Overview
SIST ISO 9110-1:2021 - "Hydraulic fluid power - Measurement techniques - Part 1: General measurement principles" sets out the general principles for measuring hydraulic fluid power performance parameters under static or steady‑state conditions. It gives guidance on expected sources and magnitudes of measurement uncertainty, practical requirements for assessing a measurement system’s capability, and steps to develop systems that meet prescribed uncertainty limits. The document is intended to be used alongside other ISO 9110 parts addressing specific parameters (flow, pressure, torque, speed, temperature).
Key Topics and Requirements
- Measurement scope: Applies to static or steady‑state testing of hydraulic components and systems.
- Uncertainty guidance: Identifies common uncertainty sources (calibration, data reduction, readability, environmental influences) and methods to estimate their magnitudes.
- Measurement accuracy classes: Defines three classes of measurement accuracy - Class A (scientific/research), Class B (component selection, quality audits), and Class C (diagnostics, routine checks) - with requirements and permissible uncertainty tables to be provided in specific test procedures.
- Calibration and traceability: Requires all reference standards and instruments to be calibrated against nationally or internationally traceable standards (CIPM/BIPM or national institutes) and for the reference standard and its uncertainty to be recorded.
- Calibration intervals: Recommends determining intervals based on usage, environment, manufacturer guidance, contractual requirements and inherent stability; supports the use of control charts and trend analysis.
- Uncertainty models: Introduces first, second and third order uncertainty models and procedures for calibration uncertainty evaluation and propagation.
- Readability and instrumentation: Covers uncertainty associated with analog and digital readouts, parallax, and readout records.
- Assurance techniques and total uncertainty: Provides assurance control techniques, methods for determining the total measurement system uncertainty, and acceptance criteria.
- Informative annexes: Includes a Measurement System Acceptance sheet, guidance on uncertainty propagation, and a best practices tutorial.
Practical Applications - Who Uses It
- Test laboratories and calibration labs ensuring valid, traceable hydraulic measurements.
- Manufacturers and OEMs performing component qualification and performance testing.
- Quality managers and auditors establishing acceptable uncertainty for product evaluation.
- Design and R&D engineers conducting high‑accuracy investigations (Class A).
- Maintenance and diagnostic teams applying Class C procedures for field checks.
Related Standards
- ISO 9110 series (other parts for flow, pressure, torque, speed, temperature)
- ISO 5598 (Fluid power vocabulary)
- ISO/IEC Guide 98-3 (GUM: Guide to the expression of uncertainty in measurement)
- ISO 7870‑1 / ISO 7870‑2 (Control charts)
Keywords: SIST ISO 9110-1:2021, hydraulic fluid power, measurement techniques, measurement uncertainty, calibration, traceability, static measurement, measurement system capability.