ASTM D7110 Standard Test Method for Determining the Viscosity-Temperature Relationship of Used and Soot-Containing Engine Oils at Low Temperatures
6. Apparatus
6.1 Test Cell - Shown in Fig. 1, consisting of a matched rotor and a stator of the following critical dimensions:
6.1.1 Rotor Dimensions - Critical length is 65.5 mm +/- 0.1 mm and critical diameter is 18.40 mm +/- 0.02 mm.
6.1.2 Stator Dimensions - Critical diameter is 22.05 mm (60.02 mm) at whatever length will satisfy the immersion depth when the upper oil level is a minimum of 15 mm below the cooling liquid level over the entire temperature range.
6.2 Viscometer Drive Modules - Rotational viscometer drive modules capable of producing an analog signal to an analog-to-digital converter or other analog signal data processor such as a strip-chart recorder.
6.2.1 With the rotor and stator described in 6.1.1 and 6.1.2, the viscometer drive module must be capable of measuring to at least 90 000 mPa·s (cP).
6.3 Test Cell Alignment Device - Simultaneously maintains a vertical axial alignment and reasonably consistent positioning of the rotor in the stator to give repeatable torque readout from test to test when setting up the apparatus for analysis.
6.3.1 Viscometer Support - Supports the viscometer drive module and aligns it vertically.
6.3.2 Stator Collar - Clamps the stator and supports it when the stator collar is attached to the viscometer support.
6.4 A means of providing a dry gas atmosphere over the top of the test sample is necessary to prevent condensation and freezing of water on the oil surface.
6.5 Programmable Liquid Cooling Bath - Liquid bath capable of running either the calibration or the testing program with temperature control of +/- 0.1 °C over the temperature range desired at 3 °C/h.
6.5.1 Temperature Controller is set up to operate according to two programs, the calibration program and the test program. At any temperature the controller modulates temperature within 0.1 °C of the desired value.
6.6 Computer, Analog-to-Digital Converter, and Analysis Program - Means of receiving data from the viscometer drive module and converting this data into the desired information.
6.7 Sample Pre-treatment Water or Air Bath - A programmable water or air bath for both precise control of the test oils at 90 °C +/- 2 °C and immersion time after the sample reaches pre-treatment temperature.
6.8 Calibrated Liquid-in-Glass or Digital Contact Thermometer, calibrated at 90 °C and reading to +/- 0.2 °C.
7. Materials
7.1 Calibration Oil - A Newtonian calibration oil of known dynamic viscosity over a temperature range of -5 °C to -35 °C.
7.2 Gelation Index Reference Oils, GIR-series, non-Newtonian Reference Oils, having gelation indices of established values as well as related values for the gelation index temperatures.
7.3 Finger Cots, latex, used to close the top of the oil-filled stators when they are in the pre-treatment heating baths, particularly if subject to water condensation inside the stator when heated in water baths.
7.4 Viscometer Heads, equipped with torque signal output and suitable sensitivity.
7.5 Temperature-programmable, Low-temperature Bath.
7.6 Torque Signal Recorder - Computer, analog-to-digital converter, and data analysis program.
7.7 Constant-temperature Oven or Water Bath, (programmable or non-programmable) for preheating samples.
7.8 Operator Calibrated, Temperature Measuring Devices, for 90 °C and -20 °C.
7.9 Newtonian Calibration Oil.
7.10 Source of Dry Air or Nitrogen Gas and means of gas introduction over top of stator.
