ISO/TR 6057:2023

Overview

ISO/TR 6057:2023 – "Hydraulic fluid power - Sample calculations for ISO 11171" is an ISO technical report that provides worked examples showing how to apply the normative mathematical formulae and tools introduced in ISO 11171:2022. The report demonstrates practical calculation methods and step‑by‑step examples for calibrating automatic particle counters (APCs) used in hydraulic fluid power contamination control. Examples use particle size units of µm(c) and follow traceability and data‑acceptance principles from ISO 11171.

Key topics and requirements

• APC calibration curve construction: worked examples for selecting threshold voltage settings, logarithmic spacing of thresholds, and generating calibration curves consistent with ISO 11171 formulas and tools.
• Data quality evaluation: procedures to calculate total particle counts, the data quality factor (DQ), identify outliers and determine acceptability of measurement runs.
• Sample dilution and normalization: standardized method for diluting calibration suspensions (Annex G in ISO 11171) and normalizing counts to account for dilution and coincidence error limits.
• Particle size threshold mapping: examples relating APC threshold voltage to particle size both for sizes ≤30 µm(c) and for primary calibration of larger sizes.
• Instrument performance limits: worked examples for coincidence error limits, working flow rate limits (Annex C), resolution (Annex D), coefficient of variation for sample volume, and verification of counting accuracy and secondary calibration suspensions.
• Conformance: all examples explicitly reference clauses and tables from ISO 11171:2022 to ensure consistency and repeatability.

Applications and who uses it

ISO/TR 6057:2023 is practical guidance for:

• Calibration laboratories performing APC primary and secondary calibrations.
• Instrument manufacturers designing and validating particle counters and threshold settings.
• Maintenance and reliability engineers in hydraulic systems who require traceable contamination monitoring.
• Quality assurance and contamination control specialists in industries using hydraulic fluids (mobile equipment, industrial hydraulics, aviation).
• Test laboratories and OEMs establishing SOPs for particle counting, dilution protocols, and data acceptance.

The worked examples help practitioners produce reliable calibration curves, ensure measurement traceability, manage coincidence error, and validate APC data quality.

Related standards

• Normative reference: ISO 11171 - Hydraulic fluid power: Calibration of automatic particle counters for liquids (primary standard that ISO/TR 6057 illustrates).

Keywords: ISO TR 6057:2023, ISO 11171, hydraulic fluid power, automatic particle counters (APCs), calibration, particle counting, µm(c), contamination control, threshold voltage, calibration curve, coincidence error, dilution, data quality.