Fire Protection Principle
Fire prevention principle of fireproof coatings can be generally inquired to the following five points:
(1), the fire-resistant coating itself cannot be burble, so that the protected substrate is not directly Contact with oxygen in the air,
(2), the fire coating has a lower thermal conductivity, delays the conductivity rate of the high temperature to substrate;
(3), fire-resistant coating is thermally divided into inert Gas, dilute the flammable gas that is protected by heat, so that it is not easy to combustion or the combustion rate slows down.
⑷, nitrogen-containing fire-resistant coating is thermally decomposed, NO, NH3 and other groups, combined with an organic pan-based, interrupt the chain reaction, and reduce the temperature.
⑸, the expansive fireless coating is thermally expanded, forming a carbonaceous foam insulation layer to block the protected object, delayed heat and the transfer of the substrate, prevents the object from fire burning or due to temperature increase The intensity decreases.
Thick coating steel structural fire painting is: glue (silicate cement, chloride or inorganic high temperature bonding, etc.), aggregate (expansion Pelicite, expanded pearl rock, aluminum silicate fiber, mining cotton, rockwin, etc.), chemical aid (modifier, hardener, water repellent, etc.), water. Steel structural fire-resistant coating material, silicate cement, chloride cement and inorganic bonding, commonly used inorganic bonds include alkali metal silicates and phosphate substances.
However, there is often a free alkali metal ion in alkali metal silicate, and the acid gas and CO2 in the air will chemically react with them. If the coating film is not resistant to water, no moisture, weather resistance, and the coating can easily occur when the base is used as the base of the coating. Therefore, if an alkali metal silicate is used as a base of the steel structure, the key problem to be solved is to modify it, that is, to solve the inhibitory problem of free alkali metal ions.
Phosphate binder is also a common inorganic bonding, which avoids the problem of alkaline oxide and the acid gas reactions in the air as a base of the fire-resistant coating, thereby improving the paint Physicochemical performance indicators such as weather resistance, water resistance. However, the molar ratio (M fin metal, P is phosphorus) in the phosphate binder has a direct impact on the storage stability, water resistance of the coating and the adhesion of the coating and steel substrate. . Therefore, in the development of steel structural fire coating, the control of the binder molar ratio is important in the development of the steel structure of phosphate.
Due to the thickness of the thick steel structure, the coating is thick and the amount is used, and the building is increased. Therefore, at the coating should be taken to add some lightweight materials and high efficiency insulation aggregates to reduce the density of the coating. The most useful light insulation bark is mainly expanded with vermiculite and expanded pearl rock.
The vermiculite is an aluminum silicate mineral containing iron-containing, magnesium having a layered structure with crystalline water between the layers. When it is thermally expanded, it will be as peristalized like a water, so the vermiculite is known. The vermiculite is dried, broken, screening, calcined at temperatures of 850 to 1000, and the particles are expanded more than 20 times to form expanded vermiculite. Its density is 80 ~ 200kg / m3, the thermal conductivity is 0.17 ~ 0.25W / (m · k), the fire resistance is strong, sound absorbing, sound insulation, non-toxic and tasteless, is an important blend of fireproof coatings.
Pearl rock is a glass rock, crushing, screening, preheating, instant roasting, can expand to 20 times, forming an expansion perlite having a honeycomb foam structure. The mass of the expansive pearl rock is extremely light, the weight is 80-250kg / m3, the thermal conductivity is 0.042 ~ 0.076W / (m · k), with heat preservation, insulation, non-combustible, non-toxic, chemical stability, etc. An important filler in the fire paint.
1. You can perform a preliminary examination of the quality of the product on site: expansive fire-resistant coating examination, 2 to 3 pieces in a substrate that have been constructed Sample, or take a small amount of sample to coated on 2 to 3 blocks of 150 mm × 150 mm plywood, painted according to the actual construction. After drying, check the flames of the alcohol lamp. The flame height is about 40mm, and the time of application of the flame is generally 20 min and check the coating foam. Normally, according to the specified amount of amount (generally 500 g / m2), the secondary fire coating has a thickness of 20 mm or more, and the secondary fire coating has a thickness of 10 mm or more, and the bubble layer should be uniform.
2. When the expansive fireless coating is burned by a strong fire, a large amount of expansion, the surface aggregation projections, no burning phenomenon in minutes, and counterfeit and shoddy Then there is basically no bubble, there will be a large amount of scattered slag, and the wood base material will also occur in the phenomenon of combustion damage.
3. Check if the product has a qualified inspection report issued by the National Fire Quality Inspection Center or inquire. Fireproof coating implements a national mandatory product certification system, and fire-proof coatings sold in the market should have national mandatory product certification certificates and type inspection qualified reports.
4. In actual use, in order to ensure fire protection and other use properties of fire-resistant coatings, a transparent cover coating is generally required. The fireproof coating is usually used in 350 to 500 g / m2, and the coating of the cover is generally 50 grams per square meter.
A lot of fire paint, but in accordance with the use of fireproof coatings, the thickness of the fireproof coating is generally divided into Face coating and steel structural fire painting.
Fireless coating is generally used as a protective material for flammable substrates, with certain decorative and fire resistance, and is divided into two major categories of water and solvent type. The steel structural fire-resistant coating is mainly a protective material used as a non-combustion body member. The coating of such fire coating is relatively thick, and the density is small, the thermal conductivity is low, so it has excellent heat insulation performance, and is divided into organic fire paint. And inorganic fireproof coatings.
Since the fire-resistant coating is used to block the spread of the fire, then what kind of fireproof coating is good? What kind of judgment standard? Domestic fire paint The total is divided into one, two, and three, of course, the best level performance. The quality of the quality of the fireproof coatings is actually determined by fire resistance and physical and chemical performance of fire-resistant coatings. Fire prevention performance includes four indicators such as flame-resistant time, flame propagation ratio, weight loss and carbonization volume, can be obtained in accordance with national standards, tunnel combustion method, and small chamber combustion method. The physicochemical properties mainly include solid content, viscosity, flexibility, impact strength, adhesion, dry time and water resistance. Its technical indicators are obtained after the national standard trial.
Whether the coating of fireproof coatings is thicker, the better it's the fire resistance? Generally, this is the case, for non-expanded fireproof coatings, It is depends on its own refueling and non-equivalent to prevent flames from spreading. Therefore, the thicker coating, the thicker the glaze formed at high temperatures, and the heat insulation effect of the fireproof coating will also be improved. For expanded fireless coatings, the coating is thick, fired and foamed, and the foam layer that is irritated and insulated and the heat insulating is also thicker, and [NO], [NH3] and other groups of [NO], [NH3] and other groups containing nitrogen-containing fire-resistant coatings. Increased, with an organic pan-based, the effect of interrupting the chain lock reaction is also good. Therefore, from the improved fire resistance, the wore coating is grateful, the better the coating.
Why will some fire paints will be burned? To explain this problem, we first come first, fire paintings are made of base, dispersion medium, flame retardant Composition, solvent, etc. The fireproof coating before the construction of the fire is burned in a fire, in fact, the flammable liquid solvent in the fire-resistant coating is combustion, and the material of the fire-proof coating, the material, and the like are not burned. Since solvent-based fire-resistant coatings are solvents in organic solvents, such as 200 solvent gasoline, n-butanol, acetone, cyclohexanone, toluene, etc., once the fire coating is leaking from the bucket, it is easy to cause a fire. The fire-resistant coating coated on the building component can only serve the effect of fire insulation after the solvent is evaporated.
Treatment of fire-resistant coating to improve the fire resistance effect of building components? With my country's flame retardant development, advanced, high-quality fireproof coatings come, Normal application situation, the effect is obvious.
Fireless coating; wood fire painting; steel structure fire coating, concrete structural fire painting, tunnel fire painting, cable fire painting.
The fireless coating is composed of a binder (ie film forming material), a pigment, a general coating aid, a fire aid, and a dispersion medium such as a dispersion medium. In addition to the fire aid, other coating components The role of coatings is the same as in conventional coatings, but there is a special requirement in performance and dosage.
Ultra-thin or thin
Applying in a steel structure ultra-thin or thin steel structure fire-resistant thermal insulation principle is The fireproof coating layer expands foam during the fire, forming a foam, but also has good thermal insulation than the oxygen, but also has good thermal insulation performance due to its texture loose, and the speed of heat is transmitted to the protected substrate; according to the physical chemical principle Analysis, the process of the foam layer produced by the coating expanded foam exhibits a heat absorption because the volume is expanded, and the heat when burning is consumed, which facilitates the temperature of the system, and the role of these aspects, making the fire coating have been significant. Fire protection effect.
Thick steel structure
The principle of fire insulation of the fire protection coating coated on the steel member is that the coating is substantially different from the fire-resistant coating, but The coating thermal conductivity is very low, the speed of heat is passed to the substrate, the coating of the fire-resistant coating itself is not burned, the steel member starts barrier and prevents thermal radiation, avoiding flame and high temperature direct offensive steel components. There is also some components in the coating to react with each other and generate the non-combustion gas. It also consumes a lot of heat, which is conducive to reducing the system temperature, so the fire is remarkable, and the steel is highly effective. Heat protection. In addition, the steel structural fire-resistant coating is fired when the coating does not have a volume change in the abutment, which can function as an oxygen, so that oxygen cannot be protected by the flammable substrate, thereby avoiding or lowering the combustion Reaction. But the glaze protective layer of such coatings is often large, and the heat insulation effect is poor. In order to obtain a certain fire insulation effect, the thickness of fire-resistant coating generally coating can achieve a certain fire protection performance. Require.
Avoiding misunderstandings to select fire-resistant paints: Different spaces have different space requirements for fire-resistant coatings, so you can ask experienced store salesperson when purchasing coatings. The suitable fire-resistant effect can be used to use suitable fire-resistant coatings in suitable places to use suitable fire-resistant coatings.
Take the wood structure fire coating in steel structure
Due to the naked naked eye of the wood structure fire paint and steel structure, it is unrecognized, consumption Detailed properties of fire-resistant coatings that must be understood when purchasing. If the steel structure uses a fire-resistant coating of the wood structure, its adhesion is greatly reduced, and it is easy to fall off, and fire safety cannot be guaranteed.
Unexpected Solvent type and aqueous fireless coating
steel structure fire paint has two, solvent-based fire-resistant coatings and aqueous fire-resistant coatings. From the angle of adhesion, the solvent type is greater than the aqueous property, and therefore, a solvent-based fire-resistant coating should be used for the steel structure for outdoor, and the indoor steel structure can use a solvent or aqueous fire-resistant coating.
Domestic fire-proof coating produces fireproof coatings will decompose toxic gases. If the fire-resistant electrical products use this paint, once the fire will release a toxic gas. For example, the use of G60 has been eliminated with vinyl chloride fire paint, which will decompose toxic chlorine when they are fired, so they cannot be used.
The quality of the fire paint construction also has an effect on fire prevention performance of the material, so it is necessary to pay attention to the quality of the paint of fire. The coating method of different fireproof coatings is slightly different, but the essentials of its basic construction are the same.
The non-expanded fireless coating is mainly used for fire prevention of wood, fiberboard and other plates, in the wood structure roof, ceiling, door and window.
The expanded fireless coating has a non-toxic expansion fire paint, an emulsion type expansion fire paint, a solvent expansion fire coating.
Non-toxic expanded fireproof coating can be used to protect the cable, polyethylene pipes and insulating plates or fireproof putty.
Emulsion type expansion fire painting and solvent type expansion fire paint can be used for fire prevention of buildings, electric power and cables.
Novel fire paints include: transparent fire painting, water-soluble expansion fire painting, phenolic fire painting, latex fire protection coating poly acetate oxycal fire painting, room temperature self-discharged water-soluble expansion type fire paint, poly Olefin fire insulating coating, modified high chloropolyvae fireproof coating, chlorinated rubber expansion fire coating, firewall coating, foaming fire-resistant coating, wire cable flame retardant coating, new refractory coating, casting refractory coating and so on.
Fireproof coating related test method
GB forming fire painting (suitable for expansive finish coating) There is a large board burning method Three common methods for the combustion method of tunnel combustion and chamber.
Scraping method: use metal or non-metal scraper, such as hard glue, FRP scraper, beef squeezer, etc. Shaving, used to apply a variety of thick paste-type fire paints and putty.
roller coating method: The roller is a small diameter hollow cylinder, and the surface is adhered to a long velvet hair made of synthetic fibers, and the cylindrical end is equipped with 2 washers, the center with holes, curved handles. This well is passed, and the roller is immersed in the coating and then applied to the desired surface. Development of a roll coating device for transporting coatings with air compressors.
Brushing method: The brush method is suitable for use in any shape of the object, and most fireless coatings can be constructed in this method. The brushing method is easily penetrated into the fine pores of the metal surface, thus reinforcing the adhesion of the metal surface. The disadvantage is that the production efficiency is low, the labor intensity is large, and sometimes the surface of the coating has a brush mark, affecting the decorativeness of the coating.
Spraying method: Using compressed air and spray guns to make paint atomization of coating, it is characterized by uniform mass, high production efficiency. The disadvantage is that some coatings are lossed, and at the same time, due to the large amount of evaporation of the solvent, it affects the health of the operator. The key equipment for air spray is a spray gun. The spray gun is usually divided into three kinds of gravity, attraction and press-oriented, and is divided into