The TBS Viscometer was the world's first very high shear rate viscometer. In 1979 the instrument was invented, developed, and later patented by Savant Inc. and became the first instrument produced by Tannas Co. formed in 1981. The TBS is the reference instrument for high shear rate viscometry against which other instruments are compared.
The TBS measures high temperature, high shear rate (HTHS) viscosity of an oil as seen by the engine during operation. An absolute viscometer, the TBS is required for testing passenger car engine oils specified in API SL, SM; ASTM D4485; SAE J300 Viscosity Classification; ILSAC GF-2 through GF-4; and locomotive oil specifications. The ASTM test methods designated for standard operation of the TBS Viscometer are ASTM D4683 and D6616. The unit is also equivalent to CEC L-36-A-90.
The TBS has been shown to be the most versatile, accurate and precise of all high shear viscometers on the market. It also has been shown to closely correlate with, and predict, actual performance of engine oils in bearings. Shear rates as low as 50,000 and as high as 7.5 x 106 reciprocal seconds (sec-1) have been measured on the TBS - making it the only commercially available, very high shear rate, broad temperature range, absolute viscometer.
In 1998, Tannas restructured its line of TBS Viscometers by introducing, as its new workhorse, a device freshly designed and appropriately named the TBS 2100E series Viscometer. With a dramatically reduced footprint, state-of-the-art motor and transducer technology and many operator-friendly features, the 2100E series effectively carries Tannas well into the 21st millennium.
Another TBS model, TBS 600 is a more powerful design for testing higher viscosity oils and sooted oils as well as various high shear conditions at temperatures below 100°C. This is the preferred model for the locomotive industry when testing in the 40° to 80°C ranges.
Both models are easy-to-operate, bench-top devices designed to measure HTHS viscosities on a variety of fluid and lubricant types. The most widely used are engine oils and automotive transmission fluids (ATF). As a research tool, the TBS has tested other organic and water-based fluids such as hydraulic fluids, inks, low-melting waxes and polymeric solutions with viscosities ranging from 1 to 100 centiPoise (cP).
Depending on the temperature control source chosen, the operating temperatures of the two units range from 40°C to over 200°C with close temperature control of ±0.1°C.
There are two models of the TBS now available from Tannas; TBS 2100E series and TBS 600. All previous models sold by Tannas (TBS 500, SSTBS and original TBS 2100) have been effectively replaced by the 2100E. With the TBS Semi-Automation Package, the unit can operate on a continuous, virtually unattended, basis. Using the chase-flush technique originally developed by Tannas, an oil sample is injected into the viscometer in a manner completely replacing the previous sample without the need for time-consuming solvent cleaning. With the use of a special Idling Oil, the unit can remain running indefinitely on standby.