Overview
ISO 3015:2019 specifies a standardized laboratory method for the determination of cloud point in petroleum and related products. The cloud point is defined as the temperature at which a cloud of wax crystals first appears when a liquid is cooled under specified conditions. ISO 3015:2019 applies to transparent samples in 40 mm layers with cloud points below 49 °C, including diesel fuels (up to 30 % V/V FAME), paraffinic diesel (up to 7 % V/V FAME), 100 % FAME and lubricants. The standard updates the previous edition with expanded scope and inclusion of digital contact thermometers.
Key topics and technical requirements
- Scope and sample types: Transparent petroleum products, diesel blends with FAME, paraffinic diesel, biodiesel (FAME) and lubricants.
- Principle: Cool a defined sample at a controlled rate and inspect periodically; record the temperature at first visible cloud at the bottom of the test jar.
- Apparatus:
- Specified clear glass test jar (approx. 33.2–34.8 mm outside diameter, 115–125 mm height) with sample height marked at 54 mm ± 3 mm.
- Jacket and gasket to isolate the jar in a cooling bath.
- Temperature measuring devices: liquid-in-glass thermometers or Digital Contact Thermometer (DCT) meeting Annex A requirements (e.g., display resolution 0.1 °C, accuracy ±0.5 °C, specified sensor dimensions and response time).
- Cooling baths and temperature ranges: Series of baths (e.g., 0 °C, −18 °C, −33 °C, −51 °C, −69 °C) with defined sample temperature ranges for transferring jars between baths.
- Procedure highlights:
- Preheat and dry samples (at least 14 °C above approximate cloud point, ≤49 °C).
- Pour to the mark, insert thermometer so bulb/probe rests on jar bottom.
- Inspect at each 1 °C increment; total jar removal and inspection should take ≤3 s.
- Report cloud point to the nearest 1 °C.
- Precision:
- Repeatability: difference between repeated tests by same operator exceeds 2 °C in one case out of 20.
- Reproducibility: difference between labs exceeds 4 °C in one case out of 20.
- Test report: Product identification, reference to ISO 3015:2019, result, deviations, and test date.
Applications and users
ISO 3015:2019 is used by:
- Petroleum and biodiesel producers for quality control and specification compliance.
- Independent test laboratories and certification bodies performing fuel characterization.
- Refiners and fuel distributors evaluating cold-weather operability of diesel blends and lubricants.
- Regulatory agencies and standards committees assessing fuel performance limits.
Practical benefits include consistent cloud point measurement, comparability across laboratories, and informed decisions on cold-flow additives, blending limits and storage/transport requirements.
Related standards
- ISO 3170, ISO 3171 (sampling of petroleum liquids)
- ASTM D7962 (immersion depth & sensor drift)
- ASTM E644, ASTM E2877 (thermometer specifications and digital thermometer guide)
Note: Users should follow safety precautions; the standard includes warnings about hazardous materials and operations.
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