To monitor the state of a hydraulic fluid there are three variations, each with a different information value:
Visual inspection:
The colour of a pressure fluid (in particular mineral oil) is a measure of its ageing. However, this is very inaccurate, as a black discolouration of the fluid alone does not necessarily affect its usability in any way.
Quick analysis in operations:
Ongoing control using components of a measuring case, which allow the review of the fixed foreign particles according to their type, quantity and size, the quantitative determination of the water content and the measurement of the viscosity. This produces good results over a long period.
Exact oil examinations:
These take place in laboratories with the oil supplier. As a rule, the process is only worthwhile when using larger oil quantities.