Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by the counting method using an optical microscope.
Standard ISO 4407 outlines the method used to determine the contamination caused by solid particles in the fluids used in hydraulic systems via the counting of the number of particles deposited on the surface of a membrane filter using an optical microscope. This includes the counting of the solid particles by adopting two methods: manual and image analysis, using either transmitted or incident lighting systems.
Standard ISO 4407 determines the quantity of contaminants that are tested by counting and dividing the particles present into class sizes.
Separation of the contaminant via vacuum filtration.
Brief extract from standard ISO 4407
To download the standard: ISO 4407