Classification of fire resistance of building materials

Update:17 Jul 2017

   Building fire protection is an important proposition […]

   Building fire protection is an important proposition that all kinds of buildings must face. Building material is an important factor to determine the safety of the building itself, directly related to the safety of people's lives and property. In building fire safety, the building blocks required for fire protection are beam, column, floor, wall and so on. In order to ensure the fire safety of buildings, fire building materials must use qualified, take necessary precautions against fire, which has a certain refractory, even if the fire will not cause too much damage. Fire resistance is usually indicated by fire rating. The fire resistance rating of a building is not decided by the fire resistance of one or two members, is decided by the refractory component of all buildings, which is determined by the main component of building wall, column, beam, floor, combustion performance and fire resistance.
   The combustion performance of building materials refers to the burning or fire all the physical and chemical change, the performance by the material surface ignition and flame spread, heat, smoke, carbonization, weightlessness, and toxicity product production characteristics to measure. Our national standard GB8624-97 divides the combustion performance of building materials into the following grades.
Class A: nonflammable building material, hardly burned material.
Class A1: non flammable, no flame.
Class A2: non flammable, with a small amount of smoke.
Class B1: nonflammable building materials, nonflammable materials have good flame retardant effect. It is difficult to fire when exposed to flame or high temperature in air. It will not spread quickly and will stop burning immediately when the fire source is removed;
B2 grade: flammable building materials, flammable materials have certain flame retardant effect. In case of fire or air will immediately burst into flames at high temperature, easily lead to the spread of fire, such as wood, wooden frame, wooden beams, wooden stairs etc..
B3 grade: flammable building materials, without any flame retardant effect, easy to burn, fire risk is great.
   Our country now applies the building exterior wall energy conservation heat preservation material mainly is EPS, XPS, they all are flammable thermoplastic high polymer foam plastics, when meets the fire high temperature, the reaction will melt, drops, will cause the fire. Modified polyurethane as a thermosetting foam plastic, in the event of fire attack, the surface of the material will quickly form a carbonized layer, it can stop and stop the fire continues to erupt, spread, and achieve a certain fire protection function. But without the modification of chemical molecular structure polyurethane, under the high temperature flame attack, its carbonization function is extremely small, the most is the B2 class, actually is still a flammable material, has the serious fire hazard.
   In addition, the foam sandwich plate more used at present, its bright color, good overall effect, convenient installation, low cost, is a versatile material, especially in the temporary facilities for construction site such as office, warehouse, wall etc.. But usually the fire rating is B3, that is, flammable materials. Mainly because of the foam sandwich panels, the middle of polystyrene foam board is flammable.