Fire extinguishing equipment is often ineffective in conditions of intense fire spread in rooms with flammable materials. This is not necessarily about warehouses with paints and varnishes, chemicals, and other products that might spark from a spark. A quite familiar wood or plastic finish will also cause a lot of problems in case of fire if it is not properly treated. Specifically for such needs, preparations for protection against fire are produced, which act for a long time and do not harm the structure of the target material.
What is a refractory preparation?
Basically, refractory products for combustible materials are compositions for external use, impregnation and, less often, dusting powders. The main task of this type of processing is to form a layer that slows down the combustion and smoldering processes. In some cases, the most effective formulations in principle prevent the spread of fire on the treated surface. This applies to impregnations, which not only create a surface protective layer, but penetrate deep into the structure. The most common is wood impregnation for protection against fire, not changing the operational and decorative qualities of the product. One way or another, all materials in this group are flame retardants. This is the name of the chemical base, which can be included in the composition of varnishes, enamels, paints, impregnations or bulk materials.
The basic composition of the 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 include harmful heavy metals, which is the main motive for the gradual abandonment of this kind of drugs.
- Halogen-containing substances make up about 25% of the total volume of produced flame retardants and provide a protection effect that is quite acceptable for industrial facilities.
- Inorganic compounds for fire protection are based on hydroxides (magnesium and aluminum), red phosphorus and ammonium polyphosphate. Such compounds make up about half of the fire fighting equipment on the world market.
- Nitrogen-containing preparations are used in special conditions - as a rule, for processing polymers.
- New generation products include polymer nano-composites, intumescent combinations, pre-ceramic refractory materials, etc.
Regardless of the composition, all of these drugs are focused on suppressing fire through physical or chemical effects. Another thing is that the conditions and the form of their use can vary - for example, in a condensed or gas phase.
The principle of the drug
The chemical composition directly affects the mechanics of exposure. Fire retardant can be activated at different stages of combustion - during pyrolysis, ignition and the spread of fire. For example, halogen-containing preparations work in the conditions of the gas phase of combustion. The principle of deceleration is realized through the use of hydroxides and is expressed in a combination of several physicochemical processes. During heating, water vapors are released that cool the polymer matrix to the desired temperature regime, sufficient to stop combustion. Phosphorus-containing anti-fire preparations provide solid phase reactions. In the process of thermal destruction of such a flame retardant goes into a state of polyphosphoric acid, which catalyzes the dehydration reaction of the polymer substrate. Phosphorus compounds are also used, which act on the principle of radical capture in the gas phase like halogens.
Varieties of drugs
First of all, liquid and solid agents 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 advantages of the liquid form, they gradually switched to the production 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 relates to the principle of action. All preparations for protection against fire can be divided into active and passive. Active agents include impregnations that include boric acid and phosphoric salt. Under thermal exposure, the components of the composition melt, which forms a protective layer. Passive drugs do not change their protective structure. The basic coating initially creates a thin layer of heat reflection, which does not change even at elevated temperatures.
Dangerous and safe flame retardants
A number of chemical elements that are used in flame retardants, at high temperatures of the order of 500-600 ° C, together with the products of pyrolysis release dangerous toxic substances. For example, for this reason, brominated diphenyl oxide, as well as carcinogenic dioxins and furans, were banned. Modern flame retardants have not completely eliminated the release of highly toxic substances, since in some areas their effectiveness is justified, but in principle, standards tighten the manufacturing technology of agents that reduce the combustibility of materials. For domestic use, there are a whole line of safe preparations for burning, which have minimal harm to the environment. These include the same aluminum and magnesium hydroxides. Another thing is that environmentally friendly flame retardants have many other operational shortcomings, such as low physical and mechanical properties of the protective spectrum and unsatisfactory characteristics associated with deformation.
Preparations based on nano-composites
One of the most promising areas for the development of flame retardants is associated with polymer composites. These are matrix agents characterized by a balanced distribution of active components in the composition. For example, technologists can differently group reinforcing additives, among which disperse-densified, fibrous and layered substances. The properties of fire protection preparations based on composites are determined by the structure of interphase boundaries. Thus, one of the main problems of traditional flame retardants was solved - the separation of functions between components. While one active element is working, 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 relevant for the current stage of combustion are included in the work. This principle is especially pronounced in nano-composites, including layered silicates and polymer molecules. These compounds are distributed over the interlayer space of the matrix preparation.
What you should know about intumescent supplements?
The principle of intumescence, which can also be represented as the effect of expansion, arises against the background of the simultaneous foaming and carbonization of the protected material. This phenomenon can be useful in the combustion process, therefore, additives provoking it are added to the flame retardants. In practice, the use of fire protection with intumescence forms 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 the burning time. But, such additives also have negative qualities associated with application problems by traditional methods and solubility in an aqueous medium.
Solution preparation
Special flame retardants are prepared by dissolving them in a volume of water specified by the instructions. For mixing, it is advisable to use a construction mixer, including it at minimum speed. The concentration will depend on the type, moisture and density of the target material. So, if a preparation is used to protect against fire in relation to fresh wood, then the consumption will have to be about 300-350 g / m 2 . After preparation, the mixture settles, and then the precipitate is drained.
Instructions for the use of fire protection
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 uniformity of application, you can also use a spray gun with a suitable nozzle, but it is important to understand that many flame retardants due to the inclusion of special additives have a higher density compared to conventional paints. As for impregnation, in this case, the treatment for protection against fire is performed after a special abrasive stripping. 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 flame retardants
Since there are many environmentally hazardous substances among flame retardants, it is important to familiarize yourself with the composition initially. If there are manufacturer's warnings regarding even minimal toxic indicators, then personal protective equipment should also be considered. In particular, a fire preparation of this type should be applied with gloves and with a respirator. Increased safety is also provided by goggles and protective clothing. And in any case, work in the room should only be carried out with working 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 domestic segment, flame retardants for wood processing are mainly offered. The most popular brands include “Old Elm”, “Senezh Ognebio” and “Bioshchit” preparations for fire and biological protection. Moreover, they are inexpensive. So, the complex solution “Bioshchit” of 5 l can be purchased for 400-500 rubles. Moreover, it is important to emphasize that it is a multifunctional system that, together with a flame retardant effect, also provides protection against fungus, mold, insects, etc.