Overview
ISO 8655-7:2022 specifies alternative measurement procedures for the determination of volume of piston-operated volumetric apparatus (POVA). It covers complete systems - the basic apparatus plus all parts selected for use (disposable or reusable) involved in the measurement-by-delivery process. The standard describes multiple practical measurement methods (gravimetric, photometric, titrimetric, hybrid and batch testing) and gives normative procedures in Annexes A–E, plus guidance on converting liquid mass to volume.
Key topics and technical requirements
- Scope and applicability
- Applies to a wide range of piston-operated volumetric apparatus including pipettes, burettes, dilutors, dispensers and precision syringes used as complete systems.
- User responsibility to select the appropriate measurement method for the nominal volume and application.
- Measurement methods (normative)
- Gravimetric method (mass-to-volume conversion)
- Dual-dye ratiometric photometric method
- Single-dye photometric method
- Photometric/gravimetric hybrid method for multichannel POVA
- Titrimetric method
- Batch testing procedures for high-throughput checks
- Metrological and quality requirements
- Metrological confirmation and specified uncertainty of measurement principles
- Performance tolerances, evaluation of mean volume, systematic error, and random error
- Operator qualification and guidance to reduce operator impact on results
- Test conditions and procedures
- Requirements for test equipment, room/environmental conditions and test liquids
- Guidance for test volumes, number of measurements per test volume and standard dispense procedures for single- and multi-channel pipettes, positive-displacement pipettes, dilutors, dispensers and syringes
- Reporting
- Standardized reporting of results and conversion of mass to volume (Annex F)
Practical applications and users
- Manufacturers: quality control, production testing and issuing manufacturer declarations.
- Calibration laboratories and test houses: independent calibration, verification and conformity assessment.
- Clinical and research laboratories: routine performance checks, instrument validation and method selection for volumetric accuracy.
- Procurement and QA teams: acceptance testing of lots and batch inspections.
Practical benefits include standardized, repeatable procedures for volume determination, options suited to different volumes and throughputs (e.g., gravimetric for high accuracy, photometric for small volumes, batch testing for throughput), and clearer operator and environmental controls to improve measurement reliability.
Related standards
- ISO 8655 series (Parts 1–9) - terminology, pipettes, burettes, dilutors, dispensers, gravimetric and photometric reference methods, syringes
- ISO 8655-6 (gravimetric reference) and ISO 8655-8 (photometric reference) for complementary reference procedures
Keywords: ISO 8655-7, piston-operated volumetric apparatus, volume determination, gravimetric method, photometric method, titration, calibration, pipette testing, multichannel pipettes, batch testing, metrological confirmation.
Open preview (PDF)Piston-operated volumetric apparatus — Part 7: Alternative measurement procedures for the determination of volume