Overview
ISO 21018-1:2024 - Hydraulic fluid power - Monitoring the level of particulate contamination of the fluid - Part 1: General principles - provides guidance for monitoring particulate contamination in hydraulic systems when instruments cannot be calibrated to ISO 11171. This second edition updates core definitions and gives a structured framework for selecting, applying and assessing particulate contamination monitors (PCMs) used to track cleanliness, flushing progress and support/test rig conditions. The techniques described can also apply to other liquids such as lubricants, fuels and process liquids.
Key topics and requirements
- Scope and purpose: Applies to monitoring equipment that is not ISO 11171‑calibratable and clarifies that such instruments are not claimed as full particle counters even if they use similar physical principles.
- Terms and definitions: Updated definitions for automatic particle counters (APC), particle contamination monitors (PCM), coincidence error, dynamic range, mesh, gel, in-line, off-line and on-line analysis.
- Selection of monitoring technique: Guidance on choosing the correct monitor based on application needs, precision requirements and operating environment.
- Procedures and precautions:
- Sampling: Obtaining representative samples, off-line sampling and analysis.
- Analysis modes: On-line, in-line and off-line analysis considerations and limitations.
- Calibration and validation: Practical calibration procedures where applicable, checking data repeatability and controlling precision of the technique.
- Health, safety and environment: Electrical, mechanical, grounding and chemical compatibility precautions; handling flammable/combustible liquids.
- Training and reporting: Competence requirements and required contents for a test report.
- Informative annexes: Annex A summarizes technique attributes; Annex B describes relative merits of different contaminant monitoring techniques.
Applications and users
ISO 21018-1:2024 is practical for:
- Hydraulic system operators, maintenance engineers and contamination control specialists monitoring cleanliness levels and flushing progress.
- OEMs and test laboratories evaluating support equipment and test rigs where traceable ISO 11171 calibration is impractical.
- Industries using hydraulic and other process fluids - mobile and industrial hydraulics, manufacturing and processing plants - needing rapid “go/no‑go” monitoring or workplace instruments.
Related standards (key references)
- ISO 11171 - Calibration of automatic particle counters for liquids
- ISO 11500 - Determination of particulate contamination by automatic particle counting
- ISO 4406 - Coding contamination level by solid particles
- ISO 3722, ISO 4021, ISO 5598 and ISO 12103‑1 - supporting sampling, terminology and test contaminant references
ISO 21018-1:2024 helps practitioners choose appropriate particulate monitoring techniques, implement robust sampling/analysis procedures, and interpret monitor results to protect hydraulic system performance and reliability.