ASTM D7843 uses dE* D65/10 (total color difference) to relate the intensity of insoluble color bodies from a lubricant dissolved in solvent and filtered through a membrane patch to the color quality of in-service turbine oils.
ASTM D7843 Standard Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils using Membrane Patch Colorimetry
ASTM - American Society of Testing and Materials, West Conshohocken, PA USA www.astm.org
Scope or Abstract:
1.1 This test method extracts insoluble contaminants from a sample of in-service turbine oil onto a patch and the color of the membrane patch is analyzed by a spectrophotometer. The results are reported as a dE*value, within the CIE LAB scale.
1.2 This test method is not appropriate for turbine oils with dyes.
How HunterLab Instruments Meet the Requirements of this Method:
- MiniScan EZ 45/0 LAV (preferred for reading down on filter) or ColorFlex EZ.
- Verify membrane patch is not UV optically brightened (should not be), or optionally use 420 nm UV cut-off filter on instrument if it is.
- Configure display for CIE L*, a*, b*, dE* D65/10.
- Set standard to Working.
- Place in good contact at the port.
- Average 2 -3 readings per filter.
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