ASTM D1747-09(2019)

Standard Test Method for Refractive Index of Viscous Materials

SIGNIFICANCE AND USE
5.1 Refractive index is a fundamental physical property that can be used in conjunction with other properties to characterize pure hydrocarbons and their mixtures.  
5.2 The use of refractive index in correlative methods for the determination of the gross composition of viscous oils and waxes often requires its measurement at elevated temperatures.
SCOPE
1.1 This test method covers the measurement of refractive indexes, accurate to two units in the fourth decimal place, of transparent and light-colored viscous hydrocarbon liquids and melted solids that have refractive indexes in the range between 1.33 and 1.60, and at temperatures from 80 °C to 100 °C. Temperatures lower than 80 °C can be used provided that the melting point of the sample is at least 10 °C below the test temperature.  
1.2 This test method is not applicable, within the accuracy stated, to liquids having colors darker than ASTM Color No. 4, ASTM color as determined by Test Method D1500, to liquids which smoke or vaporize readily at the test temperature, or to solids melting within 10 °C of the test temperature.  
Note 1: The instrument can be successfully used for refractive indices above 1.60; but since certified liquid standards for ranges above 1.60 are not yet available, the accuracy of measurement under these conditions has not been evaluated.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm) for additional information. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Apr-2019
• ICS: 17.180.30 - Optical measuring instruments
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0D - Physical and Chemical Methods

Relations

• Replaces: ASTM D1747-09(2014) - Standard Test Method for Refractive Index of Viscous Materials
• Effective Date: 01-May-2019
• Refers: ASTM D1500-24 - Standard Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
• Effective Date: 01-Mar-2024
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D841-19 - Standard Specification for Nitration Grade Toluene
• Effective Date: 15-Nov-2019
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D841-17a - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jul-2017
• Refers: ASTM D841-17 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Jun-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM E77-14 - Standard Test Method for Inspection and Verification of Thermometers
• Effective Date: 01-May-2014
• Refers: ASTM D6299-13e1 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Oct-2013
• Refers: ASTM E1-13 - Standard Specification for ASTM Liquid-in-Glass Thermometers
• Effective Date: 01-May-2013
• Refers: ASTM D841-13 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Feb-2013
• Refers: ASTM D1500-12 - Standard Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
• Effective Date: 01-Dec-2012
• Refers: ASTM D841-12 - Standard Specification for Nitration Grade Toluene
• Effective Date: 01-Nov-2012

Overview

ASTM D1747-09(2019) is the internationally recognized standard for measuring the refractive index of viscous materials, specifically transparent and light-colored viscous hydrocarbon liquids and melted solids. Developed by ASTM International, this test method is vital for laboratories and industries dealing with petroleum products, oils, and waxes. The standard allows for accurate determination of the refractive index, a fundamental physical property used to characterize pure hydrocarbons and their mixtures, at temperatures typically ranging from 80°C to 100°C. Employing such measurements supports quality control, product specification, and research on material properties.

Key Topics

• Measurement Range: Covers refractive index values between 1.33 and 1.60 for applicable viscous hydrocarbon liquids and melts.
• Sample Suitability: Applies only to samples that are transparent or light-colored (ASTM Color No. 4 or lighter) with refractive indexes in the defined range. Samples must not smoke, vaporize readily, or melt within 10°C of the test temperature.
• Test Temperatures: Standard is designed for measurements at 80°C to 100°C, but can be used at lower temperatures if the sample remains stable and melted at least 10°C below the testing point.
• Use of Certified Standards: Requires calibration with primary liquid standards, such as n-hexadecane or 1-methylnaphthalene, to ensure measurement accuracy.
• Accuracy: Delivers refractive index results precise to two units in the fourth decimal place, supporting rigorous analytical and quality requirements.
• Safety: Addresses safety precautions-mercury-containing thermometers are permitted but must be handled per regulatory guidance due to health and environmental risks.

Applications

The ASTM D1747-09(2019) Standard Test Method for Refractive Index of Viscous Materials finds broad application in:

• Petroleum Industry: Characterization of oils and waxes; correlating refractive index with product composition and purity.
• Quality Assurance: Implementing refractive index measurements for specification compliance, batch consistency, and performance analysis.
• Research and Development: Supporting studies of hydrocarbon mixtures and their physical properties at elevated temperatures.
• Process Control: Providing consistent, reliable data for controlling production of lubricants, paraffins, and specialty hydrocarbon products.
• Correlative Methods: Used in conjunction with other test data to estimate the gross composition of viscous materials, especially for products that must meet strict industry benchmarks.

Related Standards

Astute compliance professionals and laboratory personnel should be aware of these related ASTM standards:

• ASTM D1500: Standard Test Method for ASTM Color of Petroleum Products
• ASTM D6299: Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• ASTM E1: Specification for ASTM Liquid-in-Glass Thermometers
• ASTM E77: Test Method for Inspection and Verification of Thermometers

Adherence to these and ASTM D1747-09(2019) promotes high-quality, consistent refractive index data, supporting traceable, reproducible results essential for international trade and regulatory compliance.

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Keywords: ASTM D1747, refractive index, viscous materials, petroleum products, oils, waxes, hydrocarbon liquids, quality control, laboratory test methods, standardization, calibration, instrumentation safety

Standards Content (Sample)

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.
Designation: D1747 − 09 (Reapproved 2019)
Standard Test Method for
Refractive Index of Viscous Materials
This standard is issued under the fixed designation D1747; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This test method covers the measurement of refractive
1.6 This international standard was developed in accor-
indexes, accurate to two units in the fourth decimal place, of
dance with internationally recognized principles on standard-
transparent and light-colored viscous hydrocarbon liquids and
ization established in the Decision on Principles for the
meltedsolidsthathaverefractiveindexesintherangebetween
Development of International Standards, Guides and Recom-
1.33 and 1.60, and at temperatures from 80°C to 100°C.
mendations issued by the World Trade Organization Technical
Temperatures lower than 80°C can be used provided that the
Barriers to Trade (TBT) Committee.
melting point of the sample is at least 10°C below the test
temperature.
2. Referenced Documents
1.2 This test method is not applicable, within the accuracy
2.1 ASTM Standards:
stated,toliquidshavingcolorsdarkerthanASTMColorNo.4,
D362SpecificationforIndustrialGradeToluene(Withdrawn
ASTM color as determined by Test Method D1500, to liquids
1989)
which smoke or vaporize readily at the test temperature, or to
D841Specification for Nitration Grade Toluene
solids melting within 10°C of the test temperature.
D1500Test Method forASTM Color of Petroleum Products
NOTE1—Theinstrumentcanbesuccessfullyusedforrefractiveindices
(ASTM Color Scale)
above 1.60; but since certified liquid standards for ranges above 1.60 are
D6299Practice for Applying Statistical Quality Assurance
notyetavailable,theaccuracyofmeasurementundertheseconditionshas
and Control Charting Techniques to Evaluate Analytical
not been evaluated.
Measurement System Performance
1.3 The values stated in SI units are to be regarded as
E1Specification for ASTM Liquid-in-Glass Thermometers
standard. No other units of measurement are included in this
E77Test Method for Inspection and Verification of Ther-
standard.
mometers
1.4 Warning—Mercury has been designated by EPA and
many state agencies as a hazardous material that can cause
3. Terminology
central nervous system, kidney, and liver damage. Mercury, or
3.1 Definitions:
its vapor, may be hazardous to health and corrosive to
3.1.1 refractive index—the ratio of the velocity of light (of
materials.Cautionshouldbetakenwhenhandlingmercuryand
specified wavelength) in air, to its velocity in the substance
mercury-containing products. See the applicable product Ma-
under examination. The relative index of refraction is defined
terial Safety Data Sheet (MSDS) for details and EPA’s website
as the sine of the angle of incidence divided by the sine of the
(http://www.epa.gov/mercury/faq.htm) for additional informa-
angle of refraction, as light passes from air into the substance.
tion. Users should be aware that selling mercury or mercury-
If absolute refractive index (that is, referred to vacuum) is
containingproducts,orboth,inyourstatemaybeprohibitedby
desired, this value should be multiplied by the factor 1.00027,
state law.
the absolute refractive index of air. The numerical value of
1.5 This standard does not purport to address all of the
refractive index of liquids varies inversely with both wave-
safety concerns, if any, associated with its use. It is the
length and temperature.
responsibility of the user of this standard to establish appro-
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee D02.04.0D on Physical and Chemical Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2019. Published June 2019. Originally the ASTM website.
approved in 1960. Last previous edition approved in 2014 as D1747–09 (2014). The last approved version of this historical standard is referenced on
DOI: 10.1520/D1747-09R19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1747 − 09 (2019)
TABLE 1 Primary Liquid Standards
shall provide for adequate immersion of the temperature-
Approximate Refractive Index, measuringdeviceandforfreeflowofthecirculatingfluid.The
Certified Standard
n
D
temperature-measuring device holder assembly shall be insu-
n-Hexadecane 1.41
lated with a suitable material, such as cork.
trans-Decahydronaphthalene 1.44
1-Methylnaphthalene 1.59
NOTE 4—In the precision Abbé type refractometer, the thermostating
liquid should pass the thermometer on leaving, not on entering, the prism
assembly.
6.4 Thermocouple, copper-constantan foil type, 0.013mm
4. Summary of Test Method
thickness, and precision potentiometer. The thermocouple is
4.1 Therefractiveindexnormallyismeasuredbythecritical
calibrated by immersing to a depth of 25 mm in a circulating
angle method using monochromatic light from a sodium lamp.
liquidthermostatandcomparingwithathermometerofknown
The instrument is previously adjusted by means of calibration
accuracy.
obtained with certified liquid standards.
6.5 Light Source, Sodium Arc Lamp—The light source shall
be a sodium arc lamp, which shall be used only after the
5. Significance and Use
removalofAmicicompensatingprisms,ifthereareanypresent
5.1 Refractiveindexisafundamentalphysicalpropertythat
in the instrument.
canbeusedinconjunctionwithotherpropertiestocharacterize
pure hydrocarbons and their mixtures.
NOTE5—Ifthefielddivisionasobservedin12.2shiftswhentheAmici
prismisrotated,theprismshouldberemovedtoavoidincorrectreadings.
5.2 The use of refractive index in correlative methods for
the determination of the gross composition of viscous oils and
7. Solvents
waxesoftenrequiresitsmeasurementatelevatedtemperatures.
7.1 Cleaning Solvent, any suitable solvent capable of clean-
ing the apparatus as described in Section 10. 1,1,1, Trichlo-
6. Apparatus
roethane has been found suitable to use. (Warning—Harmful
6.1 Refractometer, precision Abbé-type, having a range in
if inhaled. High concentration can cause unconsciousness or
refractive index from 1.30 to 1.63. Other instruments reading
death. Contact can cause skin irritation and dermatitis.)
to at least four decimal places may be used.
7.2 Toluene, conforming to Specification D362 or Specifi-
NOTE 2—When other instruments are used, follow the manufacturer’s
cation D841.(Warning—Flammable. Vapor harmful.)
instructions for operation, maintenance, calibration, and analysis. For
accepting the instrumentation for use, analysis of an NIST-traceable
8. Reference Standards
certified material to ensure accuracy should be performed.
8.1 Primary Liquid Standards—Organic liquids listed in
6.2 Thermostat and Circulating Pump,capableofmaintain-
Table 1, with the values of their refractive indexes for the
ing the indicated prism temperature constant within 0.02°C.
sodium D line certified at 20°C, 25°C, 30°C, 80°C, and
Thecirculatingfluidconsistsofethyleneglycoloramixtureof
100°C. (Warning—Primary standards are combustible.)
30% to 40% by volume of glycerin in water flowing through
the prisms at a fixed rate of at least 2.5 L/min. For work at 8.2 Working Standards—For working standard
100°C, properly controlled wet steam is also suitable. hydrocarbons, reasonably well-purified samples of
n-hexadecane, trans-decahydronaphthalene, and
NOTE 3—The constancy of the prism temperature can be seriously
1-methylnaphthalene may be used. Their exact values are
affected by variations in ambient conditions, such as air drafts or changes
determined by comparison with standard samples of the same
inroomtemperature.Reasonableprecautionsshouldbetakentominimize
these factors. Insulation placed on the thermostat, circulating fluid lines,
hydrocarbons having certified values of refractive index.
and refractometer also may prove to be helpful.
(Warning—Working standards are combustible.)
6.3 Thermometers, or Equivalent Temperature-Measuring
9. Sample
Devices, conforming to Thermometer 21C for determinations
at 80°C or Thermometer 22C for determinations at 100°C as 9.1 Asampleofatleast0.5mLisrequired.Thesampleshall
given in Specification E1 are recommended. See Test Method
be free of suspended solids, water, or other materials that tend
E77 for guidance on inspection and verification of mercury- to scatter light. Water can be removed from hydrocarbons by
in-glass thermometers. Equivalent temperature-measuring de-
treatment with calcium chloride followed by filtering or
vices should have the same accuracy and resolution as Ther- centrifugingtoremovethedesiccant.Thepossibilityofchang-
mometers 21C and 22C.
ing the composition of a sample by action of the drying agent,
6.3.1 In case of dispute, the test method shall be carried out by selective adsorption on the filter, or by fractional
using the specified mercury-in-glass thermometer.
evaporation, shall be considered.
6.3.2 The temperature-measuring device, suitably
calibrated, shall be positioned to measure the temperature of
The sole source of supply of the apparatus known to the committee at this time
theprism(seeNote4)withinanappropriateholder.Theholder
is RdF Corp., 23 ElmAvenue, Hudson, NH 03051. If you are aware of alternative
suppliers, please provide this information to ASTM International Headquarters.
Your comments will receive careful consideration at a meeting of the responsible
4 1
The Abbé-type precision refractometer is no longer available but may be technical committee, which you may attend.
obtainablefrominstrumentexchangesorusedequipmentsuppliers.Otherprecision Available from API Standard Reference Office, Carnegie-Mellon University,
refractometers may be suitable, but they have not as yet been tested cooperatively. Pittsburgh, PA15213.
D1747 − 09 (2019)
10. Preparation of Apparatus temperature. Determine the refractive indices for the API
Standard compounds, n-hexadecane, trans-
10.1 The refractometer shall be kept scrupulously clean at
decahydronaphthalene,and1-methylnaphthaleneatthedesired
all times. Dust and oil, if allowed to accumulate on any part of
temperaturebyplottingthecertifiedrefractiveindicesat20°C,
the instrument, will find its way into the moving parts, causing
25°C, 30°C, 80°C, and 100°C against temperature and
wear and eventual misalignment. If permitted to collect on the
drawing a smooth curve between the points.
prism, dust will dull the polish, resulting in hazy lines.
11.6 Precautions—In using pure liquids for calibration or
10.2 Thoroughlycleantheprismfaceswithfresh,cleanlens
checking of calibration of an Abbé-type refractometer, the
tissue or surgical-grade absorbent cotton saturated with a
following precautions should be observed:
suitable solvent. Pass the swab very lightly over the surface
11.6.1 Before inserting the hydrocarbon calibrating liquids,
untilitshowsnotendencytostreak.Repeattheprocedurewith
the prisms should be flushed with solvents and cleaned as
a fresh swab and solvent until both the glass and adjacent
described in 8.2. It is advisable to preheat the solvent before
polished metal surfaces are clean. Do not dry the prism faces
use to minimize thermal shock to the prism. This should be
by rubbing with dry cotton.
followed by several such flushings with the test liquid and
10.3 Adjust the thermostat so that the temperature as indi-
wiping with lens paper.After such cleaning, a reading with the
cated by the thermocouple inserted between the prism faces
test liquid should be taken as described in Section 11. This
and wet with oil is within 0.2°C of the desired test tempera-
should be followed by another flushing with the test liquid
ture. This temperature is to be held constant to within 0.02°C
beforetakinganotherreadingofthetestliquidintheprescribed
during the test. Observe and record the thermometer reading
manner. The prisms cannot be considered free from contami-
corresponding to the test temperature. Turn on the sodium arc
nating substances until two such determinations on the test
lamp and allow it to warm up for 30 min.
liquid agree within the limits given in 11.6.2.
11.6.2 In setting the edge of the field on the crosshairs,
11. Standardization with Reference Liquids
readings should be taken in pairs, approaching the alidade
setting from one direction only as recommended by the
11.1 Introduce a sample of the API Standard trans-
manufacturer. Several such sets will probably be necessary
decahydronaphthalene to the prism which is adjusted to the
before satisfactory agreement is obtained. Satisfactory agree-
chosen test temperature of 80°C or 100°C, turn the telescope
ment is 0.00005 to 0.0001.
adjustment screw until a refractive index scale reading corre-
11.6.3 For results of highest accuracy, the calibration with
sponding to the certified refractive index for trans-
hydrocarbons of known properties should be made immedi-
decahydronaphthalene is observed, and adjust the instrument
ately before the determination on the sample.
according to the instructions given by the manufacturer until
11.6.4 Fluctuationsinambienttemperaturesshouldbemini-
the sharp boundary between the light and dark portions of the
mized as much as possible during the test.
field passes through the intersection of the crosshairs of the
telescope.
12. Procedure
11.2 Check the accuracy of this setting by loading a fresh
12.1 Thoroughly clean the prism faces as described in 10.2.
sample of trans-decahydronaphthalene and measure its refrac-
Adjust the thermostat so that the temperature indicated by the
tive index at the test temperature following the procedure
thermocouple placed between the faces of the closed prism
described in Section 12. If the value for the refractive index
(loaded with oil) is within 0.2°C of the desired value. The
differs from the certified value by 0.0001 or more units, then
thermocouple is used for establishing the correct temperature
repeat the procedure given in 11.1 until a satisfactory check is
level and may be removed during measurements of refractive
obtained.
index. The observed reading of the thermometer at this
11.3 Measure the refractive index of API Standard
temperature must be held constant to 0.02°C in the measure-
n-hexadecane and 1-methylnaphthalene at the test temperature
ments to follow.
following the procedure described in Section 12.
12.2 Close the prism box and let it stand for 3 min to 5 min
11.4 Construct a calibration curve for use at the chosen test
to ensure temperature equilibrium between the prisms and the
temperature. Plot the difference betwee
...