GB/T 3555-1992 Determination of Saybolt Color of Petroleum Products (Saybolt Chromometer Method)

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.

Source limitations: The source table is disordered and does not provide all color-number correspondences for the shorter sample columns. Missing color numbers are not inferred. The implementation date contains extraction noise. Adoption and apparatus wording are retained as source-card statements, pending independent technical verification.

Card type: test method

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

• Standard number: GB/T 3555-92
• Chinese title, translated: Determination of Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• English title: not provided in the available source.
• Replacement relationship: not provided in the available source.
• Adoption relationship: the source card states that this standard equivalently adopts ASTM D 156—87, Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method), of the American Society for Testing and Materials; this statement has not been independently verified here.
• Approval/implementation: approved by the State Bureau of Technical Supervision on 1992-08-24 and implemented on 1993-05-01 (the extracted source reads "1993-C5-01 implemented"; requires confirmation against the source standard).
• Proposal/administration/drafting: proposed by China Petrochemical Corporation; technically administered by the Research Institute of Petroleum Processing; drafted by Fushun Research Institute of Petroleum and Petrochemicals; main drafters Lai Yuzhen and Yang Lingru.

2. Scope and exclusions

• Applies to the determination of Saybolt color of petroleum products by the Saybolt chromometer method.
• Note: petroleum products darker than Saybolt color —16 may be tested using GB/T 6540.
• Other exclusions: not provided in the available source.

3. Principle

Adjust the sample liquid-column height by the specified procedure until the sample is distinctly lighter than the color standard. Report the Saybolt color number corresponding to the preceding liquid-column height, whether the color at that preceding height was darker, doubtful or matched the standard.

4. Reagents and materials (purity / preparation)

• Distilled water (for instrument calibration, 6.3; fill the sample tube with distilled water to compare colors).
• Acetone or other solvents (for cleaning the sample tube, color-standard glass tube and glass disc, 6.1).
• Soap and water (for removing deposits, 6.1).
• Multiple layers of qualitative filter paper (to filter a cloudy sample, Chapter 7).
• Color standards: circular glass discs in full-thickness and half-thickness forms. Their colorimetric characteristics, calculated from spectral transmittance using the 1931 International Commission on Illumination ICI standard illuminant C, namely luminous transmittance r and chromaticity coordinates X, Y, Z, shall meet Appendix A2:
  • Full-thickness color standard: r 0.860~0.865; X 0.342~0.350; Y 0.367~0.378; Z 0.272~0.291.
  • Half-thickness color standard: r 0.888~0.891; X 0.327~0.331; Y 0.344~0.350; Z 0.319~0.330.
• Purity and specific preparation concentrations: not provided in the available source.

5. Apparatus

The Saybolt chromometer comprises a sample tube, color-standard glass tube, light source, color standards and optical system. See Appendix A and Figure A1. Main contents of Appendix A (supplement):

• A1 Saybolt chromometer
  • A1.1 Sample tube: borosilicate glass or glass with equivalent color characteristics; inside diameter 16.5~17.5mm, outside diameter 21.25~22.75mm. Close the bottom with a flat, optically clear glass disc 6.25mm thick, free from blemishes and scratches. The length from the upper surface of this disc to the tube top is 508~510mm. Mount the tube in a metal sleeve fitted with a metal drain valve. Graduate at 1/8in (3.2mm) intervals, with a circumferential line every 1in (25.4mm), and number upward from the 2in (50.8mm) line. Note: Pyrex glass is suitable, or glass of comparable quality may be used; the source states that domestic GG17 glass is comparable.
  • A1.2 Sample-tube heater: for petroleum wax testing; fits the sample tube specified in A1.1 and has a 60W heating wire distributed uniformly over the whole tube. It must keep the wax liquid while allowing readings to be taken.
  • A1.3 Color-standard glass tube: the same material, color, inside diameter and outside diameter as the sample tube; length 483mm, open at both ends, with the lower end fixed in a metal sleeve. The optical path through the sleeve contains a removable black metal diaphragm with a 12mm aperture and a rotating holder for the color standards. Total assembled length: 516~518mm.
  • A1.4 Glass-tube color requirements: no color difference shall be observable between the sample tube and color-standard tube when both are empty or when the sample tube is filled with distilled water (compare on the instrument according to Chapter 6).
  • A1.5 Tube assembly: fix the sample tube and color-standard glass tube vertically, aligned with the center of the optical eyepiece. Cover the upper ends with removable diaphragm metal caps about 25mm long; the diaphragm aperture diameter is 14mm.
  • A1.6 Optical viewing assembly: comprises a prism and viewing lens; the prism refraction angle matches the refracting region. Adjust the prism so that light passing through the tubes is refracted into the photometric head. The eyepiece presents a circular field: half illuminated by light through the sample and half by light through the color standard. The field shall be free from distortion and parallax. A1.6.2 An adapter (Figure A3) may direct the light through the eyepiece center. It is a metal sleeve that fits closely over the eyepiece, about 50mm long, closed at one end by a metal diaphragm with a central aperture about 2.5mm in diameter.
  • A1.7 Illumination: use an opal-glass or clear-glass reflector with a uniform bright silver coating, set at an appropriate angle so that reflected light of equal intensity passes through the tubes as parallel rays. Diffused light may alternatively enter the tubes directly from below the instrument.
  • A1.8 Light source: artificial daylight. Diffused light entering the tubes shall be free from glare or shadows, and all other external light interference shall be excluded.
• A2 Color standards: see Section 4.
• A3 Daylight lamp
  • A3.1 Lamp: a nominal 60W opal household lighting bulb, with the inner surface polished, color temperature about 2750K and luminous efficacy about 13 lm/W, mounted in a standard socket fitted with a hemispherical reflector. The surface-treatment wording is retained from the source card and has not been independently verified.
  • A3.2 Reflector: hemispherical, with its inner surface polished using very fine aluminum-bronze powder and then uniformly sprayed with heat-resistant bronze liquid. The polished coating shall have no selective absorption and an initial reflectance above 65%.
  • A3.3 Daylight filter: a convex-concave glass piece, with the concave surface hardened by sandblasting and acid treatment, fitting closely over the hemispherical reflector opening to exclude dust. The colorimetric characteristics calculated from spectral transmittance with the 1931 ICI standard illuminant A, namely luminous transmittance r and chromaticity coordinates X, Y, Z, shall be: r 0.107~0.160; X 0.314~0.330; Y 0.337~0.341; Z 0.329~0.349. A3.3.2 Spectrophotometric check: a satisfactory daylight filter has transmittance above 60% at 410nm and below 10% at 700nm. The transmittance curve in this region shall be smooth and have no characteristic cobalt absorption peak. Its transmittance at 570nm shall be no more than 3% above the straight line joining the transmittances at 540nm and 590nm. Its transmittance at 700nm shall also not exceed that at any shorter wavelength, such as 600nm, by more than 3%.

6. Recommended operating conditions

• Light source: artificial daylight (A1.8, A3).
• Lamp: 60W opal household lighting bulb, color temperature about 2750K and luminous efficacy about 13 lm/W (A3.1).
• Petroleum wax sample heating temperature: 8~17°C above its congealing point (8.2.1).
• Other operating conditions: not provided in the available source.

7. Sampling and sample preparation

• If the sample is cloudy, filter through multiple layers of qualitative filter paper until clear (Chapter 7).
• Petroleum wax sample: heat to 8~17°C above its congealing point, determined by SH/T 0132 (8.2.1).
• Other sampling requirements: not provided in the available source.

8. Analysis procedure

• 6 Instrument calibration
  • 6.1 Remove the glass disc from the sample-tube bottom. Clean the sample tube, color-standard glass tube and glass disc. If deposits cannot be removed by wiping and solvent, wash with soap and water, rinse with distilled water, acetone or another solvent, and dry. Assemble the clean tubes and glass disc on the instrument.
  • 6.2 Remove the diaphragm with a 12mm inside diameter from the bottom of the color-standard glass tube. Illuminate with the specified light source and reflector. Observe the light intensities of the optical fields of the empty tubes and adjust the light source until both half-fields have equal intensity.
  • 6.3 Reinstall the 12mm diaphragm at the bottom of the color-standard glass tube. Fill the sample tube with distilled water. The two optical half-fields must still have equal intensity for the glass tubes to be regarded as color-matched and the instrument suitable for use. Glass optical properties are critical and can vary between batches of the same material. Use color-matched tubes; if a tube breaks, replace the pair with a color-matched pair.
• 8.1 Procedure for refined light petroleum products and white oils
  • 8.1.1 Rinse the sample tube with a portion of sample and drain it completely, leaving no oil droplets on the wall. Fill the tube with sample slowly. Remove any bubbles with a glass rod.
  • 8.1.2 Compare the sample with one full-thickness color standard. If the sample is lighter, substitute a half-thickness standard. If the sample at a liquid-column height reading of 6.25 is darker than one full-thickness standard, use two full-thickness standards.
  • 8.1.3 After selecting the color standard, adjust the sample height so that it is darker than the standard. Drain according to the sample heights in Table 1, to the nearest liquid-column height listed in Table 1 for that selected standard. If the sample remains darker, drain to the next height in Table 1 and compare again. Repeat until the sample color is the closest match or differs only slightly. Then drain to the next liquid-column height specified in Table 1. Once the sample is unmistakably lighter than the standard, record the Saybolt color number corresponding to the preceding liquid-column height.
  • Note: experience with the instrument may allow selection of the color standard without following every step in 8.1.3. Examples of the determination procedure are given in Table 2.
• 8.2 Procedure for petroleum waxes
  • 8.2.1 Heat the petroleum wax sample to 8~17°C above its congealing point, determined by SH/T 0132.
  • 8.2.2 Preheat the sample tube, fill it with melted petroleum wax and switch off the heater. When heat waves in the wax sample disappear, follow the procedure in 8.1.
• Table 1, relationship between Saybolt color number and sample liquid-column height (the extracted table structure is disordered; the following follows legible source content and requires confirmation against the source standard):
  • 1 half-thickness standard: liquid-column height in 20.00 / 18.00 / 16.00 / 14.00 / 12.00; mm 508 / 457 / 406 / 355 / 304; corresponding Saybolt color numbers +30 / +29 / +28 / +27 / +26.
  • 1 full-thickness standard: liquid-column height in 20.00 / 18.00 / 16.00 / 14.00 / 12.00 / 10.75 / 9.50 / 8.25 / 7.25 / 6.25; mm 508 / 457 / 406 / 355 / 304 / 273 / 241 / 209 / 184 / 158; corresponding Saybolt color numbers +25 / +24 / +23 / +22 / +21 / +20 / +19 / +18 / +17 / +16.
  • 2 full-thickness standards: liquid-column height in 10.50 / 9.75 / 9.00 / 8.25 / 7.75 / 7.25 / 6.75 / 6.50; mm 266 / 247 / 228 / 209 / 196 / 184 / 171 / 165; corresponding Saybolt color numbers +15 / +14 / +13 / +12 / +11 / +10 / +9 / +8.
  • Subsequent liquid-column heights (in / mm): 6.25/158, 6.00/152, 5.75/146, 5.50/139, 5.25/133, 5.00/127, 4.75/120, 4.50/114, 4.25/107, 4.00/101, 3.75/95, 3.625/92, 3.50/88, 3.375/85, 3.25/82, 3.125/79, 3.00/76, 2.875/73, 2.75/69, 2.625/66, 2.50/63, 2.375/60, 2.25/57, 2.125/53. Corresponding Saybolt color numbers are not fully given in the available source and require confirmation against the source standard.
• Table 2, operating examples:
  • One full-thickness color standard: at 16.00 in (406 mm) the sample is darker than the standard; at 14.00 in (355 mm) it is darker; at 12.00 in (304 mm) the comparison is doubtful; at 10.75 in (273 mm) it is lighter. Saybolt color number: +21.
  • Two full-thickness color standards: at 4.50 in (114 mm) the sample is darker than the standard; at 4.25 in (107 mm) it is darker; at 4.00 in (101 mm) the comparison is doubtful; at 3.75 in (95 mm) it is lighter. Saybolt color number: -2.

9. Identification, quantification and calculations

• Definition of Saybolt color: compare the sample column with the color standards and determine the liquid-column height giving the closest match to one of the three color-standard combinations. Obtain the Saybolt color number from Table 1. The scale runs from -16 (darkest) to +30 (lightest).
• Result decision: once the sample is unmistakably lighter than the color standard, record the Saybolt color number corresponding to the preceding sample liquid-column height (8.1.3).
• Calculation formula: not provided in the available source.

10. Precision

Judge the reliability of test results according to the following provisions (95% confidence level).

• 9.1 Repeatability: the difference between duplicate results obtained by the same operator shall not exceed 1 Saybolt color number.
• 9.2 Reproducibility: the difference between results submitted by different laboratories shall not exceed 2 Saybolt color numbers.

11. Report

Report the recorded color as "Saybolt color number X". If the sample was filtered, include the words "sample filtered".

12. References

• GB/T 6540, Determination of Color of Petroleum Products.
• SH/T 0132, Determination of Congealing Point of Petroleum Waxes.
• ASTM D 156—87, Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method) (equivalent adoption stated in the source card; not independently verified here).

13. Source and verification

• Source provenance reported by the card: Free Standards website (www.freebz.net), extracted text from source-text extraction or the text layer; this does not constitute independent verification of the original standard.
• Verification status: the text contains extraction noise and disordered tables. Affected numbers and tables are marked as requiring confirmation against the source standard; items absent from the source are explicitly identified as not provided.

14. Quick-reference questions