Overview
ISO/TR 19686-2:2018 - Petroleum products - Equivalency of test method determining the same property - Part 2: Density of petroleum products - evaluates whether internationally used test methods for measuring the density of petroleum products are technically equivalent. The Technical Report follows the guidance in ISO/TR 19686‑100 and helps laboratories, manufacturers and regulators determine if results produced under one standard can be accepted against another in quality specifications for fuels, lubricants and related petroleum products.
Key topics
- Methods compared
- Oscillating U‑tube: ISO 12185:1996 (IP 365) vs ASTM D4052‑16
- Hydrometer: ISO 3675:1998 (IP 160) vs ASTM D1298‑12b(2017)
- Pyknometer methods (e.g., ISO 3838, ASTM D1217) are not considered here.
- Equivalency conclusions
- Oscillating U‑tube: ISO 12185 and ASTM D4052 are equivalent for middle distillates when density is expressed in kg/m3, but different for other product types (scope and bias differences).
- Hydrometer: ASTM D1298 and ISO 3675 are considered identical for density when expressed in kg/m3.
- Technical differences highlighted
- Scope and applicable product ranges (gasoline, distillates, crude oils, basestocks, lubricants).
- Viscosity bias and correction - ASTM allows instrument viscosity correction; ISO 12185 (edition used) recommended minimizing viscosity effects via calibration fluids.
- Procedures and QC - ASTM D4052 includes two‑injection procedures and dedicated QC sections; ISO 12185 specifies calibration verification frequency and check‑sample practice.
- Calibration and precision - calibration standards traceable to national/international standards; precision and reproducibility statements differ between methods.
- Verification intervals - e.g., hydrometer and thermometer verification practices differ between ASTM and ISO hydrometer standards.
Applications
- Laboratories seeking to certify product density against multiple standards or to accept alternate test reports.
- Quality managers and compliance officers comparing test method equivalency in procurement and specification clauses.
- Test instrument manufacturers developing density meters (oscillating U‑tube, hydrometer) and needing to align features (e.g., viscosity correction) with standard requirements.
- Accreditation bodies and regulators evaluating whether test results from one standard are acceptable for specifications written to another.
Related standards
- ISO/TR 19686‑100 (methodology for equivalency assessments)
- ISO 12185 (IP 365), ASTM D4052, ISO 3675 (IP 160), ASTM D1298
- Note: Pyknometer methods such as ISO 3838 and ASTM D1217 are referenced but not evaluated in this part.
Keywords: ISO/TR 19686‑2:2018, density of petroleum products, equivalency of test methods, oscillating U‑tube, hydrometer, ASTM D4052, ISO 12185, ISO 3675, ASTM D1298, laboratory certification.