There are three types of steel fire doors: Class A steel fire doors shall have a fire resistance time of not less than 1.5 hours, Class B steel fire doors shall have a fire resistance time of not less than 1.0 hours, and Class C steel fire doors shall have a fire resistance time of not less than 0.5 hours.

ZHTdoors yong’inga qarshi eshiklar, yong’in eshiklari va derazalarida 31 yillik ishlab chiqarish tajribasi. Asosiy UL yong’in eshiklari, EN yong’in eshiklari, BS EN yong’in eshiklari va boshqalar.