The number of insoluble particles offers an indicator of the level of contamination in a system from the outside, but also sheds light on erosion or cavitation from the inside. Photographs of the particles allow possible causes to be identified more easily. The additional information on particle size provides valuable data when optimising filtration.

In the case of heavily contaminated coolant samples, OELCHECK measures the elements using filtration at 0.45 μm. This not only allows you to protect your test devices, but is also a handy additional test for unfiltered measurements of smaller impurities and, in particular, turbid coolants. While the unfiltered measurement detects undissolved, but suspended tiny particles (i.e. < 5 μm), the filtered measurement (0.45 μm) establishes only the components dissolved in the coolant. The results can provide additional insight into the additives used, the type of chemical bonds or the origin of the elements.

The pH value and reserve alkalinity take a coolant’s acid-base balance into account. The pH value describes the current state, while reserve alkalinity allows us a glimpse into the future, providing information about the quantity of acid that the additive system can still neutralise. However, the assessment of reserve alkalinity depends heavily on the additive technology and the materials used.

As a rule of thumb, a coolant’s glycol content is calculated using the refractive index. It is assumed that the remaining part is water. However, this does not apply if a coolant contains very large quantities of additives or additives of glycerin, or if it is a mixture of different types of glycol or mixed with other aqueous fluids (such as AdBlue or alcohol derivatives). In that case, it is best to establish the water value using the Karl Fischer method to take an unknown factor out of play.

Although contamination in coolants is relatively rare, it does occur every so often. The conditions for growth are often ideal – low-temperature circuits are rarely hot enough to boil everything in sight, but are warm enough to generate growth. This results in the formation of a biofilm on surfaces in circulation, which can dissolve and lead to turbidity of the fluid. In the worst case, deposits form in the filters or on heat-transfer surfaces, and the formation of acid and subsequent corrosion may also occur. This could then lead to a system failure.

The Particle Quantifier index provides information about magnetisable iron wear particles in the entire sample. These originate, for example, from production residues, damage to moving parts (such as the coolant pump), and from external contamination or wear due to cavitation.