Normally closed fire doors are closed at ordinary times and need to be pushed open when someone walks around. The normally closed fire door does not need to be set with electric automatic control, so the cost is low; The normally closed state can isolate and protect some important equipment and facilities.

ZHTdoors albaabbada dabka, 31 sano oo waayo-aragnimo wax soo saar ah oo albaabbada dabka iyo Daaqadaha. Albaabada dabka UL ee ugu muhiimsan, albaabada dabka EN, BS EN albaabbada dabka, iwm.