ASTM D1747-99(2004)e1
(Test Method)Standard Test Method for Refractive Index of Viscous Materials
Standard Test Method for Refractive Index of Viscous Materials
SIGNIFICANCE AND USE
Refractive index is a fundamental physical property that can be used in conjunction with other properties to characterize pure hydrocarbons and their mixtures.
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 to 100oC. Temperatures lower than 80C can be used provided that the melting point of the sample is at least 10oC 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 D 1500, to liquids which smoke or vaporize readily at the test temperature, or to solids melting within 10oC 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. The values stated in inch-pound units are for information only.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D1747–99 (Reapproved 2004)
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. A number 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 Department of Defense.
´ NOTE—Warning notes were editorially moved into the standard text in May 2004.
1. Scope D841 Specification for Nitration Grade Toluene
D1218 Test Method for Refractive Index and Refractive
1.1 This test method covers the measurement of refractive
Dispersion of Hydrocarbon Liquids
indexes, accurate to two units in the fourth decimal place, of
D1500 TestMethodforASTMColorofPetroleumProducts
transparent and light-colored viscous hydrocarbon liquids and
(ASTM Color Scale)
melted solids that have refractive indexes in the range between
E1 Specification for ASTM Liquid-in-Glass Thermometers
1.33 and 1.60, and at temperatures from 80 to 100°C. Tem-
peratures lower than 80°C can be used provided that the
3. Terminology
melting point of the sample is at least 10°C below the test
3.1 Definition:
temperature.
3.1.1 refractive index—the ratio of the velocity of light (of
1.2 This test method is not applicable, within the accuracy
specified wavelength) in air, to its velocity in the substance
stated, to liquids having colors darker thanASTM Color No. 4,
under examination. The relative index of refraction is defined
ASTM color as determined by Test Method D1500, to liquids
as the sine of the angle of incidence divided by the sine of the
which smoke or vaporize readily at the test temperature, or to
angle of refraction, as light passes from air into the substance.
solids melting within 10°C of the test temperature.
If absolute refractive index (that is, referred to vacuum) is
NOTE 1—The instrument can be successfully used for refractive indices
desired, this value should be multiplied by the factor 1.00027,
above 1.60; but since certified liquid standards for ranges above 1.60 are
the absolute refractive index of air. The numerical value of
not yet available, the accuracy of measurement under these conditions has
refractive index of liquids varies inversely with both wave-
not been evaluated.
length and temperature.
1.3 The values stated in SI units are to be regarded as
standard. The values stated in inch-pound units are for infor- 4. Summary of Test Method
mation only.
4.1 Therefractiveindexnormallyismeasuredbythecritical
1.4 This standard does not purport to address all of the
angle method using monochromatic light from a sodium lamp.
safety concerns, if any, associated with its use. It is the
The instrument is previously adjusted by means of calibration
responsibility of the user of this standard to establish appro-
obtained with certified liquid standards.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 5. Significance and Use
5.1 Refractive index is a fundamental physical property that
2. Referenced Documents
canbeusedinconjunctionwithotherpropertiestocharacterize
2.1 ASTM Standards:
pure hydrocarbons and their mixtures.
D362 Specification for Industrial Grade Toluene
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.
This test method is under the jurisdiction of ASTM Committee D02 on
6. Apparatus
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis. 4
6.1 Refractometer, precision Abbé-type, having a range in
Current edition approved May 1, 2004. Published May 2004. Originally
refractive index from 1.30 to 1.63. Other instruments reading
approved in 1960. Last previous edition approved in 1999 as D1747 – 99. DOI:
10.1520/D1747-99R04E01. to at least four decimal places may be used.
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 Abbé-type precision refractometer is no longer available but may be
the ASTM website. obtainable from instrument exchanges or used equipment suppliers. Other precision
Withdrawn. refractometers may be suitable, but they have not as yet been tested cooperatively.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D1747–99 (2004)
TABLE 1 Primary Liquid Standards
inhaled. High concentration can cause unconsciousness or
Approximate Refractive Index, death. Contact can cause skin irritation and dermatitis.)
Certified Standard
n
D
7.2 Toluene, conforming to Specification D362 or Specifi-
n-Hexadecane 1.41
cation D841.(Warning—Flammable. Vapor harmful.)
trans-Decahydronaphthalene 1.44
1-Methylnaphthalene 1.59
8. Reference Standards
8.1 Primary Liquid Standards—Organic liquids listed in
Table 1, with the values of their refractive indexes for the
NOTE 2—When other instruments are used, follow the manufacturer’s
sodium D line certified at 20, 25, 30, 80, and 100°C.
instructions for operation, maintenance, calibration, and analysis. For
(Warning—Primary standards are combustible.)
accepting the instrumentation for use, analysis of an NIST traceable
8.2 Working Standards—For working standard hydrocar-
certified material to ensure accuracy should be performed.
bons, reasonably well purified samples of n-hexadecane, trans-
6.2 Thermostat and Circulating Pump, capable of maintain-
decahydronaphthalene, and 1-methylnaphthalene may be used.
ing the indicated prism temperature constant within 0.02°C.
Theirexactvaluesaredeterminedbycomparisonwithstandard
The circulating fluid consists of ethylene glycol or a mixture of
samples of the same hydrocarbons having certified values of
30 to 40 volume % of glycerin in water flowing through the
refractive index. (Warning—Working standards are combus-
prisms at a fixed rate of at least 2.5 L/min. For work at 100°C,
tible.)
properly controlled wet steam is also suitable.
9. Sample
NOTE 3—The constancy of the prism temperature can be seriously
9.1 Asampleofatleast0.5mLisrequired.Thesampleshall
affected by variations in ambient conditions, such as air drafts or changes
in room temperature. Reasonable precautions should be taken to minimize be free of suspended solids, water, or other materials that tend
these factors. Insulation placed on the thermostat, circulating fluid lines,
to scatter light. Water can be removed from hydrocarbons by
and refractometer also may prove to be helpful.
treatment with calcium chloride followed by filtering or
centrifuging to remove the desiccant. The possibility of chang-
6.3 Thermometers, conforming to Thermometer 21C for
ing the composition of a sample by action of the drying agent,
determinations at 80°C or Thermometer 22C for determina-
by selective adsorption on the filter, or by fractional evapora-
tions at 100°C as given in Specification E1 are recommended.
tion, shall be considered.
Thetemperaturemeasuringdevice,suitablycalibrated,shallbe
positionedtomeasurethetemperatureoftheprism(seeNote4)
10. Preparation of Apparatus
within an appropriate holder. The holder shall provide for
10.1 The refractometer shall be kept scrupulously clean at
adequate immersion of the temperature measuring device and
all times. Dust and oil, if allowed to accumulate on any part of
for free flow of the circulating fluid. The temperature measur-
the instrument, will find its way into the moving parts, causing
ing device holder assembly shall be insulated with a suitable
wear and eventual misalignment. If permitted to collect on the
material, such as cork.
prism, dust will dull the polish, resulting in hazy lines.
NOTE 4—In the precision Abbé type refractometer, the thermostating
10.2 Thoroughly clean the prism faces with fresh clean lens
liquid should pass the thermometer on leaving, not on entering, the prism
tissue or surgical grade absorbent cotton saturated with a
assembly.
suitable solvent. Pass the swab very lightly over the surface
6.4 Thermocouple, copper-constantan foil type, 0.013-mm
until it shows no tendency to streak. Repeat the procedure with
(0.0005-in.) thickness, and precision potentiometer. The ther-
a fresh swab and solvent until both the glass and adjacent
mocouple is calibrated by immersing to a depth of 25 mm (1
polished metal surfaces are clean. Do not dry the prism faces
in.) in a circulating liquid thermostat and comparing with a
by rubbing with dry cotton.
thermometer of known accuracy.
10.3 Adjust the thermostat so that the temperature as indi-
6.5 Light Source, Sodium Arc Lamp—The light source shall
cated by the thermocouple inserted between the prism faces
be a sodium arc lamp, which shall be used only after the
andwetwithoiliswithin0.2°Cofthedesiredtesttemperature.
removalofAmicicompensatingprisms,ifthereareanypresent
This temperature is to be held constant to within 0.02°C during
in the instrument.
the test. Observe and record the thermometer reading corre-
sponding to the test temperature. Turn on the sodium arc lamp
NOTE 5—If the field division as observed in 12.2 shifts when theAmici
prism is rotated, the prism should be removed to avoid incorrect readings.
and allow it to warm up for 30 min.
7. Solvents
11. Standardization with Reference Liquids
7.1 Cleaning Solvent, any suitable solvent capable of clean-
11.1 Introduce a sample of the API Standard trans-
ing the apparatus as described in Section 10. 1,1,1, Trichloro-
decahydronaphthalene to the prism which is adjusted to the
ethane has been found suitable to use. (Warning—Harmful if
chosen test temperature of 80 or 100°C, turn the telescope
adjustment screw until a refractive index scale reading corre-
sponding to the certified refractive index for trans-
decahydronaphthalene is observed, and adjust the instrument
The sole source of supply of the apparatus known to the committee at this time
is RdF Corp., 23 Elm Avenue, Hudson, NH 03051. If you
...
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