The basics of designing a compressed air system
When designing an air compressor system, numerous parameters have to be taken into account and many decisions have to be made to meet the requirements of the operator, the specific compressed air application, and to achieve the lowest possible operating costs. The installation should also be designed to accommodate future expansion if this becomes necessary.
It is important to note that the machines themselves, as well as the planning and installation, only account for a small part of the total life cycle costs. The later operating costs, particularly energy consumption, make up the bulk of the total costs. For this reason, all planning should focus on maintenance-friendly and efficient technology - from the compressors and the pipework system to the compressed air dryers and filters. The type of compressed air technology that should be used, on the other hand, is dictated by the application or the processes that will require the compressed air.
Demand is the main variable in the configuration of a compressed air system
Before the air compressors for the installation can be specified in terms of efficiency and compressed air quality, the expected compressed air requirement must be known, including any desired redundancy (a reserve quantity of compressed air) and any foreseeable requirements for production expansion.
Another significant factor is the operating pressure. This has a major influence on the specification of the compressors, dictating not only their size but also the future energy requirements of the compressed air system. Sometimes it is more economical to provide several compressed air networks, with different air compressors providing for different pressure levels. This may take up more floor space but will pay for itself quite quickly.
Determining the total compressed air requirement
To calculate the compressed air requirement, it is advisable to start by preparing a list containing all compressed air consumers, including all the technical data and their required air volume.
If there is no information available on compressed air demand or duration of use, default values should be used or the values should be estimated. As this part is quite difficult for many consumers, it can be helpful to compare the planned installation of compressed air users with an existing comparable system in order to get a good basis for the estimation.
To determine the total compressed air requirement, the requirements of the individual consumers should be added together. Since it is unlikely that all machines will run simultaneously and uninterruptedly, the duty cycle must be considered in the form of a "simultaneity factor". This factor must usually be estimated by the user. A reserve for wear and tear, compressed air pipework leakages, and foreseeable expansions should also be included.
Redundancy in the form of a backup compressor is not compulsory for all compressed air installations. The safety needs of the compressed air consumer machinery and the factory as a whole will dictate whether this is a requirement on a case by case basis.
From this "total" compressed air requirement - expressed in liters of compressed air per second, per minute, or in standard cubic meters per hour - you can draw conclusions about the size or output performance of the required compressor or compressors to be combined.
Having a clear idea for the total compressed air requirement of the site is a significant part of specifying a compressed air system but, of course, not the only one.
