Overview
ISO 22285:2018 - "Petroleum products and lubricants - Determination of oil separation from grease - Pressure filtration method" - defines a laboratory test to quantify oil separated (bleeding) from lubricating grease under controlled temperature, time and pressure. The method evaluates storage stability (oil separation during storage in pails and drums) and is widely cited for assessing grease formulation and quality control.
Key topics and technical requirements
- Test principle: A sample of grease is placed in a metallic separation cup closed by a stainless-steel gauze cone. Under specified temperature and duration, oil that bleeds through the gauze is collected and weighed to give the mass fraction of oil separated.
- Apparatus and materials: separation cup with stainless-steel gauze (63 µm aperture, 43 µm wire - 240 mesh), receiver (cup), metal weight (100 ± 0.1 g), oven capable of 40–120 °C (±1 °C), precision balance to milligram, spatula, and cleaning solvent (heptane or white spirit).
- Conditions and variants: typical temperatures 40–120 °C; normal test duration 168 h (short test 18 h). For NLGI grade 2 and higher the 100 g weight applies (pressure filtration); grades 0 and 1 may be tested with or without weight; very soft greases (00, 000) often cannot be tested if they flow unchanged through the sieve.
- Repetition and result expression: tests are normally done in triplicate (duplicate allowed as a simplified procedure). Oil separation S is reported as mass fraction (%) averaged and rounded per the standard.
- Limitations: not applicable to very soft greases that flow through the mesh; does not simulate in-service separation - it predicts storage behavior only.
- Safety note: the standard warns about hazardous materials/operations and requires users to apply appropriate safety measures.
Practical applications
- Quality control of lubricating grease formulations to monitor oil bleeding (grease bleeding / oil separation from grease).
- Comparative assessment during formulation development to optimize thickener/base oil interactions and gel structure.
- Predicting storage stability of greases in packaging (pails, drums) and helping prevent packing-related hardening, bearing clogging or valve issues due to oil loss.
- Supplier-customer specification testing and acceptance of grease batches.
- Lubricant and grease manufacturers (R&D and QC labs)
- Tribology and reliability engineers
- Third‑party testing laboratories
- Purchasing/specification engineers needing storage-stability data
Related standards
- ISO 2137 (cone penetration, NLGI grade determination)
- ISO 2194 (wire cloth / mesh designations)
- ISO 12924 (grease family and specifications)
- ASTM D1742 (alternative oil separation method)
- ASTM D4057 (sampling practice)
Keywords: ISO 22285, oil separation from grease, pressure filtration method, grease bleeding, storage stability, lubricating grease testing, NLGI grades.