GB2339955A

GB2339955A - Fire or flashover simulation

Info

Publication number: GB2339955A
Application number: GB9916104A
Authority: GB
Inventors: Ewen Macrae Duncan; Charles William Sandema Duncan
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-10
Filing date: 1999-07-12
Publication date: 2000-02-09
Anticipated expiration: 2019-07-12
Also published as: GB9916104D0; GB2339955B

Description

1 2339955 APPARATUS FOR USE IN FIRE SIMULATIO The present invention

relates to an apparatus for use in fire simulation. In particular, though not exclusively, the present apparatus may be used to provide a demonstration of the development and spread of a flame front in an enclosed and\or partially enclosed space.

When a material, such as wood, cloth or a plastics material is heated above a threshold temperature, inflammable vapours are released. These vapours may accumulate in an enclosed or partially enclosed space, mixing with air to form an inflammable vapour\air mixture.

The tendency for the mixture to ignite and burn is dependant on a number of factors such as the ratio of air to vapour in the mixture, and the temperature of the mixture. Thus, as heating of a material continues, there comes a point when the temperature of the mixture and the ratio of air to vapour in the mixture is such that the mixture will ignite on exposure to a flame or spark. This point is known as the mixture's lower explosive limit or flash point. when the mixture is ignited at or above this limit, a flame front propagates from the point of ignition through the mixture.

Propagating flame fronts or "flashovers" are often encountered in burning buildings and present a common hazard for 'Lire-fighters. To control the spread of a fire within a burning building in an effective manner, and for 2 their own safety, it is critical that fire-fighters understand how flame fronts behave and develop in an enclosed or partially enclosed space.

Accordingly, it is desirable to be able to simulate the spread of a flame front for the purpose of educating and training individuals in the principles and techniques of fire-fighting and fire-control.

GE 2294572 A describes a flashover simulator unit for simulating the spread of a flame front through an inflammable mixture of fuel and air. The unit comprises a housing formed from a 12.2 m x 2.4 m (401 x 81) fabricated haulage container. The housing defines two interconnecting chambers which are separated by internal doors. A fire is lit in one of the chambers causing the temperature of the chamber to rise. When the temperature of the chamber reaches a threshold value, the internal doors are opened and pressurised hydrocarbon fuel is introduced into the housing. The fuel spontaneously ignites and the combustion of pressurised hydrocarbon fuel causes a flame front to propagate through the housing.

It is among the objectives of embodiments of the present invention to provide an apparatus for use in fire simulation which allows for the creation and observation of flame fronts produced by the combustion of materials commonly encountered in burning buildings and other situations likely to be encountered by firefighters.

According to one aspect of the present invention there is provided an apparatus for use in fire simulation, the 3 apparatus comprising:

a non-combustible elongate housing defining an area towards an end of the housing for containing material to be heated, and observation means for allowing the interior of said housing to be observed from the exterior thereof, in use, material being heated within said housing to release inflammable vapours which accumulate within said housing and mix with air to produce an inflammable vapour\a-4r mixture, the mixture being ignited in said housing to produce a propagating flame front which spreads through the vapour\air mixture, the development and spread of the flame front being observable from the exterior of said housing via said observation means.

is The apparatus may be used to simulate the spread of a flame front through, for example, a burning building.

When combustible material is heated within the housing, vapour and smoke are produced. The vapour accumulates within the housing and mixes with air to form an inflammable vapour\air mixture. As the heating proceeds, more vapour is released, and there comes a point when the temperature of the mixture and the ratio of air to vapour in the housing are such that the air\vapour mixture in the housing will ignite on exposure to a flame or spark.

This point is known as the mixture's lower explosive limit.

When the mixture in the housing is ignited, a flame front is produced and spreads from the point of ignition through the vapour\air mixture. Because the flames are 4 contained within the housing, observers may safely view the combustion process from the exterior of the housing, without being exposed directly to the flames. Thus, the operation of the apparatus may be supervised safely by a single operator.

The flammability of the vapours released within the housing is dependent on the nature of the material used.

In burning buildings, inflammable vapours released from wood-based materials are commonly encountered. Thus, to simulate such a situation, similar wood-based materials may be heated within the housing, such as treated or untreated - timber, medium density fibreboard (MDF) and chipboard. In other simulations, materials such as polyurethane may be utilised. The material may be provided in any shape or is form, for example, as boards, blocks or as fragments of various sizes.

The material may be heated by lighting a small fire within the housing. For example, kindling may be lit in the vicinity of the material causing the material to decompose and ignite, releasing vapour and smoke in the process. The flames produced during the course of combustion may serve to ignite the mixture on reaching its lower explosive limit. In other embodiments, heaters or spark producing means may be provided.

Preferably, the observation means takes the form of one or more windows in the housing. The windows may be formed of any suitable transparent material, for example, heat resistant glass or plastics. The interior of the housing may also be observed using a closed circuit television (CCTV) system. Alternatively, the interior of the housing may be monitored by a video imaging system.

Preferably, the apparatus further comprises control means for regulating the flow of air into and out of the housing. The control means may take the form of one or more ports, hatches or vents which may be opened by varying degrees to demonstrate that flame behaviour is dependent on the amount of air present within the housing. The housing may further comprise a vent which may be opened to allow smoke and gas to escape from the housing.

In a preferred embodiment, the apparatus further comprises extraction means for removing smoke and gas from the vicinity of the apparatus. Conveniently, the extraction means is in the form of a hood mounted over the body of the apparatus. For example, a conventional fume hood may be used. Such an arrangement has a number of benefits: removal of smoke and gas from the apparatus enables firefighters to watch the development of the fire without being encumbered by specialised firefighting clothing or endangered by potentially toxic fumes, as well as preventing smoke build-up from obscuring the view of the apparatus.

Preferably, the housing is adapted to receive a container for the material to be heated. The container may be lined with the material to be heated. In. one embodiment, the container is adapted to receive a wire frame for securing boards or panels of material against the 6 inside walls of the container. The open structure of the wire frame ensures that, when the boards are heated, any vapour and smoke released is free to spread into the remainder of the housing. Conveniently, the container is in the form of a box or drawer.

Conveniently, the apparatus is mounted on base members which raise the main body of the housing relative to a supporting surface so as to minimise the risk of heat damage to the supporting surface, which may be a stand, table, desk or portable support, such as a trailer.

Advantageously, the apparatus is portable.

According to a further aspect of the present invention, there is provided a method for simulating a fire, said method comprising the steps of:

providing an apparatus comprising a non-combustible housing, and observation means for allowing the interior of said housing to be observed from the exterior of said housing, heating material within said housing to release inflammable vapours, and allowing the inflammable vapours to (I) accumulate within said housing and mix with air to produce an inflammable vapour\air mixture, and then (ii) ignite to produce a propagating flame front which spreads through the vapour\air mixture, the development and spread of said flame front being visible from the exterior of said housing via said observation means.

Preferably the method further comprises the step of 7 removing smoke and\or gas from the vicinity of said housing.

These and other aspects of the present invention will now be described with reference to the following drawings in which:

Figure 1 is a perspective view of an apparatus for use in fire simulation, in accordance with a preferred embodiment of the present invention, Figure 2 is an exploded view of the container of the apparatus of Figure 1, and Figure 3 is a perspective view of the apparatus of Figure 1 including a fume extraction hood.

Figures 1 to 3 depict an apparatus 10 in accordance with a preferred embodiment of the present invention. The apparatus 10 comprises a non-combustible housing in the form of an elongate mild steel box 12 measuring 92.075 cm x 25.4 cm x 25.4 cm (36.2511 x 1011 x 1011). The box 12 includes a releasable lid 14, and is adapted to receive a drawer-like container 16 at one end.

The box 12 comprises a plurality of windows 18 which are formed of heat resistant glass and secured in position by retaining clamps 20. The windows 18 allow the interior of the box 12 to be viewed from the outside. The box 12 also comprises a main hatch 22, side hatches 24, and a vent 26 for regulating the flow of air into and out of box 12.

In this example, the container 16 is lined on three sides with panels of medium density fibreboard (MDF) (Figure 2). Two panels 42 of MDF are positioned between 8 the sides of a wire frame 40 and the side walls of the container 16. A third panel 44 is placed over the top of the frame 40. By positioning the boards 42, 44 in this manner, the flame front produced in the box 12 tends to simulate, on a smaller scale, a flame front such as may be produced when inflammable vapours released from the walls and ceiling of a burning building are ignited. The open structure of the frame 40 and the open end of the container 16 ensure that vapours released from the panels 42, 44 are free to flow from the container 16 into the remainder of the elongate box 12.

once lined, kindling (not shown) is placed in a corner of the container 16 and ignited. The container 16 is then mounted within an end portion of the box 12 (Figure 1) and secured in position by clips 28.

The heat generated by the burning kindling causes the MDF panels 42, 44 to decompose. With time, the burning kindling may also ignite the panels.

The smoke and vapour produced by the decomposition and burning processes accumulate within the box and mix with air to form an inflammable vapour\air mixture. As the burning continues, there reaches a point when the temperature of the mixture, and the ratio of air and vapour in the mixture, are such that the mixture will ignite. At this point, the vapour\air mixture in the upper region of the box 12 is ignited by the burning kindling, causing a flame front to spread along the length of the ceiling of the box from the container 16.

9 The ignition of the vapours in the upper region of the box 12 may be controlled to some extent by the use of a baffle plate 32. The baffle plate depends from the lid of the box and is positioned towards the end portion of the box 12, adjacent to the container 16. As shown in Figure 1, the baffle plate 32 is coupled to a bar 34 rotatably mounted in recesses 36 defined by the walls and lid 14 of the box 12. An end 38 of the bar 34 extends outside the box 12; by turning the bar end 38 the baffle plate 28 may be rotated through 900.

Initially, the baffle plate 28 is positioned at right angles to the lid of the box. In this position, the vapours accumulating in the upper region of the box 12 very quickly reach the lower explosive limit.

is When the baffle plate 28 is pressed against the lid 14 of the box 12, vapour\air mixture in the region labelled "All (Figure 1) of the box 12 is exposed to the f lames in the container 16. Thus, when mixture in region "All is at its lower explosive limit the baffle plate 28 may be pressed against the lid 14 of the box to ignite the mixture, causing a flame front to spread from the point of ignition along the ceiling of the box 12. The propagation of the flame front may be observed from outside the box 12 through the windows 18.

The hatches 22, 24 may be opened by varying degrees during the combustion process to demonstrate that the behaviour of a flame will vary depending on the amount of air present. Additionally, the flow of gases\smoke out of the box 12 may be controlled by opening the vent 26.

The apparatus 10 is mounted on a frame 46 to raise the box 12 relative to a supporting surface. Accordingly, when the apparatus 10 is in use, the risk of heat damage to the supporting surface is minimised.

In a preferred embodiment, the box 12 and frame 46 are located within an extractor hood 48 (Figure 3) connected to an exhaust vent 50. This enables removal of smoke and gas from the apparatus 10, so preventing observers from being affected by smoke, and reducing obstruction of the view of the apparatus by smoke. The hood 48 also includes protective front and side walls 52, in order to shield observers from the apparatus should any malfunctions occur.

Various modifications may be made to the embodiment described above without departing from the scope of the invention. For example, the f loor of the box 12 may be carpeted. During combustion, the carpet may ignite and f lames may spread along the length of the box 12. This will provide a realistic simulation of a fire spreading across the carpeted floor of a building.

Further, the apparatus may be provided with several compartments, or a number of boxes may be connected, to simulate a building having two or more rooms, corridors or even stairways. This allows firefighters to observe the development of a fire through a building.

Claims

1. An apparatus for use in fire simulation comprising:

a non-combustible elongate housing defining an area towards an end of said housing for containing material to be heated; and observation means allowing the interior of said housing to be observed from the exterior; in use, the material being heated so as to release inflammable vapours which accumulate within said housing and mix with air, and the resulting air\vapour mixture being ignited in said housing to produce a propagating flame front.

2. The apparatus of claim 1 wherein said apparatus includes one or both of means for heating material and means for ignition of said air\vapour mixture.

3. The apparatus of claim 2 wherein said ignition means also forms said heating means.

4. The apparatus of any preceding claim wherein said observation means comprises one or more heat-resistant windows in said housing.

5. The apparatus of any preceding claim wherein said observation means includes a CCTV system.

12 G. The apparatus of any preceding claim wherein said observation means includes a video imaging system.

7. The apparatus of any preceding claim which includes means to regulate the flow of air into and out of said housing.

8. The apparatus of claim 7 wherein said regulation means is in the form of vents which may be opened and closed.

9. The apparatus of any preceding claim including a vent which may be opened to allow smoke and gas to escape from said housing.

10. The apparatus of any preceding claim further comprising extraction means for removing smoke and gas from the vicinity of the apparatus.

11. The apparatus of claim 10 wherein said extraction means comprises a hood mounted over said housing.

12. The apparatus of any preceding claim wherein said housing is adapted to receive a container for material to be heated.

13. The apparatus of claim 12 wherein said container is lined with material to be heated.

13

14. The apparatus of claim 12 or 13 wherein said container is in the form of a drawer.

15. The apparatus of any preceding claim wherein said housing includes means for raising said housing relative to a supporting surface.

16. The apparatus of any preceding claim in combination with a portable support.

17. The apparatus of any preceding claim wherein the housing is divided into a number of separate communicable compartments.

18. An apparatus substantially as herein described.

19. A method for simulating a fire, the method comprising the steps of:

providing an apparatus comprising a non-combustible housing, and observation means for allowing the interior of said housing to be observed from the exterior of said housing; heating material within said housing to release inflammable vapours; allowing said inflammable vapours to accumulate within said housing and mix with air to produce an inflammable vapour\air mixture; and igniting said mixture to produce a propagating flame 14 front, the development and spread of said flame front being visible from the exterior of said housing via said observation means.

20. The method of claim 19 further comprising the step of removing smoke and\or gas from the vicinity of said apparatus.