Particulate impurities in oils and lubricants

Particles in oils

Particle contaminations in liquid mineral oil products, especially gear and motor oils, as well as hydraulic fluids can be relevant with regard to wear behaviour already from particle size 2 µm. The analysis of particles in this size range thus places special demands on analysis equipment and analysis methods and is described in ISO 4406 / ISO 4407.

In contrast to anaysis methods with extinction particle counters / optical particle counters, the method used by CleanControlling also enables the analysis of modern oils, whose additives can influence the counting accuracy of optical particle counters, by means of a material microscope.

The particle contamination of the liquid to be analysed is separated by means of analysis filtration and, if necessary, prior dilution on suitable analysis filters and automatically analysed by means of a special material microscope. The analysis is carried out according to the ISO 4406 code by count per size class per 100 ml of liquid.

Particles in lubricating greases

Solid materials or particle contamination in lubricating greases have a significant influence on the operating life of rolling bearings, which is why increasingly higher demands are being placed on the cleanliness of lubricating greases. The quantitative determination of the content of solid substances above 25 µm particle size is carried out by CleanControlling according to DIN 51813 by means of high-pressure filtration and washing out with a solvent mixture.

The analysis of particle loads in used greases provides information for conclusions on the wear behaviour of rolling bearings. In conjunction with the microscopic analysis method based on cleanliness inspections of technical cleanliness, the results are particularly informative from a particle size of 25 µm or, alternatively, as from 10 µm, since the particle occurrence is completely measured, counted and classified according to shiny behaviour such as "metallically shiny" and "non-shiny" and documented with particle images of the largest particles. An essential step before microscopic analysis is the dissolution of the consistent greases with a suitable, tempered solvent mixture and subsequent analysis filtration.

Oil testing according to ISO 4406 / ISO 4407

Particle analyses of lubricating greases