Steel fire doors are “rated” by time (in minutes or hours) that a door can withstand exposure to fire test conditions. Hourly fire ratings include 1-1/2-hours, 1-hour, 3/4-hour, and 1/3-hour, or 3 hours with the maximum ratingrequired of any swinging type fire door being three hours.
our factory got the fire rated steel hollow metal doors with UL WHI or FM certicates .
