Compressed air installations - inventory
The specific nature of compressed air means that , within a few years, most systems are rebuilt, modified and extended. No wonder that the plants lack up-to-date maps of the compressed air network. The solution to this problem is taking an inventory of the compressed air system.
Why is it worth taking an inventory of your compressed air system?
The documentation and knowledge of flow and pressure allows you to determine whether your compressed air system is efficient or not. Lack of such knowledge can lead to chaos. It may turn out that air receivers connected to the fully loaded branch of the network will interfere with the operation of the previously installed ones. The inventory of the compressed air installation that, when combined with measurements or flow estimates, allows you to assess the throughput of the cross-section used and gives the ability to analyse whether it is possible to connect a receiver to a given branch. On the basis of such documentation, the infrastructure manager may issue permits to users to connect receivers, which is very important for maintaining the efficiency of compressed air transmission. The lack of such documentation results in uncontrolled consumption in the pipeline branches, whose cross-section may be too small leading to excessive pressure drops.
What are the recommendations?
The frequently asked questions regarding network adequacy are not catalogued in any standard. There are only recommendations resulting from good manufacturing practice, which are published by pipeline suppliers and auditors. Good practice recommends that the pressure drop from compressor stations to consumers should not be greater than 2% of the initial value, but not greater than 0.2 bar. Ideally, the pressure drop from the compressor station to the receivers should be below 0.1 bar. The Compressed Air Challenge, on the other hand, recommends an acceptable pressure loss of less than 2% of the initial pressure. However, according to the same Agency, the recommended speeds in main lines should be below 30 feet per second (i.e. below 9 m/s) and in receiver connections below 50 feet per second (i.e. below 15 m/s) in the actual pipeline speed range. Compressed air systems shall be closed in a loop and in such a way that the largest consumers are closest to the compressor room. Translating this into European conditions - it is worth applying the 5-10-15 rule, i.e. 5 m/s in the compressor collector, below 10 m/s in the main arteries and below 15 m/s in the connections for the shortest possible distance.
The final result of the installation
During the inventory, our auditors apply the course of pipelines with their diameters and lengths to the available layout during the Department's work. The results of our work include:
- network diagram printed on the layout of the Plant in .dwg format,
- determination of pipeline diameters,
- calculation of the capacity and efficiency of the system and the pressure drop on the transmission, which allows the assessment of the efficiency of the compressed air network,
- optional compressed air system measurement design,
- optional suggestions for changes to improve transmission efficiency,
- optionally, a proposal for a layout of the compressed air system based on proven and reliable technology of aluminium pipelines dedicated to compressed air
The observation of the data obtained from monitoring that can be properly designed based on the current inventory described above, allows to obtain further savings resulting from prevention of the irrational behaviour of some users. It can also lead to a reduction in the network pressure, which gives savings of about 7% from 1 bar of reduced pressure.
NOTE: Too high a pressure and overproduction of air for absurd applications causes statistically c.a. 20% of the air loss in the system!
Current maps of the compressed air system are very much needed. They provide a full overview of the system, facilitate the possible expansion or application of measurement points and allow for safe connection of new receivers.