There are three principal methods to measure the contamination level in a component, circuit, or system. The methods are Gravimetric Measurement (ISO 4405); Particle Size Distribution Analysis (ISO 4406 or NAS 1638); Maximum Particle Size Analysis (ISO 4407).
Maximum Particle Size Analysis (ISO 4407)
This evaluation is done using a microscope. A microscope is used to identify and measure the size of individual pieces of contaminant. Particle size is important in reference to maximum clearances of hydraulic components.
Whether hydraulic assembly cleanliness applies to you or not, it is worthwhile to understand the significant impact that contamination levels can have on the life of hydraulic system components.
Implementing a thorough cleanliness system may have a significant impact on warranty returns for hydraulically powered equipment.