High-temperature Saybolt

The Saybolt Eurol viscometer is mostly used in the United States and the testing procedure is described in ASTM D 88 (2013), ASTM D 7496 (2011) (for emulsified asphalts), ASTM E 102 (2009) (for bituminous materials at high temperatures) or AASHTO T 72 (2010). 

ASTM E 102/E 102M. 2009. Standard test method for Saybolt Furol viscosity of bituminous materials at high temperatures. West Conshohocken, PA ASTM International. 

Saybolt Furol viscosity the time, in seconds (Saybolt Furol seconds, SFS), for 60 mL of fluid to flow through a capillary tube in a Saybolt Furol viscometer at specified temperatures between 70 and 210°F the method is appropriate for high-viscosity oils such as transmission, gear, and heavy fuel oils. 

The Saybolt viscometer works on a similar principle (ASTM D88)—the fluid is loaded to a tube calibrated to 60 ml. A cork is removed from the bottom of a narrow capillary and a timer is initiated. When 60 ml of the fluid is drained, the timer is halted. The time to drain the 60 ml volume is known as Saybolt seconds. The instrument operates at temperatures from ambient to as much as 99 °C. Because of the high sensitivity of viscosity to temperature, substantial efforts are devoted to maintaining isothermal conditions quoted uncertainties around the temperature are on the order of 0.03 °C. The accuracy of Saybolt viscometers is better than 0.2%. In order to ensure accuracy, they should be calibrated at regular intervals. For fully developed laminar flows, the drain time through the capillary at the base is directly proportional to viscosity. However, since the capillary section of the tube is short, a correction factor to the time is... 

All the above viscosities are to be expressed as Saybolt Universal seconds. The relationship was originally developed for viscosities at 210°F. between 45 and 160 Saybolt Universal sec. but has since been extended to include a wider range. V.I. is unfortunately not an additive property for mixtures. For lubricants required to work over a wide temperature range, high V.I is desirable. 

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