm centres. Preferably each hole has a diameter of about 5 mm, corresponding to a cross- sectional area of about 20 mm². A hole of about this size is preferred in that it is unlikely to be occluded by sand and similar debris carried by seeping water and is not so large as to materially impede the insulating properties of the panel. When exposed to fire the expanding intumescent material quickly closes the holes. Given these competing factors, hole diameters in the range of 2 mm to 20 mm (corresponding to cross-sectional areas of about 3 mm² to about 320 mm²) are preferred. Of course, holes other than round holes are possible.

The panel and its holes may be formed with the aid of a suitably shaped mould.

Alternatively, the holes may be formed by a post-moulding material-removal operation such as drilling or punching.

Referring to Figure 15, the panel application process preferably commences with cleaning step 201 . The surface to be protected is preferably free of wax and other contaminates. A wax remover such as PREPSOLE™ may be used. The cleaning step 201 may be followed by an adhesive deposition step 203.

Adhesive is deposited onto the rear of the panel. Preferably the deposition is at locations selected so as not to occlude any one of the holes, e.g. parallel stripes of adhesive may be applied along the gaps between parallel rows of holes.

Preferably the adhesive is applied to a thickness of at least 10 mm to ensure adhesive contact even when there is a less than fully conformal fit between the panel and the surface to be protected. The lines of the adhesive are preferably at least 10 mm wide.

The placement of the adhesive may be aided by a suitable jig and/or entirely automated. It is also contemplated that the panels might be pre-fabricated with suitable adhesive (e.g. covered by a suitable removable cover sheet) to eliminate the deposition step 203 from the method 200. After step 203, the panel 107 is then placed against the surface S (Figure 14) of the concrete lining CL at placement step 205. During this step mechanical fasteners 1 15 are applied to hold the panel 107 in place until the adhesive has set. Preferably the mechanical fastening is a nail and most preferably the nail is applied with the aid of a handgun such as an explosive handgun. Nails sold under the trade mark HILTI™ are suitable.

Only a small number of mechanical fasteners are required. In the example of Figure 2 there are five mechanical fasteners 1 15 to hold the 1 .1 m x 1 .1 m panel 1 in place. Of course, other methods of holding the panel in place until the adhesive cures are possible and adhesiveless application techniques may also be practical.

The mechanical fasteners also assist if and when the panel is exposed to fire. Like the fasteners 4 of Figures 4a and 4b, the fasteners 1 15 co-operate with the mesh of the panel to retain the activated intumescent material even if that material breaks away from the adhesive or the adhesive fails. The application process 200 is repeated until the area to be protected is covered. Adjacent panels may be butt-jointed.

In the context of large panels and tunnel walls that nominally curve in two dimensions and are in any case somewhat irregular, butt joints can be associated with significant gaps. Whilst butt joints may be ample for some applications, preferred variants of the panel have profiled sides for forming overlapping joints. Two forms of overlapping joint are illustrated in Figures 16a, 16b.

Figure 16a illustrates an option wherein one of the edges is a female edge and the complementary edge of the adjacent panel is a male edge, whereby when the panels are assembled side by side the complementary male and female portions overlap. Figure 16b illustrates edges having less than half-thickness flanges at the front and back respectively. Both joint options have the rears of the panel in mutual alignment and the fronts of the panels in mutual alignment. Other profiles, e.g. tongue and groove, are possible. Preferably the panels are rectangular (e.g. square) and each adjacent two of the edges are of one type (e.g. male) and the other adjacent two of the edges are of a complementary type (e.g. female). Other shapes and arrangements of edges are possible. By way of example, hexagonal panels can be efficiently tessellated and may be used to create a more interesting aesthetic.

The panels may be formed by laying down liquid intumescent material, reinforcing mesh, and further intumescent material in turn within a mould having suitably profiled sides. Preferred variants of the panel are sufficiently flexible to be lifted from the mould despite any overhanging side-profile-forming portions of the mould. The thickness of the intumescent material is preferably selected to suit the necessary fire rating. Preferred forms of the panel are configured to provide four-hour fire protection to concrete structures such as tunnels, the undersides of concrete soffits and to other structural concrete features such as beams and columns. The panel may be configured to insulate against hydrocarbon-type fires, jetstream fires and cellulose fires. Of course, the panel is not limited in application to the context of tunnels. It may well be usefully applied in a wide variety of commercial, industrial and even residential settings.

Variants of the disclosed panels may have fire rating levels such as: FRL 60, 90, 120 and 240 minutes. Preferred variants are tested to comply with one or more of: · UL 1709 Hydrocarbon;

• Jet Fire in accordance with HES Standard OTI 95 634;

• Up to 4 hours in accordance with UL 263 (ASTM E1 19);

AS 1530 pt 4, AS 4072 pt 1 , AS 1668 pt 1 , AS 3784;

BS 7436 pt 20, ISO 834 and RSW Standards; · USA (NFPA 502, Standard for road tunnels, bridges and limited access

highways); Italy (UNI 1 1076);

• Austria (OVBB);

• Singapore (KPE project); and

• UAE, Dubai (The Palm Jumeirah development). To achieve these fire ratings, the panel preferably has a total thickness of

intumescent material of at least 3 mm. In the described variant, a single thickness of intumescent material is provided. In other variants, the intumescent material may be divided into separate layers, e.g. a total thickness of 5 mm might be made up of two layers that each have a thickness of 2.5 mm and are separated by a layer of reinforcing material.

When exposed to fire, the preferred epoxy based intumescent materials expand in thickness by a factor of about 30 or 40 or more. As such, preferred forms of the panel expand in thickness by a factor of at least 25 when exposed to fire.

The preferred forms of intumescent material have a dull matt finish. This finish is particularly suited to lining vehicular tunnels because (relative to more effective materials) they produce less reflections that might distract drivers driving through the tunnel. To minimise problematic reflections, the outer of the panel 1 17 is preferably treated, e.g. painted, to give it a matt finish.

According to preferred forms of the disclosed panels the volume of the panel body's material (e.g. the volume of the material through which the holes passes) is at least predominantly occupied by a solid material. This is in stark contrast to various insulating products made up of fibres spaced to define air trapping voids. Such fibrous products may not be suitable to wet environments because they may deform when they become wet and heavy and/or provide a growing medium for mould and other undesirables.

In various examples discussed thus far, intumescent material provides substantially all of the fire protection to the underlying substrate (e.g. the underlying sheet metal) to which it is applied. It is contemplated that the intumescent material may be used conjunction with other fire-protecting layers but preferred that the intumescent material provides at least most of the fire protection to the substrate.

Whilst various examples have been described, the invention is not limited to these examples. Rather, the invention is defined by the claims.

Claims

1 . A web, for insulating vulnerable material from fire, including intumescent material configured to activate, to form activated material, in response to fire; and mesh capable of remaining intact to support the activated material.

2. The web of claim 1 wherein at least most of the mesh is bracketed by the intumescent material.

3. The web of claim 1 wherein at least most of the mesh is within a middle 20% of a thickness of the intumescent material. 4. The web of any one of claims 1 to 3 wherein the mesh is carbon fibre mesh.

5. The web of any one of claims 1 to 4 including insulation positionable between the vulnerable material and the intumescent material to insulate the vulnerable material until the intumescent material has activated.

6. A web, for insulating vulnerable material from fire, including intumescent material configured to activate, to form activated material, in response to fire; and insulation positionable between the vulnerable material and the intumescent material to insulate the vulnerable material until the intumescent material has activated.

7. The web of claim 5 or 6 wherein the insulation is non-intumescent insulation. 8. The web of claim 5, 6 or 7 wherein the insulation has an R value of at least 1 .0.

9. The web of claim 5, 6 or 7 wherein the insulation has an R value of at least 1 .5.

10. The web of any one of claims 5 to 9 wherein the insulation is composite-ceramic insulation.

1 1 . The web of any one of claims 1 to 10 including adhesive to adhere the web relative to the vulnerable material. 12. The web of claim 1 1 wherein the adhesive is pressure-sensitive adhesive.

13. The web of claim 1 1 or 12 including a backing removable to expose the adhesive.

14. The web of any one of claims 1 to 13 including a shield for shielding the intumescent material from water. 15. The web of claim 14 wherein the shield is metallic.

16. The web of any one of claims 1 to 15 being a panel having a first edge and a second edge; the second edge being shaped to co-operate with a first edge of an adjacent panel identical to the panel to form an overlapping point. 17. A web, for insulating vulnerable material from fire, including intumescent material; and being a panel having a first edge and a second edge; the second edge being shaped to co-operate with a first edge of an adjacent panel identical to the panel to form an overlapping point. 18. The web of claim 16 or 17 having a third edge and a fourth edge; the fourth edge being shaped to co-operate with a third edge of an adjacent panel identical to the panel to form an overlapping point.

19. The web of any one of claims 1 to 18 being a flexible web.

20. The web of any one of claims 1 to 19 wherein the intumescent material provides at least most of a capacity of the web to insulate against fire.

21 . A method, of insulating vulnerable material against fire, including placing the web of any one of claims 1 to 20 over the vulnerable material.

22. The method of claim 21 including adhering the web to the vulnerable material.

23. The method of claim 21 or 22 including applying mechanical fasteners to fasten the web to the vulnerable material.

25. A method, of insulating vulnerable material against fire, including placing the web of any one of claims 1 to 6 over the vulnerable material; and passing at least one mechanical fastening portion through the mesh to keep the activated material in place.

26. The method of any one of claims 21 to 25 wherein the vulnerable material is one of an HVAC duct, structural steel, and a concrete interior of a vehicular tunnel. 27. A prefabricated HVAC duct section including walls insulated by one or more webs in accordance with any one of claims 1 to 20.