An Air Relief Valve, Air Release Valve, or Air Valve is a safety device used to release air pockets that may have formed in a pressurized pipeline. These valves help to prevent various issues such as flow problems, pump failures, corrosion, faulty instrumentation readings, and pressure surges. In addition, trapped air in the pipeline system requires additional energy to operate.
Sources of Air in a Pipeline
Air can enter into a pipeline from a variety of sources. These include: • The pipeline itself – At the time of commissioning and start-up, air is typically filled in the pipeline. Once the fluid enters, it will displace the air and take its place. All the air must be removed during this stage to avoid accumulation at the highest points. • Water – Water typically contains 2% of air by volume, and adhesives or thick fluids can trap air in pockets. When the fluid flows through the system the air can separate out, leading to accumulation. • Equipment – Pumps, packing, valves, and pipe joints can also suck in air, which can then accumulate at the highest points.
Problems Caused by Air Accumulation
Air accumulation in a system can lead to a number of issues. These include: • Increased pressure head loss – When air accumulates, it creates a flow restriction, and this leads to an increase in head loss. This means more pumping cycles, more energy consumption, and higher costs. • Water hammer – When the velocity of the fluid is not high enough to carry away the air pockets, they will continue to grow. This can create an air-bound system, leading to complete flow stoppage. In addition, when the air pockets break away and are carried downstream, the increased pressure can cause water hammer, which can damage pumps, valves, and pipes.
Benefits of Air Release Valves
Air Release Valves are used to eliminate excess air from the system, allowing for a more efficient operation. These valves open against internal pressure to release the accumulated air, while also protecting against water hammer.
Working of Automatic Air Release Valves
Automatic air release valves are essential components used to release the accumulated air in pipelines and other fluid systems to maintain their functionality. The air relief valves are located at the high points of the pipeline, where air naturally collects. These valves work automatically without any manual intervention, allowing air bubbles to enter and displace the inside liquid. The displaced liquid level reduces until it no longer buoys the float. At this point, the float drops, causing the valve to open and vent the accumulated air into the atmosphere.
Components of an Air Release Valve
An air release valve comprises different components such as the main body, inner float assemblies, and other mechanisms. The compact metal body houses the inner floats and upper mechanism. The inner float assemblies consist of various parts, including a large orifice float, small orifice float, upper float, upper seat, mesh outlet, and cover. These components work together to maintain the air-free system.
Proper Installation of Air Relief Valves
It is essential to install air relief valves at high points in the piping or pipeline system where air is likely to accumulate. Installing the device vertically with the inlet down is preferable to ensure that it works effectively. When servicing is required, a shut-off valve must be added below the air relief valve. Air release valves are generally installed in various locations, such as maximum high points, temporary high points, long rising or falling pipe sections, after fast-closing valves, after flow throttling or boosting devices, long horizontal runs, flow meters, and transient locations.
Advantages of Air Release Valves
Air release valves have many benefits, including maintaining the efficiency and functionality of the pipeline or fluid system, reducing the risk of air locking and cavitation, and preventing corrosion and erosion. The air relief valves also help to reduce energy consumption and enhance the lifespan of the system by removing air from the system.
In conclusion, air release valves are essential components used to ensure that pipelines and fluid systems work effectively by removing accumulated air. The proper installation and use of air relief valves in the pipeline or fluid system provide many advantages, including improved efficiency, preventing corrosion and erosion, and reducing energy consumption.
Air Release Valves: Applications, Advantages, and Disadvantages
Air release valves are an essential component of closed-loop or pressurized piping or pipeline systems that have the potential of entrapping air. In this section, we will discuss the applications, advantages, and disadvantages of air release valves.
Applications for Air Relief Valves
Air relief valves are commonly used in water pipelines and sewer force mains. However, they are also suitable for any type of pressurized piping or pipeline system that may accumulate air. These valves are most effective in applications where smaller volumes of air need to be exhausted. They are commonly used in the following locations:
- Maximum high points
- Temporary high points
- Long rising or falling pipe sections
- After fast closing valves
- After flow throttling/boosting devices
- Long horizontal runs
- Flow meters
- Transient locations
Advantages of Air Relief Valves
Air release valves provide several benefits to piping and pipeline systems, including:
- Protection: They safeguard the pipeline and piping system from damage.
- Efficiency: They maintain system efficiency by reducing pressure loss.
- Automation: They are automatic and do not require manual operation.
- Continuous air venting: They continuously vent entrapped air from high points.
- Allow air back in: They allow air back into the pipeline during the emptying of liquid.
Disadvantages of Air Relief Valves
While air release valves have many advantages, there are also some disadvantages to be aware of. One disadvantage is that they may not be suitable for quick filling or emptying of pipelines. In such situations, air relief valves must be accurately sized for the specific application.
Conclusion
In conclusion, air release valves are crucial components of any closed-loop or pressurized piping or pipeline system that has the potential of entrapping air. They provide several benefits, including protecting the pipeline and piping system, maintaining system efficiency, and being automatic. However, they may not be suitable for certain applications, and accurate sizing is necessary for optimal performance.