Particle Count

What Is Particle Count Testing?

Particle Count testing involves analyzing the number and size distribution of solid particles suspended in the oil. The results are expressed as a cleanliness code that helps assess oil purity and determine necessary filtration or maintenance actions.

We use advanced laser-based particle counters to quantify contaminants across multiple size ranges, ensuring accurate detection and compliance with global standards.

Test Standard

  • NAS 1638: Cleanliness standard originally developed for aerospace hydraulic fluids; adapted for industrial applications
  • ISO 4406: International cleanliness code using a 3-number format (e.g., 18/16/13) for particles ≥ 4μm, 6μm, and 14μm

Key Gases Measured

Insulating Liquids – Measurement of Relative Permittivity, Dissipation Factor (Tan δ) and DC Resistivity.

Cleanliness Classification
Sample Cleanliness Classifications (ISO 4406)
ISO 4406 Code Particle Count/mL
(≥4μm / ≥6μm / ≥14μm)
Cleanliness Level
14/12/10 Very low Very Clean (new oil / post-filtration)
17/15/12 Low to moderate Normal (in-service transformer)
20/18/15 High Contaminated – filtration advised
22/20/18+ Very high Critical contamination – immediate action
Why Particle Count Testing Matters

Our Testing Process

  • Vacuum-sealed sample collection with barcode tracking
  • ISO 4406 & NAS 1638 particle analysis using laser particle counters
  • 3-channel size classification: ≥4μm, ≥6μm, ≥14μm (ISO); and NAS range
  • Visual inspection (optional) for fiber, metal, and sludge presence
  • ERP-integrated reporting and cleanliness trend tracking
Report Includes

Why Choose Tru-FIL?

  • ISO 4406 & NAS 1638-compliant testing
  • NABL-accredited lab with certified particle analysis equipment
  • AI-powered ERP reporting for instant insights and history
  • Nationwide vacuum-based sample pickup
  • 24/7 laboratory operations and fast turnaround time