Fire-retardant breathing manhole is developed by our factory according to market demand and referring to advanced technology data at home and abroad. It is a safety emergency ventilation device installed on the storage tank of petroleum, chemical and other materials, usually used in conjunction with the fire-retardant breathing valve, which can avoid the accident caused by the sudden overpressure or vacuum in the tank due to unexpected reasons, and damage the storage tank; It can also play a safe role in fire resistance. It is an ideal device for protecting the safety of storage tanks in China, and the product fills the domestic gap.