EXPLANATION
The Houillon viscometer tube method offers automated determination of kinematic viscosity. A typically a sample volume of less than 1 mL is required for the analysis. The method is applicable to both fresh and used lubricating oils. The range of kinematic viscosity covered by this test method is from 0.2 to 1000 mm2/s in the temperature range between 20° and 150°C.
TEST SUMMARY
The kinematic viscosity is determined by measuring the time taken for a sample to fill a calibrated volume at a given temperature. The specimen is injected into the apparatus and then flows into the viscometer tube which is equipped with two detection cells. The specimen reaches the test temperature of the viscometer bath and when the leading edge of the specimen passes in front of the first detection cell, the automated instrument starts the timing sequence. When the leading edge of the specimen passes in front of the second detection cell, the instrument stops timing the flow. The time interval thus measured allows the calculation of the kinematic viscosity using a viscometer constant determined earlier by calibration with certified viscosity reference standards.
TEST PRECISION
Bias - Since there is no accepted reference standard suitable for this determination, no bias can be determined. However, based on interlaboratory studies conducted following relative bias statements can be made:
At 40°C D445predicted = (Houillon viscosity result) - 0.290
At 100°C D445predicted = (Houillon viscosity result) - 0.133
At 40°C D7042predicted = 0.9952 (Houillon viscosity result)
There were not sufficient ASTM D7042 results obtained at 100°C to calculate correlation between ASTM D7042 and Houillon results at that temperature.