ISO 22995:2019

Overview

ISO 22995:2019 - Petroleum products - Determination of cloud point - Automated step-wise cooling method - specifies an automated, optical detection method to determine the cloud point of petroleum products. The method uses a step-wise cooling sequence executed by automated equipment with optical sensors and is applicable to distillate fuels, fatty‑acid methyl esters (FAME), paraffinic diesel fuels and their blends (including those with flow‑improvers or other additives) intended for diesel engines and domestic heating. The method can also be applied to other liquids (e.g., vegetable oils, lubricants), although precision data are not available for those products.

Key topics and technical requirements

• Principle: sample is cooled in discrete temperature steps and examined optically for the first appearance of cloudiness (paraffin crystals). The observed temperature is reported as the cloud point.
• Automated optical detection: device must detect trouble/crystals at least every 1 °C (continuous or periodic detection possible depending on location inside the jacket).
• Step-wise cooling ranges (equipment bath setpoints and sample temperature intervals):
  • Bath 1: 0 ±1.5 °C - sample to +9 °C
  • Bath 2: −18 ±1.5 °C - sample +9 to −6 °C
  • Bath 3: −33 ±1.5 °C - sample −6 to −24 °C
  • Bath 4: −51 ±1.5 °C - sample −24 to −42 °C
  • Bath 5: −69 ±1.5 °C - sample −42 to −60 °C
• Apparatus: specified glass test tube dimensions and jacket, sample temperature probe with resolution 0.1 °C and accuracy 0.5 °C, humidity‑sealing device, optional spacer/disc or annular seal to avoid contact with jacket.
• Sample preparation: sample must be homogeneous, free of water/particles; if necessary heat to ≥14 °C above assumed cloud point (but ≤49 °C) and filter through non‑linting paper (5 ±1 μm).
• Result expression: cloud point is rounded to the next lower integer °C (e.g., +4.9 → +4 °C; −3.1 → −4 °C) to harmonize with manual methods.
• Precision: repeatability (r) from interlaboratory study is 1.1 °C (difference not expected to exceed this more than once in 20). Reproducibility and further precision data are provided in the standard based on an ILS.

Applications and users

• Who uses it: fuel laboratories, refineries, biodiesel producers, quality control teams, equipment manufacturers (automated cloud point testers), and regulatory bodies specifying fuel quality for diesel engines and heating systems.
• Practical applications:
  • Ensuring diesel and biodiesel blends meet low‑temperature operability requirements.
  • Verifying additive effectiveness (flow‑improvers) on cloud behavior.
  • Quality control for shipping, storage and seasonal fuel formulation.
  • Comparative testing between automated and manual cloud‑point methods.

Related standards

• ISO 3015 (manual cloud point method) - harmonized principle
• ISO 3170 / ISO 3171 - sampling of liquid petroleum products
• ISO 4259 - statistical treatment of interlaboratory data (precision)
• ISO 2049 - color index considerations

Keywords: ISO 22995:2019, cloud point determination, automated step-wise cooling, petroleum products, FAME, paraffinic diesel, optical detection, fuel quality, low‑temperature properties.