According to different fire resistance, steel fire doors can be divided into three grades: A, B and C. The fire resistance limit of Class B fire door is 60 minutes. The fire door is not only strong in fire resistance, but also considered in the design to prevent smoke diffusion.

Iminyango yomlilo ye-ZHTdoors, iminyaka engu-31 yesipiliyoni sokukhiqiza eminyango yomlilo kanye neWindows. Iminyango yomlilo eyinhloko ye-UL, iminyango yomlilo ye-EN, iminyango yomlilo ye-BS EN, njll., Sine-certification.ZHTdoors isekela i-OEM kanye ne-design yamahhala.Izinzuzo zethu: ikhwalithi enhle, intengo yefekthri, isevisi enhle.Siyakwamukela ukuthi uxhumane nathi.