Note: Descriptions are shown in the official language in which they were submitted.
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~YSTEM FOR INHIBITING THE SPREAD
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0~ E IN A BUILDING STRUC~URE
,I?~ELD AND BACKGROUND OF THE INVENTION
This invention relates to systems for inhibiting the
spread of fire in a building structure.
An air conditioning system in a building structure
requires a delivery path for delivering conditioned air to
each compartment of the building and a ~ent path for extract-
ing 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 compar-tment walls are
constructed to provide a measure of fire retardation the
products of a fire in one compartment can spread to other
compartments through the air conditioning system. Commonly
2~ when the fire starts in carpetting, curtaining and furnit~ure
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 th~t is the greatest danger to life before there
is any substantial spread of flames.
SUMMARY OF THE INVENTION
According to the invention, there is provided a system
for inhibiting the spread of the products of combustion
within a building structure, comprising closuxe means for
mounting in the air conditioning delivery and/or vent paths
associated with a compartment of a bui~ding structure, and
control means responsive to the presence of combustion,
preferably a smoke de-tector, 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. I
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It is advantageous to pro~ide also said closure means
in the air delivery path at or ad~acent lts 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 sti~ling of the
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 t~
trigger closure of said closure means in the delivery and
vent ducts where they enter and exit the compartment. In
2~ 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 main-
tained 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 douse the fire.
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 of
the presence of combustion.
The invention further provides a method of inhibiting
the spread of the 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
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~en~ path fox ex~rac~;ing foul air fxom the çompartment, at
or adjacent the point where the vent path exits from the
compartment, ~dvantageously the air conditioning delivery
path is also closed automatically at or adjacent its point
o~ 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
e~it from, the compartment.
It is particularly advantageous to use in a system
~0 according to the invention, at least one duct closure assembly
comprising 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,
~5 and vent means in the wall of the duct or duct section, the
arrangement being such that, in said open position, the
closure means inhibits flow through said vent means an~, in
said closed position, the closure means inhibits flow through
the duct or duct section while allowing substantially
2Q unrestxicted 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 detec-
tion 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 of the 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 whereby the vent aperture communicates with
a flue duct e~tending outside the building structure thereby
to discharge the products of combustion to the ambient
atmosphere. The building structure could be provided with a
ser~es 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
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ducts.
Yet a~other possibillty could ~e to retuxn the results
of eo~bustion baek into the purpose made ~ising Builders
Ser~iees Duct from which both de~ivery and extract ducts
could e~anate.
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
1~ means.
An embodiment of the invention provides an assembly
comprising a duct extending through a partition between
separate compartments of a building structure for passage
of air therebetween, closure means movably mounted in the
~5 duct between an open position in which it permits air flow
through the duct and a closed position in which it inhibits
such air flow, control means to maintain the closure means
in its open position which control means are responsive to
the presence of combustion to release the closure means when
com~ustion is detected and the closure means being adapted
to move to its closed position when so released, and a vent
- aperture in the duct, the arrangement being sueh that, in
its open position,-the elosure means inhibits flow through
said ~ent aperture and, in its elosed position, the closure
means inhibits flow through the duct while allowing substan-
tially unrestricted flow through the vent aperture.
In some embodiments of the invention, said ~ent aperture,
which is generally in an upper part of the wall of the duet,
may eommunieate with a vent passage leading to the outside
of the building structure. Preferably the vent passage
communicates with a plurality of compartments of the build-
ing structure.
The closure means may be in the form of a pivotally
mounted elosure member, e.g a hinged flap, The invention
ineludes a duet or duet seetion for an assembly as aforesaid,
whieh d~et has therein said elosure means mounted as afore-
said, said means to maintain the closure member in its open
position and said ~ent aperture which is controlled by the
closure means as aforesaid.
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The inve~ti~n further provides ~ method of controlling
an air ~low in a duct extending through a partition between
separate co~par~ments of a building structure, which
c~mprises provi~ng in the' duct closure rneans held in an
open position permitting air flow through the duct and
closing a vent aperture in the wall of the duct by means
responsive to the presence of combustion which are actuated,
when a particular temperature is exceeded, to release the
closure means to close the duct to prevent hot air and fumes
~0 and other material created by a fire in one compartment
~rom reaching another compartment and t~ divert the hot air
and fumes through said vent aperture for return to said one
compartment or for venting to the outside of the building
structure.
~5 An advantage of such an assembly is that it provides a
means of diverting the pressurized air carrying the products
of a conflagration either back into the compartment in which
the fire started or directly to the outside of the building
structure. When the air is returned to the compar~ment of
the fire there will be a tendency to douse the fire as the
increasing concentration of smoke without an added oxygen
supply takes effect.
In a further embodiment, ~he above-mentioned assem~ly
has a vent aperture provided in a portion of th wall of
the duct spaced from the top thereof, e.g. a vent aperture
disposed in a side po,rtion of the duct wall, and means are
provided to move said closure means from said open position
thereof to said closed position thereof when said combus-
tion responsive contrcl means release the closure means when
3Q combustion is detected. Generally said means to move the
closure means are provided with resilient means,acting on
the closure means, which may therefore be spring loaded in
some embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
~ mbodiments of the invention will now be described by
~ay of example and with reference to the accompanying
drawin~s in ~hich:~
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Figure l ~S a di~grammat~c plan view of part of a
~ullding struct~re f~tted with an air conditioning system;
Figure 2 is a dia~ammatic detail of a fire shunt
located in the extract duct of the a~r conditioning system;
Figures 3 and 4 are perspective viewsof the fire shunt
unit;
Figures 5A to C are diagrammatic views showing operation
of the fire shunt of Figures 3 and 4;
Figure 6 is a diagrammatic plan view of a floor of an
"open planl' design having air conditioning ~acilities;
Figure 7 is a diagrammatic sectional representation of
an air conditioning duct section for use in a system accord-
ing to the invention and shown in the free-flow position;
Figure 8 is a diagrammatic sectional representation of
the duct of Figure 7 showing the flow diverting condition
thereof;
Figure 9 is a diagrammatic perspective view of another
duct section arrangement; and,
Figure lO is a diagrammatic perspective representation
2~ o~ a further embodiment of a duct section in accordance with
~ the inve~*ion. c~
DETAILED DESCRIPTION
Referring to Figure l of the drawings, a building
structure has a number of separate compartments, one of
which is shown in Figure l and is designated by reference
numeral (10). The building structure has an air conditioning
system which includes a delivery duct (ll) 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 extract duct system with connec-
tions therefrom to the neighbouring compartments. Conditioned
air is driven by a fan, represented diagrammatically by
numeral (13) through the delivery duct which extends through
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t~e ~uilding compartments and into the individual compart-
ments through the inlets therein. Foul air from the compart-
ments is extracted through the duct system~(12) by means of a
fan diagr~mmatically 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 of the compartment
(10) into the adjoining compartment through a fire proofed
dividing wall (19). Flow control devices (17 and 18) are
also provided in the delivery duct (11) and extract duct
(12), respectively, at positions in the adjoining compart-
ment 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
2~ respective duct, or a duct section fitted in such duct.
A hin~e flap (21) is normally held to close the vent aperture
by a releasable latching device (22), which for example ;~
comprises a la~tching member associated with a solenoid for
~ove~ent between a "latc~" position and an "unlatched1'
p~sition. When the latching device (22) is in its "unlatched"
position the flap (21) drops to close the duct or duct
section-to inhibit fiow therethrough and acts to divert such
flow through the vent aperture (20) and back into the compart-
ment (10~ ~rom which it came. Further constructional details
of such a flow control device are given in Figures 7 to 10
which are described hereinafter.
A control system is provided for actuating the flow
control devices (15 to 18). A smoke detector (23) may for
éxample 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
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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 flowing along the extract
duct are diverted through the vent aperture (20) back into
the compartment (10). Electric contro] signals are also
trans~itted 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 combus-
-tion taking place in the compartment tçnds to be stifled
by the products of such combustion which are diverted back
into the compartment.
Therefore on detection of combustion in the compart-
ment, which very often will initially produce smoke which
can be detected by any suitable known smoke detector, the
outlet of the 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 elosing flow eontrol device (17). This prevents further
air being dri~en into the compartment by fan (13) which would
tend to promote the combustion. The closing o~ 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 of the excessive heat in the compart-
ment (10) builds up suffieiently to be able to drive out
such products through the pressurized delivery duct. The
closing of flow eontrol deviee (18) at the inlet to the
compartment 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 compart-
ment (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 combus-
tion with the closure of the other flow control devices
taking place simultaneously or subsequently.
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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 aperture
for allow.ing a ready recycle of the products of combustion
back into the compaxtment 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.
~0 In any of the constructions described above the closing
of any one of the flow control devices.or indeed of the
devices shown in Figures 7 to 10, which are described herein-
after, 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 particular
compartment of the building and/or to sound an alarm.
A feature 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 aompartment should
~Q opera~e to isolate the products o combustion to those
compartments.
The invention also provide~ 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 de-tector 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 from 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 compart-
ment of the building structure, are linked in their owncircuit, 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
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every othe~ flow contro:L unit to provide a means of restrict-
ing spread of the 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 de~ice shutting
off the supply of pressurized conditioned air to the
compartment does not take place immediately following 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 compart-
ment to return the combustion products thereto, would be
connected to pass such products outside the compartment into
2~ an extract passage or a respective such passage :Eor a group
of compartments for venting outside the building structure.
This extract passage could be provided by a lift or other
purpose made shaft fitted with an extract fan for opera-tion
- during an extraction step. An electronic control system
could be provided to detect closure of the flow control
devices in the building. If this system detects that flow
control devices associated with more than one compartment
.7, are actuated indicating a failure of at least one such
device in the compartment where combustion started, the
3~ 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 atmos-
phere at a preferred position at each floor.
~ eferring to Figure 6, a floor of a building structure
has a central passageway (31), the walls of which need to
provide a ~-hour fire delay, The "open plan" floor is then
subdi~ided into individual compartments as required. The
Rislng 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 condition-
ing system when there is a fire, either to the lift shaft
(33) or the service shaft (32) or a purpose made vertical
flue duct (38) inside or outside the service shaft.
Referring to Figures 7 and 8, an air conditioning duct
11~, e.g. either the delivery or vent duct of a system shown
15 i~ ~igures 1 to 6, extends through a partition wall 111 between
two ccmparbmen~s 112, 113 of a building. me direction of air flow is
shown by the arrows. The duct 110 is located in an aperture in the wall
111 by means of a sleeve 114 made of one or more sections of a load
bearing and fire retardant material.
~he duct 110 has a vent aperture 115 in an upper part
thereof and a hinged control flap 116 held to close the
vent aperture 115 by a fusible link 109, e.g. a rivet or
similar element made of a fusible material. The length of
the flap is preferably equal to the depth of the duct. When
the heat inside or outside the duct reaches the "control"
temperature the free edge of the flap 116 is released and
the flap hinges downwardly to engage a stop 117 provided by
~7 a piece of angle iron or similar element located at the
~ottom of the duct, to close the duct. The flap could be
longer;than the depth of the duct so that the stop 117 isnot required. The flap also acts to deflect the hot air
and toxic fumes upwardly through the vent aperture 115,
which is now open, as shown by the arrows in Figure 8.
The air moves under pressure of driving fans in the duct
or by natural convection upwardly through the vent aperture
so that smoke, toxic fumes and hot air are returned to the
compartment 112 in which the conflagration started. The
duct sealing arrangement described above can be built into
standard duct sections or can be supplied as a separate
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flanged un~t f~r location intermediate along the length of
a duct installation. The duct may be of ~arious different
cross-sections, e.g. square, rectangular, round or "modified"
rectangular ducts which has rounded, outwardly projecting
side walls. In the case of round or "modified" rectangular
ducts it ~ill be necessary to provide a separate closure
unit to be introduced in the duct system and fitted to
adjoining "transformation" sections.
The system shown in Figure 9 is similar to that shown
in Figures 7 and 8, except that the vent aperture in the
upper wall o the main air duct 110 discharges into a connect-
lng duct section 120 which extends a short distance upwardly
of the duct 110 and then extends sidewards thereof to
communicate at its outlet end with a vertical flue duct 121
extending through the building structure. The air ducting
from each compartment of the building structure similarly
communicates with the flue duct 121 which receives the
products of a conflagration, e.g. toxic fumes, combustion
particles and black smoke, in any compartment of the structure
and discharges such products directly to the ambient atmos-
phere,
- In the arrangements of Figures 1 to 9, the vent aperture
may be at the top of the duct and the closure means, in the
~orm of a plate, drops under gravity to its closed position.
There may be constructions where space above the duct
is restricted, particularly if a central common outlet
flue for all the building compartments is used requiring an
'7 individual connecting duct section with the ~ent aperture
-of each compartment. In such a situation a construction
according to the present invention is preferable whereby
a "side" position for the vent aperture can be employed.
Referrlng to Figure 10 the duct 130, which is of
rectangular section, has a vent aperture 131 in a side
wall thereof. The aperture 131 is n~rmally closed by a
control flap 132 which is connected to the duct side wall
by a spring loaded hinge 133 extending along a vertical
side of the aEerture 131. The flap 132 is held in its
position closing the ~ent aperture 131 by a fusible link,
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e.g. one or more rivets or similar elements 134 made of a
usible material. Air flow is then permitted through the
duct as shown by arrows X.
When the heat inside or outside the duct rises to a
degree to melt the fusible link holding the flap open, the
spring provided in the hinge assembly 133 acts to move
the flap 132 to close the duct 130 and also to open the
vent aperture 131. The heated air and fumes then flow
through the vent aperture as shown by arrows Y. In its
~0 closed position the flap may be held against stops provided
on the wall of the duct opposite to the~vent aperture.
However such stops are not required if the flap is made
longer than the width of the duct. The continuing pressure
of air assists in closing the flap and in maintaining the
flap in its closed position, since the fans for driving the
air along the duct would still be working.
~ n the embodiments of any of Figures 7 to 10, the closure
plate or flap may be released by a latch member controlled by
a control system as described above in relation to Figure 2.
2~
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