ASTM D6045-20

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Designation: D6045 − 12 (Reapproved 2017) D6045 − 20
Standard Test Method for
Color of Petroleum Products by the Automatic Tristimulus
Method
This standard is issued under the fixed designation D6045; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method covers the automatic determination of color of a wide variety of petroleum products such as undyed motor
and aviation gasoline, aviation turbine fuels, naphthas, kerosine, pharmaceutical white oils, diesel fuel oils, heating oils, and
lubricating oils by the automatic tristimulus method. This test method correlates to Test Method D156 and Test Method D1500 as
calculated by the instrumentation.
NOTE 1—With the appropriate sample handling, this test method would apply to petroleum waxes, but they were not used in the round robin, and the
precision of this test method with regard to waxes is unknown.
1.2 This test method reports results in terms of Test Method D156 or Test Method D1500.
1.3 This test method has a one-to-one correlation for the entire range of Test Method D1500 ASTM Color and for the range
from 0 to +30 for Test Method D156 Saybolt color.
1.4 This test method does not apply to solid samples, petroleum products containing dye, and petroleum products having
extreme fluorescence.
1.5 This test method does not apply to cloudy samples. Such samples shall be filtered so they are clear before measuring.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D156 Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
D1500 Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
D2500 Test Method for Cloud Point of Petroleum Products and Liquid Fuels
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
E284 Terminology of Appearance
E308 Practice for Computing the Colors of Objects by Using the CIE System
2.2 Energy Institute Standard:
IP 17 Determination of Colour—Lovibond Tintometer
3. Terminology
3.1 Definitions:
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.
Current edition approved July 1, 2017May 1, 2020. Published July 2017June 2020. Originally approved in 1996. Last previous edition approved in 20122017 as
D6045 – 12.D6045 – 12 (2017). DOI: 10.1520/D6045-12R17.10.1520/D6045-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Methods for Analysis Testing, available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6045 − 20
3.1.1 ASTM color, n—the name of an empirical scale of expressing the color of a petroleum liquid darker than Saybolt color
based on a scale of 0.5 (lightest) to 8.0 Dil (darkest) and determined by Test Method D1500.
3.1.2 CIE—the abbreviation for the French title of the International Commission on Illumination, or Commission Internationale
de l’Eclairage. E284
3.1.3 CIE Standard Illuminant C, n—Colorimetric illuminant, representing daylight with a correlated color temperature of
6774 K, defined by the CIE in terms of a relative spectral power distribution. E284
3.1.4 CIE 1931 standard observer, n—ideal colorimetric observer with color matching functions x(λ), y(λ), z(λ) corresponding
to a field of view subtending a 2° angle on the retina; commonly called the “2° Standard Observer.” E284
3.1.5 Saybolt color, n—the name of an empirical scale for expressing of the color of a clear petroleum liquid based on a scale
of −16 (darkest) to +30 (lightest) and determined by Test Method D156.
3.1.6 tristimulus values, n—The amounts of three specified stimuli required to match a color.
3.1.6.1 Discussion—
In the CIE system, they are assigned the symbols X, Y, and Z. E284
4. Summary of Test Method
4.1 The sample is poured into the glass sample container, and the container is placed into the light path of the automatic
instrument. A transmittance measurement is performed in order to determine the CIE tristimulus values (under CIE Standard
Illuminant C and the CIE 1931 Standard Observer) of the sample in question. These are then converted instrumentally by the
appropriate algorithm to Saybolt color or ASTM color values.
4.2 The color of the sample is reported in either Test Method D156 or Test Method D1500 values, as appropriate.
5. Significance and Use
5.1 Determination of the color of petroleum products is used mainly for manufacturing control purposes and is an important
quality characteristic because color is readily observed by the user of the product. In some cases the color may serve as an
indication of the degree of refinement of the material. When the color range of a particular product is known, a variation outside
the established range may indicate possible contamination with another product. However, color is not always a reliable guide to
product quality and should not be used indiscriminately in product specifications.
6. Apparatus
6.1 Either instrument described in 6.1.1 or 6.1.2 may be used in this test method.
6.1.1 Spectrophotometer—The spectrophotometer used in the measurement shall satisfy the following specifications:
6.1.1.1 Wavelength Range—380 nm to 780 nm.
6.1.1.2 Effective Wavelength Width—The effective wavelength width of the radiant flux from the slit of the spectrophotometer
shall be 10 nm 6 2 nm or 5 nm 6 1 nm.
6.1.1.3 Linearity—60.5 % of full scale. Photometric reproducibility—60.2 %.
6.1.1.4 Wavelength Accuracy—61 nm.
6.1.1.5 Geometrical Conditions—Normal illumination and collection. The illumination light flux shall not include a ray which
has an angle of five or more degrees toward the central line. The angle of the center line inclination of the illumination flux shall
be 0° 6 2° toward the normal line of the sample surface.
6.1.1.6 The spectrophotometer shall have the capability to compute tristimulus values (CIE XYZ) using CIE Standard
Illuminant C and the CIE 1931 Standard Observer.
6.1.1.7 A spectrophotometer that gives results comparable to those of the instrument described in 6.1.1.1 through 6.1.1.6 shall
be satisfactory.
6.1.2 Tristimulus Filter Colorimeter—Instrument designed for high precision color measurement of clear liquids. The
instrument shall be capable of converting the light transmitted by a sample (under normal illumination/normal detection) into
tristimulus values (CIE XYZ) using the CIE Standard Illuminant C and the CIE 1931 Standard Observer using Practice E308. A
correlation between measured tristimulus values and Test Method D1500 and Test Method D156 numbers shall be used to yield
an equivalent instrumental ASTM color, or Saybolt value, or both. The instrument shall be capable of automatically computing
ASTM color or Saybolt values, or both (see Section 12).
6.1.3 Sample Cell—Sample cell shall be clean, clear, colorless, and unaffected by the petroleum product being measured. Cells
with path lengths of 33 mm have been found suitable for measuring ASTM color, and cells with path lengths of 100 mm have been
found suitable for measuring Saybolt values. The operator shall follow the instrument manufacturer’s procedures and
recommendations.
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6.2 Ultrasonic Bath, Unheated—(optional), of suitable dimensions to hold container(s) placed inside of bath, for use in
effectively dissipating and removing air or gas bubbles that can be entrained in viscous sample types prior to analysis.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Diluent—Kerosine (Warning—Combustible. Vapor harmful.) having a color of +21 saybolt color or lighter by this test
method or Test Method D156, or 1.5 by method B of IP 17. This material is used for diluting dark samples to be measured for
ASTM color. As an alternative, other solvents, such as white oil or solvent neutral 100 of satisfactory purity that meet the color
requirements specified here in 7.2, are also acceptable.
8. Sampling
8.1 Samples shall be taken in accordance with Practice D4057.
8.2 For some sample types, such as viscous lube oils that are prone to having entrained air or gas bubbles present in the sample,
the use of an ultrasonic bath (see 6.2) without the heater turned on (if so equipped), has been found effective in dissipating bubbles
typically within 10 min.
9. Preparation of Sample
9.1 Liquid Petroleum Products such as Lubricating Oils—If the sample is not clear, heat it 6 °C (10 °F) above its cloud point
(see Test Method D2500) and observe the color at that temperature. When the sample is darker than ASTM Color 8, mix 15
volumes of the sample into 85 volumes of the kerosine, and test the mixture.
10. Procedure
10.1 Calibration—Prepare the spectrophotometer or tristimulus filter colorimeter for operation following the manufacturer’s
instructions.
10.1.1 Periodic measurement of suitable Test Method D1500 or Test Method D156, or both, comparative samples would verify
instrumental performance. Refer to the manufacturer’s documentation for specific details. A method for creating suitable samples
is included in Appendix X1.
10.1.2 Basic calibration procedures are given in Appendix X2.
10.2 Measurement—Place the cell filled with the sample in the instrument, and measure according to the manufacturer’s
instructions.
10.3 Record the ASTM color value or Saybolt number as appropriate.
11. Report
11.1 Report the following information:
11.1.1 The color of the sample as either Saybolt color to the nearest whole number or ASTM color according to the following
procedure: (1) for results with decimal numerical values of x.1 to x.4, precede the value with the capital letter “L” or with a “<”
and change the decimal value to x.5 (for example, for 3.1–3.4, report L3.5 ASTM color or <3.5 ASTM color); (2) for results with
decimal numerical values of x.5, report as stated (for example, for 3.5, report 3.5 ASTM color); (3) for results with decimal
numerical values x.6–x.9, precede the value with the capital letter “L” or with a “<” and round up to the next larger whole value
(for example, for 3.6–3.9, report as L4 ASTM color or <4 ASTM color); (4) for results with decimal numerical values of x.0, report
as stated (for example, for 4.0 report as 4.0 ASTM color); (5) for results greater than 8.0, report as D8 ASTM color or >8 ASTM
color.
11.1.2 If the sample has been diluted in accordance with 7.2, report the color of the mixture followed by the abbreviation “Dil,”
for example, “L7.5 Dil ASTM color” or “<7.5 Dil ASTM color” (see Note 2).
NOTE 2—For samples that are diluted in 11.1.2, it is permissible for the laboratory to annotate the report in any suitable manner, provided that the
information clearly conveys to the data recipient that the sample analyzed was diluted.
11.1.3 When the sample has been filtered, add the words, “sample filtered.”
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not listed by the American Chemical Society, see
AnnualAnalar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial
Convention, Inc. (USPC), Rockville, MD.
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12. Precision and Bias
12.1 A correlation has been derived between the manual Test Method D156 Saybolt color and the manual Test Method D1500
ASTM color, and this automatic method in a cooperative program involving five laboratories and ten petroleum materials. Data
were generated in 1993 and details and statistical analyses are on file at ASTM Headquarters.
12.2 Precision—The precision of this test method as obtained by statistical examination of interlaboratory test results is as
follows:
12.2.1 Repeatability—The difference between successive test results obtained by the same operator with the same apparatus
under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the
test method, exceed the following value only in one case in twenty):
12.2.1.1 r = 0.14 Saybolt color units (Test Method D156).
12.2.1.2 r = 0.10 ASTM color units (Test Method D1500).
12.2.2 Reproducibility—The difference between two single and independent test results obtained by different operators working
in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method,
exceed the following value only in one case in twenty:
12.2.2.1 R = 1.24 (correlation with Test Method D156).
12.2.2.2 R = 0.48 (correlation with Test Method D1500).
12.3 Bias:
12.3.1 There is no bias in the correlation between this test method and Test Method D1500.
12.3.2 There is no bias in the correlation between this test method and Test Method D156 in the range from 0 to +30. There
is a bias for the range from 0 to −16.
13. Keywords
13.1 ASTM color; automatic colorimeter; color measurement; petroleum products color; Saybolt; tristimulus
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1356. Contact ASTM Customer
Service at service@astm.org.
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APPENDIXES
(Nonmandatory Information)
X1. PREPARATION PROCEDURE OF THE COLOR STANDARD SAMPLES
INTRODUCTION
This appendix is an explanation about preparation of color standard samples referred to in
RR:D02-1356. It is also an example of the preparation of possible standard samples that can be used
for periodic checks (see 10.1.1).
X1.1 Scope
X1.1.1 This appendix describes the preparation procedure of the Saybolt color standard samples and ASTM color standard
samples.
X1.2 Referenced Documents
X1.2.1 IEC Standard: IEC 867 Insulating Liquids—Specifications for Unused Liquids Based on Synthetic Aromatic Hydrocar-
bons
X1.2.2 Japanese Industrial Standard: K 0510 High Purity Dodecane
X1.3 Apparatus
X1.3.1 The apparatus shall conform to the specifications set forth in 6.1 through 6.1.3.
X1.3.1.1 Cells—The optical path lengths shall be 10 mm, 33 mm, and 100 mm.
X1.3.1.2 Balance—The balance shall have a readability of 0.1 mg or better.
X1.3.1.3 Pipette—The capacity shall be 2 mL.
X1.3.1.4 Volumetric Flasks—The capacity shall be 200 mL and 250 mL.
X1.3.1.5 Erlenmeyer Flasks with Standard Taper Joint—The capacity shall be 100 mL.
X1.3.1.6 Beaker—The capacity shall be 50 mL.
X1.4 Reagents
X1.4.1 Dyes:
X1.4.1.1 3-Methyl-1-phenyl-4-(phenyl azo)-pyrazol-5-ol (hereinafter referred to as Yellow 5GS-EX). The CAS RN (Chemical
Abstracts Service Registry Number) is 4314-14-1.
X1.4.1.2 1-(phenyl azo)-2-naphthalenol (Orange EX). CAS RN 842-07-9.
X1.4.1.3 1,4 bis(butylamino)-9,10-anthracenedione (Blue SB). CAS RN 17354-14-2.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from Japanese Standards Association (JSA), Mita MT Bldg., 3-13-12 Mita, Minato-ku, Tokyo 108-0073, Japan, http://www.jsa.or.jp.
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X1.4.1.4 1-[[4-[(dimethylphenyl)azo]dimethylphenyl]azo]- 2-naphthalenol (Red 5B-SP). CAS RN 1320-06-5.
X1.4.1.5 1,5 (or 1,8)-bis[(4 methyl phenyl)amino]-9,10-anthracenedione (Violet 3R). CAS RN 8005-40-1.
X1.4.1.6 1-hydroxy-4-[(4-methyl phenyl)amino]-9,10anthracenedione (Violet B-2R). CAS RN 81-48-1.
X1.4.1.7 1,4-bis[
...