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According to an EU study (“Compressed Air Systems in the European Union”), in 80% of all enterprises the compressed air distribution systems are the weakest link in compressed air technology. This means that each year thousands of euros are literally blown out of the window for energy costs.
Compressed air distribution has the job of transporting the energy carrier compressed air with as little impact as possible on the
Each compressed air consumer in the network requires a specific optimal operating pressure. If the operating pressure is too low, e.g. caused by too narrow tube cross sections, the performance of the consumer is disproportionately reduced. By contrast, if pressure is too high it not only pushes energy costs up unnecessarily, it also shortens the service life of the consumers.
It goes without saying that the correct dimensioning of the compressed air network has a direct impact on the performance of the compressors, the consumers and hence on the costs of compressed air production.
The most important design criteria for the compressed air network are:
If these criteria are taken into account it is possible to ascertain the correct diameter for the compressed air lines. The pipeline diameter is dimensioned either
The first line, A (pipe length) is connected to line B (intake quantity) and extended to axis 1. Then line E (system pressure) is connected to line G (targeted pressure loss). Finally, the resulting intersections on axes 1 and 2 are connected by a straight line. This straight line cuts across line D; the required internal diameter can be read from this.
As a rule the nominal width of the compressed air line should be big. Some of the greatest losses of pressure occur owing to compressed air lines that are dimensioned too small or rather too narrow. Experience shows that in the case of an originally correctly-dimensioned compressed air network over the course of time an increasing number of consumers is attached to the existing pipeline network with the network having been redimensioned to accommodate new requirements. It is not unusual for just the compressor output to be raised to cover the increased consumption.
With an optimally designed compressed air network the drop in pressure between generation and consumer is subdivided as follows:
The pressure loss in the individual components of the compressed air treatment system can be represented as follows:
The amount of the overall pressure loss depends on:
The less auspiciously a compressed air pipe is conceived, the higher the performance of a compressor must be in order to build up the required pressure and maintain it. This means: 1 bar loss in the compressed air system = 1 bar more output on the compressor = approx. 10% higher power consumption.
Each element in a compressed air pipe system, irrespective of whether it concerns treatment elements or pipeline fixtures, cause a pressure loss owing to flow resistances.
Taking pressure loss due to fittings into account, in this connection a straight pipeline would be ideal. However, owing to constructional circumstances, as a rule pipelines cannot be laid from the producer to the consumer without fittings.
Changes of direction, for example when circumnavigating supporting pillars, can be avoided by laying the compressed air line next to the obstacle. 90° angles can easily be replaced by large-dimensioned 90° bends (s. Illustr. 5). This makes it possible to reduce the pressure loss to a fraction of the original pressure loss.
In addition to these influences, materials adapted to the various applications must also be used. Factors influencing the use of correct materials include the following:
Another good way of extending the “overrun” compressed air lines is to install a parallel line, which you connect to the existing distributor line. The piping system can hence be extended at no great cost to form a ”loopline system”.
You can find further information on the following topics:
also under the header “Saving money".