What is the function of air valves?
At Water Care, we are keen to provide a group of articles in which we explain the various types of valves. Including air valves, which play an important role in water treatment plants and wastewater treatment plants.
The function of air valves
Air valve is hydromechanical devices with an internal float mechanism designed to release trapped air and wastewater gases during the filling and operation of the piping system.
It also ensures air entry during drainage to maintain positive pressure. This is important because negative pressure causes a vacuum that can collapse pipes and introduce contaminants into the system.
Therefore, air valve provides protection from transient pressures and trapped air in pipelines, which are the main causes of pipeline bursting, collapsing, and cracking.
What is the importance of using air valves?
With the correct use of air valve, you will achieve:
- Reducing energy consumption and operating costs
- Low-pressure loss
- Reduce delays when filling the piping system
- Reducing the risk of water hammer
- Avoid failure or inaccuracy in flow measurement
- Low wear
- Reduce the risk of contamination
- Reduced risk of pipe bursting and collapse
- Reduce replacement costs
- Reduced consumption due to increased network lifetime
What are the types of air valves?
There are three types of air valve installed in water systems: automatic air valve, air and vacuum valves, and combination air valves.
- Automatic air valve continuously release relatively small amounts of air from a pressurized line. Automatic air valve is also known as small orifice air valve and pressure air valve.
- Air and vacuum valves discharge large amounts of air when filling the pipeline. Air and vacuum valves make it possible to accept large volumes of air when lines are drained or when the pressure suddenly drops below atmospheric pressure. Air and vacuum valves are also known as kinetic air valve, large orifice air valve, vacuum breakers, low-pressure air valve, air relief valves, and individual air valves.
- Combination air valve combine the function of automatic air valve and air and vacuum valve. The automatic air release function releases accumulated air from the system when it is under pressure, and the air and vacuum function evacuates and accepts large volumes of air while filling or draining pipelines. Compound air valve is also known as double-orifice air valve, double-acting air valve, and double-orifice air valve.
What is the size and location of the air valve?
Air valve is dimensioned for a specific installation taking into account the flow, location, and performance of the air valve. Therefore, the DN of the air valve is not equal to the DN of the pipe on which it is installed. The size and location of air valve for a given project are determined by advanced calculation software that provides analyses such as fill rate analysis, drainage analysis, surge analysis, water column separation analysis, and energy-saving analysis.
The primary function of an air valve is to release unwanted air pockets from the pipeline. But it only works effectively when installed correctly. Proper location of the air valve can greatly improve the water flow performance. Therefore, air valve should be installed at those points where the pipeline is most susceptible to vacuum conditions. In general, the optimal installation of an air valve is at the top of the pipeline, and the valve should always be installed vertically.
Before installing the air valve, consideration must be given to the location. So that the valve is protected against freezing, contamination, and flooding. The air valve must be easily accessible to allow maintenance, operation, and inspection.
