An air lock in a water pipe is a blockage caused by trapped air or vapor at a high point in the pipe system, restricting or completely stopping the flow of water. This trapped air, being less dense than water, rises to the highest points in the pipe, forming a pocket that prevents water from passing through. This phenomenon is also sometimes called vapor lock.
How Air Locks Form
Several factors can contribute to the formation of air locks:
- Air entering the system: Air can enter through leaks in pipes, faulty fittings, or during initial filling of the system.
- Water pressure fluctuations: Changes in water pressure can cause air to become trapped.
- Evaporation: Repeated heating of water in pipes, such as in hot water systems, can lead to evaporation and the formation of vapor pockets.
- System design: Poorly designed pipe systems with high points or insufficient venting can be prone to air locks.
Identifying an Air Lock
Symptoms of an air lock include:
- Reduced or no water flow: This is the most obvious sign.
- Gurgling or banging sounds: These sounds might indicate air escaping.
- Inconsistent water pressure: The water flow might be intermittent.
Solving Air Locks
Several methods can help clear air locks:
- Opening bleed valves: Many systems have bleed valves at high points to release trapped air.
- Using a pressure relief valve: This valve can help relieve pressure and dislodge air pockets.
- Running water at multiple taps: This can sometimes help push the air through the system.
- Checking for leaks: Repairing leaks prevents further air ingress.
- Improving system design (if necessary): A plumber may be able to suggest changes to improve pipework.
Examples: A common location for air locks is at the highest point of a hot water system, preventing hot water from reaching all fixtures. Similarly, in a rural water supply system, air locks can frequently occur due to pressure fluctuations.
This information is consistent with multiple sources, including Wikipedia's definition of an air lock as a "restriction of, or complete stoppage of liquid flow caused by vapor trapped in a high point of a liquid-filled pipe system," and various online articles and forum discussions detailing causes, identification, and solutions for air locks in water pipes.
