ISOLATION DAMPER

Description

[0001] The present invention relates to an isolation damper for gas ducts and more particularly to an isolation damper of the slide type.

[0002] Isolation dampers are used to close off a gas duct. A valve member of some type in the damper is brought into sealing engagement with the seat of the damper, or some other sealing element, to form a gas tight seal preventing gas leakage past the damper. Conventional dampers are of three types viz., the poppet type wherein a flexible sheet of steel is deformed onto the seat of the damper under system pressure or negative pressure; the slide type in which an inflexible steel plate is slid across the duct and into sealing engagement with sealing means on the damper seat and the butterfly type in which two pivotably connected inflexible plates are folded into or out of sealing engagement with the sealing means on the damper seat. The poppet type valve cannot be conveniently used as an isolation damper intermediate the ends of a gas duct. The slide type suffers from the disadvantages that, firstly, a secondary seal system, which is susceptible to wear, is required to make sealing contact with the slide and, secondly, a housing is required to hold the plate when it has been withdrawn from the duct which is both unsightly and expensive to build. One curtain damper is described in Australian Patent Specification 212476 the damper comprises a frame, a gas-impermeable curtain, means for mounting the curtain to one side of the frame, means for drawing the curtain across the frame to a closed position, and means for effecting a seal between the margins of the curtain extending in the direction of movement and the frame in the closed position comprising strips of sheet material extending along the margins, flexible along their length and resiliently flexible across their width, and arranged to be resiliently flexed across their width in the closed position of the curtain to effect the seal.

[0003] A flexible curtain valve for large gas ducts is described in U.S. Patent Specification 3410311 it comprises a flexible curtain valve for large gas ducts comprising a fixed upper drive roller, a vertically movable lower idle roller, and a downwardly looped flexible curtain running therebetween. The idle roller divides the curtain into a downstream panel portion and an upstream panel portion. The upper edge of the downstream panel is fixed, the downstream panel contacting and being supported by a lateral grid. The curtain passes under and around the idle roller, the upstream panel portion of the curtain extending from the upstream tangential edge of the idle roller to the downstream tangential edge of the drive roller. This "reverse looping" arrangement assures continuous urging both of the idle roller and the downstream curtain panel into a tight seal with the grid.

[0004] Again a valve is described in U.S. Patent Specification 4204662 for use for fluids, gases or liquids, in which the closure member of the valve is supported, when in closed position, in such fashion that pressure on the intermediate or central portion of the closure causes the periphery of the closure to move upstream, into contact with seats or seals carried by the valve body. Specifically, the plate, when closed, is forced by the pressure of the fluid being controlled against fulcrum members, these fulcrum members being located closer to the periphery of the closure member than to its centre, whereby the net effect of pressure on the plate as a whole is effective to deflect the central portion of the plate downstream while deflecting the peripheral portions of the plate upstream into sealing, seating engagement with the seals or seats carried by the valve body.

[0005] The present invention in contradistinction to the above is directed to a slide type isolation damper which does not have the disadvantages of known slide type dampers while having the advantage of the poppet type valve.

[0006] According to the present invention there is provided an isolation damper for a gas duct comprising a damper blade, a pair of guide members arranged to the guide the damper blade along a path transverse to the gas duct, and means to move the damper blade along the said path between a first position in which the damper blade extends across the duct and a second position in which it is substantially withdrawn from the duct, the damper blade being relatively thin and flexible such that when in the first position under an applied gas pressure, it can elastically deform to enter into sealing engagement with the guide members and in that a plurality of first and second support elements are disposed intermediate the guide members in close juxtaposition with opposite sides respectively of the path of the damper blade, so that the damper blade is supported by said first and second support elements respectively when pressure is applied to the face of the damper blade distal to said first and second support elements respectively, characterised in that the means to move the damper blade are operable to bend it substantially 90° and move it along a planar path outside the gas duct when the blade travels between said first and second positions.

[0007] The use of a thin, flexible damper blade allows the blade to be elastically deformed onto the guide members, which constitute the damper seat, without the need for a secondary sealing system. The flexibility of the blade also allows the blade to follow a non-linear path as it is introduced into, and drawn out of, the duct. The blade could, for instance lie in a plane parallel to and slightly above the gas duct and be turned through 90° just before entering the duct. In this way the isolation damper could be made more cheaply and would be less unsightly.

[0008] The damper blade is preferably formed of a material such as stainless steel and preferably has a thickness of no more than 5 mm., preferably no more than 3 mm. The use of such a thin damper blade facilitates the movement of the blade into and out of the duct as the thin blade can cut through any duct accumulation which occurs in the guide means.

[0009] The support elements preferably comprise an array of parallel bars or rods, however a grid of such bars or a perforate plate could also be used provided that the flow of gas through the duct is not unduly impeded. The support elements are preferably provided on each side of the damper blade path such that the damper blade will be supported against undue deformation upon the application of a positive pressure to either of its faces.

[0010] Hereinafter given by way of example only is a preferred embodiment of the invention described with reference to the accompanying drawings in which:-

Figure 1 is a vertical sectional view through an isolation damper according to this invention, and

Figure 2 is a view taken on section station A-A of Figure 1.

[0011] The isolation damper 10 is mounted in a gas duct 11, the gas moving through the duct in the direction of the arrow B of Figure 1. The damper comprises a damper blade 12, a frame 13 surrounding the duct 11 which frame includes a pair of channel shaped side members 14 constituting guide members for the damper blade 12, and drive means 15 to move the damper blade 12 into and out of the duct 11 that is to say into a first position in which the damper blade 12 extends across the duct 11 and a second position in which the damper blade 12 is substantially withdrawn from the duct 11.

[0012] The damper blade 12 comprises a sheet of stainless steel 3 mm thick which is connected at its end remote from the duct to the drive means 15 as hereinafter described. The blade extends horizontally at the point of its connection to the drive means 15, it then turns through 90° before entering the guide slots 16 defined by the side members 14.

[0013] The frame 13, in addition to the side members 14, includes a base member 17 and a top member 18 containing a slot 23. The base member 17 includes a longitudinally extending slot 19 in alignment with slots 16 in the side members 14, and into which the lower end of the damper blade 12 slides when the damper is fully closed. A flap 20 is hingedly connected to the underside of the base member 17 and can be opened to release dust which has lodged in the frame. A plurality of first and second support elements or bars 21 extends between the base member 17 and the top member 18 on either side of the path traversed by the damper blade 12. The bars 21 are formed of mild steel or erosion resistant steel and may have an aerodynamically efficient cross sectional shape if desired.

[0014] The top member 18 may be formed with a removable top cover 22 such that the slot 23 in the top member 18 through which the damper blade 12 is introduced into the frame 13 may be closed when the damper blade 12 is completely removed from the frame 13.

[0015] The drive means 15 comprises a reversible motor 24 which drives a pair of endless chains 25 about drums 26. The chains are connected to the free end of the damper blade 12. Upon actuation of the motor 24 the damper blade 12 can be moved into or out of the duct 11.

[0016] If the damper blade 12 is introduced fully into the duct 11 and a force applied to one side of the blade 12 it will be elastically deformed against the edges of the slots 16, 19 and 23 of the frame 13 and will sealingly engage therewith in view of the relatively thin, flexible, nature of the damper blade 12. As the blade 12 is forced against the edges of the slots it will similarly be forced against the support bars 21 on the side of the slots opposite the direction from which the force is applied to the blade 12. The support bars 21 give to the damper blade 12 the structural integrity lacking due to its flexible nature.

Claims

1. An isolation damper (10) for a gas duct (11) comprising a damper blade (12), a pair of guide members (14) arranged to guide the damper blade (12) along a path transverse to the gas duct (11), and means (15) to move the damper blade (12) along the said path between a first position in which the damper blade (12) extends across the duct (11) and a second position in which it is substantially withdrawn from the duct (11), the damper blade (12) being relatively thin and flexible such that when in the first position under an applied gas pressure, it can elastically deform to enter into sealing engagement with the guide members (14) and in that a plurality of first and second support elements (21) are disposed intermediate the guide members (14) in close juxtaposition with opposite sides respectively of the path of the damper blade (12), so that the damper blade (12) is supported by said first and second support elements (21) respectively when pressure is applied to the face of the damper blade (12) distal to said first and second support elements (21) respectively, characterised in that the means (15, 25, 26) to move the damper blade (12) are operable to bend it substantially 90° and move it along a planar path outside the gas duct (11) when the blade travels between said first and second positions.

2. An isolation damper as claimed in Claim 1 characterised in that the damper blade (12) is formed of stainless steel having a thickness of no more than 5 mm.

3. An isolation damper as claimed in Claim 2 characterised in that the damper blade (12) has a thickness of no more than 3 mm.

4. An isolation damper as claimed in any one of the preceding claims characterised in that the support elements (21) comprise an array of parallel bars or rods.

5. An isolation damper as claimed in Claim 4 characterised in that each of the bars or rods has an aerodynamically efficient cross sectional slope.

Ansprüche

1. Absperrschieber (10) für einen Gaskanal (11), mit einem Schieberblatt (12), einem Paar Führungsteile (14), die des Schieberblatt (12) entlang einer Bahn quer den Gaskanal (11) führen, und einer Einrichtung (15) zum Bewegen des Schieberblattes (12) entlanq dieser Bahn zwischen einer ersten Stellung, in welcher das Schieberblatt (12) quer durch den Kanal (11) verläuft, und einer zweiten Stellung in welcher as im wesentlichen aus dem Kanal (11) zurückgezogen ist, wobei das Schieberblatt (12) relativ dünn und derart biegsam ist, daß es sich in der ersten Stellung unter einem angelegten Gasdruck elastisch verformen kann, um in Dichteingriff mit den Führungsteilen (14) zu treten, und wobei eine Vielzahl von ersten und zweiten Stützelementen (21) zwischen den Führungsteilen (14) in enger Nebeneinanderlage mit den jeweils entgegengesetzten Seiten der Bahn des Schieberblattes (12) angeordnet ist, so daß das Schieberblatt (12) von den ersten und zweiten Stützelementen (21) jeweils abgestützt wird, wenn ein Druck auf die Seite des Schieberblattes (12) angelegt wird, die von den ersten und zweiten Stützelementen (21) jeweils entfernt ist, dadurch gekennzeichnet, daß die Einrichtung (15, 25, 26) zum Bewegen des Schieberblattes (12) betätigbar ist, um es im wesentlichen um 90° abzubiegen und entlang einer ebenen Bahn außerhalb des Gaskanales (11) zu bewegen, wenn sich das Blatt zwischen der ersten und zweiten Stellung bewegt.

2. Absperrschieber nach Anspruch 1, dadurch gekennzeichnet, daß das Schieberblatt (12) aus rostfreiem Stahl hergestellt ist, der eine Dicke von nicht mehr als 5 mm hat.

3. Absperrschieber nach Anspruch 2, dadurch gekennzeichnet, daß das Schieberblatt (12) eine Dicke von nicht mehr als 3 mm hat.

4. Absperrschieber nach irgendeinem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Stützelemente (21) eine Anordnung von parallelen Stäben oder Stangen aufweisen.

5. Absperrschieber nach Anspruch 4, dadurch gekennzeichnet, daß jeder Stab oder jede Stange eine aerodynamisch wirksame Querschnittsneigung hat.

Revendications

1. Registre isolant (10) pour une gaine de gaz (11) comprenant une lamelle de registre (12), une paire d'organes de guidage (14) agencés pour guider la lamelle (12) du registre le long d'une trajectoire transversale à la gaine de gaz (11), et un moyen (15) pour déplacer la lamelle (12) du registre le long de ladite trajectoire entre une première position dans laquelle la lamelle (12) du registre s'étend à travers la gaine (11) et une seconde position dans laquelle elle est sensiblement retirée de la gaine (11), la lamelle (12) du registre étant relativement mince et flexible de façon que lorsqu'elle est dans la première position sous une pression appliquée de gaz, elle puisse élastiquement se déformer pour entrer en engagement d'étanchéité avec les organes de guidage (14) et en ce qu'un certain nombre de premier et second éléments de support (21) sont disposés entre les organes de guidage (14) en proche juxtaposition des côtés opposés respectivement de la trajectoire de la lamelle (12) du registre, de façon que la lamelle (12) du registre soit supportée par lesdits premier et second éléments de support (21) respectivement lorsqu'une pression est appliquée à la face de la lamelle (12) du registre qui est éloignée desdits premier et second éléments de support (21) respectivement, caractérisé en ce que les moyens (15, 25, 26) pour déplacer la lamelle (12) du registre servent à la fléchir sensiblement sur 90° et à la déplacer le long d'une trajectoire plane en- dehors de la gaine de gaz (11) lorsque la lamelle se déplace entre lesdites première et seconde positions.

2. Registre isolant selon la revendication 1 caractérisé en ce que la lamelle (12) du registre est formée en acier inoxydable ayant une épaisseur ne dépassant pas 5 mm.

3. Registre isolant selon la revendication 2 caractérisé en ce que la lamelle (12) du registre a_i une épaisseur qui ne dépasse pas 3 mm.

4. Registre isolant selon l'une quelconque des revendications précédentes caractérisé en ce que les éléments de support (21) comprennent une série de barres ou tiges parallèles.

5. Registre isolant selon la revendication 4 caractérisé en ce que chacune des barres ou tiges a une pente en section transversale aéro- dynamiquement efficace.

Drawing