Technical means of fire fighting are often ineffective in conditions of intensive fire spread in rooms with flammable materials. We are not necessarily talking about warehouses with paints and varnishes, chemicals and other products that can flare up from a spark. Quite familiar wood or plastic trim will also cause a lot of problems in a fire if it is not properly treated. Especially for such needs, fire protection preparations are produced that act for a long time and do not harm the structure of the target material.
What is a fire retardant?
Mostly refractories for combustible materials are compositions for external use, impregnations and, less often, powders. The main task of this type of processing is to form a layer that slows down the processes of combustion and smoldering. In some cases, the most effective compositions in principle prevent the spread of fire on the treatedsurfaces. This applies to impregnations, which do not just create a surface protective layer, but penetrate deep into the structure. The most common wood impregnation for fire protection, which does not change the operational and decorative qualities of the product. One way or another, all materials of this group belong to flame retardants. This is the name of the chemical base, which may be included in the composition of varnishes, enamels, paints, impregnations or bulk materials.
Basic composition of flame retardant
The most common systems consisting of phosphorus compounds, halogen-containing inclusions, nitrogen and inorganic substances:
- Organophosphorus agents are traditional flame retardants and may also contain harmful heavy metals, which is the main motive for the gradual abandonment of this kind of drugs.
- Halogen-containing substances make up approximately 25% of the total amount of fire retardants produced and provide a protection effect that is quite acceptable for industrial facilities.
- Inorganic fire protection compounds based on hydroxides (magnesium and aluminum), red phosphorus and ammonium polyphosphate. Such compounds make up about half of the fire fighting products on the world market.
- Nitrogen-containing preparations are used in special conditions - usually for the treatment of polymers.
- New generation products include polymer nano-composites, intumescent combinations, pre-ceramic refractory substances, etc.
Regardless of the composition, all of the abovepreparations are guided by the suppression of fire through physical or chemical effects. Another thing is that the conditions and form of their use may differ - for example, in the condensed or gas phase.
How the drug works
The mechanics of exposure is directly affected by the chemical composition. The flame retardant can be activated at different stages of combustion - during pyrolysis, ignition and the spread of fire. For example, halogen-containing drugs work in the gas phase of combustion. The principle of deceleration is implemented through the use of hydroxides and is expressed in a combination of several physical and chemical processes. During heating, water vapor is released, cooling the polymer matrix to the desired temperature regime, sufficient to stop combustion. Phosphorus-containing fire fighting preparations provide solid phase reactions. In the process of thermal destruction, such a flame retardant passes into the state of polyphosphoric acid, which catalyzes the dehydration reactions of the polymer substrate. Phosphorus compounds are also used, which act on the principle of radical capture in the gas phase, similar to halogens.
Varieties of drugs
First of all, liquid and solid products are separated. In one case, we are talking about paints and varnishes like the same varnishes with enamels and impregnations, and in the second - about backfills and coatings. At the very beginning of the formation of the segment of refractory preparations, manufacturers specialized in the production of products in solid forms, but due to the advantagesliquid form gradually switched to the manufacture of concentrates and solutions. The advantages of such mixtures include the absence of fine dust in the air, which increases the safety of their use.
Another classification concerns the principle of operation. All preparations for fire protection can be conditionally divided into active and passive. The means of active action include impregnations, including boric acid and phosphorus s alt. Under conditions of thermal exposure, the components of the composition melt, which forms a protective layer. Passive drugs do not change their protective structure in any way. The base coat applied initially creates a thin layer of heat reflection that does not change even at elevated temperatures.
Dangerous and safe fire retardants
A number of chemical elements that are used in flame retardants emit dangerous toxic substances together with pyrolysis products at high temperatures of the order of 500–600 °C. For example, for this reason, brominated diphenyl oxide was banned, as well as carcinogenic dioxins and furans. Modern flame retardants have not completely got rid of the release of highly toxic substances, since in some areas their effectiveness justifies itself, but in principle, the standards tighten the manufacturing technologies for agents that reduce the combustibility of materials. For domestic use, there are whole lines of safe preparations for burning, which have minimal harm to the environment. These can beinclude the same hydroxides of aluminum and magnesium. Another thing is that environmentally friendly fire retardants have a lot of other operational disadvantages, such as low physical and mechanical properties of the protective spectrum and unsatisfactory characteristics associated with deformation effects.
Drugs based on nano-composites
One of the most promising directions in the development of flame retardants is associated with polymer composites. These are matrix products that are distinguished by a balanced distribution of active components in the composition. For example, technologists can group reinforcing additives in different ways, including dispersion-compacted, fibrous and layered substances. The properties of fire protection preparations based on composites are determined by the structure of interfacial boundaries. Thus, one of the main problems of traditional flame retardants, the separation of functions between components, was solved. While one active element is working, the others are protected from the negative effects of the current phase by special membranes. When their turn comes, the protective layer is destroyed and the active components that are relevant for the current stage of combustion are included in the work. This principle is especially pronounced in nanocomposites, including layered silicates and polymer molecules. These compounds are distributed over the interlayer space of the matrix preparation.
What should you know about intumescent supplements?
The principle of intumescence, which can also be represented as a swelling effect, occurs against the backgroundsimultaneous foaming and carbonization of the protected material. This phenomenon can be useful in the combustion process, so additives are added to fire retardants that provoke it. In practice, intumescent fire protection products form a coke-like foam on the target surface. It acts as a kind of barrier between the material and the flame, thereby increasing the insulating effect with a delay in burning time. But, such additives also have negative qualities associated with the problems of application by traditional methods and solubility in the aquatic environment.
Preparing the solution
Special flame retardants are prepared by dissolving them in the volume of water specified by the instructions. For mixing, it is advisable to use a construction mixer, turning it on at minimum speed. The concentration will depend on the type, moisture and density of the target material. So, if a fire protection agent is used for fresh wood, then the consumption will have to be about 300-350 g/m2. After cooking, the mixture is settled, and then the sediment is drained.
Instructions for the use of fire retardants
Surface treatment with flame retardant solutions is carried out according to the principles of applying ordinary paint or varnish. That is, you can use a standard painting tool in the form of a roller or brush - it depends on the processing area. For uniform application, a spray gun with a suitable nozzle can also be used, but it is important to understand that many fire retardants, due to the inclusionspecial additives have a higher density compared to conventional paints and varnishes. As for the impregnation, in this case, the treatment for fire protection is carried out after a special abrasive cleaning. It is important to open the pores of the material with coarse grinding tools. After that, clean with dust removal and also complete the operation with painting work.
Safety precautions when using fire retardants
Since there are many environmentally hazardous substances among flame retardants, it is important to first familiarize yourself with the composition. If there are manufacturer's warnings regarding even minimal toxic indicators, then it is necessary to consider personal protective equipment. In particular, this type of fire preparation should be applied with gloves and with a respirator. Increased safety is also provided by goggles and overalls. And in any case, work indoors should be carried out only with ventilation or open channels of natural ventilation.
Conclusion
On the market you can find a lot of tools that allow you to manually protect various materials from fires. For the household segment, fire retardant compounds for wood processing are mainly offered. The most popular brands include Stary Elm, Senezh Ognebio and Bioshield preparations for fire and biological protection. And they are inexpensive. So, a complex solution "Bioshield" with a volume of 5 liters can be purchased for 400-500 rubles. Moreover, it is important to emphasize that it isabout the multifunctional system, which, together with the flame retardant effect, also provides protection against fungus, mold, insects, etc.
