The fire is unpredictable, it does not act selectively, but strikes everything in its path. How do PVC products behave in a fire? A lot of research has been done on this topic, which has led to certain conclusions..
A significant amount of stabilizing and filling substances is introduced into the composition of PVC profiles, making polyvinyl chloride more resistant to external influences.
Polyvinyl chloride is difficult to ignite, and further combustion is not supported if there is no fire source (international fire safety standards have determined PVC to be significantly higher than wood).
If we talk about the amount of heat released by PVC during combustion, then it is much less than the amount of heat released by wood during a similar process. This means that the use of polyvinyl chloride in the production of window structures can reduce the likelihood of fire and reduce the spread of fire during a fire..
Chlorine in PVC also counteracts combustion.
Combustion of polyvinyl chloride is accompanied by the release of gaseous substances – carbon monoxide and carbon dioxide (carbon monoxide) in concentrations not exceeding the corresponding indicators when burning other organic materials.
The hydrogen chloride released during the combustion of PVC, with its pungent smell, warns of ignition at the very beginning of the fire. Interacting with water vapor, hydrogen chloride turns into hydrochloric acid, which causes corrosion of metal structures of buildings. However, the concentration of this substance is very low and there is no danger to the structure, as well as to human health..
The fire resistance of PVC windows largely depends on the use of various components used when filling frame elements:
- the use of various glasses (ordinary, reinforced, triplex);
- the use of a sandwich lined with plastic or aluminum;
- the presence of wooden elements in the window structure (lining, various finishing plates).
If we compare the ignition temperature of a wooden and a plastic window from an external source, then it is, respectively, 210-270 degrees for the first and 310-400 for the second. As for the temperature of spontaneous combustion, for a wooden window it is about 260 ° C, for a PVC window – 450 ° C.
As you know, maintaining combustion requires the presence of oxygen at a certain concentration. There is an indicator (the percentage of oxygen in the air) at which the substance completely burns out when ignited. We are talking about the oxygen index (LOI) of a substance – the higher this value, the more difficult the combustion of the material occurs. For polyvinyl chloride, this number is in the range of 45–49 (for wood – 18, natural rubber – 17, polycarbonate – 26–28).
In terms of the rate of combustion propagation (another indicator for comparison), PVC shows significantly lower indicators (21) in comparison with pine lining (51) and even slate (63).
Thus, we can conclude that PVC is a hardly flammable material with low smoke generation, which does not differ from other building structures used in the production of components for the construction of buildings..