Fire retardant treatment

Fire retardant treatments Fire-tube furnace Fireworks... 

A small amount of particleboard is made with a fire-retardant treatment for use in locations where codes require this material, as in some offices and elevators. Particleboards receive overlay and finishing treatments with ease. Wood veneers, melamine overlays, printed paper overlays, vinyl overlays, foils, and direct grain printing can all be done quite simply. A small amount of particleboard is also made in the form of shaped, molded articles such as furniture parts, paper roU plugs, bmsh bases, and even toilet seats. There is another small increment of particleboard made by the extmsion process. These products are made in small captive operations owned by furniture manufacturers which consume all of this production in their furniture. The extmsion process differs from conventional flat-pressed particleboard in that the wood furnish is forced between two stationary heated surfaces. The mats are formed from one edge and this edge is alternately formed and pushed between the heated platens, which are maintained at a distance equal to the thickness of board produced. This is an old, slow, small-scale process, but is stiU in use in at least one location. 

Finally, a modification has been carried out in which a polyacrylate emulsion is added to a normal tetrakis(hydroxymethyl)phosphonium sulfate [55566-30-8] (THPS), urea, and TMM fire-retardant treatment in an attempt to completely alleviate the strength loss during the finishing. Indeed, better retention of tensile properties is achieved with no loss in fire resistance (85). 

Cotton—Wool Blends. Although they command only a very small fraction of the cotton blend market, cotton—wool blends are easier to make fire resistant than cotton itself. As might be expected, twiU fabrics containing both cotton and wool had decreased burning rates and increased 01 values both before and after fire-retardant treatment (147). 

Wood Shingles and Shakes. Early roofs in the United States were primarily hand-spHt hickory or cypress shakes. The natural beauty and style of these materials make them popular. Fire-retardant treatment and underlays may be needed to meet local fire codes. Wood shingles are sawn cedar having a uniform thickness. Wood shakes are usually hand-spHt and resawn. 

Another problem occurs when some fire retardant formulations ate exposed to elevated temperatures (eg, when used as roof tmsses or as roof sheathing) thermal-induced strength reductions can occur in-service. The thermo-chemical factors were discussed by LeVan and Winandy (26), and a kinetic degrade model was developed (27). The treater should be consulted to obtain appropriate in-service modifications for specific fire retardant treatments. 

The surface burning characteristics (flame spread index and smoke developed index) for wood and wood products as measured by American Society for Testing and Materials (44) can be reduced with fire retardant treatments, either chemical impregnation or coatings (48). Fire retardant treatments also reduce the heat release rate of a burning piece of wood (49,50). The heat release rates (51) of the burning materials are an important factor in fire growth. 

Fire retardant treatment, for wood, 26 348 Fire science, 11 450 Fire test methods, 11 449—450 Fire test terminology, 19 588 Fire-tube furnaces, 12 319—320, 327 Firing, of ferrites, 11 73 Firming agents, 12 32 as food additives, 12 57 First aid and rescue, 21 858 First aid, for nitric acid exposure, 17 192 First failure, time to, 26 987 First falling rate period, 23 67 First-generation ionic liquids, 26 837-838, 841, 865... 

A. R. T. Denues, Fire Retardant Treatments of Liquid Oxygen Explosives, V. S. Bur. Mines Bull. 429, Washington, 1940. 

F or centuries man has attempted to devise an effective process by which combustible materials could be rendered noncombustible or at least fire-resistant, but until about 10 years ago progress in this field was very limited and the effectiveness of the processes was questionable. Back in the days of the Roman Empire, efforts were made to reduce the fire hazard in props, curtains, and decorative-effect materials used in stage and theatrical plays by impregnating the fabrics with fine clay, and at about the same time clay, gypsum, and other types of plaster were used to coat wood, in an effort to make it resistant to fire. Since that time there has been steady progress in the field of fire-resistive and fire-retardant treatment processes, but it has been slow and the field of activity has been rather limited. 

The loss of 867 lives and the injury to hundreds of other persons in the Boston night club fire, the Natchez, Miss., night club fire, and the Ringling Brothers Circus fire would not have occurred if the highly combustible materials used had been treated with proper fire-retardant treatment processes. 

McNaughton, G. C., Natl. Fire Protect. Assoc. Quart., Fire-Retardant Treatment of Wood. ... 

Effect of Fire-Retardant Treatments on Performance Properties of Wood... 

To reduce the contribution of wood to fire losses, much research through the years has gone into development of fire-retardant treatments for wood. A total of 21.3 million pounds of fire-retardant chemicals were reported used in 1974 to treat 5.7 million cubic feet of wood products (2). The amount of wood treated was about one tenth of 1 percent of the total domestic production of lumber and plywood and has increased ninefold in 20 years. 

How does our research stand in rendering wood fire retardant What is the effect of fire-retardant treatments on the fire performance properties of wood and on the physical and mechanical properties of wood that are important to its utility Discussion will be limited to fire retardancy obtained by pressure impregnation, which is currently the most effective method. Fire-retardant coatings, wood-plastic combinations, and chemical modifications of wood will not be considered. 

Fire-retardant chemicals used by the commercial wood-treating industry are limited almost exclusively to mono- and diammonium phosphate, ammonium sulfate, borax, boric acid, and zinc chloride (4,8). It is believed that some use is also made of the liquid ammonium polyphosphates (9). Some additives such as sodium dichromate as a corrosion inhibitor are also used. Aqueous fire-retardant treatment solutions are usually formulated from two or more of these chemicals to obtain the desired properties and cost advantages For leach-resistant type treatments, the literature shows that some or all of the following are used urea, melamine, dicyandiamide, phosphoric acid, and formaldehyde (10-12) ... 

Effect of Fire-Retardant Treatment on Fire Performance Properties... 

What are the fire performance properties of untreated wood and how are these properties altered by fire-retardant treatments ... 

Usually the fire-retardant treatment of wood slightly increases the temperature at which ignition will take place. 

An extensive review of the literature to 1958 on thermal degradation of wood is given by Browne (5). Beall and Eickner (15) and Goldstein (4) add additional review information on this complex subject. Shafizadeh s (21) review of the pyrolysis and combustion chemistry of cellulose gives a basis for understanding these processes in wood and the effect of fire-retardant treatment on these processes. 

Commercial fire-retardant treatments generally do not add significantly to the fire endurance of assemblies. It is often more advantageous from the cost standpoint, either to use thicker wood members or to select species with lower charring rates, than to add the cost of the fire-retardant treatment. In some assemblies, however, it has been found worthwhile to use some fire-retardant-treated components in order to gain the extra time which will bring the fire endurance time up to the goal desired. For example, treated wood studs in walls and treated rails, stiles, and cross bands in solid wood doors have been used. 

Gerhards (57) reviewed the results of 12 separate studies on strength properties of fire-retardant-treated wood conducted at the FPL and other laboratories. He concluded that modulus of rupture (MOR) is consistently lower and modulus of elasticity (MOE) and work to maximum load are generally lower for fire-retardant-treated wood than for untreated wood if fire-retardant treatment is followed by kiln drying. The effect may be less or negligible if the fire-retardant-treated wood is air dried instead of kiln dried. The most significant loss was in work to maximum load, a measure of shock resistance or brashness, which averaged 34 percent reduction. 

Studies are currently being conducted on smoke development and heat release rate from treated and untreated wood and wood products (52,56). An evaluation of the available treatment systems for wood shingles and shakes was completed using artificial weathering (11). A further development from this work was a new ASTM Standard Method D2898 (67,68) for testing durability of fire-retardant treatment of wood. 

Effective fire-retardant treatments for wood for exterior uses under conditions of leaching and weathering have been needed for many years. For wood shingle or shake roofing, a commercial treatment system has been developed (61) in the United States that meets acceptance requirements of Underwriters Laboratories, Inc. Lumber and plywood are also available with this exterior-type treatment. 

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