Why Are Air Valves Used? Where Are They Used?

Air valves are an important part of the water supply network. Whether it is a distribution pipe or a sewer main, you will find air valves there. So, what is an air valve? What role do air valves play in critical pipeline infrastructure?

Air in water pipes

The formation of air and vacuum in water pipes can lead to serious operational problems and even some serious consequences. Air can enter a plumbing system in a number of ways.

Empty pipes

Unoperated pipes are occupied by air. Most of this is evacuated during startup, but some air pockets may remain in the system.

Air in fluids

Depending on temperature and pressure, fluids such as water may contain trapped or dissolved air. During fluid flow, it separates from the fluid and may become trapped at high points in the system. 

Mechanical Equipment

Air can also enter the pipeline through mechanical systems such as pumps, fittings, and valves. Leaks or sealing defects in these components can cause air to seep into the piping system.

A vacuum in a pipeline occurs when the pressure in the pipeline falls below atmospheric pressure. Or a vacuum may occur due to a sudden change in the velocity of the flowing fluid. The formation of air and vacuum in pipelines can have serious consequences for the operation of the pipeline. Some of these consequences include: reduced pumping efficiency, pipeline corrosion, metering and instrumentation equipment failure, air hammer, etc.

What is an air valve?

How can I prevent air and/or vacuum from forming in my water supply system? One solution is the air valve, a special hydrodynamic flow control device that allows metering of fluid flow in one or both directions. Its function in the pipeline is to release accumulated gas or allow air to enter the pipeline during filling, venting or operation of the liquid piping system. Please follow LIWEI to see more.

Air Valve Installation

It is important to choose the correct location to install an air valve. For maximum efficiency, air valves are placed at critical locations in the pipe runs. For proper ventilation and venting of water and wastewater systems, air valves are required at the following points.

Maximum high point

Air bubbles build up and form air pockets that get stuck at the highest point of the system. Placing an air valve here helps to vent the air pockets to the atmosphere.

Temporary High Point

A local high point can also be used as a collection point for air bubbles. The air valve here discharges the air bubbles to the atmosphere.

After rapid closing of the valve

When the valve is suddenly closed, a vacuum will form downstream of the valve due to the momentum of the flow. For proper pipeline operation, the negative pressure needs to be relieved by introducing air into the pipeline.

Finally, always install air valves in an accessible, well-ventilated location. This ensures that they always have enough air entering the system and that the exhausted air has a discharge path. In addition, it makes it easier to reach the valve for maintenance.