ISO 4787:2021

Overview

ISO 4787:2021 - Laboratory glass and plastic ware - Volumetric instruments - Methods for testing of capacity and for use defines standardized methods for testing, calibrating and using volumetric instruments made of glass and plastic. It applies to instruments with nominal capacities from 100 µl to 10 000 ml, including single‑volume and graduated pipettes, burettes, volumetric flasks and graduated measuring cylinders. The standard emphasizes the gravimetric determination of volume (mass of water → volume using density and buoyancy corrections) and sets reference conditions to achieve best accuracy in routine laboratory use.

Key topics and technical requirements

• Scope and instruments covered: single‑volume pipettes (ISO 648), graduated pipettes (ISO 835), burettes (ISO 385), volumetric flasks (ISO 1042 / ISO 5215), graduated cylinders (ISO 4788 / ISO 6706). Pycnometers (ISO 3507) are not covered specifically but many procedures are applicable.
• Gravimetric method: volume determined from mass of calibration liquid (water) with buoyancy and density corrections.
• Reference temperature: standard reference temperature is 20 °C (27 °C permitted where adopted nationally).
• Apparatus & calibration liquid: minimum balance performance requirements are specified by nominal capacity (see Table 1), plus requirements for measurement devices and calibration liquid quality.
• Factors affecting accuracy: temperature (instrument and liquid), cleanliness and surface condition, delivery/waiting time, and handling.
• Meniscus setting: procedures for aligning meniscus for both transparent and opaque liquids, including updated guidance on convex meniscus adjustment.
• Calibration and use procedures: test room conditions, filling/delivery techniques for different instrument types, weighing, and calculation of volume and uncertainty.
• Uncertainty & repeatability: guidance and calculation formulas provided (Annex C and Annex E).
• Informative annexes: cleaning procedures for glassware and plasticware, thermal expansion coefficients, and uncertainty estimation.

Practical applications and who uses ISO 4787:2021

• Calibration laboratories and metrology services use it to certify volumetric instruments and report measurement uncertainty.
• Clinical, analytical and research laboratories adopt the methods to ensure accurate volumetric measurements in assays and sample preparation.
• Manufacturers of laboratory glassware and plasticware follow the testing and marking requirements during production and quality control.
• Quality managers, laboratory technologists and regulatory auditors use the standard to demonstrate conformity and traceability of volumetric workflows.

Related standards (selected)

• ISO 385 (Burettes), ISO 648 (Single‑volume pipettes), ISO 835 (Graduated pipettes), ISO 1042 / ISO 5215 (Volumetric flasks), ISO 4788 / ISO 6706 (Measuring cylinders), ISO 3507 (Pycnometers), ISO 3696 (Water for analytical use).

Keywords: ISO 4787:2021, volumetric instruments, calibration, testing, laboratory glassware, plasticware, pipettes, burettes, volumetric flasks, gravimetric method, measurement uncertainty.