Süütepiiri

Süütepiiri is an Estonian term that translates to "ignition limit" or "flammability limit." It refers to the minimum concentration of a combustible substance in a mixture with air (or another oxidant) that will support combustion. Below this limit, the mixture is too lean to burn, and above it, the mixture is too rich. The concept is crucial in understanding fire safety and explosion risks in various industrial and domestic settings.

The lower süütepiiri is the lowest concentration at which a flame can propagate. This is also known as the Lower Explosive Limit (LEL). If the concentration of flammable vapor or gas falls below the LEL, it will not ignite. The upper süütepiiri, or Upper Explosive Limit (UEL), is the highest concentration at which a flame can propagate. Above the UEL, there is insufficient oxygen to support combustion. The range between the LEL and UEL is known as the flammable range or explosive range.

Factors such as temperature, pressure, and the presence of inert gases can influence the süütepiiri values. For example, higher temperatures can lower the LEL, making ignition easier. Understanding these limits is essential for designing safe ventilation systems, selecting appropriate fire suppression methods, and implementing handling procedures for flammable materials. Regulations and safety guidelines often specify permissible exposure limits based on these flammability characteristics to prevent fires and explosions.