Moreover, ASTM has developed bias correction formulas to align D7042 measurements with D445 results, ensuring practical equivalence between the two methods. These formulas are integrated into all SVM viscometers, automating conversions and eliminating manual calculations.
Broad industry acceptance and compliance Since its introduction, ASTM D7042 has gained widespread adoption in petroleum industry specifications. It is recognised in key standards such as: • SAE J300 (Engine Oils) & J306 (Driveline Lubricants) • ASTM D2270 (VI) • ASTM D6158 & D8029 (hydraulic oils) • ASTM D2140 & D2501 (transformer oils) • ASTM D975 & EN 590 (diesel fuels) • ASTM D396 (fuel oils) • ASTM D3699 (kerosene) • ASTM D1655 & ASTM D7566 (aviation fuels)
A key advantage of the D7042 method is that it can be used to measure both viscosity and density simultaneously, enhancing its versatility. This meets specifications that require density as a parameter, allowing for dual certification. Notably, modern SVM instruments ensure full compliance with ASTM D4052 for density measurement.
Reduced maintenance and operational efficiency A major benefit of the D7042 measurement principle is its single measuring cell, which spans the entire viscosity range. This eliminates the need for tracking multiple glass capillaries in a quality management (QM) system. Additionally, SVM viscometers are factory-calibrated across a broad temperature and viscosity range, and adjustments are only necessary when significant deviations from reference materials occur, which can be automated.
In contrast, maintaining accuracy with glass capillary viscometers is far more complex and requires frequent checks of both timing devices and bath thermometers as specified by D445 at regular intervals. And although D445 does not regulate the frequency of viscosity tube calibration, many manufacturers mandate recalibration, particularly when operating at a new temperature.
The future of viscosity testing ASTM D7042 represents a significant improvement over the traditional ASTM D445 method by allowing for the direct measurement of dynamic viscosity and density, enabling precise kinematic viscosity determination. It reduces sample and solvent use while covering a wide viscosity range with a single measuring cell. The advanced capabilities of D7042 viscometers (Anton Paar SVM series) include viscosity index calculations, time/temperature scans, and carbon-type analysis. ASTM bias equations ensure compatibility with D445, supporting industry adoption. By overcoming the limitations of glass capillary viscometers, ASTM D7042 delivers a future- ready, efficient, and sustaina-ble viscosity testing solution.
More information on SVM:
i
ASTM Research Report RR: D02 -1555 ASTM International, 100 Barr Harbor
ASTM Research Report RR: D02 -1741 ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA, 19428-2959, USA.
Drive, P.O. Box C700, West Conshohocken, PA, 19428-2959, USA. ii
LUBE MAGAZINE NO.187 JUNE 2025
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