Air behaviour in pipelines
Water and wastewater always contain free air and dissolved air. Dissolved air is transformed to free-flowing air due to changes in temperature, pressure, and velocity. Free-flowing air can get trapped inside the pipes and that causes flow restrictions, pressure surges, and incorrect metering.
How air enters a pipeline
Air can get into pipelines in several common ways:
- If pipes are not completely filled, it leaves air trapped at high points or inside valves and fittings
- Air that is naturally dissolved in the water, which is released when pressure drops or temperature rises
- Whirlpools near pumps that pull air into the system
- Air leaking in through joints, seals, valves, or other openings
Problems caused by trapped
air Too much air in a pipeline can reduce efficiency, damage equipment, and create safety risks:
Reduced performance
- Water does not flow smoothly, making drainage slower
- Flow area inside the pipe is reduced, increasing energy use
- Pumps work harder and less efficiently
- Flow and volume readings become inaccurate
Damage to the system
- Sudden pressure changes can stress or damage pipes
- Pipes and metal components corrode faster
- Moving parts and measuring devices wear out more quickly
Safety risks
- Large pockets of compressed air can be released suddenly
- Fast‑moving air and water can endanger workers and equipment
Problems caused by avoiding air-intake into the pipeline
Damage to the system
- Pipe collapse due to vacuum formation
- Complete pipeline, including valves and fittings will be deformed and damaged
Why air control is important
Removing the unwanted air from pipelines improves system efficiency and enhances operational safety.
Good air control:
- Improves flow and energy efficiency
- Protects pipes, pumps, and valves
- Increases system reliability
- Reduces maintenance and repair costs
- Improves safety for operators
This is why proper air release and vacuum protection devices are essential in modern pipeline systems.