If you look at the costs of a compressor over its entire life cycle, energy costs account for around 75 percent of the total costs - the larger the system and the more operating hours, the higher this proportion. In contrast, the costs for purchase, maintenance and spare parts are hardly significant.

In order for a compressor to maintain its efficiency and thus its energy consumption, all components must be optimally matched and replaced regularly. Spare and wear parts that do not exactly meet the manufacturer's specifications can, for example, increase the differential pressure, which then has to be compensated for by increasing the energy consumption of the compressor. This also has a negative impact on its service life, maintenance intervals and reliability. Only original parts that have been tested and approved by the manufacturer will ensure the long-term efficiency of the compressor. Original filters, separator cartridges or lubricants are verified by a large number of tests and several thousand hours of continuous operation before they are approved. Pirate parts may appear to be the cheaper alternative at first glance. However, problems often occur during operation.

The most important maintenance parts are the oil separator, oil filter and air filter.

The oil-air mixture produced during the compression process first enters a pressure vessel for pre-separation. The oil droplets still contained in the compressed air are combined into larger droplets by the oil separator elements (or spin-on separators), then collected and fed back into the oil circuit. This minimizes the oil consumption of the compressor and the oil input into the compressed air network.

Filter material that is too dense results in a high differential pressure. © Boge

In oil separators, filter material that is too dense ensures high separation rates, but also high pressure losses. As a result, a lot of energy is lost. If, on the other hand, the filter material is of poor quality or too thin, the separation is too weak and the oil transfer into the compressed air network is correspondingly high. In the case of internal oil separators, there is a further requirement: good earthing of the element prevents static charging and thus the risk of ignition. Only original oil separators ensure minimal oil transfer, consistent separation rates and minimized pressure loss over the service life.

Air to work with

A filter that is too thin, on the other hand, leads to high oil carryover. © Boge

The ambient air contains many millions of particles, dust and pollen that can have a negative impact on the performance of a compressed air system. If these mostly microscopic particles are not removed by an intake filter, damage can occur to bearings and rotors, and the service life of downstream oil filters and oil separators is reduced. The filter elements absorb the dirt and must therefore be replaced regularly. The material used, the size and the differential pressure also play a decisive role in the intake filter. Only original parts guarantee a high-quality filter material with a high dirt holding capacity and a constantly low differential pressure. In addition, they provide an optimum seal between the filter housing and element so that no unfiltered air flows into the machine.

In oil-lubricated compressors, the oil has a variety of tasks: sealing, cooling, lubricating and removing dirt. The oil filter removes the dirt particles and abrasion absorbed by the oil from the oil circuit and retains them in the filter material. It is constantly exposed to pressure fluctuations, vibrations and high temperatures. Poor filter material results in poor filtration, which leads to a contaminated oil circuit and, in the worst case, clogging of the filter. If the oil filter is not changed regularly, the filter material becomes clogged. If the filter is completely sealed, the bypass valve installed in the original filter is used. This opens so that the lubricating film does not break off and the compressor stage continues to be supplied with oil. However, all accumulated particles are returned to the oil circuit unfiltered. This can lead to costly damage to the compressor and other components or even complete machine failure. Regular, timely filter replacement is therefore essential.

The compressor oil

As mentioned above, the oils used in a compressor must meet the highest standards. The oil should cool the components in the compressor and seal the gaps between the rotors or pistons and cylinders. It removes deposits before they can impair the function of the compressor. Above all, it lubricates all components. To fulfill all these functions, additives are added to the oil to create the required properties. The most important properties influenced by additives are foaming, water separation, viscosity and corrosion protection.