Overview
EN ISO 9029:1995 (ISO 9029:1990) specifies a standard laboratory distillation method for determining water in crude petroleum. The method covers test principle, apparatus, solvent, calibration and recovery checks, sampling and sample handling (Annex A), test procedure, expression of results and precision data. Precision data have been established only for water contents up to 1 % (V/V). The procedure is widely used for quality control and custody-transfer volume corrections.
Key topics and technical requirements
- Principle: Water is co‑distilled from a crude/solvent mixture under reflux; condensed solvent and water separate in a graduated trap while solvent returns to the flask.
- Apparatus: Recommended assembly includes a 1 000 ml round‑bottom distillation flask with 24/39 joint, Liebig condenser, 5 ml graduated glass trap (0.05 ml graduations, readings estimated to 0.025 ml) and heater. Additional items: drying tube with self‑indicating desiccant, jet‑spray wash tube, pick/scraper and optional magnetic stirrer.
- Solvent: Xylene complying with ISO 5280. The procedure requires use of dry xylene (blank xylene water content checked).
- Calibration & recovery: Initial trap calibration using 0.05 ml increments; recovery checks using 400 ml dry xylene and addition of known water volumes (e.g., 1.00 ml and 4.50 ml) to verify system accuracy. Recovered volumes must lie within tolerances given in the standard.
- Sampling and sample handling: Sample selection and homogenization follow ISO 3170 / ISO 3171 guidance; test‑portion sizes are chosen according to expected water content (table in the standard).
- Procedure controls: Slow controlled heating to avoid bumping; collect distillate at ~2–5 drops/s; wash condenser and redistill if water clings; read trap after cooling and transfer of any adhering drops.
- Expression of results & reporting: Results reported on a volume or mass basis and rounded as specified (standard requires reporting to nearest 0.025 %). Test report must cite the standard, test results, individual test portions and any deviations.
Practical applications and users
- Who uses it: Petroleum testing laboratories, refinery QC labs, custody‑transfer and trading verification teams, inspection bodies, and standards organizations.
- Why it’s used:
- Accurate determination of free and some dissolved water for custody transfer volume correction.
- Quality control during refining and processing.
- Regulatory and contractual compliance for crude oil sale/purchase.
- Limitations: Precision established only up to 1 % (V/V) water; volatile water‑soluble substances can be measured as water using this method.
Related standards
Keywords: EN ISO 9029:1995, ISO 9029:1990, crude petroleum water determination, distillation method, xylene solvent, trap calibration, sampling, precision data.
