GB2103483A - A system for inhibiting the spread of fire in a building structure - Google Patents

Abstract

Closure means (15, 16, 17, 18) are provided in the delivery and/or vent paths (11, 12) of an air conditioning system together with control means which respond to the presence of combustion in the associated compartment of a building structure to effect closure of the closure means when combustion therein is detected. Preferably closure means are provided at the entry and exit points of both the vent and delivery lines to each compartment so that the compartment in which combustion starts is automatically sealed off from the other compartments to inhibit the spread of the combustion products through the air conditioning system. It is also preferred that the closure means, when moved to the closed position, divert the combustion products into a vent passage or service duct leading directly to the outside of the building structure. <IMAGE>

Description

SPECIFICATION A system for inhibiting the spread of fire in a building structure This invention relates to systems for inhibiting the spread offire in a building structure.

An air conditioning system in a building structure requires a delivery path for delivering conditioned air to each compartment ofthe building and a vent path for extracting foul air from each compartment to maintain pressure balances and habitable conditions in those compartments. The building services, e.g. ducting, which provide these delivery and vent paths must pass through walls of the compartments.

Therefore even if the compartment walls are constructed to provide a measure offire retardation the products of a fire in one compartment can spread to other compartments through the air conditioning system. Commonly when the fire starts in carpetting, curtaining and furniture padding, a large quantity of smoke and toxic gases is produced before the combustion spreads through flames and intense heat. It is often the inhalation of the smoke and toxic fumes that is the greatest danger to life before there is any substantial spread of flames.

According to the invention, there is provided a system for inhibiting the spread of the products of combustion within a building structure, comprising closure means for mounting in the air conditioning delivery and/or vent paths associated with a compartment of a building structure, and control means responsive to the presence of combustion, preferably a smoke detector, which control means when actuated effect closure of said closure means. The closure means should act to close at least the vent path at or adjacent the point where it exits from the compartment.

It is advantageous to provide also said closure means in the air delivery path at or adjacent its point of entry into the compartment. Such closure means would also be closed automatically when said control means are actuated in order to prevent further air from being pumped into the compartment thereby to assist in causing stifling ofthe fire in the compartment.

Preferably closure means are provided in said vent path, and most preferably also in said delivery path at or adjacent at their points of entry to and exit from said compartment. When closure means are so provided in both the delivery and vent paths both at entry to and exit from the compartment, it is possible to seal off quickly the entire compartment once combustion is detected. Therefore when for example a smoke detector or any one of a plurality of such detectors in the compartment detects smoke and other products of combustion, a control system is actuated to trigger closure of said closure means in the delivery and vent ducts where they enter and exit the compartment. In this way a fire can be contained and confined within the compartment.Since pressurized air is no longer pumped into the compartment, the air pressure balance therein is maintained substantially constant and the fire is thereby denied an air supply so that the increasing concentration of smoke and other products of combustion tends to dousethefire. In a building structure, each compartment would generally be provided with a set of the aforesaid closure means and a control system therefor which includes detectors for location in the respective compartments so that a fire starting in any individual compartment can be confined to that compartment.

The aforesaid control means may include means to give an alarm and/or advise a control panel of the actuation ofthe presence of combustion.

The invention further provides a method of inhibiting the spread ofthe products of combustion within a building structure, which method comprises detecting the presence of combustion in a compartment of the building structure and in response thereto automatically closing an air conditioning vent path for extracting foul air from the compartment, at or adjacent the point where the vent path exits from the compartment. Advantageously the air conditioning delivery path is also closed automatically at or adjacent its point of entry into the compartment. Most preferably the vent path, and desirably also the delivery path, is closed automatically at or adjacent its points of entry to, and exit from, the compartment.

It is particularly advantageous to use in a system according to the invention, at least one duct closure assembly substantially as described in my British Patent Applications Nos. 8,116,733 and 8,119,839.

Therefore the invention also provides a duct or duct section comprising closure means movably mounted in the duct or duct section between an open position in which it permits fluid flow through the duct and a closed position in which it inhibits such fluid flow, and vent means in the wall of the duct section, the arrangement being such that, in its open position, the closure means inhibits flow through said vent means and, in its closed position, the closure means inhibits flow through the duct or duct section while allowing substantially unrestricted flow through said vent means. The closure means may be controlled by control means which are responsive to the presence of combustion, e.g.

smoke and/or heat detection means. For example the closure means can be used in conjunction with one or more smoke detectors which when activated produce a signal to release a latching device holding the closure means in its open position, whereupon the closure means moves under gravity or under the action of biassing means, e.g. a spring, to its closed position.

Apart from use ofthe aforesaid duct or duct section assembly in the above described system where the products of combustion are confined within the compartment in which the combustion originates, such an assembly can be used in an arrangement similar to that described in my British Patent Application No. 8,116,733 in particular with reference to Figure 3 thereof, whereby the vent aperture communicates with a flue duct extending outside the building structure thereby to discharge the products of combustion to the ambient atmosphere. The building structure could be provided with a series of such flue ducts for discharging combustion products to atmosphere at each floor level. Another possibility is to use lift or other purpose made shafts for such discharge flue ducts.

Yet another possibility could be to return the results of combustion back into the purpose made rising Builders Services Duct from which both delivery and extract ducts could emanate.

An extraction fan or fans could be provided to draw combustion products through the lift or similar shaft. The fan(s) could be started automatically by the aforesaid control means which, when actuated, causes closing of said closure means.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which: Figure lisa diagrammatic plan view of part of a building structure fitted with an air conditioning system; Figure 2 is a diagrammatic detail of a fire shunt located in the extract duct of the air contitioning system; Figures 3 and 4 are perspective views of the fire shunt unit; Figures 5A to C are diagrammatic views showing operation of the fire shunt of Figures 3 and 4; and Figure 6 is a diagrammatic plan view of a floor of an "open plan" design having air conditioning facilities.

Referring to Figure 1 ofthe drawings, a building structure has a number of separate compartments, one of which is shown in Figure 1 and is designated by reference numeral (10). The building structure has an air conditioning system which includes a delivery duct (11) and an extract or vent duct (12) which extend through each compartment. In each compartment branches of the main delivery and extract ducts may extend to separate inlet and outlet air apertures located at different parts in the false ceiling of the compartment. In some possible arrangements the space above the false ceiling containing the delivery duct, may itself comprise a portion of the extractductsystem with connections therefrom to the neighbouring compartments.Conditioned air is driven by a fan, represented diagrammatically by numeral (13) through the delivery duct which extends through the building compartments and into the individual compartments through the inlets therein.

Foul air from the compartments is extracted through the duct system (12) by means of fan diagrammatically represented by numeral (14), so as to maintain a pressure balance in the compartments.

In the system embodying the invention shown in the drawings, flow control devices, as illustrated in Figures 2 to 5, are located in the delivery and extract ducts. Flow control devices (15 and 16) are provided in the extract duct (12) and delivery duct (11) respectively at positions in those lines adjacent where they pass out ofthe compartment (10) into the adjoining compartment through a fire proofed dividing wall (19). Flow control devices (17 & 18) are also provided in the delivery duct (11) and extract duct (12), respectively, at positions in the adjoining compartment adjacent the fire proofed partition wall (30) between the two compartments.

Referring to Figures 2 to 5, each flow control device comprises a vent aperture (20) in the upper part of the respective duct, or a duct section fitted in such duct. A hinge flap (21) is normally held to close the vent aperture by a releasable latching device (22), which for example comprises a latching member associated with a solenoid for movement between a"latch" position and an"unlatched" position. When the latching device (22) is in its "unlatched" position the flap (21) drops to close the duct or duct section to inhibit flow thereth rough and acts to divert such flow through the vent aperture (20) and back into the compartment (10) from which it came. Further constructional details of such a flow control device are given in my British Patent Applications Nos. 8,116,733 and 8,119,839.

A control system is provided for actuating the flow control devices (15 to 18). A smoke detector (23) may for example be provided and located either in the extract duct (12) adjacent the outlet flow control device (15) or at any other suitable place in the compartment. Indeed several such smoke detectors may be provided at strategic positions in the compartment. When the detector detects the presence of smoke it generates an electric signal which is communicated to the latching device (22) of flow control device (15) so that the flap becomes "unlatched" and drops to close the outlet of the extract duct to the next compartment. In so doing, the smoke and toxic fumes along the extract duct are diverted through the vent aperture (20) back into the compartment (10).Electric control signals are also transmitted to "unlatch" the latching mechanisms (22) of the flow control devices (16,17,18) in order to effectively seal off the compartment. In this way the further delivery of air to the compartment is also prevented so that the combustion taking place in the compartment tends to be stifled by the products of such combustion which are diverted back into the compartment.

Therefore on detection of combustion in the compartment, which very often will initially produce smoke which can be detected by any suitable known smoke detector, the outlet ofthe extract duct from the particular compartment is closed by flow control device (15) to prevent the products of the combustion being drawn out by the extractor fan (14) into other compartments of the building. The next step is to close the inlet of the delivery duct to the compartment by closing flow control device to7). This prevents further air being driven into the compartment by fan (13) which would tend to promote the combustion. The closing of flow control device (16) at the outlet of the compartment of the delivery duct prevents smoke and other combustion products passing into other compartments of the building through the delivery duct after the pressure ofthe excessive heat in the compartment (10) builds up sufficiently to be able to drive out such products through the pressurized delivery duct. The closing of flow control device (18) at the inlet to the compart- ment of the extract duct similarly stops pressure in the compartment (10) from forcing the combustion products back through the inlet of the extract duct to the compartment (10).The flow control devices (15 to 18) do not need to be closed in sequence, but flow control device (15) must be closed as quickly as possible after detection of combustion with the closure of the other flow control devices taking place simultaneously or subsequently.

It is possible although probably less desirable to operate a system as described above but using known types of flow control devices which do not incorporate a vent aper for allowing a ready recycle of the products of combustion back into the compartment in which the combustion is taking place.

In other embodiments the flow control devices (15 to 18) may be controlled by heat responsive devices rather than from smoke detectors.

In any of the constructions described above the closing of any one of the flow control devices or indeed ofthe devices described in my British Patent Applications Nos. 8,116,733 and 8,119,839 can be used in conjunction with means, e.g. electrically operated signalling means, to advise a control panel of the presence of combustion and in which particularcompartmentofthe building and/orto sound an alarm.

Afeature of the system described above is that if any of the flow control devices failed to close when triggered, the flow control devices in the adjacent compartment should operate to isolate the products of combustion to those compartments.

The invention also provides systems adapted to take account of possible malfunctions of the individual flow control devices as described above for isolating a building compartment when combustion starts therein. Instead of providing a smoke detector only in flow control device (15), a smoke detector could be provided in each of the flow control devices (15 to 18), with control circuitry provided to receive signals form all the smoke detectors and to effect closure of all the flow control devices when a signal is received from any one or more of the smoke detectors. In this way, failure of any individual smoke detector would not prevent closure of the flow control devices.

Furthermore the four flow control units of each compartment of the building structure, are linked in their own circuit, and the circuits of adjacent compartments can be linked together and indeed cross linked to each and every other flow control unit in the building structure. In this way each and every flow control unit is linked to each and every other flow control unit to provide a means of restricting spread ofthe products of combustion throughout the building structure if there is a failure of one or more of the flow control units.

In systems in accordance with the invention where the flow control units of each compartment are not linked by an electrical control system so that closure of one unit effects closure of the other three units for that compartment, each flow control unit then operates individually. Such systems do not then effect a rapid cut off in the supply of oxygen to the compartment, since the flow control device shutting off the supply of pressurized conditioned air to the compartment does not take place immediately fol- lowing closure of the flow control device preventing venting off the products of combustion from the compartment through the extract duct.

In such systems, the vent apertures of the flow control devices, instead of communicating directly with the compartment to return the combustion products thereto, would be connected to pass such products outside the compartment into an extract passage or a respective such passage for a group of compartments for venting outside the building structure. This extract passage could be provided by a lift or other purose made shaft fitted with an extract fan for operation during an extraction step. An electronic control system could be provided to detect closure ofthe flow control devices in the building.If this system detects that flow control devices associated with more than one compartment are actuated indicating a failure of at least one such device in the compartment where combustion started, the system could send a signal to start the extract fan in at the top of the lift shaft to extract combustion products from each compartment or from each floor through extract ducts in each room which communicate directly with the lift shaft or any other separate extract duct provided at each floor. Alternatively the separate extract duct could discharge directly out of the building to the ambient atmosphere at a preferred position at each floor.

Referring to Figure 6, a floor of a building structure has a central passagewav (31), the walls of which need to provide a 2-hourfire deiay. The "open plan" floor is then subdivided into individual compartments as required. The Rising Builders Brick duct (32) for services normally has a 4-hour fire delay as should the construction around the lift shaft (33) and the stairways (34). The air condition system includes extract paths (35) and a delivery path (36). Flow control devices (37), as described above, are provided in the delivery and extract paths (36, 35) as shown to pass the products of combustion, extracted through the air conditioning system when there is a fire, eitherto the lift shaft (33) or the service shaft (32) or a purpose made vertical flue duct (38) inside or outside the service shaft.

Claims (19)

1. A system for inhibiting the spread of the products of combustion within a building structure, comprising closure means for mounting in the air conditioning delivery and/or vent paths associated with a compartment of a building structure, and control means responsive to the presence of combustion in that compartment, which control means when actuted effect closure of said closure means.

2. A system according to Claim 1, wherein the closure means are positioned to close at least the vent path at or adjacent the point where it exits from the compartment.

3. A system according to Claim 1 or Claim 2, wherein said closure means are also provided in the air delivery path at or adjacent its point of entry into the compartment, such closure means being closed automatically when said control means are actuated in orderto prevent further airfrom being pumped into the compart'v.ent

4. A system according to any preceding Claiir., wherein closure means operable by said control means are provided in said van pdth at or adjacent its point of entry to and exit from said con-,partment.

5. A system according to Claim 4 wherein closure means operable by said control means are also provided in said delivery path at or adjacent its point of entry to and exit from said compartment.

6. A system according to Claim 5. including a set of the aforesaid closure means for each of a plurality of compartments of a building structure and a control system therefor which includes detectors for iocation in the respective compartments, said control system being adapted to close automatically a set of closure means associated with a compartment in which products of combustion are detected by ti.e detector therein.

7. A system according to any preceding Claim.

including a duct, or duct section for insertion in a duct, incorporating said closure means movabiy mounted in the duct or duct section between an open position in which it perm'ts fluid flow through the duct and a closed position in which it inhibits such fluid flow, and vent means provided in the wall of the duct or duct section and positioned se that, in its open position, the closure means inhibits flow through said vent means and, in its closed position, the closure means inhibits flow through the duct or duct section while allowing substantially unrestricted flow through said vent means.

8. A system according to any preceding Claim, wherein said vent means communicate with a flue duct or service shaft or other vent passage ultimately extending outside the building to the ambient atmosphere.

9. A system according to any preceding Claim wherein the closure means are controlled by control means which include one or more smoke detectors which when activated produce a signal to release a latching device holding the closure means in its open position, whereupon the closure means moves under gravity or under the action of biassing means to its closed position.

10. A system according to any preceding Claim wherein the closure means are controlled by temperature responsive control means.

11. A system according to any preceding Claim wherein said control means include means to give an alarm and/or advise a control panel of the actuation ofthe closure means when combustion is detected in a building compartment.

12. A method of inhibiting the spread ofthe pro ducts of combustion within a building structure, which method comprises detecting the presence of combustion in a compartment of the building struc ture and in response thereto automatically closing an air conditioning vent path for extracting foul air from the compartment, at or adjacent the point where the vent path exits from the compartment.

13. A method according to Claim 12 wherein the air conditioning delivery path is closed automatically at or adjacent its point of entry into the compartment when combustion is detected.

14. A method according to Claim 13 wherein the ant path is closed autor.^ C3ity as aforesaid at or adjacent its point of entry to, art exit from, the compartment.

15. A method according to Claim 14 wherein the delivery path is also closed automatically at or adjacent its point of entry to, and exit from, the compartment when combustion is detected.

16. A method according to any of Claims 12 to 15 wherein products of combustion in said vent and!or delivery paths are either returned to said compartment or passed through vent means leading to the outside of the building structure when the flow thereof in said vent and, or delivery paths is inhibited by the closing thereof as aforesaid.

17. A method according to any of Claims 12 to ,6, wherein an alarm is automatically actuated and. or a control panel is au o natically advised ofthe detection ofthe presence of combustion in a build no compartment.

18. A system for inhibiting the spread of the products of the combustion, which system is substan rally as herein before described with reference to and as iliustrated in the accompanying drawings.

19. A method cf i nhibiting the spread of the products of combust; n, substantially as hereinbefore described with reference to the accompanying drawings.