KAESER Know How blog post
KAESER Know How Blog

In this blog we look at the typical causes of low pressure and how they can be resolved.

Under pressure to reduce your compressed air costs?
KAESER Know How Blog

In this blog we look at the typical causes of low pressure and how they can be resolved.

Under pressure to reduce your compressed air costs?

Under pressure to reduce your compressed air costs?

Why it pays to get the correct pressure at the air connection

KAESER Know How blog post: Why it pays to get the correct pressure at the air connection

November 2015

What do you do if the compressor station pressure is actually correct, but the pressure is too low at point of use? Do you choose a quick fix solution such as setting the station pressure 1 bar higher, or do you first identify the causes and then review what the appropriate solution may be to implement? In this blog we look at the typical causes of low pressure and how they can be resolved.

If the pressure is too low at point of use it may be tempting to turn to a quick fix - that being to just set the station pressure 1 bar higher. However, this is problematic! Every pressure increase of 1 bar increases the energy consumption of the compressor station by 6% and, it also sharply increases the leakage rate. With the energy costs attached to running a typical compressed air system accounting for nearly three quarters of its lifetime costs, reducing unnecessary energy wastage is therefore key to keeping these costs to a minimum. It is therefore advisable to first identify the causes of low pressure at the point of use and then consider the appropriate measures to take. 

There may be a number of reasons why the pressure is too low at point of use. Common culprits are hoses, quick couplings and pressure regulators. However, there are three areas which should be assessed in order to fully determine the cause and implement an appropriate solution; 

  1. Assess the pipe network
    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 can be divided into three sections; the main line, distribution line and connection line. From an efficiency perspective, in an optimised compressed air system, the following pressure drops are reasonable;
    Main line: 0.03 bar
    Distribution line: 0.03 bar
    Connection line: 0.04 bar
    In addition;
    Dryer: 0.2 bar
    Maintain. unit/hose: 0.5 bar
    Total 0.8 bar

  2. 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*. Bottlenecks can also be avoided by implementing a ring main piping system which creates two paths for the air to travel. This also halves the pressure drop and allows for more air flow through the pipe.

  3. 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". A direct downward pipe should only be used if the possibility of condensate formation in the pipeline can be excluded with 100% certainty. 

For further information fill in the form below to download a complimentary copy of the Kaeser guidebook 'Compressed Air Engineering; Basic Principles, tips and suggestions' 

*Kaeser offers a number of calculators in its online Toolbox including a pressure drop calculator and pipe length calculator. Click here to visit the Kaeser Toolbox.

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