Correct compressed air pressure at the air connection

Jun 13, 2020 | Compressed air

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The compressor station pressure is actually correct, but pressure is too low at the air-consuming equipment. What’s the cause?

In this case, hoses, quick couplings and pressure regulators are commonly the offending components. But often the pressure at the take-off point in the system is too low: for example, of the 6.8 to 7bar originally available for the tools, a mere 5 bar remains.

Operators often turn to a quick fi x: “Let’s just set the station pressure 1 bar higher, who cares!” But this is problematic, because for every pressure increase of 1 bar, the energy consumption of the compressor station increases by 6% – and the leakage rate also sharply increases.

It’s therefore advisable to identify the causes and implement an appropriate solution.

Pipe network as the source of the problem

When the pressure directly downstream of the compressor is correct and there is no disproportionately large reduction due to downstream treatment components, the problem can only be in the pipe network.

This is divided into three sections: the main line, distribution line and connection line (fig.1). In an optimised compressed air system , the following pressure drops are reasonable from an efficiency perspective:

correct pressure in the compressed air system
Fig. 1: Main components of a compressed air distribution system: Air-main (1), Distribution piping (2), Connection piping (3), Dryer (4), Maintenance unit/hose (5)

Eliminate ‘bottlenecks’

Upon closer inspection, it often becomes apparent that although the main line and distribution lines have the correct dimensions, the connection lines are too narrow.

For these, the pipe width should not be less than DN 25 (1”). For precise determination of the cross-section, KAESER KOMPRESSOREN offers a convenient on-line tool.

Ensure correct connections

To prevent disruptions and damage due to potential moisture, the connection between the distribution and connection lines should be designed as a flow-optimised “swan neck” (fig. 2): a direct downward pipe should only be used if the possibility of condensate formation in the pipeline can be excluded with 100 % certainty (fig. 3).

correct pressure in the system
Fig. 2: Swan neck
pressure calculation
Fig. 3: Direct downward pipe

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