Fire doors can be divided into normally closed fire doors and normally open fire doors according to the opening state. Normally closed fire doors are usually closed under the action of door closers. Therefore, it can prevent smoke from spreading in case of fire; Normally open fire doors are usually opened under the action of door closers. In case of fire, the automatic release switch is automatic, and the fire door closers are closed under the action of door closers and aligners.

Deriyên agir ZHTdoors, 31 sal ezmûna hilberînê di deriyê agir û pencereyan de. Deriyên agir ên sereke yên UL, deriyên agir EN, deriyên agir BS EN, hwd.. Em xwedî sertîfîkayê ne.