GB2141817A - Ventilating air flow damper - Google Patents

Abstract

A damper for regulating a flow of air comprises means 8,9,10 defining an air passage and at least one blade 29,30 pivotally mounted at 31 and movable from a position in which the blade substantially closes the air passage to a position in which the air passage is open, said blade being substantially horizontal when the air passage is closed, the blade pivoting upwardly when air flows through the damper so that air flows between the upwardly inclined blade and the means defining the air passage. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a damper The present invention relates to a damper and more particularly relates to a pressure regulating damper.

There are various situations where it is desirable to utilise a pressure regulating damper.

Buildings are often provided with ventilation systems which become operable in the event of a fire, and frequently these ventilation systems are so adapted as to ensure a supply of fresh air to fire exits, passages, lobbies and stairways. It is thus preferable to be able to maintain such areas within the building at a slightly higher pressure than the remaining areas in the building by supplying fresh air under pressure to these areas. Thus a constant supply of fresh air is maintained to the areas, and there is only a minimum chance of the areas becoming contaminated with smoke or other fumes.

It is often necessary to provide such areas with dampers which permit air to flow through the dampers away from the zones in question when the pressure within the zone reaches a predetermined level. However, such dampers should shut rapidly if there is a drop of pressure within the zone, for example if an escape door is open, since otherwise smoke or other noxious fumes may be drawn into the zones under consideration.

Another application for a pressure control damper is in connection with rooms which must be maintained sterile or clean, such as operating theatres in hospitals, and "clean rooms" in manufacturing facilities and in laboratories. In such situations it is often desirable to maintain the clean or sterile area at a slightly higher pressure than the adjacent areas.

In such a situation a damper is often provided to permit the flow of air away from the high pressure area.

It has been proposed previously to provide a damper constituted by a plurality of pivoted blades.

The blades have been disposed horizontally and have been pivoted adjacent their upper edges. Thus, the blades hang substantially vertically with the free edge of one blade lying lower than the point of pivotal support of the next adjacent blade. Such a damper can only open in one direction, and when a high pressure is experienced on one side of the damper the blades pivot away from the vertical position towards their horizontal position, permitting a flow of airthrough the damper.

A problem encountered in connection with prior proposed dampers of this type is that the damper merely acts as a non-return valve, and does not act in any appreciable way to maintain a desired pressure differential between the inlet side of the damper and the outlet side of the damper. The pressure differential that exists at any point in time is related to the rate of flow of air through the damper.

The present invention seeks to provide an improved damper device.

According to one aspect of this invention there is provided a damper for regulating a flow of air, said damper comprising means defining an air passage and at least one blade pivotally mounted and movable from a position in which the blade substantially closes the air passage to a position in which the air passage is open, said blade being substantially horizontal when the air passage is closed, the blade pivoting upwardly when air flows through the damper so that air flows between the upwardly inclined blade and the means defining the air passage.

Preferably the damper blade is pivotally mounted about an axis located closer to one edge of the blade than the other edge, said other edge being moved upwardly when the damper opens.

Conveniently said one edge of the blade constitutes a counterweight, which at least partly balances the movement of the part of the blade between the axis and said other edge of the blade.

In one embodiment said blade includes a substantially planar portion extending substantially from the axis of pivotal support of the blade away from the counterweight towards said other edge, the said other free edge of the blade terminating at a point below the plane defined by said panar portion.

Preferably the said other edge of the blade forms the termination of an arcuately curving portion of the blade that curves out of said plane.

Advantageously means are provided on the blade for mounting, on the blade, a selected weight or weights.

Conveniently the blade is provided with one or more recesses adapted to accommodate said weight or weights.

Sealing means are provided adapted to be engaged by the damper when in the closed position so that the damper forms a substantially airtight seal.

Preferably in its rest position, the damper blade is horizontal plus or minus 10 , most advantageously plus or minus 5O.

The blade may be mounted in position by being mounted on a rod, the rod being rotatably mounted in a frame. The damper means incorporate a plurality of damper blades.

According to another aspect of this invention there is provided a damper, said damper comprising means defining an airflow passage, and a blade pivotally mounted and movable between a position in which the blade substantially closes said airflow passage to a position in which the air flow passage is open, said blade comprising a substantially planar portion having a free edge which terminates at a position below the plane defined by said planar portion.

In order that the invention may be more readilly understood, and so that further features thereof may be appreciated, the invention will now be described by way of example with reference to the accompanying drawing which is a perspective view of one embodiment of a damper in accordance with the invention with parts thereof cut away to facilitate an understanding of the operation of the invention.

The embodiment of the damper illustrated in the accompanying drawing has two damper blades, but it is to be understood that a damper in accordance with the invention may have any selected number of blades. Thus a small embodiment of the invention may merely have a single damper blade, whereas a larger embodiment may have several damper blades.

Referring to the drawing the damper assembly 1 is illustrated as being mounted within an aperture 2 formed in a wall or partition 3. The wall or partition can be considered as dividing a zone 4 that is intended to be maintained at a relatively high pressure from a zone 5 that is to be maintained at a relatively low pressure.

The damper incorporates an outer rectangular frame 6 which has an outwardly directed peripheral flange 7 that abuts the surface of the partition 3 facing the high pressure region 4. A rectangular passage is defined by the frame 6 interconnecting the zone 4 and the zone 5.

Three elongate members 8,9 and 10 are provided which extend tranversely across the channel defined by the frame 6. These members effectively define two airflow passages 11,12.

The elongate member 8 has a planarfrontface 13 that faces towards the zone 4, and an arcuate upwardly extending part 14thatextends up to the top of the frame 6. The member 8 is formed as an extrusion of aluminium or some corresponding ailoy and is provided with two elongate receses each of which accommodates a rod 15,16. The rods 15, 16 are inserted in appropriate apertures in the side members defining the frame 6 to mount the eleongate member 8 in position.

The elongate member 9 has a lower part corresponding precisely with the configuration of elongate member 8, and an upper part which is symmetrical with the lower part. Thus the elongate member 9 has a vertical face 17 corresponding with the face 13 described above and an arcuate part 8 corresponding with the arcuate part 14 discussed above. It then has a second arcuate part 19 and a further vertical face 20 which faces towards the zone 5. The elongate member 9 is held in position by means of rods 21, 22,23,24 that pass through appropriate recesses formed in the member 9 and that are engaged in appropriate apertures formed in the side members of the frame 6.

The elongate member 10 corresponds with the upper part of the elongate member 9, and thus has a vertical face 25 corresponding to the vertical face 20 mentioned above and an arcuate part 26 corresponding to the arcuate part 19 mentioned above.

The elongate member 10 is held in position by means of rods 27, 28 passing through recesses formed in the elongate member 10 and engaging in appropriate apertures formed in the side walls of the frame 6.

The air passages 11 and 12 defined by the above-described elongate members have precisely the same configuration. Two identical damper members 29, 30 are provided, the damper member 29 being mounted in the air passage 11 and the damper member 30 being mounted in the air passage 12.

Only one damper member will be described in detail.

The damper member 29 comprises an elongate member formed as an extrusion of aluminium or a corresponding alloy. As will be described hereinafter the member is substantially planar, and formed on the underside of the member is a recess that accommodates a rod 31. The ends of the rod are accommodated in bearings formed of "nylon 66" the bearings being mounted within the side walls of the frame 6 in such a way that the blade may pivot about the axis defined by the rod 31.

The blade, when in the rest position as illustrated, is substantially horizontal and the rod 31 is located substantially towards one side of the blade. The portion of the blade between the region adjacent the rod and the free edge of the blade that is closest to the rod is thickened 32 to form a counterweight. The moment of the counterweight about the rod is slightly less than the moment about the rod of the rest of the blade, and thus the blade naturally moves to the rest position illustrated.

The portion of the blade 29 to the other side of the rod 31 comprises a substantially planar portion 33. A plurality of recesses 34 are formed on the underside of this planar portion 33, and the purpose of these recesses 34 will be described hereinafter. The free edge of the blade 35 that is located remote from the rod 31 is located at a level which is beneath the plane defined by the planar portion 33. In the illustrated embodiment the blade 29 curves arcuately adjacent the free edge 35 thereof, but it is envisaged that in alternative embodiments the blade may terminate with an inclined portion, thus having an angular configuration, or may even terminate with a thickened bead or the like.

In the rest position as illustrated the free edge of the blade 35 rests on a sealing gasket 36 that is located in position on the elongate member 9.

With the damper in the illustrated position the zone 4 is substantially sealed from the zone 5. The free edge 35 of the damper is resting on the sealing gasket 36, and the rear surface of the counterweight 32, which is of arcuate configuration, is located immediately adjacent the inner surface of the arcuate portion 14 of the elongate member 8. When the pressure present in the zone 4 has a predetermined differential relative to the pressure within the zone 3 the damper will begin to open. The damper will move pivotally about the axis of the rod 31, with the counterweight 32 moving downwardly, and the free edge 35 of the damper blade 29 moving upwardly.

An air channel will thus be created between the zone 4 and the zone 5. It has been found that a required pressure differential can be maintained between the zone 4 and the zone 5 over a very wide range of rates of air flow through the damper. Thus, under conditions of increasing air flow the damper plate 29 will move pivotally further and further away from the initial rest position, thus increasing the size of the effective air flow passage between the zone 4 and the zone 5. However, by virtue of the design of the dam per, a substantially constant pressure differential will be maintained.

It will be appreciated that the damper 29 will commence to open at a predetermined pressure differential which depends upon the material utilised that a construction of the damper, and the precise reationship between the moment of the counterweight 32 about the rod 31, and the moment of the remainder of the blade about the axis of the rod 31, together with the area of the blade. However, it is to be appreciated that dampers may be required to operate at very different relative pressures depending upon their precise application. Consequently the recesses 34 are provided on the undersurface of the blade 29, as mentioned above.It is possible to introduce weights into one or more of the recesses 34, thus altering the relationship between the moment of the counterweight 32 and the moment of the rest of the blade, and by appropriately selecting the weights that are located in position within the recesses 34, the damper blade 29 can be caused to open at a selected pressure differential within a wide range of possible pressure differentials.

Whilst operation of the damper has been described with sole reference to the function of one damper blade, it is to be appreciated that the other damper blade or blades will operate substantially in synchronism with the first blade or blades.

Many modifications may be effected to the described embodiment without departing from the present invention. Thus, if required additional sealing means may be provided, for example in the form of a gasket or the like that is abutted by the counterweight of each damper blade when in the rest position. Also sealing means may be provided to constitute a seal between the ends of the damper blades and the vertical side walls of the frame.

Whilst the damper has been illustrated in the form of an exhaust damper for exhausting air from the zone 4 to the zone 5, in an alternative embodiment the damper may be constituted as a supply damper.

This effectively involves the reversal of the frame 6 and the associated outwardly directed flange 7 with reference to the remaining components as described.

The various components may be formed of any suitable material, and the damper blades may be formed of a plastics material if desired.

Claims (16)

1. A damper for regulating a flow of air, said damper comprising means defining an air passage and at least one blade pivotally mounted and movable from a position in which the blade substantially closes the air passage to a position in which the air passage is open, said blade being substantially horizontal when the air passage is closed, the blade pivoting upwardly when airflowsthrough the damper so that air flows between the upwardly inclined blade and the means defining the air passage.

2. A damper according to claim 1 wherein the damper blade is pivotally mounted about an axis located closer to one edge of the blade than the other edge, said other edge being moved upwardly when the damper opens.

3. A damper according to claim 2 wherein said one edge of the blade constitutes a counterweight, which at least partly balances the movement of the part of the blade between the axis and said other edge of the blade.

4. A damper according to claim 2 or claim 3 wherein said blade includes a substantially planar portion extending substantially from the axis of pivotal support of the blade away from the counterweight towards said other edge, the said other free edge of the blade terminating art a point below the plane defined by said planar portion.

5. A damper according to claim 4 wherein the said other edge of the blade forms the termination of an arcuately curving portion of the blade that curves out of said plane.

6. A damper according to any one of claims 1 to 5 wherein means are provided on the blade for mounting, on the blade, a selected weight or weights.

7. A damper according to claim 6 wherein the blade is provided with one or more recesses adapted to accommodate said weight or weights.

8. A damper according to any one of the preceding claims wherein sealing means are provided adapted to be engaged by the damper when in the closed position so that the damper forms a substantially air-tight seal.

9. A damper according to any one of the preceding claims wherein, in its rest position, the damper blade is horizontal plus or minus 10 .

10. A damper according to claim 9 wherein, when the damper is in the rest position the damper blade is horizontal plus or minus 5 .

11. A claim according to any one of claims 1 to 10 wherein the blade is mounted in position by being mounted on a rod, the rod being rotatably mounted in a frame.

12. A damper according to any one of the preceding claims incorporating a plurality of damper blades.

13. A damper, said damper comprising means defining an air flow passage, and a blade pivotally mounted and movable between a position in which the blade substantially closes said air flow passage to a position in which the air flow passage is open, said blade comprising a substantially planar portion having a free edge which terminates at a position below the plane defined by said planr portion.

14. A damper according to claim 13 wherein the blade is substantially horizontal when the air passage is closed.

15. A damper substantially as herein described with reference to and as shown in the accompanying drawing.

16. Any novel feature or combination of features disclosed herein.