Overview
ISO 4626:2023 specifies a standardized laboratory method for determining the boiling range of volatile organic liquids used as raw materials. The procedure is intended for chemically stable, non‑corrosive organic solvents with normal‑pressure boiling points between 30 °C and 300 °C. Typical product classes covered include hydrocarbons, esters, alcohols, ketones, ethers and similar solvents. The test is a simple batch distillation using a defined flask size and controlled operating conditions to record initial boiling point, dry point and end point.
Key topics and technical requirements
- Scope and applicability: Liquids boiling 30–300 °C, chemically stable and non‑corrosive during distillation.
- Principle: Distillation of a 100 ml test portion under prescribed conditions equivalent to simple batch distillation; systematic recording of thermometer readings and condensate volumes with correction to standard atmospheric pressure.
- Apparatus: Specified components include a 200 ml heat‑resistant distillation flask, specified condenser and receiver configurations, and approved mercury‑in‑glass thermometers with defined calibration and correction procedures.
- Thermometer and correction rules: Requirements for thermometer aging, thermometer bore and bulb corrections, and barometer correction to report values at standard pressure.
- Procedure details: Assembly, filling of cooling bath, sample preparation, operating conditions for materials above/below 150 °C, and definitions of initial boiling point, dry point and end point.
- Quality and precision: Guidance on repeatability and reproducibility, recovery and distillation loss calculations.
- Safety and notes: Precautions covering peroxide formation, flammability and safe heating methods; informative Annex B includes a peroxide test.
- Normative references: ISO 3165 (sampling safety) and ISO 15528 (sampling for paints/varnishes).
- Differences from related methods: Notes on how ISO 4626 differs from ISO 918 and ISO 3405 in flask volume, condenser/receiver type and flask support details.
- Annexes: Annex A (normative) on thermometer specifications and correction factors; Annex B (informative) on peroxide testing.
Applications and users
ISO 4626 is practical for:
- Quality control laboratories verifying incoming organic solvent raw materials.
- Manufacturers of paints, varnishes and coatings and their raw‑material suppliers (ISO/TC 35 context).
- R&D and formulation labs assessing solvent volatility and batch consistency.
- Organizations preparing Safety Data Sheets (SDS) and regulatory submissions that require standardized boiling‑range data.
- Third‑party testing labs providing conformity and comparative testing.
Using ISO 4626 helps ensure consistent, comparable boiling‑range results, aids process control, supports product specification compliance, and improves safety handling decisions for volatile organic liquids.
Related standards
- ISO 918 (other solvent distillation methods) - differs in flask volume, cooler and receiver.
- ISO 3405 (distillation for petroleum products) - differs in flask volume and flask support design.
- ISO 3165, ISO 15528 - sampling and safety references applicable to implementation.
Open preview (PDF)Volatile organic liquids — Determination of boiling range of organic solvents used as raw materials