Test standards and oil purity
Definition of the required filter fineness
The components located in the hydraulic system are essentially decisive for determining the filter fineness.
In order to guarantee reliable operation for years to come, certain components are required to comply with a specified oil cleanliness class.
The filter material and the filter fineness are determined by the most sensitive system component.
Laser particle counters are used to measure oil cleanliness in accordance with ISO 4406 (1999). The laser particle counters are used to count the number of particles >4 μm (c), >6 μm (c) and >14 μm (c)in 100 ml of hydraulic oil. The number of particles is then assigned to a classification number (e.g. 14/11/8), which then corresponds to the ISO purity class.
It should be noted that the number of particles doubles for each next higher class.
The oil purity class to be achieved is an important criterion for selecting the appropriate filtration.