Venting Device

Abstract

A vent device comprising at least one control member pivotably supported in an opening in a frame, for movement, in response to differential gas pressure between opposite sides of the opening, between a closed position in which the control member(s) substantially blocks the opening and an open position in which the control member(s) leaves the opening substantially unobstructed for flow of gas therethrough, wherein the or at least one of the control members has associated therewith a restraining mechanism, operable to apply a force to the control member to influence movement thereof between its open and closed positions.

Description

This invention relates to a venting device. More particularly, it relates to a fire suppression vent, that is to say a device for facilitating ingress and egress of large volumes of gas to and from an enclosed space such as a building or room in a building. Such large flows of gas may be caused to take place in the event of operation of a fire suppression system in the enclosed space.

Fire suppression systems operate, when a fire is detected in an enclosed space, by releasing a large quantity of gas into the space. The gas may be an inert gas, to displace air from the space and hence to deprive the fire of the oxygen it would need to continue burning, or a chemical composition which, in addition to displacing air, interferes chemically with the combustion process to absorb heat and hence extinguish a fire. The latter is less common these days since the Halon substance commonly utilised is prohibited from current use, as causing damage to the earth's ozone layer.

The quantity of gas released into an enclosed space when a fire suppression system operates is sufficient to raise the pressure in the space significantly above atmospheric pressure outside the space. This can be sufficient to cause structural damage to a building. Therefore, there is a need for venting a large volume of gas from the space when the system operates. In the case of a chemical fire suppression agent, an initial reduction in pressure in the space may be followed by an increase in pressure as the chemical agent reacts with the fire.

The provision of one or more fire suppression vents in the boundary of a fire-suppressed enclosed space enables the problems of over- or under-pressurisation of the interior of the space to be overcome. Known fire suppression vents include a frame which affords an opening of sufficient cross-sectional area, in view of the volume of the space and the nature of the fire suppression system. In the frame are provided a number of control members comprising blades or vanes which are pivotally movable between closed positions in which together they substantially completely occlude the opening, and open positions in which they offer little obstruction to flow through the opening. By way of example, the blades should start to open when there is a pressure difference of some 80 to 100 Pascals between opposite sides thereof, and be completely open if a pressure differential of 100 to 150 Pascals exists. Generally, the blades have been arranged to extend horizontally across the frame, pivoted near to their respective top edges, and returned to their closed positions by gravity. Such blades have been able to open only in response to a pressure differential in one direction across the opening, i.e. a positive pressure inside the space compared the exterior pressure or a negative pressure inside the space compared with the exterior thereof. To provide for both large-volume outflow and inflow, it is known to provide a frame with two sets of blades, one of which opens under positive pressure conditions and the other which opens under negative pressure conditions, but this means that the vent as a whole is considerably larger than would be necessary if a single set of blades were to be able to open in controlled manner under both pressure conditions.

It is broadly the object of the present invention to provide a fire suppression vent in which pivoted blades are able to operate in a controlled manner under both pressure conditions.

According to the invention, we provide a vent device comprising at least one control member pivotably supported in an opening in a frame for movement, in response to differential gas pressure between opposite sides of the opening, between a closed position in which the control member(s) substantially blocks the opening and an open position in which the control member(s) leaves the opening substantially unobstructed for flow of gas therethrough, wherein the or at least one control member has associated therewith a restraining mechanism, operable to apply a force to the control member to influence movement thereof between its open and closed positions.

Preferably the or each control member is able to pivot in opposite directions from its closed position to respective open positions, in accordance with the direction of the differential gas pressure between opposite sides of the opening.

The restraining mechanism preferably provides a check to hold the control member in its closed position until a predetermined pressure difference between opposite sides of the opening is reached.

The restraining mechanism may comprise a cam and cam follower mechanism, the cam and cam follower undergoing relative movement as the control member moves between its open and closed positions. Conveniently the cam follower is provided on the control member, and the cam is provided on the frame relative to which the control member is pivotably moveable, but in an alternative arrangement the cam can be provided on the control member, and the cam follower can be provided on the frame. The cam follower may be resiliently biased into engagement with a cam surface of the cam member.

Preferably the force of the biasing of the cam follower is adjustable.

The cam surface of the cam member may provide a generally uniform resistance to movement of the control member as the control member moves from its closed position to its open position(s), or the form of the cam surface may be such that the resistance to movement of the control member varies in the course of such movement. Possibly, in the case of a control member or members moveable in opposite directions from a closed position to two alternative open positions, respective cam surface parts engaged by the cam follower during the opposite movements of the control member may be of different form from one another, so the restraining force applied to the control member(s) differs for the two directions of movement.

The check provided by the restraining mechanism, when the or each control member is in a closed position, may be afforded by a recess or depression in the cam surface, with which the cam follower engages.

Preferably the centre of gravity of the or each control member is positioned substantially on, or in the vicinity of, the axis about which the control member is pivotable relative to the frame of the vent device. The control member may be weighted e.g. by an internal weight member, so as to cause the centre of gravity to be so positioned.

A mechanism may be provided for holding the control member(s) in a closed position, to enable the device to function as a fire barrier. The mechanism may also bring the control member(s) to the closed position, if it or they are not in such position.

The invention will now be described by way of the example with reference to the accompanying drawings, of which:

FIG. 1 is a front view of a vent device in accordance with the invention, with part of one of the control members thereof removed;

FIG. 2 is a section on the line AA of FIG. 1;

FIG. 3 is a perspective view of the vent device, with control members in a closed position;

FIG. 4 is an enlarged view of part of FIG. 3;

FIG. 5 is a view as FIG. 3, but with the control members in partially open positions; and

FIG. 6 is an enlarged view of the marked part of FIG. 5.

FIG. 7 is a perspective view of part of a further embodiment of vent device in accordance with the invention, FIG. 7a being an enlargement of part thereof;

FIG. 8 is an end view a further embodiment of vent device in accordance with the invention;

FIG. 9 is a section on 9-9 of FIG. 8.

Referring firstly to FIGS. 1 and 2 of the drawings, these show a vent device, specifically a fire suppression vent as described above, which has a peripheral frame indicated generally at 10, comprising spaced parallel horizontal frame members 12, 14 and spaced parallel vertical frame members 16, 18 extending between the frame members 12, 14. The frame members are metal sections, e.g. of steel. The frame 10 defines a rectangular central opening and in the opening are supported, for pivotal movement as described hereafter, two control members 20, 22 which are in the general form of blades or vanes. The frame 10 is intended to be installed in an aperture in a wall or panel of a building structure to provide for fire-suppression venting of a room or enclosed area of the structure, or of the building structure as a whole. One wall 12a, 14a of each of the frame members 12, 14, and corresponding walls of the frame members 16, 18, lies against the surface of the wall or panel of the building structure, and may be secured thereto by screws or other means.

Each of the control members 20, 22 is of hollow “double skin” construction, comprising two wall members of the same cross sectional shape as one another, inter-fitting with one another in back to back arrangement. Alternatively, each control member could be made as a single construction, such as by way of a single pressing. In FIG. 2, the two wall members 24, 26 of the control member 22 are visible, while in this and all the other figures of drawings the wall member 26 of the control member 20 has been removed leaving only the wall member 24 thereof. The configuration of each of the wall members 24, 26 is clearly shown for the wall member 24 of the control member 20: it will be noted that it has at its upper edge an inverted “V” shaped portion 28 which inter-fits with the corresponding inverted “V” shaped portion of the other wall member 26 in the complete control member. Hence it will be appreciated that the top edge of the control member is slightly weighted by this construction. An additional weight member may be fitted to the control member, preferably between its wall members 24, 26, to bring the centre of gravity of the control member to be coincident with or extremely close to the pivot axis of the control member as described hereafter. Hence little or no pivotal bias will be exerted on the control member by the force of gravity thereon.

The control members 20, 22 are pivotably supported in the frame 10 for movement about respective pivot axes, that for the control member 20 being indicated in FIG. 1 at 30. The control member is provided at each of its ends with a respective support block 32 from which a pivot pin 34 extends outwardly, to be received in a bearing 36 held in a bearing block 38 carried by the frame member 16 or 18 as the case may be. At one end of the control member, seen in FIGS. 3 to 6 of the drawings, the bearing block 38 forms a cam member having a cam track or surface 40, while at the other end the bearing block 38 does not have a cam surface 40, although if desired, in the interests of using common components, the opposite bearing block 38 could be the same as the bearing block with the cam surface.

The position of the centre of gravity of each of the control members 20, 22 is, by suitable weighting of the members, controlled so as to be substantially coincident with the respective pivot axis as 30 of the control member, with reference to FIGS. 1 and 2. In a closed position, the control members lie in the general plane of the opening defined by the frame and, together, substantially close the opening defined by the frame 10. When the control members are subject to a differential gas pressure of sufficient magnitude, since their centres of pressure are spaced from their pivotal axes with reference to FIGS. 1 and 2, they are pivoted to a position substantially at right angles to the position of FIG. 2, the direction of such pivoting depending on whether the higher gas pressure exists to the left hand side or right hand side of FIG. 2. When thus pivoted, the control members leave the opening substantially unobstructed (other than the relatively small obstruction afforded by the thickness of the control members). The expression “substantially unobstructed” herein refers to such a condition, the thickness of the control members being minimal compared with the cross sectional area of the opening in which they operate.

The substantial coincidence of the axis of rotation of each control member with its centre of gravity means that the vent device may function in any orientation irrespective of the direction of gravitational force relative to the device.

The control member 20 carries a cam follower member, most clearly seen in FIG. 6, which co-operates with the cam surface 40 of the bearing block 38 as the control member pivots about its axis 30. The support block 32 has connected thereto a somewhat U shaped element 44 of resilient material such as spring steel. From the support block 32, the spring element 44 extends towards the opposite end of the control member and then back towards the adjacent end of the control member, at which the free end part 46 of the element 44 is turned at right angles to carry a roller cam follower element 48 which engages the cam surface 40. The spring force of the element 44 urges the cam follower 48 towards the centre of the bearing block 38 to press against the cam surface 40. When the control member 20 is in the closed position, i.e. the upright position shown in FIG. 2 in which, together with the control member 22, it substantially closes the opening afforded by the frame 10, the cam follower 48 engages in a recess 50 in the cam surface 40, to provide a check or detent which tends to hold the control member in the closed position. The control member is capable of pivoting in either direction from the closed position, in which case the cam follower 48 is displaced out of the recess 50 of the cam surface, deforming the spring element 44 against the resistance offered thereby. As the control member pivots further, the cam follower 48 moves along the cam surface 40, and it will be appreciated that the profile of the cam surface 40 enables a force to be exerted on the control member depending on the amount to which the latter has pivoted from its closed position.

The resistance afforded by the resilient element 44 to displacement of the cam follower 48 out of the recess 50 may be adjustable. To this end, the U shaped portion (52) of the element 44 remote from the cam follower 48 is embraced by a member 54 having a U shaped cut-out 56 within which the portion 52 of the element 44 fits. The member 54, which may be of sheet metal for example, is adjustable in the direction of the length of the control member and able to be set in position relative to the control member by a fixing device, not shown, such as a locking screw. It will be appreciated that if the member 54 is displaced so that a greater length of the resilient element 44 lies within the cut-out 56, the resistance of the element 44 to movement of its limbs away from one another as the cam follower 48 is caused to leave the recess 50, as the control member pivots from its closed position, is increased: hence the resistance to initial pivotal movement of the control member from its closed position is increased.

The respective configurations of the parts of the cam surface 40 on opposite sides of the recess 50 may be the same (in mirror image) as one another, so that the effect of the restraining mechanism constituted by the cam and follower arrangement is the same whichever direction the control members pivot from their closed position. Alternatively, the respective parts of the cam surface may be of different configuration from one another, so that the effect on pivoting movement of a control member is different depending on the direction of such pivoting. The cam surfaces may provide a generally uniform resistance to pivoting of the control members once the initial movement from their closed positions has taken place, or the resistance to pivoting may vary with the amount by which the control members have moved from the closed position.

Thus, the invention provides a wide range of possibilities for adjustment of the operating characteristics of a vent device, in terms of the forces required to displace the control members initially from the closed position and to change the extent of opening of the control members.

Referring now to FIG. 7 of the drawings, this shows part of an embodiment of vent device whose operating principle is the same as that above described, but whose detailed design differs. Accordingly, in the description relating to FIG. 7 the reference numerals used above to identify different elements of the device are now used with the addition of 100 to identify elements in FIG. 7 which correspond in function to those above described.

FIG. 7 shows part of a vent device which comprises three control members indicated generally at 120, 121,122. The control members are supported in a frame for movement about respective pivot axes which are parallel to one another, a vertical frame member of the frame being indicated at 116. The control members 120, 121, 122 are of similar construction to the control members 20, 22, and the control member 121 is shown with one of its wall members removed to show the components disposed in the interior of this control member. For pivotal support of the control member at the illustrated end thereof, a support block 132 is provided, with a pivot pin 134 extending outwardly therefrom to be received in a bearing 136 in the frame member 161. A counterweight member 127 is carried in the control member 121 adjacent its uppermost edge, so that the centre of gravity of the control member lies on or very close to the pivotal axis provided at the respective end of the control member by the pivot components 132, 134, 136.

The control member 121 carries a support element 144 in the form of an arm, pivotally connected to the control element at a pivot 138. At its free end the arm 144 carries a roller cam follower element 148, and a tension spring 145 acts on the arm 144 so that its free end, having the cam follower element 148, is spring biased upwardly, having regard to the orientation in which these components are shown in FIG. 7 of the drawings. The tension of the spring 145 is adjustable by an adjuster screw 143, accessible by way of an opening 152 at the uppermost edge of the control member.

The frame member 116 is provided with a somewhat W-shaped opening 138, approximately half of which is visible in the view shown in FIG. 7 and the remainder of which, concealed behind the end part of the control member 121, extends generally in mirror image of the visible part. The latter part of the opening is shown in broken lines in FIG. 7a. The cam follower element 148 engages a cam surface 140 defined by the uppermost boundary of the opening 138, and the effect of the spring 145 is to bias the cam follower element into contact with the cam surface. The cam surface includes a central recess 150, with which the cam follower element engages when the control member 121 is in the upright, closed, orientation illustrated.

In use, the mode of operation of the embodiment of FIG. 7 is as described above in relation to FIGS. 1 to 6. As is the case in the embodiment of FIGS. 1 to 6, the two parts of the opening 138 in the frame member 116 need not be an exact mirror image of one another, thereby providing a different resistance to pivoting of the control member in respective opposite directions from its closed position.

Referring now to FIGS. 8 and 9 of the drawings, these illustrate the additional provision of a mechanism for holding the control members of a vent device in the closed position. The device then may be capable of acting as a fire barrier, for which it is required to withstand a fire test for a prolonged period of time. Hence a means of locking the control members in the closed position is required if the vent device is to perform this function.

In FIGS. 8 and 9, which show part of a vent device as shown in FIG. 7 but at the opposite end of its three control members, the pivot pins 134 of the respective control members are extended beyond the bearings by which they are supported in the frame of the vent device, and are provided with disc-like end portions 71 which carry respective cylindrical bosses 80 extending back towards the control member. It will be appreciated that when the control members pivot, such bosses move in respective arcs up to 90 degrees each side of the closed position in which each boss lies beneath its respective pivot pin.

A control plate 82 is mounted on the outside of the frame member 118, being constrained to move vertically relative to the frame member by mounting posts 83 which extend through vertical slots 77 in the control plate 82 and are provided at their free ends with retaining members 84. The extended vertical movement of the plate 82 is limited by the extent of the slots 77. A spring or springs, not shown, of any suitable form is provided for spring biasing the plate 82 downwardly, to the lowest position permitted by the slots 77.

The plate 82 is provided with respective openings co-operable with the bosses 80 carried by the pivot pins of the respective control members. In FIG. 8, the disc 71 of the pivot pin of the middle control member has been removed to illustrate the shape of the opening 78. It is somewhat an inverted T-shape, comprising a generally rectangular lower portion with a relatively narrow upper portion extending upwardly from the central region of the lower portion. The width of the upper portion of the opening is sufficient to receive the respective boss 80.

A fuseable link assembly 72 having a lug 79 engages an opening in the plate 82 above the opening 78 therein. The fuseable link assembly holds the plate 82 in the uppermost position in which it is depicted in FIG. 8, until a temperature, e.g. 70° C. at which low temperature solder holding the link assembly together melts, whereupon the plate 82 is released and is free to move downwardly under the influence of its spring(s).

When the plate is in the position shown in FIG. 8, the boss 80 on each of the control members is free to move through an arc of movement of approximately 180° in total, within the boundaries of the lower portion of opening 78. When the fuseable link melts as above described and the plate 82 is moved downwardly under the influence of its spring(s), the bosses 80 are engaged by the respective recesses 78 to cause the control members to be brought to the closed position, and the bosses enter the uppermost part of the opening 78 to hold the control members in that position. The spring(s) acting on the plate 82 have some residual tension when the plate 82 has reached its lowermost position, ensuring that the control members are held in the closed position.

When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A vent device comprising at least one control member pivotably supported in an opening in a frame, for movement, in response to differential gas pressure between opposite sides of the opening, between a closed position in which the at least one control member substantially blocks the opening and an open position in which the at least one control member leaves the opening substantially unobstructed for flow of gas therethrough, wherein at least one control member has associated therewith a restraining mechanism, operable to apply a force to the control member to influence movement thereof between its open and closed positions.

2. A vent device according to claim 1, wherein the at least one control member is able to pivot in opposite directions from its closed position to respective open positions, in accordance with the direction of the differential gas pressure between opposite sides of the opening.

3. A vent device according to claim 1 wherein the restraining mechanism provides a check to hold the control member in its closed position, until a predetermined pressure differential between opposite sides of the opening is reached.

4. A vent device according to claim 1 wherein the restraining mechanism comprises a cam and cam follower arrangement, the cam and cam follower undergoing relative movement as the control member moves between its open and closed positions.

5. A vent device according to claim 4 wherein the cam follower is provided on the control member and the cam is provided on the frame relative to which the control member is pivotably moveable.

6. A vent device according to claim 5 wherein the cam is provided on the control member and the cam follower is provided on the frame relative to which the control member is pivotably moveable.

7. A vent device according to claim 4 wherein the cam follower is resiliently biased into engagement with a cam surface of the cam member.

8. A vent device according to claim 7 wherein the force with which the cam follower is biased into engagement with the cam surface is adjustable.

9. A vent device according to claim 7 wherein the form of the cam surface provides a generally uniform resistance to movement of the control member as the control member moves from its closed position to its open position(s).

10. A vent device according to claim 7 wherein the form of the cam surface of the cam member is such that resistance to movement of the control member from its closed position to its open position(s) varies in the course of such movement.

11. A vent device according to claim 2, wherein the restraining mechanism provides for different characteristics in respect of movement of the control member in its opposite directions from its closed position to its open positions.

12. A vent device according to claim 2 wherein the restraining mechanism provides the same characteristics in respect of movement of the control member from its closed position to its respective open positions.

13. A vent device according to claim 4 wherein the cam has a recess, with which the cam follower engages to provide a check to hold the control member in its closed position, until a predetermined pressure differential between opposite sides of the opening is reached.

14. A vent device according to claim 1 wherein the control member is of double-wall construction, comprising two wall members secured together with a space therebetween.

15. A vent device according to claim 14 wherein the wall members are identical to one another.

16. A vent device according to claim 14 wherein a part of the restraining mechanism is accommodated between the wall members of the control member.

17. A vent device according to claim 1 wherein the centre of gravity of the control member is positioned substantially on or adjacent the pivot axis of the control member.

18. A vent device according to claim 17, wherein an edge of the control member is weighted so as to cause the centre of gravity to be so positioned.

19. A vent device according to claim 1 comprising a mechanism for bringing the control member(s) to a closed position and/or retaining it/them in that position.

20. A vent device according to claim 19 wherein the mechanism is temperature-responsive.

21. (canceled)