Why do I need to service my compressed air filters?

When a compressor produces compressed air it draws in atmospheric air which will have some degree of water and solid particles in it. In a lubricated compressor you will also have a third contaminant in your compressed air - that being oil. And, when ambient air is compressed we further concentrate the contaminates as we are reducing the air volume. For example for an air compressor with final pressure of 10 bar the air is therefore compressed 10 times ambient, therefore you could say that there might be 10 times more contaminates per final volume. These contaminants must be effectively removed in order to produce compressed air to the specific air quality level that an application or process requires. 

Different processes and applications require different air quality levels, for example the air quality level required for breathing air will be different from plant air. Air quality levels are uniformly defined into Classes by the international standard ISO 8573-1:2010. This compressed air specification defines air quality classes by the maximum number of particles per m³. 

The primary function of compressed air filtration is to remove contaminants from the air in order to reach the specified air quality standard. Depending on the air quality required, a compressed air system may therefore have a number of different types of filters located at different points within the system. 

But selecting the right filter technology and opting for high quality products is not the end of the story. To ensure the specified air quality standard is consistently met, filters need to be serviced and maintained.

There are a number of reasons why you need to service and maintain your compressed air filters: 

1. To maintain the air quality standard required
   Unmaintained filters can cause a number of problems – not least impact the air quality class. Depending on the application, if a compressed air system stops meeting the air quality class required, the consequences could be detrimental, e.g. think of the impact if you’re a food manufacturer using contaminated air in your production line. 
2. To protect your compressed air system and air consuming equipment
   If contaminants are not effectively eliminated, they can wreak havoc on a compressed air system and the associated equipment, for example if your expensive new packaging machine used compressed air and you filled it up with particulates and oil, because your air filters are not maintained, that would not be a good thing…And, in terms of the compressed air system itself it could; cause airline pipes to rust, create a build up of sludge (which is the formation of the contaminants) that will not only cause undue wear and tear to the system - and make the compressed air system less efficient in producing compressed air - but it could ultimately lead to the compressor breaking down. And, no one wants the downtime and unplanned costs associated with that! 
3. To keep operating costs in check
   It’s also highly likely that unmaintained filters will cost you more to operate. As an example, when a filter is ‘full’, the pressure drop will increase. This means that contaminants are now getting through the filter and into the airline. First of all - in the long term it’s likely that this will damage your compressed air system (see 2 above), and secondly it will impact the successful production of the specific air quality required (see 1 above). But also, every bar of pressure loss increases your energy costs by around 6% per m³/min of compressed air. In other words, it's now also costing you more to operate your compressed air system in energy / electricity terms. You can see why in this example, changing your filter elements at the prescribed intervals is so important. 

If you are already following the OEM’s recommendations for service and maintenance - how do you know in between service visits if your filters are working properly? For a quick indication of how a filter is operating you can check its differential pressure gauge. This allows you to monitor the pressure loss (i.e. efficiency) at a glance. If this is high you know it’s time to call your service provider. High differential pressures across line filtration can greatly impact the functionality - and increase the cost - of running your compressed air system.

Even better still, if your filters are fitted with differential pressure transducers - these values can be transmitted to a master control system - eliminating the need to manually check the mechanical differential pressure gauge on every filter. As an example, Kaeser filter products can be equipped with an optional - factory fitted - Analog differential pressure transducer. Along with the differential pressure, the three-wire sensor transmits the air main pressure downstream from the filter as a 4-20 mA signal. Both values can then be passed on to master control systems such as the Sigma Air Manager 4.0 from Kaeser and from there to the Sigma Network (e.g. direct to Kaeser Air Service). This means results can be reviewed and alarms can be triggered so you are able to remotely and in real-time know what is going on - from a PC, notebook or mobile phone. And, if you are a Kaeser service customer and you are connected to the Sigma Network - Kaeser Air Service also knows when an alarm is triggered and action is required.

Maintaining and servicing your compressed air filters next to the OEM’s recommendations is essential if you want to consistently meet the specific air quality level required, as well as protect - and operate - a reliable and efficient compressed air system.