GB/T 6540-1986 Petroleum products — Determination of colour

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full title / English title / replacement relationship

• Standard number: GB 6540-86 (file name recorded as GBT-6540-1986)
• Chinese title: Petroleum products — Determination of colour
• English title: Petroleum products — Determination of colour
• UDC: 665.5:543.41 (elsewhere in the main text source-text extraction is used as “UDC.295.5:548”, requires confirmation against the source standard (source-text extraction))
• Replacement relationship: not provided in the available source
• Adoption relationship: the additional notes state “prepared by equivalent adoption of the American Society for Testing and Materials standard ASTM D1500-1982 ‘Petroleum products — Determination of colour’” (the original text “[garbled Chinese method title in the source extraction]” is source-text extraction noise, requires confirmation against the source standard (source-text extraction))
• Publication/implementation: published on 1986-06-25, implemented on 1987-06-01; approved by the National Bureau of Standards

2. Scope of application and exclusions

• This method specifies the visual determination of the colour of various petroleum products such as lubricating oils, kerosene, diesel fuel, petroleum wax, etc.
• Not applicable: not provided in the available source.

3. Method principle

Pour the sample into the sample container, compare using a standard light source against colour glass discs arranged from values 0.5 to 8.0, and take the matching colour number as the colour number of the sample. If no exact colour match is found for the sample colour and it falls between two standard colours, report the higher of the two colours.

4. Reagents and materials (purity / preparation)

• Diluent: kerosene, used to dilute dark samples during testing. The colour of the kerosene is required to be lighter than the colour of a solution prepared by dissolving 4.8 milligrams of potassium dichromate in 1 litres of distilled water.
• Other reagent purity and preparation details: not provided in the available source.

5. Apparatus and equipment

• 2.1.1 Colorimeter: composed of a light source, glass colour standard plates, a covered sample container, and an observation eyepiece (see Appendix A).
• 2.1.2 Sample container: a transparent colourless glass sample container. For arbitration testing, use the glass sample cup as shown in the figure (Figure 1 Standard glass sample cup). For routine testing, a transparent flat-bottomed glass test tube with an inner diameter of 30 to 33.5 millimetres and a height of 115 to 125 millimetres is permitted.
• 2.1.3 Sample container cover: may be made of any suitable material, the inner surface of the cover is dark black, and the covers of both containers described in 4.1 must be able to completely shield against external light.
• Appendix A Colorimeter (supplementary document):
  • A.1 The colorimeter shall have two illuminated surfaces of equal size and shape, one being the illuminated surface through the colour standard comparison plate and the other being the illuminated surface through the sample; the two illuminated surfaces are symmetrically distributed on both sides of the vertical centre line, and the closest parts in the horizontal direction are separated by a distance such that the viewing angle to the observer's eye is not less than 2 degrees and not greater than 3.6 degrees; each illuminated surface has a diameter subtending at least 2.2 degrees in the field of view, and the illuminated surface may be extended to any size and shape, provided that within the field of view there are no two light spots separated by a distance subtending an angle greater than 10 degrees.
  • A.2 Artificial light source: composed of a colour lamp at a temperature of 2856 kelvin, daylight filter glass, and a flashing translucent opal glass; the spectral characteristics of the combined elements are similar to north window light, providing a translucent background with an illuminance of 900100 metre-candles (value requires confirmation against the source standard (source-text extraction)); the illuminated translucent opal glass background shall be free from flashing and shadows; the light source must be designed so that there is no interference from external light during observation.
  • A.2 Note ①: The colorimeter shall be designed so that when no power source is used, north window light can be utilised; in this case, no coloured objects are permitted to exist directly in front of the light.
  • A.2 Note ②: Spectrophotometric tests of qualified daylight filter glass show that the radiant energy transmittance at 410 nm is not less than 0.60, with only one half descending curve (wording requires confirmation against the source standard (source-text extraction)), and at 700 nm the transmittance is lower than 0.10; the curve has no peak significantly characteristic of excess cobalt; a typical cobalt curve has an increased transmittance at 570 nm, which lies above the straight line connecting the transmittances at the two points 540 nm and 590 nm, and also has a transmission peak above 660 nm; qualified filter glass at 570 nm shall have a transmittance not exceeding 0.03 of the line connecting the transmittances at the two points 540 nm and 590 nm, and the transmittance at 700 nm shall also not exceed 0.03 of the transmittance at any shorter wavelength (such as 660 nm).
  • A.2.2 Qualified daylight filter shall also have the following characteristics: when calculated using spectral transmittance data for standard illuminant A at 1931 CIE, the colour coordinates and luminous transmittance T[A] values are as follows: x 0.107 to 0.160; y 0.314 to 0.330; z 0.337 to 0.341; T[A] 0.329 to 0.349 (the original table source-text extraction is incomplete, requires confirmation against the source standard (source-text extraction)).
  • A.3 Glass colour standard comparison plates: the table specifies sixteen glass colour standard comparison plates; the standard comparison plates shall be installed so as to be convenient to use; the width of the glass colour standard comparison plates shall be not less than 14 millimetres.
  • Colour coordinates and luminous transmittance of glass colour standard comparison plates (CIE standard light source D65):
    • Colour number 0.5: x 0.462, y 0.473, z 0.065, T[A] 0.86±0.96 (requires confirmation against the source standard (source-text extraction))
    • Colour number 1.0: x 0.489, y 0.475, z 0.036, T[A] 0.77±0.06
    • Colour number 1.5: x 0.521, y 0.464, z 0.015, T[A] 0.67±0.06
    • Colour number 2.0: x 0.552, y 0.442, z 0.006, T[A] 0.55±0.06
    • Colour number 2.5: x 0.582, y 0.416, z 0.002, T[A] 0.44±0.04
    • Colour number 3.0: x 0.611, y 0.388, z 0.001, T[A] 0.31±0.04
    • Colour number 3.5 (original text “3.n”, requires confirmation against the source standard (source-text extraction)): x 0.640, y 0.359, z 0.001, T[A] 0.22±0.04
    • Colour number 4.0: x 0.671, y 0.328, z 0.001, T[A] 0.152±0.022
    • Colour number 4.5: x 0.703, y 0.296, z 0.001, T[A] 0.109±0.016
    • Colour number 5.0: x 0.736, y 0.264, z 0.000, T[A] 0.081±0.012
    • Colour number 5.5: x 0.770, y 0.230, z 0.000, T[A] 0.058±0.010
    • Colour number 6.0: x 0.805, y 0.195, z 0.000, T[A] 0.040±0.008
    • Colour number 6.5: x 0.841, y 0.159, z 0.000, T[A] 0.026±0.006
    • Colour number 7.0: x 0.877, y 0.123, z 0.000, T[A] 0.016±0.004
    • Colour number 7.5: x 0.915, y 0.085, z 0.000, T[A] 0.0081±0.0116 (requires confirmation against the source standard (source-text extraction))
    • Colour number 8.0: x 0.956, y 0.044, z 0.000, T[A] 0.0125±0.0006 (requires confirmation against the source standard (source-text extraction))
    • Note: the tolerance of the colour coordinates is ±0.006.

6. Recommended operating conditions

• Light source: colour lamp at a temperature of 2856 K + daylight filter glass + translucent opal glass (see A.2).
• Observation method: direct visual observation or simultaneous observation of the sample and any colour standard comparison plate using an optical eyepiece.
• Other operating conditions: not provided in the available source.

7. Sampling and sample preparation

• 3.1 Liquid petroleum products such as lubricating oils: pour the sample into the sample container to a depth of 50 millimetres or more, and observe the colour. If the sample is not clear, the sample may be heated to above the cloud point by 6 ℃ or until the turbidity disappears, and then its colour is measured at that temperature. If the colour of the sample is darker than standard colour number 8, then 15 parts of the sample (by volume) are added to 85 parts by volume of diluent, mixed, and the colour of the mixture is determined.
• 3.2 Paraffin wax including slack wax: heat the sample to above the wax melting point by 11 to 17 ℃, and determine its colour at this temperature. If the colour of the sample is darker than number 8, then 15 parts of the molten sample (by volume) are mixed with 85 parts by volume of diluent at the same temperature, and the colour of the mixture is determined at this temperature.
• Other sampling requirements: not provided in the available source.

8. Analytical procedure

• 4.1 Pour distilled water into the sample container to a height of 50 millimeters or more, place the sample container in a compartment of the colorimeter, through which the standard glass color comparison plate can be observed; then place another sample container containing the sample into another compartment. Put on the cover to isolate all external light.
• 4.2 Turn on the light source and compare the color of the sample with the standard glass color comparison plates. Determine the standard glass color comparison plate number that matches the sample color; when an exact match is not possible, use the adjacent standard glass color comparison plate number with the darker color.

9. Qualitative and Quantitative and Calculation Formulas

• 5.1 The standard glass color comparison plate number that matches the sample color is taken as the color number of the sample color. For example, 3.0, 7.3.
• 5.2 If the color of the sample falls between two standard glass color comparison plates, report the darker glass color comparison plate number and add "less than" before the color number, for example: less than 3.0, less than 7.5. Never report the color as darker than the given standard, for example: greater than 2.5, greater than 7.5, unless the color is darker than 8, in which case it may be reported as greater than 8.
• 5.3 If the sample is diluted with kerosene, add the word "diluted" after the color number reported for the mixture color.
• Calculation formula: not provided in the available source.

10. Precision

Use the following provisions to judge the reliability of test results (95% confidence level).

• 6.1 Repeatability: the difference between two color number results determined by the same operator on the same instrument for the same sample shall not be greater than 0.5.
• 6.2 Reproducibility: the difference between two color number results determined by two laboratories for the same sample shall also not be greater than 0.5.

11. Report

• 5.1 The standard glass color comparison plate number that matches the sample color is taken as the color number of the sample color. For example, 3.0, 7.3.
• 5.2 When the sample color falls between two standard glass color comparison plates, report the darker glass color comparison plate number and add "less than" before the color number, for example: less than 3.0, less than 7.5; never report the color as darker than the given standard, for example: greater than 2.5, greater than 7.5, unless the color is darker than 8, in which case it may be reported as greater than 8.
• 5.3 When the sample is diluted with kerosene, add the word "diluted" after the color number reported for the mixture color.

12. Referenced Documents

• ASTM D1500-1982 "Petroleum Products Color Determination Method" (the additional notes state equivalent adoption; the original title source-text extraction is written as "[garbled Chinese method title in the source extraction]", requires confirmation against the source standard (source-text extraction))
• Other referenced documents: not provided in the available source.

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A