Currently, there are five main fire-resistance grades for fire-resistant materials:
Grade A: Non-combustible building materials that rarely ignite and burn.
Grade A1: Non-combustible, no open flames.
Grade A2: Non-combustible, smoke measurement required, must pass the criteria.
Grade B1: Flame-retardant building materials: Flame-retardant materials have good fire resistance. They are difficult to ignite in the presence of an open flame or under high-temperature conditions, and they do not propagate quickly. The combustion immediately stops when the ignition source is removed.
Grade B2: Combustible building materials: Combustible materials have a certain degree of flame retardancy. They will ignite and burn immediately when exposed to an open flame or under high-temperature conditions, and they can easily contribute to the spread of fire, such as wooden columns, wooden frames, wooden beams, wooden stairs, etc.
Grade B3: Highly flammable building materials with no flame retardant effect, extremely prone to burning, and high fire hazard.
Additionally, fire resistance grades for materials may vary according to different standards:
DIN4102: A1, A2, B1, B2, B3
EN13501-1: A1, A2, B, C, D, E, F
Additional information:
Fire-resistant materials are those that possess the ability to prevent or inhibit the spread of flames. They can be classified into non-combustible materials and flame-retardant materials. Non-combustible materials do not burn, while flame-retardant materials, although combustible, exhibit flame retardancy, making it difficult for them to ignite or char. Once the ignition source is removed, their combustion stops immediately. Therefore, they are also known as flame-retardant materials.
In the case of flame-retardant materials, with the exception of a few that inherently possess flame-retardant properties, most often, flammable materials are treated with flame retardants, fire-resistant impregnating agents, or fire-resistant coatings to achieve flame retardancy. From the perspective of fire safety, it is advisable to use fire-resistant materials instead of flammable materials in civil engineering and construction in order to reduce the fire load and slow down the spread of fire. The fire resistance performance of materials is determined through corresponding combustion tests according to different usage requirements.
Inorganic binders commonly used include water glass, gypsum, phosphates, and cement.
Fire-resistant mineral fillers include alumina, asbestos powder, calcium carbonate, perlite, and talcum powder.
Flame-retardant organic resins include polyvinyl chloride (PVC), vinyl chloride, chlorinated rubber, chloroprene rubber emulsion, epoxy resin, phenolic resin, and more.
Flame-retardant additives encompass organic compounds containing phosphorus, halogens, and nitrogen (such as chlorinated paraffin, triethyl phosphate, decabromodiphenyl ether), as well as inorganic compounds such as boron compounds (boric acid, zinc borate, aluminum borate), antimony compounds, aluminum compounds, and zirconium compounds.
The combustion performance of building materials refers to all the physical and chemical changes that occur when they burn or are exposed to fire. This performance is measured by characteristics such as ignition, flame propagation, heat release, smoke generation, char formation, weight loss, and the production of toxic substances. According to the Chinese national standard GB8624-97, the combustion performance of building materials is classified into the following grades:
Grade A: Non-combustible building materials that rarely ignite and burn.
Grade B1: Flame-retardant building materials: Flame-retardant materials have good fire resistance. They are difficult to ignite in the presence of an open flame or under high temperature conditions, and they do not propagate quickly. The combustion immediately stops when the ignition source is removed.
Grade B2: Combustible building materials: Combustible materials have a certain degree of flame retardancy. They will ignite and burn immediately when exposed to an open flame or under high-temperature conditions, and they can easily contribute to the spread of fire, such as wooden columns, wooden frames, wooden beams, wooden stairs, etc.
Grade B3: Highly flammable building materials: These materials have no flame retardant effect, are highly prone to burning, and pose a significant fire hazard.