SECTOR FOCUS: TESTING Continued from page 41
Viscosity Index Reloaded In the automatic Viscosity Index mode, temperature changes are performed automatically and the Viscosity Index is calculated in compliance with ASTM D2270. Typically, the measurements are performed at 40 °C and 100 °C, but since viscosity- temperature extrapolations according to ASTM D341 are integrated in the instrument software, the measurements can also be performed at two different temperatures and the Viscosity Index automatically calculated. The benefit of this measurement is that the actual density of the lubricating oil at both temperatures is also measured. This means that the extrapolation of the density from these two points (lying far apart) is precise. It is sometimes also referred to as a “density- temperature slope.” For the lubricating oils tested, the extrapolation error was found to be lower than 0.0001 g/cm3
.
Low Sample Volume – Importance in Real Life The viscosity is also important for used oils. Change in viscosity can reveal oil thinning due to fuel dilution or oil aging. For example, in contrast to conventional diesel, bio-diesel does not evaporate out of the engine oil and this leads to a continuous thinning, which in turn requires more frequent oil change.
In such cases of oil samples from the field, often only low sample volume is available, but a number of different tests need to be performed in the laboratory. In such cases, the low sample volume required for a multiparameter determination with SVM™ is very beneficial. The minimum sample volume required for SVM™ 3001 is only 1.5 mL; typical sample volume amounts to approximately 5 mL. Also, with the small cell of the new SVM™ the cleaning requires low solvent amounts, which means a fraction of waste liquid of that with traditional methods ensuring reduction of solvent disposal costs.
Conclusion
Having the flexibility to measure various samples with different viscosities at various temperatures with one measuring cell is perhaps one of the most striking advantages of SVM™ 3001. With one integrated viscosity and density cell, measurements of lubricating oils, fresh and used, as well as ATFs, hypoid oils and also fuels can easily be performed. Due to very fast heating and cooling rates and the wide measuring range in temperature, viscosity, and density, the SVM™ technology sets new standards for flexibility in testing. Temperature scans for kinematic viscosity, density, and dynamic viscosity – all in one scan – can be performed over an incomparably wide temperature range in the fastest manner. This not only significantly simplifies measurement routines and saves time for multiple tests, but also gives an important insight, for example, into the construction of engines for heavy duty vehicles, in this particular case for temperatures from -20 °C to +130 °C. Paired with excellent reproducibility and repeatability in both viscosity and density measurement as well as unbeatable ease of operation, the SVM™ represents one of the most versatile viscosity and density testing technologies for petroleum products.
LINK
www.anton-paar.com
Jelena Fischer,
Anton Paar GmbH, +43 316 257-0,
jelena.fischer@
anton-paar.com
Andrea Dawidczak, MAN Truck & Bus AG, +49 911 420-0,
andrea.dawidzcak@man.eu
Fig 4. Kinematic viscosity, density, and VI values of various operating fluids
42
LUBE MAGAZINE NO.144 APRIL 2018
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