Overview - ISO 9029:1990 (Crude petroleum - Determination of water - Distillation method)
ISO 9029:1990 specifies a laboratory distillation method to determine water content in crude petroleum. The procedure uses a water‑immiscible solvent (xylene per ISO 5280) that co‑distills with water; condensed solvent and water collect in a graduated trap and the water layer is measured. Precision data were established for water contents up to 1% (V/V). Annex A gives required sample‑handling and homogenization instructions. The standard includes principle, apparatus, solvent, calibration and recovery tests, sampling, procedure, expression of results, precision and test report requirements.
Key topics and technical requirements
- Principle: Reflux/distillation with a water‑immiscible solvent; separation of condensed solvent and water into a graduated trap.
- Apparatus: Recommended assembly includes a 1000 ml round‑bottom flask (24/39 joint), Liebig condenser with sealed inner tube, a 5 ml graduated trap (0.05 ml graduations), drying tube, heater (electric mantle recommended), jet‑spray tube, and pick/scraper.
- Solvent: Xylene meeting ISO 5280 specifications; solvent blank required to check solvent water content.
- Calibration & recovery: Calibrate trap (micro‑pipette increments) and verify overall water recovery by adding known water volumes to 400 ml xylene and checking measured recovery against specified tolerances.
- Sampling & sample handling: Follow ISO 3170 / ISO 3171 sampling rules; Annex A details homogenization (high‑shear mixing or equivalent) and transfer to test portions.
- Procedure & expression of results: Test portion plus xylene to 400 ml, controlled heating and rinse/wash‑down to dislodge condensate; results reported on a volume or mass basis and rounded per clause 10 (typical rounding to 0.025 %).
- Precision: Precision established for 0–1% (V/V). For the 0.1–1.0% (V/V) range, reported repeatability and reproducibility values are available in the standard (repeatability ≈ 0.08% V/V; reproducibility ≈ 0.11% V/V); lower values are shown graphically for 0–0.1% (see figure 3).
- Safety: The method involves hazardous materials and operations; users must apply appropriate safety and regulatory practices.
Applications and who uses this standard
- Refineries and custody transfer - correcting volumes for water content during purchase, sale and transfer.
- Petroleum testing laboratories - routine QC/QA determination of free and volatile water in crude oil.
- Operators and inspectors - verification of tank or pipeline contents.
- Standards and compliance teams - to ensure measurement traceability and inter‑laboratory comparability.
Related standards
Keywords: ISO 9029:1990, crude petroleum, water determination, distillation method, xylene, water content, trap calibration, sampling, precision.
