ISO 11171-2022 PDF

Full title and description

ISO 11171:2022 — Hydraulic fluid power — Calibration of automatic particle counters for liquids. This international standard defines procedures and requirements for the calibration, verification and performance limits of automatic particle counters (APCs) used to count and size solid particles in liquid hydraulic and petroleum-based fluids.

Abstract

ISO 11171:2022 specifies methods for primary and secondary particle‑sizing calibration, sensor resolution and counting performance of liquid automatic particle counters capable of analysing bottled samples. It also covers establishing acceptable operational and performance limits, verification of sensor performance using a test dust, and determination of coincidence and flow‑rate limits. The standard is intended for hydraulic fluids, aviation and diesel fuels, engine oils and other petroleum‑based fluids; it excludes particle‑sizing calibration using NIST SRM 2806b primary calibration suspensions where stated.

General information

• Status: Published / Valid
• Publication date: 18 March 2022
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 23.100.60 — Filters, seals and contamination of fluids
• Edition / version: Edition 5 (2022)
• Number of pages: 51

Scope

The standard applies to the calibration and performance verification of automatic particle counters that analyse liquid bottle samples. It defines the primary particle‑sizing calibration procedure (for particle sizes of 1 µm(c) and larger), secondary calibration using verified suspensions, methods to establish acceptable operation and performance limits, procedures for sensor verification with test dust, and methods to determine coincidence and flow‑rate limits. The scope covers hydraulic fluids, aviation and diesel fuels, engine oils and related petroleum‑based fluids, and is intended to support reliable particle counting and sizing for contamination control and cleanliness reporting.

Key topics and requirements

• Primary particle‑sizing calibration procedures for particle sizes ≥ 1 µm(c).
• Secondary calibration methods using suspensions verified against a primary calibrated APC.
• Specification of sensor resolution and counting performance requirements for APCs.
• Procedures to establish acceptable operational and performance limits (including repeatability and stability).
• Verification of particle sensor performance using an agreed test dust.
• Determination and limits for coincidence error and flow‑rate effects on counting.
• Requirements for sample preparation, dilution and handling to avoid contamination or measurement bias.
• Reporting formats and how calibrated APC results relate to commonly used cleanliness codes (as applied by other contamination control standards).

Typical use and users

ISO 11171:2022 is used by calibration laboratories, instrument manufacturers, test houses, hydraulic system and component manufacturers, engine and fuel laboratories, oil analysis service providers, and maintenance/quality teams responsible for contamination control. Typical uses include calibration and validation of APCs, establishing laboratory acceptance criteria, routine verification of online and offline particle counters, and ensuring consistency of cleanliness reporting in production, service and test environments.

Related standards

ISO 11171 is part of the contamination‑control family of fluid power standards and is closely related to: ISO 4406 (method for coding contamination levels by solid particles), ISO 4402 (older, withdrawn particle‑count calibration method replaced by ISO 11171), ISO 11943 (methods of calibration and validation for online automatic particle‑counting systems), ISO 11500 (APC procedure using the light‑extinction principle), ISO 16889 (multi‑pass filter test procedures), and other ISO/TC 131/SC 6 deliverables addressing particle counting, sample handling and filter testing. These documents together define calibration, measurement, reporting and filter test practices for fluid cleanliness control.

Keywords

automatic particle counter, APC, calibration, particle sizing, hydraulic fluids, contamination control, ISO 11171, NIST traceability, ISO MTD, coincidence error, sensor resolution, flow‑rate limits, cleanliness code, ISO 4406

FAQ

Q: What is this standard?

A: ISO 11171:2022 is an international standard that specifies calibration, verification and performance requirements for automatic particle counters used to size and count solid particles in liquid hydraulic and petroleum‑based fluids.

Q: What does it cover?

A: It covers primary and secondary particle‑sizing calibration procedures, sensor resolution and counting performance, verification using test dust, determination of coincidence and flow‑rate limits, and establishing acceptable operational/performance limits for APCs analysing bottle samples.

Q: Who typically uses it?

A: Calibration laboratories, instrument manufacturers, fluid analysis labs, maintenance and quality teams in hydraulic/aviation/automotive sectors, and any organization needing traceable particle counting and contamination control.

Q: Is it current or superseded?

A: ISO 11171:2022 is the current published edition (Edition 5) released on 18 March 2022. It replaces earlier editions including the 2020 and prior versions.

Q: Is it part of a series?

A: Yes. ISO 11171 is part of a set of ISO standards on fluid contamination and particle counting developed by ISO/TC 131/SC 6 and is commonly used together with ISO 4406, ISO 11943, ISO 11500, ISO 16889 and related standards for fluid cleanliness and filter testing.

Q: What are the key keywords?

A: Automatic particle counter (APC), calibration, particle sizing, hydraulic fluid, contamination control, NIST traceability, coincidence error, sensor resolution, ISO 4406.