Fire Performance of Ceiling Aluminum Baffles: Standard Requirements for Class A Fireproof Materials

Fire performance is the most important safety index of decorative materials in public spaces. Especially in crowded places such as shopping malls, airports, stations, schools, hospitals, office buildings, etc., the fire rating of ceiling materials is directly related to personal life safety. Relevant national specifications have strict requirements on the fire performance of ceiling materials. Aluminum baffles as metal materials have excellent fire performance, but there are also some products on the market that do not meet fire protection requirements. This article introduces the fire protection requirements of ceiling aluminum baffles in detail.

According to the national standard "Code for Fire Protection in Design of Interior Decoration of Buildings" GB 50222-2017, decorative materials are divided into four levels according to combustion performance: Class A non-combustible materials, Class B1 flame-retardant materials, Class B2 combustible materials, Class B3 flammable materials. Different places have different fire rating requirements for ceiling materials: ceiling materials of single and multi-storey civil buildings should not be lower than Class B1, ceiling materials of high-rise civil buildings should not be lower than Class B1, ceiling materials of underground civil buildings should adopt Class A, ceiling materials of important places such as crowded places, large and medium-sized computer rooms, central control rooms, telephone exchange rooms, rooms storing valuable equipment should adopt Class A. That is to say, ceiling materials of most public buildings must reach at least Class B1, and important places and underground spaces must reach Class A.

The melting point of pure aluminum is 660℃, which is a non-combustible material itself, but aluminum baffles have coatings on the surface, and sound-absorbing non-woven fabric or sound-absorbing cotton may be pasted on the back, these materials will affect the overall combustion performance. The fire rating detection of aluminum baffles is carried out in accordance with "Classification for Burning Behavior of Building Materials and Products" GB 8624-2012, divided into A1 and A2 levels, usually said Class A fire protection includes A1 and A2 levels. A1 level is completely non-combustible, will not produce any smoke and toxic gases; A2 level is non-combustible, in addition to non-combustible, but also meet smoke toxicity and smoke density level requirements. Ordinary powder coated or fluorocarbon sprayed aluminum baffles, if no organic materials are pasted on the back, can meet Class A2 fire protection requirements themselves, meeting fire protection requirements of all places; if ordinary sound-absorbing non-woven fabric is pasted on the back, because non-woven fabric is organic material, it may be reduced to Class B1; if ordinary sponge or rubber plastic cotton is pasted on the back, combustion performance may only be Class B2, which does not meet fire protection requirements of important places.

Aluminum baffles reaching Class A fire protection need to meet several standard requirements. First is base material, must be pure aluminum or aluminum alloy material, cannot contain any organic components; second is surface coating, the mass per unit area of powder coating or fluorocarbon coating cannot exceed the specified value, usually coating thickness does not exceed 120μm, coating will not produce a large amount of toxic smoke at high temperature; third is back sound-absorbing material, if sound-absorbing material needs to be pasted, Class A non-combustible sound-absorbing materials must be used, such as glass wool felt, rock wool felt, ceramic fiber cotton, etc., cannot use ordinary non-woven fabric, sponge, rubber plastic cotton and other combustible materials, even the so-called flame-retardant non-woven fabric is difficult to reach Class A; fourth is overall combustion performance test, must pass the national recognized testing institution in accordance with GB 8624-2012 standard test, reach A2 level or above, obtain fire test report, which is necessary information for fire acceptance.

Many manufacturers on the market claim that their aluminum baffles are Class A fireproof, but in fact there are many problems. First is stealing concepts, saying that aluminum alloy is metal so it is Class A, but ordinary non-woven fabric is pasted on the back, the overall combustion performance cannot reach Class A, the test report only tests the base material, not the overall product; second is using inferior recycled aluminum, which contains impurities such as plastic, will produce toxic smoke when burning; third is using thick coating or organic coating, coating thickness exceeds 200μm, producing a large amount of smoke and toxic gas when burning; fourth is using Class B1 test report to pretend to be Class A report, or using test reports of other products to pretend, confusing one thing with another; fifth is using ordinary glass wool for sound-absorbing cotton but no non-combustible test report, or using centrifugal glass wool but with too high binder content, cannot reach Class A.

Several key points need attention during fire acceptance. First is data review, aluminum baffle manufacturers must provide valid fire test reports, product name, specification model, manufacturer on the test report must be consistent with the actual products used, test standard must be GB 8624-2012, combustion performance rating reaches A2 or above, pay attention to the remarks of the test report, whether it indicates that the back sound-absorbing material is included, many test reports are bare board tests, not including the back sound-absorbing material, such reports cannot prove that products with sound-absorbing cotton are Class A; second is on-site sampling, fire department may sample on site for inspection, sampling should include back sound-absorbing material, cannot only take aluminum base material; third is on-site inspection, check the sound-absorbing material on the back of aluminum baffles, use lighter to ignite test, if it is ordinary non-woven fabric or sponge, it will ignite immediately, with black smoke and pungent smell, definitely cannot reach Class A, Class A non-combustible materials cannot be ignited or only slightly carbonized, will not continue to burn, no pungent smell; fourth is system fire protection, keels, suspenders and other accessories of the ceiling system must also be non-combustible materials, cannot use wooden keels or plastic accessories.

Many projects paste sound-absorbing cotton on the back of aluminum baffles for sound absorption effect, at this time must pay attention to the fire rating of sound-absorbing cotton. Ordinary centrifugal glass wool itself is non-combustible, but binder is added during production, if the binder content is too high, combustion performance will be reduced to Class B1. When purchasing, choose Class A non-combustible glass wool and provide fire test report of glass wool. If fire protection requirements are particularly high, ceramic fiber cotton can be selected, which is completely non-combustible and high temperature resistant, but the price is relatively high. Do not use ordinary non-woven fabric or sponge to save money, in case of fire, these materials will burn quickly, producing a large amount of toxic smoke, which is the main cause of casualties in fires.

There is another common misunderstanding that aluminum has a low melting point and will melt in fire, so fire performance is not good. In fact, although aluminum has a melting point of only 660℃, aluminum is a good conductor of heat, which will conduct heat quickly, and aluminum combustion will not produce toxic gases, nor will it drip like plastic to ignite other items. Flame temperature in fire is usually 800-1000℃, although aluminum baffles will melt, they will not fuel the fire, nor produce toxic smoke. Compared with B1 grade plastic, wood and other materials, fire performance is much better. Moreover, fire protection requirements are about the combustion performance of materials, that is, whether they will be ignited, whether they will spread flame, whether they will produce toxic smoke, not requiring materials not to melt in fire. Class A materials may also melt or deform in fire, but will not burn, will not spread flame, will not produce toxic smoke, which meets fire safety requirements.

When purchasing Class A fireproof aluminum baffles, be sure to choose regular manufacturers, require complete fire test reports, preferably overall test reports including back sound-absorbing materials, do not only look at the price, low-price products often cut corners on fire performance, there are major safety hazards. Fire acceptance is a one-vote veto item for project acceptance. Once fire protection is unqualified, the project cannot be delivered for use, and may face fines, resulting in losses far greater than material price difference.