GB2150829A - A fire and smoke damper - Google Patents

Abstract

A fire and smoke damper 1 comprises a plurality of stainless steel slats 2 each having inturned longitudinal edges for interengaging with the adjacent inturned edges of an adjacent slat 2 to form a folding shutter-type mechanism. Each of the slats 2 is formed with a longitudinally extending central rib 6 for improved structural strength and heat resistance. The slats 2 are retained in a folded, retracted position by a two-part fusible link 4. In the event of fire the link 4 breaks and the slats 2 move into a released position closing an opening in which the damper 1 is mounted. Biasing means providing two springs, each comprising a strip 20 of spring steel reeled around a shaft 22 at one end and connected at the other end to the lowermost of the slats 2, ensures that when the fusible link is broken the slats 2 close the opening regardless of the position or orientation of the damper 1 in a duct. <IMAGE>

Description

SPECIFICATION A Fire and Smoke Damper The invention relates to a fire and smoke damper particularly of the type for incorporation in a duct such as a ventilation duct.

One conventional damper of this type comprises a shutterformedfrom a plurality of hingedly connected slats mounted in the duct and movable under gravity from a retracted position to an expanded position on breaking of a heat responsive fusible link.

One problem with such dampers is that in order to operate correctly they must be mounted vertically in a horizontal section of duct with the slats in the retracted position uppermost. This not only greatly restricts the application of such dampers, but also may result in the damper not operating as required due to incorrect installation. It will be appreciated that if the damper were mounted with the slats in their retracted position lowermosttheywould not operate to close an opening in the event of a fire.

There is therefore a need for an improved fire and smoke damper which will be suitable for horizontal and vertical mounting and which will operate regardless of the positioning of the slats. There is also a need for an improved fire and smoke damper which will satisfy the requirements of BS 476 Part 8.

This invention is directed towards providing such a fire and smoke damper.

According to the invention, there is provided a fire and smoke damper comprising a damper blade means, biasing means for movement of the damper blade means from an open position into a released closed position substantially sealing an opening in which the damper is mounted, and heat responsive releasable retaining means for retaining the damper blade means in the open position.

In a preferred embodiment of the invention, the damper blade means comprises a shutter formed from a plurality of interconnected slats movable from an open, retracted position to a released position.

Preferably, the slats are hingedly interconnected for pivotal movement between adjacent slats.

Typically, each slat comprises an elongate plate having inturned edges, an inturned edge of the one plate interengaging with the adjacent inturned edge of another slat for pivotal movement between adjacent slats.

In one embodiment of the invention the slot is formed with a longitudinally extending rib.

The damper blade means may, for example, be of a stainless steel material.

In another embodiment of the invention, catch means are provided for sealable engagement of the damper blade means in the released position.

Preferably, the catch means comprises a latch and latch retainer, the free edge of the lowermost slat defining the latch for engagement in a complementary-shaped latch retainer.

In a further embodiment of the invention, the biasing means comprises a spring which may, for example, be of a spring steel material. Typically, the spring comprises a strip of spring material, one end of which is fixed to a reel shaft, the spring strip extending from the reel shaft for connection to a slat at its other end for biasing the slats into the released, closed position. Usually, the damper includes two strips of spring material connected to opposed side edges of a slat.

In another embodiment of the invention, the damper blade means is mounted in a housing, the housing being open at both ends for mounting in an opening. Typically, the housing includes a top recess portion for accommodating the damper blade means in the open position.

The housing may be of a galvanised steel material and may include a bottom recess portion accommodating the spring biasing means.

Preferably, the slats are movable in side tracks provided in the housing. Typically, each track is provided by a channel which may be of a stainless steel material fixed to a side wall of the housing.

In one embodiment of the invention, the housing includes a longitudinally extending flange surrounding the opening on both sides and onto which mating ducts are slip-jointed. In another embodiment of the invention the housing is adapted for flange jointing with mating ducts.

In a still further embodiment of the invention, the retaining means comprises a fusible link. Preferably, the fusible link comprises a two leg link, the legs of the link being soldered together and the solder melting at a predetermined temperature to release the slats. Typically, the legs of the link are of a brass material.

In a further embodiment of the invention, damper blade means comprises a damper plate, the plate being pivotally mounted in a housing and being movable by a spring biasing means from an open position transverse of the opening to a released position closing the opening. Typically, in this case the damper plate is pivotally mounted on a central spindle extending transversely across the opening.

The invention will be more clearly understood from the following description thereof given by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a perspective partially cut-away view of a fire and smoke damper according to the invention, in an open position, Fig. 2 is a perspective view of the damper of Fig. 1 in a closed position, Fig. 3 is a front elevational view of the damper of Fig. 1, Fig. 4 is a sectional view in the direction of the arrows IV--IV in Fig. 3, Fig. 5 is a sectional view in the direction of the arrows V-V in Fig. 3 with the damper in the open position, Fig. 6 is a sectional view in the direction of the arrows V-V in Fig. 3, with the damper in the closed position, Fig. 7 is a cross sectional view on an enlarged scale of portion of the damper in the position illustrated in Fig. 6, Fig. 8 is a front elevational view of an alternative construction of damper accordimg to the invention, Fig. 9 is a sectional view in the direction of the arrows VIlI-VIlI in Fig. 6, Fig. 10 is a sectional view in the direction of the arrows IX-IX in Fig. 6 with the damper in the open position, Fig. 1 is a sectional view in the direction of the arrows IX-IX in Fig. 8 with the damper in the closed position, Fig. 12 is a schematic perspective view of another damper according to the invention, and Fig. 13 is a cross sectional view of the damper of Fig.12.

Referring to the drawings and initially to Figs. 1 to 7 thereof, there is illustrated a fire and smoke damper according to the invention indicated generally by the reference numeral 1. The damper 1 comprises a damper blade means which in this case is provided by a plurality, in this case, eight stainless steel slats 2, each having inturned longitudinal edges 3 for interengaging with the adjacent inturned edge of an adjacent slat 2 to form a folding shutter type mechanism. It will be noted particularly from Fig. 7 that each of the slats 2 is formed with a longitudinally extending central rib 6 for improved structural strength and heat resistance. The slats 2 are normallyfolded into the retracted position illustrated in Figs. 1 and 5 and are retained in this position by a heat responsive releasable retaining means provided by a two-part fusible link 4.In the event of fire the fusible link 4 breaks and the concertina mechanism of the slats expands under the action of a biasing means, which in this case is provided by two clock-type springs 5 of spring steel material, to close the opening in which the damper is mounted.

The damper 1 also comprises a housing 10 open at both ends 11. The housing 10 is of 80 swg galvanised steel material and includes a top recess portion 12 for accommodating the slats in the folded retracted position and a bottom recess portion 13 for accommodating the springs 5. Opposed side recess portions 14 are provided for accommodating channel-shaped tracks 15 of stainless steel material for controlled movement of the slats between the retracted and expanded positions. In this case the housing 10 is provided with flanges 16 at the opening 11 suitable for making a slip joint connection with a duct (not shown).

In detail, each spring 5 is of the type generally referred to as Tensator springs and comprises a strip 20 of spring steel material fixed at one end to a reel shaft 22 journalled in a casing 25 welded into the bottom recess portion 13 of the housing 10. The strip 20 is reeled around the shaft 22 and extends through the track 15 and is fixed at its other end 23 to the lowermost of the slats 2. A slot 6 in one side of the casing 25 defines a latch retainer for receiving the leading edge of the lowermost slat 2 which defines a latch in the expanded position illustrated in Fig. 6. Two brackets 30 are mounted in the top recess portion 12 of the housing 10 and each depends downwardly into one of the openings 11 and is formed with a bolt hole for receiving a bolt 31 for mounting one leg 32 of the two part fusible link 4.The legs 32 of the fusible link 4 are of brass material soldered with a solder rated at 700C.

In use the damper is mounted in any convenient location in a duct either in a vertically or horizontally extending leg and in any desired orientation. In the event of the fusible link being exposed to a temperature in excess of 70"C, for example due to a fire occurring either in or outside the duct or from hot gases or smoke the link 4 breaks and the slats move under the action of the springs 5, from the retracted position illustrated in Figs. 1 and 5 to the expanded position illustrated in Figs. 2 and 6. In this position the leading edge of the lowermost slat 2 engages in the catch 26 in each casing 25 and the spread of flame and smoke through the duct is prevented.

For resetting, the lowermost slat is disengaged from the catch 26 and the slats are folded back into their retracted position and held in that position by a fresh fusible link.

The damper illustrated in Figs. 1 to 7 has been tested by an approved research centce and meets the requirements of BS 476 Part 8 1972.

One advantage of the invention is that it provides a damper which may be mounted in any location whether on a horizontal or vertical leg of a duct and in any orientation with the recess portion 12 for accommodating the slats in their retracted position lying either at the top as illustrated or at the bottom orto one side.

Referring to Figs. 8 to 11 there is illustrated an alternative construction of damper according to the invention indicated generally by the reference numeral 50. The damper is of similar construction as that described above with reference to Figs. 1 to 7 and for clarity like parts are assigned the same reference numerals. In this case the damper housing 51 is suitably shaped for a flanged joint connection to ducts.

Referring to Figs. 12 and 13there isillustrated another damper 60 according to the invention. In this case the damper comprises a damper blade 61 pivotally mounted on a spindle 62 extending transversely across the opening in a damper housing 63. The damper blade 61 is retained in the open position illustrated by a two-part fusible link 64, one part of which is attached to the damper housing 63 by a chain 65 and the other part is attached to the blade 61 by a chain 66. The blade 61 is biased into a released position closing the opening as illustrated by interrupted lines 61' by a spring biasing means, in this case a coil spring 68 fire rated up to 800on. Flanges 69 are welded to the housing 63 to provide a fire and smoke seal between the blade 61 and the side walls of the housing 63 in the closed position.

It will be appreciated that instead of the slats being folded together in the retracted position, they could in some cases, for example, be wound round a reel shaft, somewhat in the manner of a roller shutter-type mechanism.

It will further be appreciated that while for ease of construction and operation, a clock-type springbiasing means is usually used, any suitable biasing means may also be employed. The biasing means may be a spring-biasing means, such as a coil or leaf spring or may be a mechanical release mechanism, which may be spring operated, or indeed electrically, pneumatically, or hydraulically operated.

It will also be appreciated that any suitable release means may be employed such as a single barofa material selected to rupture at a predetermined temperature to allow the damper to operate.

It will further be appreciated that the housing may be of any suitable shape and configuration to fit in any desired location. Thus, the openings in the housing may be either rectangular as illustrated, circular or of any shape to mate with a complementary shaped duct. It will also be appreciated that the housing may be adapted for any suitable form of joint with a duct.

It will further be appreciated that while in the specific embodiments described the damper is mounted in a duct such as a ventilation duct it may be mounted in any location, for example, in a vertical or horizontal ventilation opening in a false ceiling or a wall.

Claims (27)

1. A fire and smoke damper comprising a damper blade means, biasing means for movement of the damper blade means from an open position into a release closed position substantially sealing an opening in which the damper is mounted, and heat responsive releasable retaining means for retaining the damper blade means in the open position.

2. A damper as claimed in claim 1, in which the damper blade means comprises a shutter formed from a plurality of interconnected slats movable from an open, retracted position to a released position.

3. A damper as claimed in claim 2, in which the slats are hingedly interconnected for pivotal movement between adjacent slats.

4. A damper as claimed in claim 3, in which each slat comprises an elongate plate having inturned edges, an inturned edge of one plate interengaging with the adjacent inturned edge of another slat for pivotal movement between adjacent slats.

5. A damper as claimed in any of claims 2 to 4, in which each slat is formed with a longitudinally extending rib.

6. A damper as claimed in any preceding claim, in which the damper blade means is of a stainless steel material.

7. A damper as claimed in any of claims 1 to 6, in which catch means are provided for sealable engagement of the damper blade means in the released position.

8. A damper as claimed in claim 7 when dependent on any of claims 2 to 6, in which the catch means comprises a latch and latch retainer, the free edge of the lowermost slat defining the latch for engagement in a complementary-shaped latch retainer.

9. A damper as claimed in any preceding claim, in which the biasing means comprises a spring.

10. A damper as claimed in claim 9, in which the spring is of a spring steel material.

11. A damper as claimed in claim 9 or 10, in which the spring comprises a strip of spring material, one end of which is fixed to a reel shaft, the spring strip extending from the reel shaft for connection to a slat at its other end for biasing the slats into the released, closed position.

12. A damper as claimed in claim 11 which includes two strips of spring material connected to opposed side edges of a slat.

13. A damper as claimed in any preceding claim, in which the damper blade means is mounted in a housing, the housing being open at both ends for mounting in an opening.

14. A damper as claimed in claim 13, in which the housing includes a top recess portion for accommodating the damper blade means in the open position.

15. A damper as claimed in any of claims 13 or 14, in which the housing comprises a bottom recess portion for accommodating the spring biasing means.

16. A damper as claimed in claim 14, in which the housing is of a galvanised steel material.

17. A damper as claimed in any of claims 13 to 16 in which the slats are movable in side tracks provided in the housing.

18. A damper as claimed in claim 17, in which each track is provided by a channel fixed to a side wall of the housing.

19. A damper as claimed in claim 18, in which the channel is of a stainless steel material.

20. A damper as claimed in any of claims 13 to 19, in which the housing includes a longitudinally extending flange surrounding the opening on both sides and onto which mating ducts are slipjointed.

21. A damper as claimed in any of claims 13 to 19, in which the housing is adapted for flange jointing with mating ducts.

22. A damper as claimed in any preceding claim, in which the retaining means comprises a fusible link.

23. A damper as claimed in claim 22, in which the fusible link comprises a two leg link, the legs of the link being soldered together and the solder melting at a predetermined temperature to release the slats.

24. A damper as claimed in claim 23, in which each of the legs of the link are of a brass material.

25. A damper as claimed in claim 1, in which the blade means comprises a damper plate, the plate being pivotally mounted in a housing and being movable by a spring biasing means from an open position transverse of the opening to a released position closing the opening.

26. A damper as claimed in claim 25, in which the damper plate is pivotally mounted on a central spindle extending transversely across the opening.

27. A damper substantially as hereinbefore described with reference to the accompanying drawings.