Particle Count
Particle Count is the quantitative measurement of the number and size distribution of solid particulate contaminants suspended in a lubricant or hydraulic fluid, reported in particles per milliliter and standardized via the ISO 4406 Cleanliness Code (format >4/>6/>14 µm).
In a ServiceGrid CMMS environment, technicians draw oil samples from critical assets such as hydraulics, turbines, and compressors, and pass them through an automatic particle counter (APC) using a laser light obscuration sensor. The resulting ISO code is logged against asset history to trigger maintenance actions like filter changes, oil flushes, or seal replacements if contamination exceeds target cleanliness levels, ensuring equipment reliability and reducing unplanned downtime.
- Ignoring Small Particles (<2 µm): Failing to monitor sub-silt particles (resin, oxidation) that cause cumulative wear and friction on moving surfaces, leading to premature component failure.
- False Positives from Bubbles/Additives: Using traditional laser counters that misread air bubbles or chemical additives as solid contaminants, triggering unnecessary oil changes and wasted maintenance budgets.
- Neglecting Sample Prep Validation: Skipping frequent on-site sensor validation or improper sample preparation, resulting in inaccurate repeatability and missed detection of phantom particles.
How is the ISO Code calculated from raw counts?
The ISO 4406 code converts counts for particles ≥4 µm, ≥6 µm, and ≥14 µm into a logarithmic series where each code increment represents a doubling (or more) of particle concentration; e.g., code 18/15/11 indicates 2,500–5,000 particles ≥4 µm, 320–640 ≥6 µm, and 20–40 ≥14 µm.
Why can particle count not identify particle composition?
Light obscuration sensors measure only the shadow size of particles, not their material; thus, a count cannot distinguish between metallic wear debris, silica (dirt), filter fibers, or varnish agglomerations without secondary spectroscopy or microscopy.
What assets benefit most from particle count testing?
High-precision systems with tight clearance tolerances, including hydraulics, compressors, turbines, robotics, injection molding machines, and filtered bearing/gear systems, as well as diesel fuel and low-viscosity lubricants (
How does particle count drive ServiceGrid work orders?
When ISO codes exceed predefined thresholds in the CMMS, the system auto-generates a preventive maintenance task for filter replacement, seal inspection, or system flushing, linking the test result to asset reliability KPIs.