An airlock in water, referring to trapped air disrupting water flow, works by obstructing the passage within a pipe or system, preventing water from flowing continuously.
Here's a breakdown of the process:
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Air Accumulation: Air can enter a water system through various means, such as dissolved air coming out of solution, leaks in the system drawing air in, or during the initial filling of the system.
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Trapping: The air tends to collect at high points in the piping system because it is less dense than water. Gravity pulls the water down, leaving the air pocket trapped.
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Flow Obstruction: As the air pocket grows, it eventually restricts the water's ability to flow. It acts like a bubble blocking the pipe. Because water is incompressible, it can't simply compress the air bubble out of the way.
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Reduced Pressure/Flow: The blockage results in reduced water pressure or even a complete cessation of flow to fixtures or components downstream of the airlock. You might notice sputtering faucets or heating systems not working efficiently.
Why Airlocks are a Problem:
- Reduced Efficiency: In heating systems, airlocks can prevent efficient heat transfer, leading to cold spots.
- Damage: In some systems, airlocks can cause pumps to cavitate (form air bubbles that collapse violently), leading to damage.
- Inconvenience: Reduced water pressure or complete lack of water flow is simply inconvenient.
Solutions:
- Automatic Air Vents: These devices are installed at high points in the system and automatically release trapped air.
- Manual Bleeding: Manual air vents (bleed valves) allow you to manually release trapped air. This is a common solution for radiators.
- System Purging: Purging involves flushing the entire system to remove trapped air.
- Careful Filling: When initially filling a water system, fill it slowly to allow air to escape.
In summary, an airlock in water disrupts flow due to trapped air creating a blockage. Addressing this requires removing the air from the system through venting or purging.
