CHEMICAL DAMPER

Abstract

According to the present invention, there is provided a damper for ducting comprising at least one fin comprising an intumescent composition.

Claims

1. A damper for ducting comprising at least one fin comprising an intumescent composition, wherein the intumescent composition comprises: (a) an intumescent material comprising phosphorus, sulfur, a halogen, a melamine compound, boron, a polyol or a mixture thereof; (b) an expandable intumescent material selected from graphite, silicate, vermiculite and mixtures thereof; (c) a polymeric binder; and (d) a fibrous material.

2. The damper according to claim 1 which is provided in a housing which fits into the ducting or is adapted to connect to the ducting.

3. The damper according to claim 1 wherein the plane of the fin is substantially perpendicular to the cross-section of the ducting.

4. The damper according to claim 1 which comprises more than one fin.

5. The damper according to claim 4 wherein the fins are substantially parallel to each other.

6. The damper according to claim 5 wherein the fins are spaced approximately equidistant from each other.

7. The damper according to claim 1 which comprises a ring shaped housing.

8. The damper according to claim 7 wherein at least one circular cross-section of the housing is closed by a mesh.

9. The damper according to claim 1 wherein the intumescent composition comprises: one or more compounds selected from ammonium polyphosphate, phosphoric acid, sulphuric acid, boric acid, salts of boric acid, ammonium tetraborate, potassium tetraborate, sodium tetraborate, ammonium phosphate, ammonium sulphate, ammonium halides, urea, guanylurea phosphate, reaction products of P.sub.2O.sub.5 and ammonia, tricresyl phosphate, alkyl phosphate and haloalkyl phosphates; a second material selected from melamine, melamine cyanurate, melamine phosphate, melamine pyrophosphate, melamine polyphosphate, dicyandiamide, azodicarbonamide, linear amines, guanidine phosphate, melamine borate, melam, melem, melon; and a third material selected from pentaerythritol, dipentaerythritol, tripentaerythritol, starch, sugar, glucose, dextrin, sorbitol, mannitol, phenol formaldehyde resins, and methylol melamine.

10. The damper according to claim 1 wherein component (a) comprise a phosphate-containing compound, a melamine compound and a pentaerythritol compound.

11-13. (canceled)

14. A damper according to claim 1 wherein component (b) comprises an expandable graphite material.

15. A damper according to claim 1 wherein component (c) comprises a styrene/acrylic component.

16. A damper according to claim 1 wherein component (d) comprises alkaline earth silicate fibers.

17. Ducting comprising a damper as claimed in claim 1.

18. An intumescent composition as defined in claim 1.

19. The damper according to claim 9 when the second material comprises the linear amines ethylene diamine-o-phosphate.

Description

[0116] A preferred embodiment of the present invention will now be further described with reference to the accompanying figures in which:

[0117] FIG. 2 shows a damper of the present invention;

[0118] FIG. 3 shows a cross-sectional view of the damper of FIG. 2; and

[0119] FIG. 4 shows the damper connected to a portion of ducting.

[0120] Preferred features of this embodiment will now be described. However it will be appreciated that these features may as appropriate apply to other embodiments of the invention.

[0121] The damper comprises a ring shaped housing 1 which is made of steel. Within the housing are a plurality of parallel fins 2 which are affixed to the internal surface of the housing 3. The fins each comprise a number of apertures 4. However it will be appreciated that fins which are solid or which are in the form of a grid or mesh could also be used. The fins in a preferred embodiment are made of steel but alternative materials may be used. In the embodiment shown the fins are spot-welded onto the inside of the housing, but other methods of fixing the fins into the housing are within the scope of the invention.

[0122] Each fin is coated on both sides with a layer of intumescent material 5. This is only shown on the bottom fin in FIG. 2. However embodiments in which only one face of the fin is coated are also within the scope of the invention.

[0123] The intumescent material may be coated onto the fin by any suitable means, for example painting, dipping or casting into sheets.

[0124] In some embodiments the intumescent composition is structurally rigid and may itself be formed directly into a fin, rather than being applied to a separate substrate. In such embodiments the fin may be cast, moulded or extruded. It may be made by any other suitable method.

[0125] Each face of the damper housing is closed by a mesh 6 which can be seen in FIG. 3 but is not shown in FIG. 2. The mesh is suitably a metal or other material which can withstand high temperatures likely to arise in a fire. The mesh may be held in position by a plurality of metal fingers (not shown). The distance between the fins is preferably approximately equal. The distance is suitably selected to ensure that a char is able to form quickly and close the gaps between the fins.

[0126] The distance between the fins is preferably 0.5 to 10 cm, more preferably 1.5 to 7 cm, most preferably 2.5 to 4.5 cm.

[0127] According to the second aspect of the present invention there is provided ducting comprising a damper of the first aspect.

[0128] The present invention may also provide an intumescent composition as described herein.

[0129] The invention will now be further defined with reference to the following example.

EXAMPLE 1

[0130] An intumescent composition of the invention was prepared comprising the following components:

TABLE-US-00001 Ingredient Amount (g) Water 245.8 Pentaerythritol 233.7 Melamine 233.7 Ammonium polyphosphate 767.4 2-amino-2-methyl-1-propanol 8.7 Alkaline earth silicate fibre 45.0 Styrene acrylic copolymer 803.2 Polyacrylate dispersion 25.4 Mineral hydrocarbon, silica and surface 2.1 active material Titanium dioxide 280.2 Expandable graphite 352.3 Preservative 2.1 Total 2999.6 g

[0131] This composition was coated onto perforated steel fins which were located in the fire damper of FIGS. 2 and 3. The damper was tested according to EN1366, Part 12. This is the fire resistance standard for non-mechanical dampers. The fire test curve that is used to heat the furnace as part of this test standard is EN1633-1 (ISO834).

[0132] FIG. 5A shows the damper prior to the test open to allow air to pass freely through the ducting.

[0133] FIG. 5B shows the damper after the test which clearly shows that a dense char has formed closing the ducting.