1、Designation: D 1747 99 (Reapproved 2004)e1An American National StandardStandard Test Method forRefractive Index of Viscous Materials1This standard is issued under the fixed designation D 1747; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTEWarning notes were e
3、ditorially moved into the standard text in May 2004.1. Scope1.1 This test method covers the measurement of refractiveindexes, accurate to two units in the fourth decimal place, oftransparent and light-colored viscous hydrocarbon liquids andmelted solids that have refractive indexes in the range betw
4、een1.33 and 1.60, and at temperatures from 80 to 100C. Tem-peratures lower than 80C can be used provided that themelting point of the sample is at least 10C below the testtemperature.1.2 This test method is not applicable, within the accuracystated, to liquids having colors darker than ASTM Color No
5、. 4,ASTM color as determined by Test Method D 1500, to liquidswhich smoke or vaporize readily at the test temperature, or tosolids melting within 10C of the test temperature.NOTE 1The instrument can be successfully used for refractive indicesabove 1.60; but since certified liquid standards for range
6、s above 1.60 arenot yet available, the accuracy of measurement under these conditions hasnot been evaluated.1.3 The values stated in SI units are to be regarded asstandard. The values stated in inch-pound units are for infor-mation only.1.4 This standard does not purport to address all of thesafety
7、concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 362 Specification for Industrial
8、Grade Toluene3D 841 Specification for Nitration Grade TolueneD 1218 Test Method for Refractive Index and RefractiveDispersion of Hydrocarbon LiquidsD 1500 Test Method for ASTM Color of Petroleum Prod-ucts (ASTM Color Scale)E 1 Specification for ASTM Liquid-in-Glass Thermometers3. Terminology3.1 Defi
9、nition:3.1.1 refractive indexthe ratio of the velocity of light (ofspecified wavelength) in air, to its velocity in the substanceunder examination. The relative index of refraction is definedas the sine of the angle of incidence divided by the sine of theangle of refraction, as light passes from air
10、 into the substance.If absolute refractive index (that is, referred to vacuum) isdesired, this value should be multiplied by the factor 1.00027,the absolute refractive index of air. The numerical value ofrefractive index of liquids varies inversely with both wave-length and temperature.4. Summary of
11、 Test Method4.1 The refractive index normally is measured by the criticalangle method using monochromatic light from a sodium lamp.The instrument is previously adjusted by means of calibrationobtained with certified liquid standards.5. Significance and Use5.1 Refractive index is a fundamental physic
12、al property thatcan be used in conjunction with other properties to characterizepure hydrocarbons and their mixtures.5.2 The use of refractive index in correlative methods forthe determination of the gross composition of viscous oils andwaxes often requires its measurement at elevated temperatures.6
13、. Apparatus6.1 Refractometer, precision Abb-type,4having a range inrefractive index from 1.30 to 1.63. Other instruments readingto at least four decimal places may be used.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsi
14、bility of SubcommitteeD02.04 on Hydrocarbon Analysis.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1960. Last previous edition approved in 1999 as D 1747 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
15、iceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4The Abb-type precision refractometer is no longer available but may beobtainable from instrument exchanges or used equipment suppliers. Other precisionrefract
16、ometers may be suitable, but they have not as yet been tested cooperatively.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 2When other instruments are used, follow the manufacturersinstructions for operation, maintenance, calib
17、ration, and analysis. Foraccepting the instrumentation for use, analysis of an NIST traceablecertified material to ensure accuracy should be performed.6.2 Thermostat and Circulating Pump, capable of maintain-ing the indicated prism temperature constant within 0.02C.The circulating fluid consists of
18、ethylene glycol or a mixture of30 to 40 volume % of glycerin in water flowing through theprisms at a fixed rate of at least 2.5 L/min. For work at 100C,properly controlled wet steam is also suitable.NOTE 3The constancy of the prism temperature can be seriouslyaffected by variations in ambient condit
19、ions, such as air drafts or changesin room temperature. Reasonable precautions should be taken to minimizethese factors. Insulation placed on the thermostat, circulating fluid lines,and refractometer also may prove to be helpful.6.3 Thermometers, conforming to Thermometer 21C fordeterminations at 80
20、C or Thermometer 22C for determina-tions at 100C as given in Specification E 1 are recommended.The temperature measuring device, suitably calibrated, shall bepositioned to measure the temperature of the prism (see Note 4)within an appropriate holder. The holder shall provide foradequate immersion of
21、 the temperature measuring device andfor free flow of the circulating fluid. The temperature measur-ing device holder assembly shall be insulated with a suitablematerial, such as cork.NOTE 4In the precision Abb type refractometer, the thermostatingliquid should pass the thermometer on leaving, not o
22、n entering, the prismassembly.6.4 Thermocouple,5copper-constantan foil type, 0.013-mm(0.0005-in.) thickness, and precision potentiometer. The ther-mocouple is calibrated by immersing to a depth of 25 mm (1in.) in a circulating liquid thermostat and comparing with athermometer of known accuracy.6.5 L
23、ight Source, Sodium Arc LampThe light source shallbe a sodium arc lamp, which shall be used only after theremoval of Amici compensating prisms, if there are any presentin the instrument.NOTE 5If the field division as observed in 12.2 shifts when the Amiciprism is rotated, the prism should be removed
24、 to avoid incorrect readings.7. Solvents7.1 Cleaning Solvent, any suitable solvent capable of clean-ing the apparatus as described in Section 10. 1,1,1, Trichloro-ethane has been found suitable to use. (WarningHarmful ifinhaled. High concentration can cause unconsciousness ordeath. Contact can cause
25、 skin irritation and dermatitis.)7.2 Toluene, conforming to Specification D 362 or Specifi-cation D 841. (WarningFlammable. Vapor harmful.)8. Reference Standards8.1 Primary Liquid StandardsOrganic liquids listed inTable 1, with the values of their refractive indexes for thesodium D line certified at
26、 20, 25, 30, 80, and 100C.6(WarningPrimary standards are combustible.)8.2 Working StandardsFor working standard hydrocar-bons, reasonably well purified samples of n-hexadecane, trans-decahydronaphthalene, and 1-methylnaphthalene may be used.Their exact values are determined by comparison with standa
27、rdsamples of the same hydrocarbons having certified values ofrefractive index. (WarningWorking standards are combus-tible.)9. Sample9.1 A sample of at least 0.5 mL is required. The sample shallbe free of suspended solids, water, or other materials that tendto scatter light. Water can be removed from
28、 hydrocarbons bytreatment with calcium chloride followed by filtering orcentrifuging to remove the desiccant. The possibility of chang-ing the composition of a sample by action of the drying agent,by selective adsorption on the filter, or by fractional evapora-tion, shall be considered.10. Preparati
29、on of Apparatus10.1 The refractometer shall be kept scrupulously clean atall times. Dust and oil, if allowed to accumulate on any part ofthe instrument, will find its way into the moving parts, causingwear and eventual misalignment. If permitted to collect on theprism, dust will dull the polish, res
30、ulting in hazy lines.10.2 Thoroughly clean the prism faces with fresh clean lenstissue or surgical grade absorbent cotton saturated with asuitable solvent. Pass the swab very lightly over the surfaceuntil it shows no tendency to streak. Repeat the procedure witha fresh swab and solvent until both th
31、e glass and adjacentpolished metal surfaces are clean. Do not dry the prism facesby rubbing with dry cotton.10.3 Adjust the thermostat so that the temperature as indi-cated by the thermocouple inserted between the prism facesand wet with oil is within 0.2C of the desired test temperature.This temper
32、ature is to be held constant to within 0.02C duringthe test. Observe and record the thermometer reading corre-sponding to the test temperature. Turn on the sodium arc lampand allow it to warm up for 30 min.11. Standardization with Reference Liquids11.1 Introduce a sample of the API Standard trans-de
33、cahydronaphthalene to the prism which is adjusted to thechosen test temperature of 80 or 100C, turn the telescopeadjustment screw until a refractive index scale reading corre-sponding to the certified refractive index for trans-decahydronaphthalene is observed, and adjust the instrument5The sole sou
34、rce of supply of the apparatus known to the committee at this timeis RdF Corp., 23 Elm Avenue, Hudson, NH 03051. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsib
35、letechnical committee1, which you may attend.6Available from API Standard Reference Office, Carnegie-Mellon University,Pittsburgh, PA 15213.TABLE 1 Primary Liquid StandardsCertified StandardApproximate Refractive Index,nDn-Hexadecane 1.41trans-Decahydronaphthalene 1.441-Methylnaphthalene 1.59D 1747
36、99 (2004)e12according to the instructions given by the manufacturer untilthe sharp boundary between the light and dark portions of thefield passes through the intersection of the cross hairs of thetelescope.11.2 Check the accuracy of this setting by loading a freshsample of trans-decahydronaphthalen
37、e and measure its refrac-tive index at the test temperature following the proceduredescribed in Section 12. If the value for the refractive indexdiffers from the certified value by 0.0001 or more units, thenrepeat the procedure given in 11.1 until a satisfactory check isobtained.11.3 Measure the ref
38、ractive index of API Standardn-hexadecane and 1-methylnaphthalene at the test temperaturefollowing the procedure described in Section 12.11.4 Construct a calibration curve for use at the chosen testtemperature. Plot the difference between the observed refrac-tive index for n-hexadecane and its certi
39、fied value along theordinate against the refractive index level along the abscissa.Also plot the difference between the observed and certifiedrefractive indices for 1-methylnaphthalene in the same manner.Draw a straight line from the point representing the deviationfound for n-hexadecane to zero at
40、the certified refractive indexof trans-decahydronaphthalene. Likewise, draw a straight linefrom this same zero point to the deviation found for1-methylnaphthalene.11.5 If it is desired to measure the refractive index ofsamples at a temperature other than 80 or 100C, obtaincalibration data by repeati
41、ng 11.1-11.4 at this desired tempera-ture. Determine the refractive indices for the API Standardcompounds, n-hexadecane, trans-decahydronaphthalene, and1-methylnaphthalene at the desired temperature by plotting thecertified refractive indices at 20, 25, 30, 80, and 100C againsttemperature and drawin
42、g a smooth curve between the points.11.6 PrecautionsIn using pure liquids for calibration orchecking of calibration of an Abb-type refractometer, thefollowing precautions should be observed:11.6.1 Before inserting the hydrocarbon calibrating liquids,the prisms should be flushed with solvents and cle
43、aned asdescribed in 8.2. It is advisable to preheat the solvent beforeuse to minimize thermal shock to the prism. This should befollowed by several such flushings with the test liquid andwiping with lens paper. After such cleaning, a reading with thetest liquid should be taken as described in Sectio
44、n 11. Thisshould be followed by another flushing with the test liquidbefore taking another reading of the test liquid in the prescribedmanner. The prisms cannot be considered free from contami-nating substances until two such determinations on the testliquid agree within the limits given in 11.6.2.1
45、1.6.2 In setting the edge of the field on the cross hairs,readings should be taken in pairs, approaching the alidadesetting from one direction only as recommended by themanufacturer. Several such sets will probably be necessarybefore satisfactory agreement is obtained. Satisfactory agree-ment is 0.0
46、0005 to 0.0001.11.6.3 For results of highest accuracy, the calibration withhydrocarbons of known properties should be made immedi-ately before the determination on the sample.11.6.4 Fluctuations in ambient temperatures should be mini-mized as much as possible during the test.12. Procedure12.1 Thorou
47、ghly clean the prism faces as described in 10.2.Adjust the thermostat so that the temperature indicated by thethermocouple placed between the faces of the closed prism(loaded with oil) is within 0.2C of the desired value. Thethermocouple is used for establishing the correct temperaturelevel and may
48、be removed during measurements of refractiveindex. The observed reading of the thermometer at thistemperature must be held constant to 0.02C in the measure-ments to follow.12.2 Close the prism box and let it stand for 3 to 5 min toensure temperature equilibrium between the prisms and thecirculating
49、bath liquid. Melt samples which are normally solidin a small container and charge as a liquid to the prism. Chargethe sample from a small pipet or medicine dropper through therefractometer opening or onto the prisms open just enough toadmit the sample. About 0.2 to 0.5 mL of the sample should beallowed to flush through before completely closing the prisms.Samples of low volatility or high viscosity may be placeddirectly onto the prism surface by means of a stirring rod, beingcareful not to touch the prism surface with the rod. If notenough sample h
