ASTM D6375 Test Method for Evaporation Loss of Lubricating Oils
ASTM D6375 Standard Test Method for Evaporation Loss of Lubricating Oils by Thermogravimetric Analyzer (TGA) Noack Method
6. Apparatus
6.1 Thermogravimetric Analyzer, with the capability to meet all the conditions required for this test method, along with the software necessary to complete the required analyses.
6.2 Aluminum Specimen Pan - This shall be cylindrical, and have a minimum inside diameter/height ratio of 0.45 and a volume of 50 +/- 3 µL. If the pans provided by the particular TGA manufacturer do not meet these criteria, alternative pans may be used and adapted to fit the pan holder of the TGA. Examples of some of the adaptations used during the evaluation of this test method are shown in Fig. 1.
6.3 Pressure Regulator, capable of maintaining air delivery pressure at the level required by the TGA instrument.
6.4 Flowmeter, with a flow control valve capable of setting and measuring the air throughput required by the TGA instrument.
7. Reagents and Materials
7.1 TGA Temperature Calibration Standards - These materials will depend on the particular TGA apparatus and its capabilities. The TGA manufacturer typically provides them and describes their use in the operating manual for the instrument.
7.2 Compressed air at a pressure suitable for operation of the TGA instrument. Reagent grade air is not necessary but may be used if there are concerns over possible contamination of the internal parts of the TGA.
7.3 Noack Reference Oil - Oil having a known Noack evaporative loss, the value of which is provided by the manufacturer.
8. TGA Preparation and Calibration (see Note 1)
NOTE 1 - This section only needs to be done if TGA has been idle for an extended period of time, has had significant repairs made to it, or has been mishandled or its location changed.
8.1 Check the temperature correlation between the specimen and control temperatures in accordance with TGA manufacturer's recommendations or Practice E 1582. Use calibration standards that will bracket 250°C. When necessary, recalibrate, and regenerate correlation.
8.2 When necessary, burn out the TGA to remove any condensed liquids or deposits, which may have formed on its inside surfaces. Generally, burn out is accomplished by raising the temperature of the TGA to a minimum of 800°C with an air purge from 200 to 500 mL/min, and by maintaining it at this high temperature until no smoke is detected from the TGA gas exhaust tube. Normally 15 to 20 min at these conditions are enough to remove most deposits. (Caution: Do not place a specimen pan in the TGA during this operation. It will melt and may damage the balance or furnace mechanisms.)
8.3 Check operation of TGA balance and adjust when necessary. Follow manufacturer's procedure and recommendations.
