Air pipe head also can be called as air vent head. The air pipe head is mainly used in all kinds of ships to keep the ventilation pipe unblocked, and the air pressure in the cabin is close to the atmospheric pressure through ventilation and inspiration, so as to ensure that the cabin pressure does not exceed its own design pressure. When the hull tilts or encounters wind and waves, water flows into the air inlet, and the floating ball in the air pipe head floats rapidly under the action of buoyancy and fits the sealing ring to close the breathable pipe, thus preventing water from entering the cabin; When the water flows out, the float drops to its original position, and the ventilation pipe continues to open.