1、Designation: D6756 10 (Reapproved 2015)D6756 17Standard Test Method forDetermination of the Red Dye Concentration and Estimationof the ASTM Color of Diesel Fuel and Heating Oil Using aPortable Visible Spectrophotometer1This standard is issued under the fixed designation D6756; the number immediately
2、 following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This
3、 test method covers the determination of the red dye concentration of diesel fuel and heating oil and the estimation ofthe ASTM color of undyed and red-dyed diesel fuel and heating oil. The test method is appropriate for use with diesel fuel andheating oil of Grades 1 and 2 described in Specificatio
4、ns D396, D975, D2880, and D3699. Red dye concentrations are determinedat levels equivalent to 0.1 mgL to 20 mgL of Solvent Red 26 in samples with ASTM colors ranging from 0.5 to 5. The ASTMcolor of the base fuel of red-dyed samples with concentration levels equivalent to 0.1 mgL to 20 mgL of Solvent
5、 Red 26 isestimated for the ASTM color range from 0.5 to 5. The ASTM color of undyed samples is estimated over the ASTM color rangeof 0.5 to 5.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purp
6、ort to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in
7、 accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 A
8、STM Standards:2D396 Specification for Fuel OilsD975 Specification for Diesel Fuel OilsD1500 Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)D2880 Specification for Gas Turbine Fuel OilsD3699 Specification for KerosineD4052 Test Method for Density, Relative Density, and API Gravity
9、 of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6045 Test Method for Color of Petroleum Products by the Automatic Tristimulus MethodD6708 Practice for Statistical Asses
10、sment and Improvement of Expected Agreement Between Two Test Methods that Purportto Measure the Same Property of a MaterialE203 Test Method for Water Using Volumetric Karl Fischer TitrationE1655 Practices for Infrared Multivariate Quantitative AnalysisE2056 Practice for Qualifying Spectrometers and
11、Spectrophotometers for Use in Multivariate Analyses, Calibrated UsingSurrogate Mixtures3. Terminology3.1 Definitions:1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Propert
12、ies of Fuels, Petroleum Coke and Carbon Material.Current edition approved Oct. 1, 2015May 1, 2017. Published December 2015May 2017. Originally approved in 2002. Last previous edition approved in 20102015 asD6756 10.D6756 10 (2015). DOI: 10.1520/D6756-10R15.10.1520/D6756-17.2 For referencedASTM stand
13、ards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an AS
14、TM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published
15、 by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 ASTM color, nthe name of an empirical scale of expressing the co
16、lor of a petroleum liquid darker than Saybolt colorbased on a scale of 0.5 (lightest) to 8 Dil (darkest) and determined by Test Method D1500.3.1.2 surrogate calibration, na multivariate calibration that is developed using a calibration set which consists of mixtureswith pre-specified and reproducibl
17、e compositions that contain substantially fewer chemical components than the samples whichwill ultimately be analyzed. E20563.1.3 surrogate method, na standard test method that is based on a surrogate calibration. E20563.2 Definitions of Terms Specific to This Standard:3.2.1 red dye, nsubstance that
18、, when added to fuel, absorbs green light and imparts a red color to the product. For this testmethod, red dyes are:3.2.1.1 product dyes, nalkyl derivatives of azobenzene-4-azo-2-naphthol (methyl derivatives of Color Index No. 26105)which are more soluble in diesel fuel.3.2.1.2 solvent red 26, nan a
19、zobenzene-4-azo-2-naphthol dye of a specific chemical structure that is used to gage the amountof red dye present in a given sample.4. Summary of Test Method4.1 Asample is introduced into the liquid specimen cell. The cell is placed into the light path of the apparatus.Abeam of visiblelight is image
20、d through the sample onto a detector, and the detector response is determined. Wavelengths of the spectrum, whichcorrelate highly with the red dye concentration and the ASTM color, are selected for analysis using selective bandpass filters. Amultivariate mathematical model converts the absorption va
21、lues from the filters to the red dye concentration and the estimatedASTM color.5. Significance and Use5.1 In the United States, high sulfur content (defined by the United States Environmental Protection Agency (USEPA) middledistillate products and diesel fuel used for off-road purposes, other than a
22、viation turbine fuel, are required by government agenciesto contain red dye. The dye concentration required to be present in high sulfur high-sulfur and off-road diesel products is regulatedby the United States Environmental Protection Agency and the United States Internal Revenue Service, respectiv
23、ely.5.2 Some fuels that are readily exchanged in the market have a color specification. The color of the base fuel is masked by thepresence of the red dye. This test method provides a means of estimating the base color of Number 1 and Number 2 diesel fueland heating oil in the presence of red dye.5.
24、3 The test method provides a means to indicate conformance to contractual and legal requirements.6. Interferences6.1 The presence of colorants other than the hydrocarbons typical of Number 1 and 2 diesel fuel and heating oils, or the presenceof red dye other than the specified types, can interfere w
25、ith the accurate determination of the red dye concentration reported asSolvent Red 26 equivalent or the base fuel ASTM color.7. Apparatus7.1 Filter Spectrophotometer, is equipped with specimen chamber, visible wavelength source, four 10 nm 6 2 nm (full widthat half transmission maximum) bandpass wav
26、elength discriminating filters having center wavelengths at 450 nm 6 2 nm, 520 nm6 2 nm, 650 nm 6 2 nm, and 700 nm 6 2 nm. The bandpass filters are used in conjunction with the visible wavelength sourceto produce light in the blue, green, red, and far-red regions of the electromagnetic spectrum. A d
27、etector converts the transmittedlight to an electronic signal that is processed by an A-D converter and a microprocessor.3,47.2 Specimen Cell, constructed of polymethacrylate or clear optical glass having a path length of approximately 1 cm. If morethan one cell is used for calibration, qualificatio
28、n, and sample measurement, the path length of the cells must be matched to60.001 cm.8. Sampling8.1 Samples shall be taken in accordance with Practice D4057 or D4177.8.2 Precautions must be taken to shield the samples from light prior to analysis.9. Calibration and Standardization of the Apparatus9.1
29、 The instrument is calibrated according to the procedure described in Annex A2.NOTE 1The DT100C3 instruments are calibrated at the factory by the vendor.3 DT100C instruments used to develop this precision statement are available from PetroSpec, Inc., 530 Main St., Acton, MA 01720.4 The sole source o
30、f supply of the apparatus known to the committee at this time is PetroSpec, Inc. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee,1 which
31、you may attend.D6756 1729.2 The instrument is qualified according to the procedure described in Annex A3.NOTE 2The DT100C instruments are qualified at the factory by the vendor.9.2.1 If the qualification procedure is performed by the vendor, then the user shall perform a quality control check accord
32、ingto the procedure described in Section 10.10. Quality Control Check10.1 To confirm the performance of the instrument, periodically measure the red dye concentration and theASTM color of threecontrol samples using the procedure outlined in Section 11. The quality control check standards should be a
33、nalyzed at least oncea week or before the sample analysis if the instrument is used less frequently than weekly or if the instrument is moved to adifferent laboratory or field location.NOTE 3Quality control samples are available from DT100CDT100C.3.10.1.1 Astandard of known dye concentration andASTM
34、 color is made according to the information in A1.4. The set of qualitycontrol samples shall have a low, medium, and high red dye concentration (0 mgL to 14 mgL 6 2 mgL) and a low, medium,and high ASTM color (0 to 5 ASTM color units).10.1.2 The standards are stable for at least one year when stored
35、in the dark in tightly sealed bottles.10.2 If the red dye concentration determined for one of the quality control samples differs from the known value by more than1.0 mgL or if the estimated ASTM color for one of the quality control samples differs from the known value by more than 0.5units, then th
36、e measurement system is out-of-control and cannot be used to determine the red dye concentration or used to estimatethe ASTM color until the cause of the out-of-control behavior is corrected.10.3 If correction of out-of-control behavior requires repair to the instrument or recalibration of the instr
37、ument, the qualificationof instrument performance described in Annex A3 shall be performed before the system is used to measure red dye concentrationor used to estimate ASTM color.11. Procedure11.1 Prepare the filter spectrophotometer for operation in accordance with the manufacturers instructions.1
38、1.2 Equilibrate the sample to between 20 C and 25 C.11.3 Without filtering the sample (see 13.6), fill a clean, dry specimen cell. The external optical surfaces shall be clean. If not,wipe clean and dry with a piece of lint-free paper (for example, lens paper).11.4 Insert the specimen cell into the
39、cell chamber of the instrument.11.5 Record the Solvent Red 26 equivalent concentration and the estimated ASTM color.12. Report12.1 Report the red dye concentration to the nearest 0.1 mgL as Solvent Red 26 equivalent dye.NOTE 4The number of milligrams per litre of Solvent Red 26 equivalents measured
40、by the DT100C instrument is labeled as ppm on the display. Theppm unit reported by the DT100C instrument is equivalent to mg/L.12.2 Report the estimatedASTM color value as: estimated ASTM color using ASTM D6756. Report the result to the nearest 0.1color value.12.2.1 The reported estimated ASTM color
41、 value can be converted to a value that mimics the reporting convention of the TestMethod D1500. For estimated ASTM color values that are x.0 or x.5, the estimated value is reported unchanged. For estimatedcolor values between x.1 and x.4, round up the value to the nearest x.5 and place an L before
42、the result. For estimated color valuesbetween x.6 and x.9, round up the value to the nearest whole number and place an L before the result. If the estimated color valueis greater than 8.0, report the estimated result as 8.13. Precision and Bias513.1 Interlaboratory tests of the procedure were carrie
43、d out using sixteen samples covering the red dye concentration rangeequivalent to 0 mgL to 16 mgL of Solvent Red 26 equivalents and covering the range of ASTM color from 0.5 to 3.0. Sevenlaboratories participated in the interlaboratory tests. The precision of this procedure as determined by the stat
44、istical examinationof the interlaboratory test results is as follows:513.1.1 RepeatabilityThe difference between successive test results obtained with the same apparatus under constant operatingconditions on identical samples would in the long run, in normal and correct operation of the test method,
45、 exceed the followingvalue in only one case in twenty:5 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1521. Contact ASTM CustomerService at serviceastm.org.D6756 173r 50.22 mg/Lfor Solvent Red 26 equivalent dye concentrati
46、ons between 0.1 mgL and 20.0 mgL, andr50.085ASTM color unitsfor samples in the ASTM color range of 0 to 5.13.1.2 ReproducibilityThe difference between two single and independent results obtained from different instruments onidentical samples, would in the long run, in normal and correct operation of
47、 the test method, exceed the following value in onlyone case in twenty:R 50.86 mg/Lfor Solvent Red 26 equivalent dye concentrations between 0.1 mgL and 20.0 mgL, andR50.20ASTM color unitsfor samples in the ASTM color range of 0 to 5.13.2 BiasSince there is no accepted reference material suitable for
48、 determining the bias for the procedure in this test method,bias has not been determined.13.3 Relative Bias (Dye Concentration)Some relative bias,5 among certain samples, was observed when the Solvent Red 26concentration results were compared to the expected Solvent Red 26 concentrations.The bias be
49、tween the theoretical and measuredSolvent Red 26 concentration is observed with the test samples that were made using Solvent Red 164, the chemical used tocommercially dye diesel fuel. The observed bias does appear to be of a systematic nature and is not known to be related to theaccuracy of this test method, since the Solvent Red 26 equivalency of the Solvent Red 164 used in sample preparation has not beendetermined, only estimated.13.4 Relative Bias (ASTM Color)Relative bias,5 for one sample, was observed when the color results were compare
