Overview
ISO 2176:1995 - "Petroleum products - Lubricating grease - Determination of dropping point" specifies a standardized laboratory method to determine the dropping point of lubricating greases. This second edition (1995) cancels and replaces ISO 2176:1972. The dropping point is defined as the temperature at which a drop of grease is extruded from a specialised cup under the method’s test conditions. The standard is intended for quality control and product characterisation, not as a direct predictor of in-service performance.
Key topics and technical requirements
- Scope and definition
- Defines dropping point and notes limitations (e.g., some greases separate oil instead of showing a state change).
- Apparatus
- Chromed brass grease cup (dimensions per Figure 1).
- Borosilicate test tube with three circumferential indentations (Figure 2).
- Partial-immersion thermometers conforming to Annex A (scale −5 °C to +300 °C, 1 °C graduation, ≤1 °C error, 76 mm immersion depth).
- Oil bath (400 ml beaker), heater with controlled heating rates, thermometer depth gauge, fixture and agitation system.
- Procedure (summary)
- Fill and prepare the grease cup; assemble cup and thermometer so the thermometer bulb does not touch the grease or cup.
- Suspend the test tube in the oil bath with thermometer immersion depth at 76 mm.
- Preheat at 4–7 °C/min to ~17 °C below expected dropping point, then heat at 1.0–1.5 °C/min until a drop is observed.
- Record temperatures on both thermometers when the drop falls; report the average to the nearest 1 °C (mean of two readings).
- Reporting
- Include reference to ISO 2176:1995, product identification, test result, any deviations from procedure, and test date.
- Performance statistics
- Repeatability: two consecutive results by same operator/apparatus should differ by no more than 7 °C (once in 20).
- Reproducibility: results from different laboratories should not differ by more than 13 °C (once in 20).
- Safety
- Standard includes a warning that hazardous materials and equipment are involved; users must apply appropriate safety and regulatory measures.
- Annex A
- Normative thermometer specifications; ASTM ZC/IP 62C noted as compliant.
Applications and users
ISO 2176:1995 is used by:
- Lubricant manufacturers for product specification and quality control
- Independent testing and certification laboratories
- Procurement/specification engineers and purchasers comparing grease grades
- Suppliers and consumers agreeing on test methods for supply contracts
Practical uses include setting manufacturing limits, batch acceptance testing, stability checks (noting some greases change with aging), and comparative product assessment.
Related standards
- Referenced thermometer standard: ASTM ZC/IP 62C noted as compliant with Annex A.
- Users should coordinate with producers and purchasers on the preferred method when multiple grease dropping-point methods exist.
