GB2402333A - A ventilating mounting for a chimney flue having heat sensitive closure means - Google Patents

Abstract

A ventilating mounting for a chimney flue comprises a slotted mounting plate 1, a mechanical heat sensitive release mechanism and a top closure plate 4 or 7. In the first embodiment the top closure plate is mounted by resilient brackets 2 arranged to hold the closure plate 4 above ventilation slots in the mounting plate 1 and in the second embodiment the closure plate 7 has slots and is rotatably mounted adjacent to the mounting plate 1. In both cases the release mechanism is actuated by excessive heat causing fusible links 5 or 5 and 9 to melt. In the first embodiment a restraining wire loop 3 disengages and the brackets 2 release the closure plate which falls onto, and closes, the ventilation slots. In the second embodiment springs held in tension are released which rotate the closure plate and cover the slots. The blocking of the ventilation slots has no effect on the flow of gases through the chimney flue.

Description

QUICK RELEASE VENTILATED FIRE STOP PLATE

This invention relates to a Quick Release Ventilated Fire Stop Plate Fire stop plates are in regular use within the prefabricated chimney and flue industry to provide a minimum half-hour fire rating around a chimney or flue where it penetrates a floor. The British Standard which sets the criteria for prefabricated chimneys and flues is BS 4543:Part 2: 1990 (1996). In order to comply with the temperature tests with closed fire stops through combustible floors, only flues with 25mm annulus filled with very high performance insulation, for example silica based powder, or a larger annulus filled with other insulation materials could be used with the standard fire stop arrangement. The British Standard requires the fire stop arrangements to provide a minimum 30 minutes fire rating in accordance with BS 476:PT 20. In recent years a development has been the use of ventilated fire stop plates which allows air movement, but not flames, through the joist compartment. This meant that chimneys or flues with a 25mm annulus, and lower insulation qualities could achieve the criteria of both the fire stop requirement, and the temperature test within the joists of combustible floors, for BS 4543 compliance.

While a ventilated firestop does provide a minimum half-hour fire resistance in accordance with BS 476 pt 20, it Is perceived that a system for closing the ventilated slots in the event of a fire would be preferable. It could also improve the fire rating above the minimum halfhour. An obvious development is the use of an intumescent material around the flue, which in the event of a fire, would seal the ventilation slots. While this method passed the requirements of BS 476 pt 20, the test results showed that closure took several minutes. The time taken to fill the void is slow as intumescent materials do not reach their peak expansion pressure until the temperature reaches approximately twice the initial activation temperature.

Thermal release mechanisms are in extensive use in the heating industry to meet safety requirements on heating appliances, for example dead weight fire valves on oil supply lines.

They are also used to release spring loaded fire dampers closing the interior of ventilation ducts.

However no system using a thermal release mechanism has been developed for use around chimneys or flues serving heating appliances operating on oil, gas, or solid fuel, where these flues pass through combustible compartments, walls, or floors.

The Quick release ventilation fire stop plate utilises a slotted plate design to ensure maximum free area, and therefore effective joist box section ventilation during normal operation of the flue system, however, in the event of a fire in the room below, it incorporates an automatic quick release mechanism which, when subjected to the pre-set temperature, activates and ensures an immediate mechanical closure using a steel plate to cover the venblabon slots. À À .

À . À . À À À À À À À À À . . . . . Àe. À - 2 The ventilated bottom plate and possibly other components may be coated, sprayed, bonded to, or by another suitable method be protected with a fire retardant substance which may help maintain or improve any or all of the load-bearing capacity (load-bearing elements only), the integrity and the insulation of the assembly.

The steel closure plate would preferably be made of metal, but it may instead be made from another fire retardant material.

A fire retardant substance may also be used to form a seal between the edge of the top closure plate, and the circumference of the flue.

Spacers/support brackets will preferably be attached to the ventilated bottom plate and will support the top closure plate as in the current design. They may alternatively be fixed between the ventilated bottom plate and a second top plate. The second top plate may then house the thermal release mechanism.

The assembly may house one or more thermal release mechanisms, thus providing back up release if required. It is preferred that these mechanisms activate in series, but operation in parallel Is possible.

The support brackeVspacers may alternatively incorporate the thermal release mechanism(s).

A further element may be incorporated into the design to act as a full seal mechanism. This may comprise a circular concertina design incorporating a thermal release mechanism, and a tensioning system.

A fusible link is the preferred thermal release mechanism.

It may be preferred to assist the operation of the wire loop, by the addition of coil springs.

Alternatively formed metal strips of standard matenal, or spring steel may be used to hold the support brackets in position.

Alternative thermal release mechanisms that may be used include other solder type, strut type, glass bulb, bi-metallic strip, memory metal, Quartzoid bulb or other thermal release mechanism.

A smoke detector operated automatic release mechanism, incorporating an electro-mechanical device, may also be used instead of, or in addition to, the thermal release mechanism for special À À À . À À À À À c À . . . À À À . . . À - 3 risk applications.

The preferred method of closing the top closure section onto the ventilated bottom plate for a vertical flue assembly is by means of gravitational pull, but spring loading with or without a clamping mechanism may be an option.

For applications suitable for use where a horizontal flue or exhaust runs through combustible walls, a spring system would be the preferred method of closure.

It may be preferred to use lighter, or heavier gauge materials, in mild steel, or stainless steel, or other fire resistant materials.

The fixed ventilated plates will incorporate some form of spacing assembly to facilitate maintaining a minimum distance from combustible materials.

The current design incorporates four off spacers to provide minimum clearance to combustibles.

It may be preferred to use a rotating top closure plate. This plate would incorporate holes to match the pattern of holes in the lower ventilated plate. This plate would be located on top of the lower plate, with the holes aligned for normal operation. This rotating top closure plate could be round or some other shape as required to allow adequate ventilation. In the event of a fire, the thermal release mechanism would activate, and a single, or multiple tensioned spring would induce rotation of the plate, in the horizontal plane through the required number of degrees to cover the holes with the corresponding blank sections of each plate. This top closure plate would be activated by a single, or multiple, thermal release mechanism. A bracket, or alternative stop device would cease the rotation when the holes through both plates were covered by the corresponding blank sections on the other plate. This system could be used in the horizontal, or vertical planes to serve floors or walls.

A preferred embodiment of the invention will now be described with reference to Figures 1 and 2 in which the main features of the plate are numbered as below.

1. Ventilated bottom plate 2. Formed support brackets/spacers to hold the top closure ring in position 3. Wire loop 4. Top closure plate 5. Thermal release mechanism (in this instance a fusible link) 6. Spacers to maintain set distance from combustible materials According to the current invention there is a quick release ventilated fire stop plate which briefly . À À À À . À À . À À À * À À À . . . À . . . À . comprises of a ventilated bottom plate (1) designed to be attached to the underside of the joists.

Attached to the top of the plate are four off formed support brackets (2), around which a wire loop (3) is fitted. The top closure section (4) is inserted into the support brackets. The support brackets/spacers are then held closed by the wire loop under tension, the two ends of which are joined together by a thermal release mechanism (5). The support brackets (2) are held in position by this wire loop (3) and hold the top closure plate (4) in position. The top closure plate (4) is positioned directly over the ventilation slots In the ventilated bottom plate (1).

Upon reaching the set temperature the thermal release mechanism (5) activates. The metallic wire loop (3) is released from tension, and falls outside the support brackets/spacers (2). The weight of the top closure plate (4) acts on the bearing surfaces of the support brackets (2) and pushes them open. The plate (4) then falls locating directly on top of the ventilation holes in the bottom plate (1), and achieves a mechanical seal, similar to that achieved by non ventilated fire stop plates. (A maximum gap of 3mm radially is allowed between the outside of the chimney/flue and the inner edge of the fire stop plate.) FIGURE 1 shows a typical installation in normal operation with the quick release thermal release mechanism (5) still holding the wire loop (3) in tension. The support brackeVspacers (2) are set at a suitable distance to allow ventilation through the joist section and to offer sufficient support for the top closure section (4). The ventilation bottom plate (1) with large apertures to maximise airflow through the joists during normal operation. This figure indicates the location of the support brackets/spacers (2), the wire loop (3) in tension, the thermal release mechanism (5) in relation to the ventilated bottom plate (1). This figure also illustrates the location of the spacers required to ensure a minimum distance to combustible material (6).

FIGURE 2 shows that the thermal release mechanism (5) has been activated and is now separated. The wire loop (3) that was previously held in tension has dropped to the ventilated bottom plate (1). The top closure plate (4) has fallen to cover the apertures in the ventilated bottom plate (1).

A further embodiment of the invention will now be described with reference to Figures 3, 4, & 5 in which the main features of the plate are numbered as before with the following additions.

7. Rotating top closure plate 8. Springs 9. Alternative thermal release mechanism (solder plug) FIGURE 3 shows an alternative design method for closing the ventilation slots. The design consists of one fixed ventilated bottom plate (1) and one rotating top closure plate (7) both with coinciding slots. In the as installed condition the ventilation slots on the rotating top closure plate À . À À. À e À e e À À Àe À À À À À À À À À À À - 5 (7) coincide with those on the fixed ventilated bottom plate (1) which allows cooling air to circulate. The rotating closure plate (7) is held in position against spring tension by either a solder plug (9) or other thermal release mechanism (5).

FIGURE 4 shows that the release mechanism, either (5) or (9) has been activated due to a rise in temperature up to the activation temperature. The springs (8) have caused the rotating top closure plate (7) to turn one half of the angular displacement pitch of the ventilation slots in the ventilated bottom plate (1) so closing the ventilation path giving the required fire barrier.

FIGURE 5 shows the front elevation illustrating the positions of the ventilated bottom plate (1), the rotating top closure plate (7) and the solder plug (9).

Claims (15)

1 The Quick release ventilated fire stop plate utilses a slotted plate design to provide free area, and therefore ventilation of the penetration section, during normal operation of a chimney flue / exhaust system, however, in the event of a fire in an adjacent room / compartment, it incorporates an automatic quick release mechanism which, when subjected to the pre-set temperature, activates and ensures an immediate mechanical closure using a top closure plate to cover the ventilation slots without effecting the normal operation of the chimney flue / exhaust system.

2. Assembly according to Claim 1 where the quick release ventilated fire stop plate comprises of a ventilated fire stop plate and an automatic quick release mechanism.

3. Assembly according to Claim 1 and 2 where the automatic quick release mechanism comprises one or more thermal release mechanisms which are activated by temperature and trigger one or more mechanical methods which result in the release or positioning of the mechanical seal covering, partially or fully, the ventilation openings In the fire stop plate.

4. Assembly according to Claim 3 where the release or positioning of a top closure plate via gravitational pull, spring loading, clamping or other mechanical methods.

5. Assembly according to Claim 3 where the top closure plate Is suitably located prior to its release or positioning via a mechanical support or positioning assembly.

6. Assembly according to Claim 1 where the top closure plate is the device to substantially close or cover the ventilation slots or openings after the thermal release mechanism has been activated thus ensuring, for a sufficient period of time as specified by the relevant building regulations, that fire cannot pass through the wall or floor penetrated by the chimney flue / exhaust system.

7. Assembly according to Claim 1 where the thermal release mechanism Is activated at a suitable temperature to ensure that requirements of the relevant building regulations can be achieved.

8. Assembly according to Claim 1 where components may be protected with a fire retardant substance which may help maintain or improve the load bearing capability, Integrity and insulation of the assembly.

9. Assembly according to Claim 1 where a fire retardant substance may be used to form a seal between the edge of the top closure plate and the circumference of the chimney flue / exhaust system or some other part of the assembly.

10. Assembly according to Claim 1 where the ventilated fire stop plate comprises a plate with the centre removed to locate the chimney flue / exhaust system and with sufficiently large apertures around the central hole to provide airflow through the penetration section during normal operation of the chimney flue / exhaust system.

11. An assembly compnsng quick release ventilated fire stop plate and a chimney flue / exhaust system, the fire stop plate utilising a slotted plate design to provide free area, allowing ventilation of the penetration section during normal operation of the chimney flue / exhaust system, however, In the event of a fire in the adjacent room / compartment, incorporating an automatic quick release mechanism which, when subjected to the pre-set temperature, activates and ensures an immediate mechanical closure using a top closure plate to cover the ventilation slots without effecting the normal operation of the chimney flue / exhaust system.

12. A method of providing a quick release ventilated fire stop plate for a chimney flue / exhaust system, the fire stop plate utlsing a slotted plate design to provide free area, allowing ventilation of the penetration section during normal operation of the chimney flue / exhaust system, however, in the event of a fire In the room below, incorporating an automatic quick release mechanism which, when subjected to the pre-set temperature, activates and ensures an immediate mechanical closure using a top closure plate to cover the ventilation slots without effecting the normal operation of the chimney flue / exhaust system.

13. Assembly according to any preceding claim where the penetration section comprises an opening in a floor or wall between two compartments in a building to allow a chimney flue / exhaust system to pass therethrough.

14. Quick release ventilated fire stop plate substantially as described herein with reference to and as Illustrated by the accompanying drawings.

15. An assembly composing a quick release ventilated fire stop plate, chimney flue / exhaust system and floor or wall substantially as described herein with reference to and as Illustrated by the accompanying drawings.

16 A method of providing a quick release ventilated fire stop plate for a chimney flue / exhaust and floor or wall substantially as described herein with reference to and as illustrated by the accompanying drawings.