Air vent heads are an essential part of a ship’s ballast tanks, fuel oil tanks, and fresh water tanks. Their main role is to let air move in and out of the tanks during filling, emptying, or changes in temperature. At the same time, they stop seawater from entering the tanks during rough weather or high seas.
1. Ball Type Air Vent Head
This is the most common design on modern ships. Inside the vent head is a lightweight floating ball. When water splashes into the vent head, the ball rises and seals the opening, preventing seawater from entering the tank. Once the water drains away, the ball drops and allows air to flow again.
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Advantages: Simple, reliable, low maintenance.
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Applications: Used for ballast tanks, fresh water tanks, and oil tanks.
2. Disc Type Air Vent Head
Instead of a floating ball, this design uses a disc or flap mechanism. When water enters, the disc lifts and seals against the seat.
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Advantages: Strong sealing performance, durable in harsh conditions.
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Applications: Often found on vessels exposed to heavy seas where protection is critical.
3. Flame Arrestor Air Vent Head
This type is designed for fuel oil tanks. It has a mesh or flame screen inside that prevents external flames or sparks from entering the tank through the vent.
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Advantages: Provides fire safety and explosion prevention.
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Applications: Fuel oil tanks and other flammable liquid storage tanks.
4. Weatherproof Air Vent Head
These are specially designed with covers, hoods, or baffles that stop rainwater, spray, or debris from entering. They may be combined with a ball or disc mechanism.
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Advantages: Extra protection from environmental conditions.
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Applications: Exposed deck areas on ships.
5. Automatic Closing Air Vent Head
This type combines a float mechanism with an automatic spring or sealing system. When water enters, the float rises and locks tightly without manual operation.
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Advantages: Higher reliability under extreme sea conditions.
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Applications: Critical safety tanks and naval vessels.
Post time: Sep-10-2025