ISO 8655-6:2022

Overview

ISO 8655-6:2022 defines a gravimetric reference measurement procedure for the accurate determination of volume of piston‑operated volumetric apparatus (POVA). It applies to complete systems - the basic instrument plus any disposable or reusable parts - used in delivery (Ex) or contained (In) measurements. The standard specifies required test equipment, test liquids, environmental and procedural conditions, evaluation methods and reporting requirements to ensure traceable, repeatable volume determinations.

Key topics and technical requirements

• Scope and applicability: Applies to pipettes, burettes, dilutors, dispensers and precision syringes as complete systems when undergoing gravimetric volume testing.
• Test equipment and traceability: Instruments used (balance, thermometers, hygrometer, barometer, reservoirs) must be traceable to the International System of Units (SI) and meet the uncertainty requirements specified by the standard.
• Balance selection: Minimum balance resolution, repeatability and expanded uncertainty requirements are provided in a dedicated table keyed to nominal volume ranges; use the table to choose appropriate balances for micro- to millilitre testing.
• Test liquid and conditions: References acceptable test water quality and defines test room conditions, evaporation control, and recommended test cycle times.
• Procedures by apparatus type: Clause 8 details preparation and test cycles for single‑channel and multi‑channel air displacement pipettes, positive displacement pipettes, burettes, dilutors, dispensers and syringes.
• Evaluation and uncertainty: Methods for calculating evaporation loss, corrected mass readings, conversion to volume (including Z‑factor correction), mean delivered volume, systematic and random errors, and measurement uncertainty are specified.
• Reporting: Required content for calibration reports and performance statements is defined to support conformity and traceability.

Practical applications and users

• Calibration laboratories and test houses: Use ISO 8655-6 as the reference method for calibrating and certifying volumetric performance of POVA.
• Manufacturers: Apply the procedure for quality control, design verification and issuance of manufacturer declarations.
• Laboratory managers and users: Use the standard to verify instrument performance, support method validation and select appropriate equipment and calibration intervals.
• Regulatory and accreditation bodies: Reference the standard in scopes and audit criteria for volumetric measurement competence.

Related standards

• ISO 8655 series: ISO 8655-1 (terminology & general requirements), ISO 8655-2 (pipettes), ISO 8655-3 (burettes), ISO 8655-4 (dilutors), ISO 8655-5 (dispensers), ISO 8655-9 (syringes).
• ISO 3696: Water for analytical laboratory use (test liquid specification).
• ISO/IEC Guide 2 and VIM (ISO/IEC Guide 99): Terminology and metrology concepts.

Keywords: ISO 8655-6:2022, gravimetric reference measurement, piston-operated volumetric apparatus, POVA, volume determination, pipette calibration, measurement uncertainty, balance requirements, laboratory calibration.