Fire Rated ACP and its Application
When we speak about Fire rated Aluminium composite panels (ACP's) we can really narrow it down to four core materials. B1 fire resistance panels, A2 non-combustible panel, Alucore or honey comb core panel and pure aluminium sheet.
Each material have it's own pros and cons to them. I wanted to take a look at each individual material and when we should be utilizing them rather than trying to find a one size that fits all scenario.
lets dive right in:
What are the differences between B1 and A2 fire resistant Aluminium composites Panels?
The difference comes down to the fire resistant qualities in the panels.
What are South African standards in fire safety for building cladding and facades?
The South African national standards have drawn up a bill of standards for Fire protection named SANS 10400 T. This document indicates that all materials used on buildings that occupy people from type C to type A buildings must have fire resistant panels. the degree of fire resistance vary on building class, type and size.
B1 grade Fire resistant core:
Contains 55% – 70% flame retardant, the main ingredients are aluminum oxide (Al₂O₃) and magnesium oxide (MgO) ; it is important to note that the term “FR” be it “fire resistant”, “fire retardant”, “Plus” or any other variation on the wording, meets no set standard. It is therefore imperative to check with your supplier what the mixture of combustible content is on a product specific basis, as this may also vary.
B1 fire resistance aluminium composite panel - B1 refers to the classification the material can achieve in accordance to the fire regulation acts consistent to that countries requirements.
These requirements are measured in minuets, the reason been is so that we can see how long the material will last under duress from a fire providing time for evacuation and fire fighting professionals to fight the fire and hopefully save valuable property.
In South Africa generally a B1 fire resistant panel on its own can achieve a 20 minuet fire rating. This material is best suitable for type A and B buildings. South African SANS 10400 states that any building material used in type A or B building up to three stories requires a minimum of a 30 minuet fire rating. In order to make a B1 panel meet the fire safety requirements one needs to use a citified fire tested sub-frame system to ensure the correct fire rating is achieved.
When B1 grade panels are put into a fire, it will catch fire after 5 minutes from been exposed to flame, the fire will extinguish after 10 seconds once the fire leave the panels.
B1 panels are preferred for internal applications as they do not spread fire.
NOTE: PE core and B2 fire resistant panels do not meet South African standards for internal application on type C - A buildings as they are combustible and fuel the fire further. these panels are suitable for small scale signage or independent signage solutions. Ask your supplier for more information on their applications.
A2 grade fireproof aluminium composite sheet / non-combustible ACM:
Contains 88% – 90% of the flame retardant, the main ingredients are aluminium hydroxide(Al(OH)3) and magnesium hydroxide (Mg(OH)2)
A2 Aluminium core panels refers to the class of fire rating it will achieve, non-combustible. this mean in the event of a fire the panels will not ignite or provide the flame with fuel to spread the fire. A2 panels will not release toxic fumes in the event of a fire as smoke inhalation is the larges killing factor in fire hazards.
A2 panels can achieve a 30 minuet fire rating on their own and require a citified fire safe sub-frame system on multi story buildings from the thirds floor upwards as a 60 - 120 minuet fire rating is required. Some citified sub-frame systems can assist this panel in achieving a three hour fire rating.
The technology in A2 panels is incomparable to other materials as the materials undergoes a chemical reaction when encountered with heat called Endothermic and exothermic reactions.
This means when the panel is subjected to heat, a chemical reaction takes place when magnesium hydroxide reaches 330 Degrees Celsius releasing water which enhances the flame retardant properties of the A2 panel. Magnesium Hydroxide during the burning reaction forms a “Char-Ash” in front of the flame, which suppresses the flame and because of its acid scavenging properties, can play a useful role in hydrogenated compounds by reducing acid gas emissions in toxic smoke.
In short A2 panels not only fight the fire and resist the spread of flame and smoke but also plays a role cleaning impurities in the toxic smoke.
An A2 panel would only catch fire after 30 minutes, the fire will then extinguish immediately when the fire leave the panel.
This panel is suitable for both internal and external applications as its deemed to satisfy and is qualified as a non-combustible material.
Aluminium sandwich panel (ASP)
Aluminium cored ACM is typically made of an external layer of refinished aluminium sheet, followed by an internal aluminium core (this can be in the traditional honeycomb pattern or dimpled) then followed by another flat layer of rear skin.
If this type of product has passed and can present certificates for SANS 10400 (complete panel including coatings and adhesive), this would fall into the DtS category for compliance. and achieve an A2 fire rating.
As this panel is comprised of Aluminium the material does not fuel the fire or release toxic fumes which enables this material to meet the A2 requirements. It however does not have the Endothermic and exothermic reaction taking place.
Aluminium core panels have a grate rigidity to them as well as incredible strength to weight ratio and impact resistance.
As this typo panel does have an A2 rating its most commonly used in internal and some external cladding and facades as it can potentially be more affordable that A2 ACM.
Pure Aluminium Sheets
Pure aluminium sheets have been used in Cladding for many years and is readily available in most instances.
Pure Aluminium may achieve an A1 fire rating as the material does note fuel the fire further nor does it release toxic fumes. the pros to making use of this material for building cladding is its availability. Aluminium sheets can be purchased with easy from most local suppliers, it has an added benefit that it can be powder coated to almost any colour you want making this material perfect to get that brand colour or specific once off finish your looking for.
However, it's not a preferred material for building cladding on a larger scale for the following reasons.
Aluminium melts at a low 630 Degrees Celsius which is far below the intensity of most building fires which make this material not suitable as a fire prevention or resistant material. Although it does not provide a fuel to spread the fire in some instances molten droplets falling onto flammable materials may well spread the fire. Pure aluminium sheets have no fire resistant capabilities. Although aluminium can easily be powder coated to get a powder coating company to guarantee thir paint for any length of time, strict guidelines must be met such as information on the location, potential harmful chemicals produced in the areas or distance from the ocean all affect the power coating guarantees if even provided. In short we cannot achieve the outdoor UV protection guarantees we can with PVDF or FEVE paint finishes provided on Aluminium composite materials. Lastly and probably the biggest down side to pure Aluminium sheets for cladding is the cost. Pure Aluminium sheet pricing can be any where from twice to five times the price of any Aluminium composite panel with an added cost of powder coating still to be added.
South Africa has come alone way in ensuring we specify fire rated materials on our buildings in the hope that we don't fall victim to a Grenfell tower incident however I would like to add that we need to take note that B1 Aluminium composite panels on their own do not meet our current regulations, you would need to contact you fire engineer to determine which material would be suitable for your project and if a fire rated sub-frame system is required.