1.What are the burning characteristics of galvanized steel?
The base material of galvanized steel is steel, which has a melting point of about 1538℃ and a boiling point of about 2750℃. The temperature of daily fires is usually 600-1200℃, which is much lower than the melting point of steel. Therefore, the steel itself will not burn and may only oxidize at high temperatures.
The zinc layer on the surface will melt first at high temperatures, and when the temperature exceeds the boiling point, the zinc will evaporate to form zinc vapor.
2.What are the potential risks of zinc vapor?
Zinc vapor itself is colorless and odorless, but it may react with oxygen in the air to produce zinc oxide (ZnO) smoke (white powder). Short-term inhalation of high concentrations of zinc oxide smoke may cause metal fume fever (commonly known as "zinc fever").
But please note: zinc oxide is not a highly toxic substance, and its toxicity is much lower than hydrogen chloride and carbon monoxide produced by burning plastics, or formaldehyde produced by burning paints, etc. It may only cause discomfort when burning for a long time in a closed space (such as the concentrated burning of a large amount of galvanized steel with extremely high zinc vapor concentration).
3.What are other possible sources of toxic gases when galvanized steel burns?
If the galvanized steel surface is coated with paint or color coating (such as color-coated coils), the organic matter (resin, solvent, etc.) in the coating will decompose during combustion, releasing carbon monoxide, carbon dioxide, volatile organic compounds (VOCs), and even chlorine- and nitrogen-containing toxic gases (such as when the coating contains chlorine-based flame retardants). The toxicity of these gases is much higher than that of zinc vapor, and they are a risk that requires more vigilance in fires.
4.Does galvanized steel release toxic gases when it catches fire?
When pure galvanized steel (without coating) burns, the main risk is short-term discomfort caused by zinc oxide smoke, and there is no highly toxic gas;
If it is coated (such as color-coated galvanized steel), the combustion toxic gas mainly comes from the organic matter in the coating, not the zinc layer;
In a fire, the priority is to prevent asphyxiating gases (such as carbon monoxide) and coating combustion products, and the health risk of the galvanized layer itself is relatively low.
5.How to avoid zinc vapor poisoning when galvanized steel catches fire?
The key to avoiding zinc vapor poisoning is to reduce inhalation: quickly evacuate high-concentration smoke areas in case of fire, wear professional respiratory protection equipment when necessary, clean up properly after the fire, and monitor health status. In contrast, high temperature, lack of oxygen, and toxic gases (such as carbon monoxide) produced by the combustion of other combustibles in fire are more harmful, and comprehensive protection is required at the same time.