The degree of contamination of an oil should not be higher than that required for the most sensitive part of the entire hydraulic system. Particle count should be an integral part of each oil analysis set to define the level of particle contamination in fluids.

The tests that can be performed are in-depth analyses that assess the presence and quantity of solid (particles) and liquid contaminants within a fluid. These contaminants may be of various kinds: metal and non-metallic particles, water or other contaminants.

Why is it important to run these tests?

• Component protection: Particles can scratch and erode the internal surfaces of pumps, valves and other components, causing premature wear and failure.
• System efficiency: The presence of contaminants can increase oil viscosity, reduce energy efficiency and cause overheating.
• Fluid longevity: Contamination accelerates the aging of oil, reducing its lubricating and protective capacity.

The most widely recognized standards for hydraulic oil classification are ISO 4406:2021, NAS 1638 and SAE AS 4059.

ISO 4406 specifies a method for coding the level of contamination by solid particulate matter in hydraulic fluids, using a cumulative system. Particle counting can be done by automatic counters (APCs) or by optical microscopy.

Unilab uses automatic scanning microscopes that offer greater advantages than APC systems, not least the possibility of having information about the shape of particles, the size distribution and details on the subdivision into reflective and non-reflective.

The fluid analysis includes an initial filtration phase with a membrane of suitable porosity to retain the particles of interest, a subsequent weight analysis according to ISO 4405 and a particle scan according to ISO 4407.

The analysis of industrial contamination is an indispensable tool for ensuring the reliability and durability of hydraulic and lubricating systems. Particle counting in particular provides crucial information on the health of the system and enables informed maintenance decisions.