Optimizing a compressed air system: 4 key elements

Author: Fabio Imbriani

Compressed air, a great consumer of power, holds an important role in modern supply chains. Recent environmental and energy-saving regulations highlighted the importance of managing and optimizing a compressed air system.

You may know how a modern air compressor works (and how to choose the right compressor for your business), however, in the beginning, compressed air systems were more “minimal” and utilized mainly piston-type compressors. Air treatment was not very widely used, and it was usually carried out using centrifugal separators and coalescence filters that allowed to retain solid particles and oils only partially. Distribution lines were put together using “black iron” pipes, which were not protected against rust and other contaminants

The most frequent issues were therefore accumulation of condensation along the lines and the obstruction of pneumatic tools caused by solid particles coming from the pipes.

Modern varnishing and production techniques contributed to the spread of rotary screw compressors and vane compressors, which ensure greater energy efficiency and a better quality of the compressed air.

Optimizing a compressed air system, 4 key elements

• Pressure drop – Most pneumatic tools work with air at working pressure of 6-7 barg. The productivity of the tool is particularly sensitive to even small pressure drops, as the power loss is proportional to the squared pressure drop. For instance, if the line’s pressure drops from 6 to 5 barg, this will result in a 25% power loss.
• Air flow – The condensation that exists in unfiltered and un-dehumidified air is the main cause for malfunction of pressure regulators. They have the important task of keeping the working pressure constant, ensuring limited wear, energy costs and maintenance costs in addition to better performance of the tools. There used to be two misconceptions regarding pneumatic tools like pneumatic drills, which were later proved wrong by accurate technical studies of the durability and reliability of such tools. The first misconception was to believe that oil, mixed with condensation, could work as a lubricator and was therefore a cure-all for the tools. This conception was proved wrong by manufacturers who suggested to use dehumidification and air filtration equipment, followed by ad hoc oil-fog lubricators. The second misconception implied that the greater the pressure of compressed air for pneumatic tools was, the better its performance would be. This is true at the beginning, but it has a negative impact on the durability of the tool itself.
• Air leaks – The volume of air that leaks from holes, cracks, faulty garnets and joints, may be quite significant. The economic consequence of such leaks become more apparent when put in relation with the air consumption of the tool. The volume of air that leaks from a hole 3 mm in diameter is equal to the air consumption of three pneumatic drills on constant use. Field research shows that air leaks of close to 25% are quite common.
• Distribution lines – It is very important to plan compressed air distribution lines adequately (network closed-loop) and to choose materials and joints with care. Distributed pressure drops are proportional to the square speed of air through the pipelines.

What discussed above shows the importance of choosing the right elements to have a law-compliant, efficient and energy-saving system.

Get in touch with the author: fabio.imbriani@progettoenergiaefficiente.it