Normally closed fire doors are usually closed under the action of door closers, so they can prevent fire and smoke from spreading in case of fire. Normally open fire doors are usually opened under the action of fire door releaser. In case of fire, the fire door releaser automatically releases, and the fire door is closed under the action of door closer and releaser, thus preventing fire and smoke from spreading.

ZHTdoors pòt dife, 31 ane eksperyans nan pwodiksyon nan pòt dife ak fenèt yo. Pwensipal UL dife pòt yo, EN dife pòt yo, BS EN dife pòt yo, elatriye,.Nou gen certification.ZHTdoors sipòte OEM ak konsepsyon gratis.Avantaj nou yo: bon kalite, pri faktori, bon sèvis.Byenveni pou konsilte nou.