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 fire doors, 31 years of production experience in fire doors and Windows. The main UL fire doors, EN fire doors,  BS EN fire doors, etc.,.We have certification.ZHTdoors support OEM and free design.Our advantages:good quality, factory price, good service.Welcome to consult us.