Fire retardant � types � treating wood w

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Fire retardant – types – treating wood with fire retardant chemicals N.KANAGARAJ BSF-06-007 BSC[FORESTRY]

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contents Introduction Caused agencies Temperature Types Fire retardant composition Fire retardant works Chemicals used for preservation References

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Introduction timber is also susceptible to fire apart from being prone to damage/deterioration by biological agencies all species of timbers catch fire catch fire though level of in flammability varies Fire retardant : A chemical , chemical mixture or coating whose proper application to wood substantially increases its resistance its resistance to flaming or burning

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Many of inorganic chemicals used today identified between 1800-1870 commercially treated wood is U.S Nevy 1895-1899. The earliest study of fire retardant treatment of wood was conducted between 1930-1935. Ammonium phosphate, first reduced to spread the fire followed by mono ammonium phosphate ammonium chloride, ammonium sulphate, borax and Zink chloride. Nearly 130 compositions tested for fire retardant. Some of properties of wood is effected.

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The temperatures Temperature generated during the igniting process determine the extent of damage that will be caused by the fire. Decayed wood is more readily ignited by fire than sound wood. The damage caused to wood at different temperatures is given below: Temperature First the catch fire. timber is charred and then it catches fire. The Wood is ignited after some time, even dry wood does not readily ted fairly fast. At this temperature, wood burns very quickly and total combustion may occur.

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Caused agencie The quantum of deterioration caused by fires depends on: Species Kind and intensity of fire and the temperatures generated by it Structure Density and porosity Moisture content Infiltrated chemical substances

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Fire retardants are a broad group of chemicals that are applied to timbers or with which they may be treated in order to minimize the damage caused by fire. They may bedivided into the 3 types Type-1 Type -2 Type-3

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Type I: This type includes highly hygroscopic chemicals which give off water vapour when exposed to fire. Due to this property they function as fire extinguishers. A typical example of this type is zinc chloride. Type II: This type of fire retardants includes chemicals, which on exposure to air give off incombustible gases like carbon dioxide, ammonia and nitrogen due to decomposition. Typical examples of these chemicals are ammonium chloride, ammonium nitrate, calcium carbonate and sodium bicarbonate

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Type III: This type of fire retardants crystallize in wood and may also swell up in the wood on exposure to fire. In this way, the pores in the timber are plugged, thus keeping out oxygen which supports the fire. Typical examples of this type include sodium tetra-borate, boric acid, borax, ammonium phosphate and magnesium phosphate.

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Fire retardant compositions Fire retardants serve to protect the timber from fires or atleast minimize the damage for a specific period of time. They may be used in solution with preservatives provide protection against deterioration by biological agencies. This can be done by adding suitable wood preservatives of the water soluble type to the fire retardant compositions. The surface of the timber is surface coated with the fire retardant once every 2 to 3 year after which the effectiveness of the chemical is greatly reduced.

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Fire retardant formulations Most of fire retardant based on phosphate, Nitrogen, aluminum, tri hydrate, few other components, Chemical impregnated in to the wood or apply to wood surface, depends on particular formulations, Most of fire retardant is not resistant to leaching by water.

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For timbers being used indoors For timbers being used outdoors Fire retardant and antiseptic compositions Important fireretardant compositions

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1. For timbers being used indoors Zinc chloride Ammonium phosphate (monobasic) Ammonium borate

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2. For timbers being used outdoors Zinc chloride and ammonium phosphate in more or less equal proportions. Magnesium arsenate. 4 parts of sodium dichromate; 4 parts of zinc chloride; 1 part of ammonium sulphate and 1 part of boric acid. 6 parts of ammonium sulphate; 2 parts of boric acid and 1 part each of ammonium phosphate and borax Trade Shows

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Chemical action in the gas phase: chemical reactions in the flame (i.e. gas phase) can be interrupted by fire retardants. However, there are situations where the released gas might be more dangerous when this type of retardant is involved. Although this allows materials to pass certain flammability tests, there is argument over if the fire safety is truly improved by the production of flammable plastic droplets

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Fire Retardant works In general, fire retardants reduce the flammability of materials by either blocking the fire physically or by initiating a chemical reaction that stops the fire. Physical There are several ways in which the combustion process can be retarded by physical action: By cooling: Some chemical reactions actually cool the material down. By forming a protective layer: This protects the remaining material. By dilution: Some retardants release water and/or carbon dioxide while burning. One example commonly used is the fire retardant, aluminum hydroxide. Not only does it break down to give off water vapor, but it also absorbs a vast amount of heat as it does so, cooling the material, and the residue of alumina (Al2O3) forms a protective layer. It provides protection in three ways at once.

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There are several classes of flame retardants chemicals; Halogenated Hydrocarbons (Chlorine and Bromine containing compounds and reactive flame retardants), Inorganic flame retardants (Boron compounds). Antimony oxides, Aluminium Hydroxide, Molybdenum compounds, Zinc and Magnesium oxides), Phosphorous containing compounds (Organic phosphate esters, Phosphates, Halogenated phosphorus compounds and Inorganic phosphorus containing salts). Fire Retardant (FR) Plywood

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Metal Hydroxide » Magnesium Hydroxide » Aluminium Hydroxide » Others Antimony Compounds » Antimony Trioxide » Sodium Antimonate » Antimony Pentoxide » Others INORGANIC

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› Halogenated Phosphates » Tris(1-chloro- 2-propyl) phosphate » Tris(2-chloroethyl) phosphate » Tris(2,3-dibromopropyl)phosphate » Others › Non-Halogenated Compounds » Phosphate Esters › Trialkyl Phosphates › Triaryl Phosphates › Aryl-alkyl Phosphates › Others » Polyols » Phosphonium Derivatives » Phosphonates » Others ORGANOPHOSPHOROS

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Paint Additive Flame Retardant VE-231 Clear flame retardant additive for all water based paints. Will not affect the color or consistency of the paint. Provides the highest fire rating for painted surfaces, including wooden scenery, floors, props, walls, plastics, and foam. Effective with coverage of 300 ft. per gallon of paint. Mix the entire contents of the 8 oz. container with one gallon of water based paint. Paint can be applied by brush, roller, or spray.

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Natural Fibers Flame Retardant For use as a penetrating flame retardant on cotton, linen, wool, burlap and most natural fiber fabrics.Apply by pad or spray. Effective with coverage of 500 ft. per gallon. Meets tests of NFPA 701-96 and NYC Tests for Fire Resistive Materials.Registered with the New York City Fire Department and the California Fire Marsha

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Synthetic Fabrics Flame Retardant For use as a flame retardant on polyester, acrylic, and most synthetic fabrics. Apply by pad or spray. Effective with coverage of 500 - 600 ft. per gallon, depending on fabric. Meets tests of NFPA 701-96 and NYC Tests for Fire Resistive Materials. Registered with the New York City Fire Department and the California Fire Marshal.

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Fire retardant materials Flame retardants are materials that inhibit or resist the spread of fire. Naturally occurring substances such as asbestos as well as synthetic materials. Usually halocarbons such as polybrominated diphenyl ether (PBDEs), polychlorinated biphenyls (PCBs) and chlorendic acid derivates, most often dibutyl chlorendate and dimethyl chlorendate, have been used in this capacity. Generally, these classes of flame retardant compounds are the most common: aluminium hydroxide, magnesium hydroxide, and various hydrates. Organobromines and organochlorines; phosphorus, in the form of organophosphates, halogenated phosphorus compounds, and red phosphorus; antimony trioxide; and boron compounds, mostly borates.

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padding method for fire protection ...

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Mechanisms of function dothermic degradation Some compounds break down endothermically when subjected to high temperatures. Magnesium and aluminium hydroxides are an example, together with various hydrates. The reaction removes heat from the surrounding, thus cooling the material. The use of hydroxides and hydrates is limited by their relatively low decomposition temperature, which limits the maximum processing temperature of the polymers

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Dilution of fuel Inert fillers, eg. talc or calcium carbonate, act as diluents, lowering the combustible portion of the material, thus lowering the amount of heat per volume of material it can produce while burning Thermal shielding A way to stop spreading of the flame over the material is to create a thermal insulation barrier between the burning and unburned parts. Intumescent additives are often employed; their role is to turn the polymer into a carbonized foam, which separates the flame from the material and slows the heat transfer to the unburned fuel.

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Methods of testing The common test methods are applicable to evaluate fire retardant treatment include, Thermo gravimetric analysis (T.G). Differential thermal analysis (DTA). Differential scanning colorimetric (DSC). Critical oxygen index test; The oxygen index test measures the minimum concentration of oxygen in an oxygen-nitrogen mixture that will just support flaming combustion of a test specimens.

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Top left: Test Deck built with 20-year old untreated redwood. Top right: Cleaned and protected Test Deck with class "B" ember* (6" x 6" x 2.5") ignited. Left: Test Deck with fire damage reduced and contained.

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. The main objective was to find a simple way to optimize the content of fire retardant in wood panels by using regression models on data from tests performed according to ISO 5660, the Cone Calorimeter.

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How to handled fire retardant wood The chemicals used in Fire Retardant Treated Wood (FRTW) are of very low toxicity and will not harm anyone who works with it. Tests have shown that smoke from is no more toxic than smoke from untreated wood. Naturally, normal safety practices for working with any wood should be followed. This means gloves, dust masks, and eye protection. Ingestion tests have demonstrated that extreme amounts of wood would have to be ingested before chemical exposure becomes significant.

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Hazards Unfortunately, many of the timber treatments have proven to be extremely hazardous both to the workers and the environment; as a result many treatment centers have been forced to close and undertake massive environmental restoration and remediation. With many of the chemicals having a long period through which they are highly dangerous, the legacy of the chemical cocktails can probably never be totally eliminated.

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Specifications for fire-treated timberA specification for treatment of wood or a timber product should include references at least to the following data:1. The species of wood or type of timber product;2. The name of the treatment to be applied;3. The nature of the treatment – and in the case of a paint – its colour and, where known, the loading;4. The method of application of the treatment;5. The test or regulation to which the treated product must comply.

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Fire retardant treated wood

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Fire safety certificate Fire-Retardant Natural Wood is certified by the Ministry of Land, Infrastructure and Transport as a semi-fireproof material for cypress, cedar, Norway spruce and larch wood types. Our fire-retardant wood bears great charms such as the warmth of nature and a tender touch for people. This wood is ideal for interior and exterior applications of houses, buildings, condominiums and public buildings, especially where building codes require fire-resistant material.

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Reference -,

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