GB2222946A - Fire damper - Google Patents

Fire damper Download PDF

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Publication number
GB2222946A
GB2222946A GB8920500A GB8920500A GB2222946A GB 2222946 A GB2222946 A GB 2222946A GB 8920500 A GB8920500 A GB 8920500A GB 8920500 A GB8920500 A GB 8920500A GB 2222946 A GB2222946 A GB 2222946A
Authority
GB
United Kingdom
Prior art keywords
shutter
damper
ramp
edge
abutment
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8920500A
Other versions
GB8920500D0 (en
Inventor
John James Mawdsley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GILBERTS
Original Assignee
GILBERTS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB888821176A priority Critical patent/GB8821176D0/en
Application filed by GILBERTS filed Critical GILBERTS
Publication of GB8920500D0 publication Critical patent/GB8920500D0/en
Publication of GB2222946A publication Critical patent/GB2222946A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A62LIFE-SAVING; FIRE-FIGHTING
    • A62CFIRE-FIGHTING
    • A62C2/00Fire prevention or containment
    • A62C2/06Physical fire-barriers
    • A62C2/12Hinged dampers
    • A62C2/14Hinged dampers with two or more blades
    • A62C2/16Hinged dampers with two or more blades multi-vane roll or fold-up type

Abstract

A fire damper 2 comprises a metal shutter 18 normally folded but released at high temperature by failure of a fusible line. When released, the shutter 18 extends across the opening in the fire damper 2. Towards the end of its travel the leading element 24 of the shutter contacts ramps 28 located on each side of the damper 2. The ramps 28 are shaped, for example in having convex ramp edges 32, to aid the engagement of a lip at the leading edge of the leading element 24 behind abutments 36 at the base of the ramp edges 32. <IMAGE>

Description

FIRE DAMPER This invention relates to a fire damper of the type comprising a metal housing open on both sides to define an opening through the housing. The housing contains a metal shutter made up of metal elements hinged together, the shutter normally being held, against a powerful spring or springs, in a folded condition in which the damper is open to the flow of air, but being releasable to adopt an extended condition in which it closes the opening through the housing. Such a damper is employed in ducting, for example air conditioning ducting, the shutter being released, to adopt its extended condition, in the event of fire. Commonly, the shutter is released to adopt its extended condition when a fusible retaining element within the housing fails, or when a latch within the housing is released electrically, for example on external sensing of smoke and/or flames.
Conventionally, fire dampers contain a pair of ramps adjacent the wall remote from the folded shutter, (hereinafter the "base wall") one on one side of the damper and one on the other side. The ramps are of sheet metal and they are mounted upright in the housing, substantially parallel to the direction of air flow through the housing. An edge of each ramp is contacted by the leading element of the shutter on extension of the shutter. The edges of the ramps are straight, and inclined to the direction of shutter travel, such that the shutter must remain in contact with them as it extends.The ends of the ramp edges terminate a short distance above the base wall, whereby a lip formed at the leading edge of the leading element engages behind the ramps, in abutments beyond the ramp edges, in the extended condition of the shutter, to prevent any return movement of the shutter in the event of the failure of the spring or springs.
It has been found, surprisingly in view of the strength of the spring or springs used, that the lip of the leading element of the shutter does not always adequately engage in the abutments, so that a large gap may be present at the base wall of the housing, which renders the fire damper largely ineffective.
According to the present invention there is provided a fire damper of the kind comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that at least part of each ramp edge contacted by the shutter during its extension is generally convex.
Preferably at least the part of each ramp edge initially contacted by the leading element of the shutter is generally convex.
In certain preferred embodiments the shape of the lower part of each ramp edge and abutment generally conform to the shape of the leading element of the shutter which is juxtaposed thereto, in the extended condition of the shutter.
In certain preferred embodiments the lower part of each ramp edge adjacent to the abutment is generally concave.
In other embodiments the part of each ramp edge adjacent the abutment may be generally convex. The part of each ramp edge adjacent the abutment may constitute a lead-in edge to guide the lip of the leading element back towards the abutment. To this end each ramp edge may curve back on itself adjacent the abutment.
Preferably, each ramp edge is generally convex over a substantial proportion of that part of the ramp edge which is contacted by the leading element of the shutter during extension of the shutter.
Suitably, curved profiles are arcs of circles.
In accordance with a further aspect of the present invention there is provided a fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that each abutment is so formed that, when the shutter is in its extended condition, the lip of the leading element thereof must move towards the base wall before it can become free from the abutments.
Preferably, each abutment is formed with a concave surface.
In accordance with a further aspect of the present invention there is provided a fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that the lower part of each ramp edge adjacent to the abutment is generally concave.
In accordance with a further aspect of the present invention there is provided a shutter inounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that at least part of the ramp edge and/or abutment of each ramp comprises a curved portion to assist engagement of the shutter behind the abutments.
The shutter may be released from its folded condition, in the event of fire, by any conventional means, for example by use of a fusible device which retains the shutter in place, or of an electro-magnetic device releasing the shutter in response to local and/or remote heat and/or smoke detection.
The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view of a fire damper, incorporating a ramp with a convex ramp edge; Figure 2 is an elevation of a further ramp with a convex edge; Figure 3 is an elevation of a further ramp; and Figure 4 is an enlarged view of a part of the ramp of Figure 3.
Figure 1 shows a fire damper 2 having a metal housing 4 which is open on both sides to define an opening through the housing. From opposite sides of a rectangular section central part 8 of the housing 4 extend aligned, rectangular-section projecting parts 10 and 12, intended for engagement in ducting. The central part 8 extends beyond the projecting parts 10 and 12 on all sides.
Mounted on the internal surface of one such side 16 of the central part 8, the top wall in use, is a metal shutter 18. The shutter is formed of a plurality of steel shutter elements 20, hinged together along hinges 22. The leading shutter element 24 has secured to each of its lateral sides a band spring 26 (of which one is seen in Figure 1). Each band spring 26 is secured at one of its ends to the leading shutter element 24, its other end being secured to a ramp 28 (of which one is seen in Figure 1) riveted to one of the side walls of the housing. The springs bias the shutter towards the base wall 30.
Each ramp 28 is of sheet metal and has a convex ramp edge 32 terminating a short distance above the base wall at a cut-away 34, the upper edge 36 of which provides an abutment behind which a folded-over lip (not shown) on the leading edge of the leading element 24 of the shutter is retained, in the extended condition of the shutter. The edge 32 is the arc of the circle, which extends from the top of the ramp to the cut-away.
Normally the shutter is retained by a fusible link in a folded condition adjacent the top wall 16 but in the event of fire the link melts and the shutter is released, being drawn by the springs into its extended condition, in which it closes the opening. During the extension of the shutter the leading element 24 contacts the ramp edges 32, and it remains in contact with them as it extends, until the lip on the leading element has passed beyond the ramp edges, to locate in the cut-aways 34, against the abutments 36. The shutter is now prevented from making any return movement, as might occur in the event of damage to or failure of the springs.
Figure 2 shows an alternative ramp 38. It has a ramp edge 40 which is substantially convex throughout its length. To be precise, it has a long convex part 41 which is the arc of a circle centered beyond the ramp, leading to a very short part 42 adjacent a cut-away 43 whose upper edge 44 acts as an abutment for the lip of the leading element of the shutter. The short part 42 is straight but is slanted towards the abutment so that it serves as a lead-in surface to guide the lip into the cut-away. Effectively, the ramp edge curves back on itself in this region. The point at which the sections 41, 42 meet as indicated by a dotted line X. The corner between the lower end of the lead-in and the cut-away is convex, rather than sharp.
Figure 3 shows a further alternative ramp 48.
Its ramp edge 50 is convex over most of its length, between the top of the ramp and a position Y approximately three-quarters of the distance to the bottom of the ramp edge. The ramp edge is then straight for a short distance, between positions Y and Z, and is then concave. At the bottom of the ramp edge, between the ramp edge and a lip-retaining abutment 52, is a rounded projecting part 54.
The lower region of the ramp edge 50, the abutment 52 and the projecting part 54 are shown in expanded view in Figure 4. It will be observed that the rounded projecting part 54 has a concave under-surface 56 leading into the abutment which helps to retain the lip of the leading element of the shutter in place. The lip must be moved downwards in order to become free from the abutment. The shape of the ramp in this region conforms to the shape of the leading element 58, shown in dotted line in Figure 4.
It has been found that a more reliable operation of the damper is achieved than is the case in prior art dampers having straight edge ramps, the shutter being more likely to adopt its fully extended condition with the lip of the leading element against the abutments.
The invention is not restricted to the details of the foregoing embodiment. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings).
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be combined in any combination, except combinations where at least some of such features are mutually exclusive.

Claims (13)

1. A fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that at least part of each ramp edge contacted by the shutter during its extension is generally convex.
2. A fire damper as claimed in Claim 1, wherein at least the part of each ramp edge initially contacted by the leading element of the shutter is generally convex.
3. A fire damper as claimed in Claim 1 or 2, wherein each ramp edge is generally convex over a substantial proportion of that part of the ramp edge which is contacted by the leading element of the shutter during extension of the shutter.
4. A fire damper as claimed in any preceding claim, wherein the shape of the lower part of each ramp edge and abutment generally conform to the shape of the leading element of the shutter which is juxtaposed thereto in the extended condition of the shutter.
5. A fire damper as claimed in any preceding claim, wherein the lower part of each ramp edge adjacent to the abutment is generally concave.
6. A fire damper as claimed in any of Claims 1 to 4, wherein at least the part of each ramp edge adjacent the abutment is generally convex.
7. A fire damper as claimed in Claim 6, wherein the part of each ramp edge adjacent the abutment constitutes a lead-in edge to guide the lip of the leading element towards the abutment.
8. A fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that each abutment is so formed that, when the shutter is in its extended condition, the lip of the leading element thereof must move towards the base wall before it can become free from the abutments.
9. A fire damper as claimed in Claim 8, wherein each abutment is formed with a concave surface.
10. A fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter, characterised in that the lower part of each ramp edge adjacent to the abutment is generally concave.
11. A fire damper as claimed in any combination of the following claims: any one of Claims 1 to 7; Claim 8 or 9; Claim 10.
12. A fire damper comprising a shutter mounted in a housing which has a top wall, a base wall and side walls, the shutter being made up of metal elements hinged together, and being capable of being folded into a folded (damper open) condition in which it is retained in place adjacent the top wall of the housing, but being loaded towards an extended (damper closed) condition, the damper comprising two ramps adjacent the base wall of the housing, one on one side of the damper and the other on the other side, each ramp having a ramp edge contacted by the leading element of the shutter on extension of the shutter and an abutment beyond the ramp edge, wherein a lip at the leading edge of the leading element is located behind the abutments in the extended condition of the shutter., characterised in that at least part of the ramp edge and/or abutment of each ramp comprises a curved portion to assist engagement of the shutter behind the abutments.
13. A fire damper substantially as hereinbefore described with reference to the accompanying drawings.
GB8920500A 1988-09-09 1989-09-11 Fire damper Withdrawn GB2222946A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB888821176A GB8821176D0 (en) 1988-09-09 1988-09-09 Fire damper

Publications (2)

Publication Number Publication Date
GB8920500D0 GB8920500D0 (en) 1989-10-25
GB2222946A true GB2222946A (en) 1990-03-28

Family

ID=10643322

Family Applications (2)

Application Number Title Priority Date Filing Date
GB888821176A Pending GB8821176D0 (en) 1988-09-09 1988-09-09 Fire damper
GB8920500A Withdrawn GB2222946A (en) 1988-09-09 1989-09-11 Fire damper

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB888821176A Pending GB8821176D0 (en) 1988-09-09 1988-09-09 Fire damper

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GB (2) GB8821176D0 (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB502436A (en) * 1938-01-12 1939-03-17 Dennison Kett & Company Ltd Improvements in roller shutters
GB517199A (en) * 1938-07-22 1940-01-23 Dennison Kett & Company Ltd Improvements in roller shutters
GB1189881A (en) * 1967-04-04 1970-04-29 Air Balance Air Control Device
GB1248117A (en) * 1968-05-17 1971-09-29 Ruskin Mfg Company Closure assembly for use as a fire damper or the like
GB1452438A (en) * 1973-07-12 1976-10-13 Ruskin Mfg Co Fire damper
GB1512374A (en) * 1974-07-31 1978-06-01 Convyron Ltd Selfclosing anti-fire shutters
US4579047A (en) * 1984-12-13 1986-04-01 Pullman Construction Industries, Inc. Fire damper assembly for sealed penetrations

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB502436A (en) * 1938-01-12 1939-03-17 Dennison Kett & Company Ltd Improvements in roller shutters
GB517199A (en) * 1938-07-22 1940-01-23 Dennison Kett & Company Ltd Improvements in roller shutters
GB1189881A (en) * 1967-04-04 1970-04-29 Air Balance Air Control Device
GB1248117A (en) * 1968-05-17 1971-09-29 Ruskin Mfg Company Closure assembly for use as a fire damper or the like
GB1452438A (en) * 1973-07-12 1976-10-13 Ruskin Mfg Co Fire damper
GB1512374A (en) * 1974-07-31 1978-06-01 Convyron Ltd Selfclosing anti-fire shutters
US4579047A (en) * 1984-12-13 1986-04-01 Pullman Construction Industries, Inc. Fire damper assembly for sealed penetrations

Also Published As

Publication number Publication date
GB8920500D0 (en) 1989-10-25
GB8821176D0 (en) 1988-10-12

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