A method for fire protecting ventilation systems in buildings

Abstract

The invention relates to a method for fire protecting a ventilation system in a building. The method comprises a) providing or constructing a ventilation system duct; b) applying, preferably spraying, a coating layer of adhesive onto said ventilation system duct; and c) applying, preferably spraying, a layer of a plaster composition onto said adhesive coated ventilation system duct.

Description

[0001] A method for fire protecting ventilation systems in buildings

[0002] Field of the Invention

[0003] The present invention relates to fire protection of ventilation systems in buildings.

[0004] Background of the Invention

[0005] In the domain of building safety, the fire protection of ventilation systems is a pivotal element. This encompasses the utilization of fire-resistant materials in the construction of ventilation ducts, designed to endure elevated temperatures and impede the propagation of fire and smoke. Metal ducts are prevalently employed owing to their inherent fire resistance. Integral to this system are fire dampers, strategically installed within the ductwork. These dampers autonomously close during fire incidents, facilitated by the melting of a fusible link or activation by smoke detectors, thereby obstructing the fire and smoke spread through the ducts.

[0006] Additionally, smoke dampers are employed, functioning analogously to fire dampers but specifically aimed at controlling smoke movement. The incorporation of fire and smoke seals around the ductwork, particularly where they traverse through different building compartments, is critical. These seals, composed of fire-resistant materials, ensure that any gaps do not permit the passage of fire and smoke.

[0007] The concept of compartmentalization in ductwork design plays a crucial role. It involves segregating the ductwork into distinct sections with fire-rated barriers, effectively limiting fire and smoke spread to other building areas. Ensuring the functionality of these systems necessitates regular inspection and maintenance, particularly of fire and smoke dampers.

[0008] Moreover, the application of fire-rated coatings on ductwork provides an additional protective layer. These coatings, which expand when exposed to high temperatures, form an additional barrier against fire and heat. The integration of ventilation systems with the building's fire alarm and suppression systems is also a key aspect. This integration may involve the HVAC system shutting down or modifying its operation during a fire, aiding in firefighting and evacuation efforts.

[0009] The environmental ramifications of fire-resistant coatings, particularly those applied in ventilation systems, present a multifaceted issue warranting comprehensive examination. The production phase of these coatings is characterized by the utilization of various chemicals and materials, each bearing its own ecological footprint. This phase encompasses the extraction of raw materials, the energy expended during manufacturing, and the resultant waste and emissions. Notably, the use of volatile organic compounds (VOCs) and other potentially hazardous materials in some coatings is a pertinent concern, given their implications for air quality and ecological well-being.

[0010] During the application process of these coatings, the emission of VOCs emerges as a significant environmental and health consideration. The shift towards low- VOC and water-based alternatives in recent years represents a concerted effort to mitigate these issues. The durability of fire-resistant coatings, while beneficial in reducing the frequency of reapplications and thereby conserving resources, also raises questions regarding their long-term environmental impact, including potential off-gassing and interactions with other building materials.

[0011] The end-of-life treatment of materials coated with fire-resistant substances is another critical environmental aspect. Particularly concerning are coatings that contain hazardous components, as these materials may not be recyclable and could necessitate specialized handling to avert environmental degradation.

[0012] A comprehensive Life Cycle Analysis (LCA) of these coatings is essential to fully understand their environmental footprint. Such an analysis would encompass all stages from raw material extraction through to disposal or recycling, offering a holistic view of the environmental impact. Regulatory frameworks increasingly scrutinize the ecological aspects of building materials, including fire-resistant coatings. This regulatory landscape has spurred the development of environmentally friendlier alternatives, encompassing coatings derived from natural, non-toxic, or recycled materials.

[0013] In summary, while the primary function of fire-resistant coatings is to enhance building safety, their environmental impact is a nuanced and complex subject that encompasses their entire lifecycle. The progression towards more environmentally sustainable building practices is influencing the development and use of these coatings, balancing safety with ecological responsibility.

[0014] Object of the Invention

[0015] The objective of the present invention is to provide a fire-resistant coating for ventilation system ducts with an acceptable environmental impact.

[0016] This has been accomplished according to this invention by coating a ventilation system duct with a layer of adhesive, and finally a layer of a plaster composition. The plaster composition is then allowed to cure or harden to form a plaster layer. Connections between individual ventilation system duct sections are completely sealed along their edges by the plaster composition, thereby improving the fire resistance.

[0017] Summary of the Invention

[0018] A first aspect relates to method for fire protecting a ventilation system in a building, the method comprising: a) providing or constructing a ventilation system duct; b) applying, preferably spraying, a coating layer of adhesive onto said ventilation system duct; and c) applying, preferably spraying, a layer of a plaster composition onto said adhesive coated ventilation system duct.

[0019] A second aspect relates to a ventilation system for a building comprising:

[0020] - a ventilation system duct;

[0021] - a layer / coating of adhesive applied onto the outer face of said ventilation system duct; and

[0022] - a layer of a plaster composition applied onto said adhesive layer / coating.

[0023] The invention is described in more detail in the following detailed description.

[0024] Detailed Description of the Invention

[0025] A first aspect relates to method for fire protecting a ventilation system in a building, the method comprising: a) providing or constructing a ventilation system duct; b) applying, preferably spraying, a coating layer of adhesive onto said ventilation system duct; and c) applying, preferably spraying, a layer of a plaster composition onto said adhesive coated ventilation system duct.

[0026] A second aspect relates to a ventilation system for a building comprising:

[0027] - a ventilation system duct;

[0028] - a layer / coating of adhesive applied onto the outer face of said ventilation system duct; and

[0029] - a layer of a plaster composition applied onto said adhesive layer / coating.

[0030] In the present context, the terms “plaster” and “gypsum” are used interchangeably and meant to be understood as normally understood in the art, i.e. , to cover compositions predominately made from calcium sulfate, preferably predominately comprising calcium sulfate hemihydrate but may also comprise calcium sulfate anhydrate, calcium sulfate dihydrate, as well as calcined gypsum. The plaster composition may also be added adhesive, such as the same adhesive that is used as the adhesive layer. However, it is an advantage with regards to using as little adhesive as possible, that it is added as a coating.

[0031] The ventilation system duct is preferably of steel, more preferably of galvanized steel.

[0032] Obviously, the adhesive should be suitable for adherence to the ventilation system duct, which is often made of galvanic steel. However, the adhesive should also be able to act as an adhesive for the uncured and cured plaster composition.

[0033] In one or more embodiments, the adhesive is selected from the group consisting of: adhesives comprising an anionic copolymer dispersion of acrylic acid ester and styrene, polyvinyl acetate adhesives, polyvinyl alcohol adhesives, polyurethane adhesives, phenolic resin adhesives, cyanoacrylate adhesives, adhesives comprising an ethylene / vinyl acetate copolymer, adhesives comprising an ethylene-vinyl acetate-vinyl chloride emulsion, and mixtures thereof.

[0034] In one or more embodiments, the coating layer of adhesive has a thickness of 0.01-1 mm, e.g., 0.02-0.9 mm, such as 0.03-0.8 mm, e.g., 0.04-0.7 mm, such as 0.53-0.6 mm, preferably, 0.05-0.5 mm.

[0035] In one or more embodiments, the adhesive is selected from the group consisting of: adhesives comprising an anionic copolymer dispersion of acrylic acid ester and styrene, polyvinyl acetate adhesives, polyvinyl alcohol adhesives, polyurethane adhesives, phenolic resin adhesives, cyanoacrylate adhesives, adhesives comprising an ethylene / vinyl acetate copolymer, adhesives comprising an ethylene-vinyl acetate-vinyl chloride emulsion, a natural rubber latex, a synthetic rubber latex, and mixtures thereof.

[0036] Examples of a synthetic rubber latex include butadiene rubber latex, styrenebutadiene rubber latex, nitrile rubber latex, polyurethane rubber latex, polychloroprene rubber latex, ethylene-vinyl acetate copolymer resin, acrylate- based latex, or combinations thereof.

[0037] The term “natural rubber latex” refers to any rubber latex available from any natural source.

[0038] The rubber materials, but also the other adhesives, are preferably provided in the form of an aqueous latex emulsion, which can be sprayed onto the batts.

[0039] In one or more embodiments, the adhesive is in the form of a (water) redispersible polymer powder. Redispersible polymer powders are polymer emulsions, which have been converted by a series of process, such as high temperatures and pressures, spray drying and surface treatment, to powdered thermoplastic resin materials. When mixed with water, these powdered organic binders can redisperse in water back into new emulsions with essentially identical properties to the original copolymer emulsions.

[0040] In one or more embodiments, step a) comprises:

[0041] - mounting a supporting net around said ventilation system duct, wherein step b) further comprises applying, preferably spraying, a coating layer of adhesive onto said supporting net, and wherein step c) further comprises applying, preferably spraying, a layer of a plaster composition onto said adhesive coated supporting net.

[0042] In one or more embodiments, step a) comprises: - mounting a supporting structure, such as a plurality of protrusions, on the outer surface of said ventilation system duct, wherein step b) further comprises applying, preferably spraying, a coating layer of adhesive onto said supporting structure, and wherein step c) further comprises applying, preferably spraying, a layer of a plaster composition onto said adhesive coated supporting structure, thereby forming anchorage points within said layer of a plaster composition.

[0043] In one or more embodiments, the supporting structure is adapted for functioning as a guide rail, e.g., comprising cured or hardened plaster, and wherein step c) comprises using said guide rail for controlling the thickness of said layer of plaster composition and / or for straightening said layer of plaster composition, and / or for smoothening said layer of plaster composition.

[0044] In one or more embodiments, the method further comprises the step of: d) allowing said plaster composition to irreversibly bind to said guide rail as it cures or harden.

[0045] In one or more embodiments, the guide rail is formed in the ventilation system duct. The guide rail preferably has a height of 5-20 mm, preferably, 10-20 mm, but could also be thicker, such as 20-40 mm.

[0046] In one or more embodiments, the plaster composition layer has a height / thickness of 5-20 mm, preferably, 10-20 mm, but could also be thicker, such as 20-40 mm.

[0047] In one or more embodiments, the plaster composition layer has a height / thickness of 5-60 mm, preferably, 10-50 mm

[0048] The layer of plaster composition may be applied in steps, such that a first layer is applied, followed by a second layer after partial or complete curing or hardening. In this way, multiple layers may possibly be applied. As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

[0049] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

[0050] EXAMPLE 1 - TEST OF ADHESIVES

[0051] This example tests six different adhesives’ effect on a ventilation system duct. The adhesives were coated or applied onto the outer surface of the ventilation system duct. The six selected adhesives were Selvol™ Polyvinyl Alcohol 205S (polyvinyl alcohol) from Sekisui Specialty Chemicals America, LLC, Wood Adhesive 730 Outdoor (Polyvinyl acetate) from Bostik A / S, Acronal® S 430 P (redispersible polymer powder based on an aqueous, plasticizer-free, anionic copolymer dispersion of acrylic acid ester and styrene) from BASF SE, and Acronal® 5018 (aqueous dispersion of acrylic acid ester and styrene copolymer, 50% w / w solid in water), Dermulsene 222 from DRT (a solvent-free water-based dispersion formulated with terpene resin and stabilized rosin ester, 50% w / w solid in water), and Dermulsene TR 602 (a solvent-free formulated with terpene phenolic resin, 50% w / w solid in water).

[0052] All six types of adhesives showed good adhesion to the ventilation system duct. EXAMPLE 2 - TEST OF SPRAY PLASTER TO ADHESIVE COATINGS This example tests the adhesive effect of a spray plaster composition onto different types of adhesive coatings, and the durability of the cured constructs. Four tubular ventilation system ducts (galvanized steel, 40 cm long) were coated with one of the four selected adhesives. The coated ventilation system ducts were then sprayed with 20 mm of a spray plaster composition. MP75 L from Knauf was used. The samples were then allowed to cure and harden to form a plaster layer. Then the samples were then placed in a climate cabinet for 120 hours. The temperature cycles were 5 degrees Celsius for 24 hours, 40 degrees Celsius for 24 hours, 5 degrees Celsius for 24 hours, 40 degrees Celsius for 24 hours, and finally 5 degrees Celsius for 24 hours. At 5 degrees Celsius, the humidity was kept at 50-80%, and at 40 degrees Celsius, the humidity was kept at about 90%. No cracks were observed in the plaster layer of any of the samples.

Claims

Claims1 . A method for fire protecting a ventilation system in a building, the method comprising: a) providing or constructing a ventilation system duct, preferably of galvanized steel; b) applying, preferably spraying, a coating layer of adhesive onto said ventilation system duct; and c) applying, preferably spraying, a layer of a plaster composition onto said adhesive coated ventilation system duct; wherein the adhesive is selected from the group consisting of: adhesives comprising an anionic copolymer dispersion of acrylic acid ester and styrene, polyvinyl acetate adhesives, polyvinyl alcohol adhesives, polyurethane adhesives, phenolic resin adhesives, cyanoacrylate adhesives, adhesives comprising an ethylene / vinyl acetate copolymer, adhesives comprising an ethylene-vinyl acetate-vinyl chloride emulsion, a natural rubber latex, a synthetic rubber latex, and mixtures thereof, and mixtures thereof.

2. The method according to claim 1 , wherein step a) comprises:- mounting a supporting net around said ventilation system duct, wherein step b) further comprises applying, preferably spraying, a coating layer of adhesive onto said supporting net, and wherein step c) further comprises applying, preferably spraying, a layer of a plaster composition onto said adhesive coated supporting net.

3. The method according to any one of the claims 1-2, wherein step a) comprises:- mounting a supporting structure, such as a plurality of protrusions, on the outer surface of said ventilation system duct, wherein step b) further comprises applying, preferably spraying, a coating layer of adhesive onto said supporting structure, and wherein step c) further comprises applying, preferably spraying, alayer of a plaster composition onto said adhesive coated supporting structure, thereby forming anchorage points within said layer of a plaster composition.

4. The method according to claim 3, wherein the supporting structure is adapted for functioning as a guide rail, e.g., comprising cured or hardened plaster, and wherein step c) comprises using said guide rail for controlling the thickness of said layer of plaster composition and / or for straightening said layer of plaster composition, and / or for smoothening said layer of plaster composition.

5. The method according to claim 4, further comprising the step of: d) allowing said plaster composition to irreversibly bind to said guide rail as it cures or harden.

6. The method according to any one of the claims 1-5, wherein the plaster composition layer has a height / thickness of 5-60 mm, preferably, 10-50 mm.

7. The method according to any one of the claims 1-6, wherein the coating layer of adhesive has a thickness of 0.01-1 mm, preferably, 0.05-0.5 mm.

8. A ventilation system for a building comprising:- a ventilation system duct;- a layer / coating of adhesive applied onto the outer face of said ventilation system duct; and- a layer of a plaster composition applied onto said adhesive layer / coating; wherein the adhesive is selected from the group consisting of: adhesives comprising an anionic copolymer dispersion of acrylic acid ester and styrene, polyvinyl acetate adhesives, polyvinyl alcohol adhesives, polyurethane adhesives, phenolic resin adhesives, cyanoacrylate adhesives, adhesives comprising an ethylene / vinyl acetate copolymer, adhesives comprising an ethylene-vinyl acetate-vinyl chloride emulsion, a natural rubber latex, a synthetic rubber latex, and mixtures thereof, and mixtures thereof.

9. The ventilation system according to claim 8, wherein said ventilation system duct comprises a supporting net mounted around its outer face and embedded within said layer of a plaster composition.

10. The ventilation system according to any one of the claims 8-9, wherein said ventilation system duct comprises a supporting structure, such as a plurality of protrusions or flanges, on its outer surface and embedded within said layer of a plaster composition.11 . The ventilation system according to claim 10, wherein said supporting structure is configured as a guide rail.

12. The ventilation system according to claim 11 , wherein said supporting structure comprises cured or hardened plaster, and wherein said guide rail is adapted for defining the thickness of said layer of plaster composition.

13. The ventilation system according to any one of the claims 8-12, wherein the plaster composition layer has a height / thickness of 5-60 mm, preferably, 10-50 mm.

14. The ventilation system according to any one of the claims 8-13, wherein the coating layer of adhesive has a thickness of 0.01 -1 mm, preferably, 0.05-0.5 mm.