GB2249624A - Air duct safety damper - Google Patents

Abstract

Automatic damper for shutting off ventilation ducting in case of fire comprises a drop down or spring assisted retractable shutter 12 held open by a heat responsive fusible link 24 mounted on a frame 10 which defines the opening controlled by the shutter. One end of the link is pivoted by a stud 30 while the other end is releasably retained by a manually releasable automatically self-engaging catch 18. So that the shutter can be released while the link is still integral, and from the downstream or upstream sides of the frame, a remote operating element, typically a pull cable 32 is led from the catch over or through the frame by-passing the shutter, to the side of the opening remote from the catch. <IMAGE>

Description

AIR DUCT SArETY DAMPER This invention relates to automatic safety dampers for air distribution or ventilation ducting to provide a fire and smoke stop.

It is known to provide a damper assembly comprising a folding or otherwise retractable shutter retained in an open condition by a fusible link or other heat responsive retaining element which reacts to a rise iri anibient temperature above a predetermined level by freein. the shutter so that it drops or is resiliently urg to a siut position to close off the related duct passage.

It is desirable ticat the link or other retaining element can readily be f freed manually without affecting its integrity for maintenance and inspection of the shutter and to facilitate installation Of replacement. Moreover, access to the interior of the ducting is often difficult and restricted, thus the shutter itself and associated parts of the assembly are often only accessi@l @@ from one side of the opening along the duct so that any components requiring manipulation, adjustment or replacement n@ve to be reached from that side.

with some kno@n constructions this may involve provision of different patterns of components depending on uni on sice access is to be gained from, and/or more commonly it is necessary to install the assembly tne correct way round to provide or suco access. It is easy to overlook this need during actual installation @@ if an error is made it can be extremely costly ann inconvenient to correct later on.

If supervision is inadequate, and incorrect installation has taken place checking and testing may be impossible or so inconvenient that it is omitted with consequent risk of violation of safety regulations and neglect leading to failure to operate or unreliable operation if a fire should break out which could have disastrous consequences.

The object of the invention is to provide a simple and inexpensive damper assembly which is readily installed and maintained and is fully adaptable in that no special components or installation procedures are called for to provide for nianual maintenance and like operations thereon even with restricted access and regardless of whether said access is gained from one side of the shutter or the other.

According to the invention there is provided an automatic safety damper assembly for air distribution or ventilation ducting including a shutter frame defining an opening between adjoining portions of the ducting in use, a folding or otherwise retractable shutter guided in the frame for movement between an oen position and a shut position at which it closes the opening ann to which it is urged by gravity and/or resilient means, and a fusible link or other heat responsive retaining element bridging a leadior edge portion of the shutter and mounted on the frare on opposite sides thereof to retain the shutter at the open position nile the integrity of the link or other said element is raintained characterized in that one end only of the element is engaged with the frame by a manually releasable automatically self engaging catch oli a first side or the opening, the other end of the element being engaged by a mounting permitting annular displecement of the element to free the shutter on disengagement of sain catch, said assembly further including a remote operating element connected for selective manual remote release of the catch and g@ided within or on the frame by-passing. the shutter for operation at least fruri the side opposite that on which the catch is mounted.

Conveniently Sd i:- other end of the element can readily be dis@n@aged from sain mounting once its said one eno has disconnected from the catch.

While the primary purpose of the remote operating element is to enable manual operation of the catch to be selectively effected from either side of the opening, it will be appreciated that this facility may also be utilized for remote operation from other locations even at a substantial distance from the shutter and within or outside the ducting, for example overriding operation to release the shutter automatically before any rise in ambient temperature takes place in the region of the shutter on an outbreak of fire at a remote location, e.g. in response to actuation of an automatic smoke detector or other sensor or alarm system or installation.

Conveniently said operating element cornprises a flexible pull cable either in the form of a sheathed "Bowden" cable or sliding in guide formations provided on or in appropriate locations of the frame.

An example of the invention is now more particularly described with reference to the accompanying drawings wherein Fig. 1 is a diagrammatic cut away perspective view of parts of a damper assembly@ Fig. 2 is a vertical cross section of main parts of the asseihly, and C 10. 3 iS d perspective view of a chassis and self engaging catch of said asse@hly.

The assembly includes a shutter frame 10 of which only an upper cross member or channel or top hat Section is shown in @ Fig. 2 only said frame defining an opening in conventional manner bet@een two adjoining sections of air distribution or ventilation ducting (not shown) where a fire and smoke stop is to be provided .c. where tile ducting passes through a main interior wall of a building which itself serves as a firs stop.

A retractable shutter 12, in this example consisting of a plurality of reversely hinged folding curtain blades, again in conventional manner, is substantially received within the channel defined by said frame cross member in the open position indicated in figs. 1 and 2 so that it will drop by gravity to a shut position at which it closes off said opening, its edges being guided in the frame.

In practice a series of depths of cross member channel are provided so that the assembly can include various sizes of shutter depending on the effective cross sectional area of the ducting without any substantial obstruction of the latter when the shutter is open.

retaining element chassis 14 (shown only diagrammatically and in part in rig. 1) is also of top hat section dimensioned to locate within the frame cross member as seen in Fig. 2 so that, when installed, it extends across the top of shutter 12 and out to both sides of the opening where it terminates in horizontal flanged portions 16a, b below respective outer edge portions of said cross member clear of the shutter.

Flange portion 16a mounts a manually releasable automatically self-engaging catch 18 a body of which defines a downwardly directed slot 2D having a coacting pivoted latch 22 with an operating at projecting outwardly and downwardly.

neat responsive fusible link 24 includes a transverse clasp bar 2 at one eno latch , when it is pressed upwardly into slot 20 is engaged a@ eutoi;iatically by latch 22 to retain it in engagement 'ith catch 13.

Flange portion 16b on the opposite side of the shutter openin: to catch 18 mounts a downwardly depending journal plate 28 to which the other end of the link 24 is hinged by a headed stud SO herein. A keyhole type slot in plate 28 receives stud 30 so that the lin' < can readily be removed or replaced when its said one -no is freed rrom catch 1C.

n link 24 is engaged as shown in Figs. 1 and 2 it bridges the leading (i.e. in this case lower) edge of the shutter 12 to retain it in the folded open condition. If the ambient temperature rises above a pre-determined level solder or other fusible metal holding two parts of the link together will melt so that said parts separate, each swinging downwardly by pivoting Ir journal plate 28 and catch 18 freeing the shutter so that it drops to the shut position.

The shutter can also be released by undoing catch 18, if there is direct access to the catch itself latch 22 will be operated manually freeing clasp bar 26 so that it can drop clear of slot 20, the entire link 24 swinging angularly about its pivotal engagement with Journal plate 28, so freeing the shutter. When the shutter is to be restored to its open position it will be refolded upwardly and link 24 swung back to the horizontal position to be automatically self-engaged in catch 18. . ~ The assembly further includes a remote operating element in the form of a flexible pull cable 32.One end of cable 32 is connected to the operating arm of latch 22 and it is guided through a series of slots 34 (Fig. 3) in chassis 14 defining path generally diagonally of the various angled steps thereof and it is also leo across the top of shutter 12 In a channel 33 defined by the uppermost portion cf the chassis.The end of cable 32 remote f to-i catch 18 terminates in a pull ring 38 which conveniently hangs adjacent to the journal plate 28, i.e. on the opposite side of the opening to catch 1 18, 8, thus the said catch car oe actuated to free link 24 by pulling ring 38 even if access to the catch itself is difficult or impcssible due to the construction of the duct and/or the @anner in which the frame and other parts or the assembly have been installed therein.

able 32 coul be extended so that release could be effected at sore distance from the assembly itself if if required. There is also the possibility of providing other pull cable connections to latch 22 e.g. as shown in broken lines at 40 in rig. 2 for operation of the catch from other remote positions e.g. on the sane side of the opening as catch if 'out some distance therefro.

Such actuation could be manual or might be automatic e.g. for closing shutter 12 as soon as an outbreak of fire or smoke is detected at a location remote from the shutter itself i.e. before the fusible link 24 has broken due to localised heating. A series of automatic safety damper assemblies in a ducting system could be coupled together in this manner so that they will all close simultaneously on a signal fro e.g. a fire detection or fire alarm system.

It will be understood that forms of heat responsive retaining element other than the type of fusible link 24 shown could be used to retain the shutter at the closed position e.g. a two part cross-member held integral by d heat responsive liquid filled frangible bulb or other types of heat sensitive retaining devices.

It uill also be understood that the invention is applicable to other forms of self-closing damper shutter e.g. a roller type shutter or one having non-folding sliding doors, and that the closing action may be by gravity or by springs or other resilient i-ens, and it is not essential tiat the shutter should close in a downward direction.

ether forms of automatic self engaging catch may be employed for example the latching action thereof may be by gravity or be spring operated.

Claims (6)

1. n automatic safety damper assembly for air distribution or ventilation ducting including a shutter frame defining an opening between adjoining upstream and downstream portions of the ducting in use, a folding or otherwise retractable shutter guide in the frame for movement between an open position and a shut position at which it closes the opening and to which it is operatively resiliently urged, and a fusible link or other eat responsive retaining element bridging a leading edge portion of the shutter and mounted on the frame to upstream and downstream sides of the opening to retain te shutter at the open position while the integrity of said element is maintained: characterized in tat one end only of the element is engaged with te frame by a manually releasable automatically selfengaging catch on one said side of tie opening, , tie other end of the element being engaged hy a mounting permitting angular displacement of the element to free the shutter on disengagement of said catch, said assembly further including a remote operating element connected for selective manual remote release of the catch and guided With thin or nn the frame by-passing t he shutter for operation at least from the other said side of the opening.

2. An assembly as in Claim 1 wherein the shutter is operatively urged to the closed position by gravity.

3. An' assembly as in Claim ]. or 2 wherein said other end of the element can be readily disengaged from said mounting once its sa a ci one end has disconnected from the catch.

4. An assembly as in Claim 1 , 2 or 3 wherein the operating element comprises a flexible sheathed "Bowden" type pull cable.

5. An assembly as in Claim 1, 2 or 3 wherein the operating element comprises a flexible pull cable slidin in quide formations on or in the frame.

6. An automatic damper assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.