ADVERTORIAL


ASTM D7042: The Future of Viscosity Testing with Anton Paar’s SVM


Dr. Wolfgang Jud, Product Manager, Anton Paar GmbH, Graz/Austria.


SVM Series: Automatic ASTM D7042 Viscometers


Introduction Viscosity is a critical parameter in quality control across various industries, especially in the petroleum industry, where it provides essential insights into the characteristics of samples ranging from crude oil fractions to refined fuels, base oils, and finished lubricants. Traditionally, viscosity measurement was performed manually and relied on glass capillary viscometers under ASTM D445, a method introduced in 1937. This gravity-dependent approach requires meticulous adherence to temperature control, capillary positioning, and lengthy equilibration times, and offers only one parameter: kinematic viscosity. Even with automation, the method remains limited in terms of throughput, is energy-intensive, and requires large volumes of solvents and sample material.


To address these drawbacks and meet modern industry demands, instrument manufacturers have developed advanced automated techniques like ASTM D7042, utilised by the Anton Paar SVM. These methods determine multiple parameters, such as dynamic viscosity, density, and kinematic viscosity in one go, while reducing sample and solvent use by up to


tenfold. Additionally, D7042 viscometers typically offer higher throughput than D445 systems due to their novel measuring principle. They feature rapid thermoelectric temperature control and a measuring cell covering the full viscosity range relevant to the petroleum industry.


The myth of direct kinematic viscosity measurement


A common misconception is that traditional glass capillary methods measure kinematic viscosity directly. In reality, these methods determine the flow time of a sample through a capillary, which is multiplied by a calibration constant to compute viscosity:


ν = C × t


where ν represents kinematic viscosity, C is a calibration constant, and t is flow time. This calibration constant depends on gravitational acceleration at the calibration site, requiring adjust- ments if measurements are conducted in different locations. ASTM D7042, however, provides a more robust alternative by eliminating gravity as a variable. Continued on page 28


LUBE MAGAZINE NO.187 JUNE 2025 27


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