ISO 4406 / ISO 4407 Particulate Contamination in Hydraulic Fluids
Particulate contamination is the leading cause of hydraulic system failures, valve wear, and premature pump damage. Yet accurate contamination monitoring still relies on tedious manual particle counting under a microscope — a slow, operator-dependent process prone to fatigue errors and subjective classification. Clemex's ISO 4406/4407 module automates this entirely: particles are detected, measured, and classified on membrane filters automatically, producing a compliant cleanliness code in minutes, with full traceability and fiber identification as required by the standard.
Stop counting particles by hand. Clemex gives you an ISO cleanliness code in minutes — with no analyst fatigue and full data traceability.
Download ISO 4406/4407 Analysis Report Example
Analytical Workflow
From Image Acquisition to Compliant Report
Clemex integrates into your existing ISO 4407 microscopic method workflow, automating the counting, classification, and reporting steps that traditionally require a trained analyst at the eyepiece.
Acquire / Load Images
Acquire images directly from the microscope or load existing images of filter samples from the membrane filtrate.
Detection of Particles
Clemex detects and segments every particle and fiber visible on the membrane filter across all size ranges.
Particle Analysis as per ISO 4406/4407
Each particle is measured and classified into the ≥4 µm, ≥6 µm, and ≥14 µm channels. Fibers are identified per ISO 4407 criteria.
Generate Report & ISO Cleanliness Code
Counts are normalized per mL, scale numbers assigned, and the ISO cleanliness code and compliant report generated.
Measurement Output
ISO 4406 — Particle Count & Scale Number Metrics
Clemex reports all parameters required by ISO 4406. The module operates at 100× incident illumination and 1.0 µm/pixel calibration, covering the standard size channels automatically.
Three Size Channels (≥4, ≥6, ≥14 µm)
Every particle is counted and binned into the three ISO 4406 channels: ≥6 µm is the primary channel for hydraulic cleanliness specifications, and ≥14 µm is the critical channel for component wear prediction.
Per-mL Normalized Count
Raw counts on the scanned area are extrapolated to the whole filter and normalized to sample volume (per mL) for each of the three size channels.
Scale Number (per channel)
The ISO 4406 logarithmic scale number is automatically derived from the per-mL count for each size channel — no manual lookup.
Final Cleanliness Code
The three-part ISO 4406 code combining the scale numbers for the ≥4 µm, ≥6 µm, and ≥14 µm channels is computed and printed automatically.
Estimated Particles (whole filter)
Count from the scanned area projected to the full effective filtration area for each size channel.
Blank Count Reference
Background particle count from a blank membrane control, filled manually or linked to an exported reference file.
Measurement Output
ISO 4407 — Fiber, Largest Particle & Scan Metadata
Beyond the cleanliness code, the report documents fibers, the worst-case particle, and full scan traceability as required by the ISO 4407 microscopic method.
Fiber Count
Fibers are detected and counted separately from particles. Defined as features >100 µm in length with a String Length / String Width ratio >10.
Largest Particle: Dimension & Nature
The maximum dimension in microns of the single largest feature on the membrane, classified as Particle or Fiber — required for worst-case contamination characterization.
Map View (> 200 µm)
Spatial map of all particles and fibers exceeding 200 µm, localizing the largest contamination events across the membrane.
Covered Area & Ratio
Total membrane area imaged by the motorized stage scan (mm²) and the ratio of covered area to effective filtration area, confirming scan completeness.
Number of Fields
Count of individual image fields acquired during the scan (16 fields in the standard configuration).
Particle Length Distribution
Histogram of particle counts by length category, providing a visual overview of contamination severity across the full size range.
Module Capabilities
Built for Industrial Fluid Cleanliness Testing
Every feature of the ISO 4406/4407 module is designed around the practical needs of laboratories and maintenance teams performing hydraulic fluid contamination analysis.
Fully Automated Membrane Scanning
Motorized stage integration scans the entire effective filtration area in a defined raster pattern. Covered area, covered ratio, and number of fields are all logged per run for traceability.
Three-Channel ISO 4406 Counting
Particles are simultaneously counted and binned into the three ISO 4406 size channels (≥4 µm, ≥6 µm, ≥14 µm). Scale numbers and the final three-part code are calculated automatically.
ISO 4407 Fiber Detection
The Vision routine automatically identifies fibers using String Length / String Width ratio criteria equivalent to the ISO 4407 definition (>100 µm, L/W >10). Fiber count is reported separately from particulate count.
Largest Particle Detection & Mapping
The module identifies and reports the largest feature on the membrane (maximum dimension in µm, nature: particle or fiber). A spatial map of all features >200 µm is included in every report.
Traceable Compliance Report
Every report includes sample ID, date/time, analyst, instrument parameters, particle counts per channel, extrapolated totals, scale numbers, final ISO code, largest particle data, fiber count, histogram, and map view — in a single locked PDF.
Dedicated to Production & QC Laboratories
Purpose-built for production environments and quality control laboratories performing routine hydraulic fluid cleanliness monitoring. It integrates into existing workflows, supports high sample throughput with minimal analyst intervention, and delivers consistent, reproducible results shift after shift.
Frequently Asked Questions
What is the difference between ISO 4406 and ISO 4407, and how does Clemex handle both?
ISO 4406 is the classification standard: it defines the three-part scale number system used to express fluid cleanliness (e.g. 20/18/15). ISO 4407 is the test method standard: it defines the microscopic membrane filtration procedure used to count particles and derive the ISO 4406 code. Clemex automates the ISO 4407 counting method and automatically calculates and reports the ISO 4406 cleanliness code as output, so both standards are addressed by a single analysis run.
One run, both standards addressed.
How does the Clemex microscopic method compare to automatic particle counters (APC)?
Automatic particle counters use light obscuration (LO) and are fast for clean, transparent fluids. However, LO is unreliable for dark or opaque fluids, water-contaminated samples, emulsified fluids, and samples with air bubbles — all common in industrial hydraulic systems. The ISO 4407 microscopic method is not affected by these interferences. It is also the method of choice when particle shape, morphology, and fiber identification are needed alongside the count. Clemex automates the microscopic method, providing the accuracy and flexibility of manual counting with the speed and traceability of automated analysis.
Microscopic counting works where APC cannot.
What magnification and pore size should I use?
ISO 4407 specifies examination at 100× effective magnification (incident illumination) with a 1 µm membrane pore size as standard. This configuration is what Clemex uses by default, with a 1.0 µm/pixel calibration. Note that ISO 4406 counting effectively starts at 4 µm in the standard three-channel code. If sub-4 µm resolution is required, a 2× coupler can be added to the optical path to increase pixel resolution.
100×, 1 µm pore size — the ISO 4407 default configuration.
How are fibers classified and counted?
ISO 4407 defines fibers as features longer than 100 µm with a Length/Width ratio greater than 10. The Clemex Vision routine implements this using a String Length / String Width ratio, which is functionally equivalent. Fibers are detected, measured, and counted separately from particles; their count appears in a dedicated column on the analysis report. If you need to adjust the ratio threshold for a specific application, this can be modified in the routine configuration. Any such change should be documented in your method records.
Fibers counted separately, per ISO 4407 criteria.
How long does a typical ISO 4407 membrane analysis take compared to manual counting?
Manual counting of a membrane at the eyepiece typically takes 20–60 minutes depending on contamination load and analyst experience, with accuracy declining as fatigue sets in. Clemex completes the full automated scan and count in approximately 8–15 minutes per membrane. Since the result is generated without analyst time at the eyepiece, the analyst is free for other tasks while the system runs. For labs testing multiple samples per day, the time and consistency benefits compound significantly.
8–15 minutes automated vs. 20–60 minutes manual, with no fatigue.
Ready to Automate Your ISO 4406/4407 Hydraulic Fluid Testing?
Talk to a Clemex specialist and see the module running on representative membrane images. On-site demonstration available.
