1、Designation: D 6875 08Standard Test Method forSolidification Point of Industrial Organic Chemicals byThermistor1This standard is issued under the fixed designation D 6875; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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. Scope1.1 This test method covers a general procedure for deter-mining the solidification point of most organic chemicalshaving
3、 appreciable heats of fusion and solidification pointsbetween 4 and 41C.NOTE 1Other test methods for determining freeze point and solidifi-cation point of aromatic hydrocarbons include Test Methods D 852,D 1015, D 1016, D 3799, D 4493, and D 6269.1.2 This test method is applicable to relatively pure
4、 com-pounds only. Solidification point depression is dependent onimpurity concentrations.1.3 The following applies to all specified limits in this testmethod: for purposes of determining conformance with appli-cable specifications using this test method, an observed valueor a calculated value shall
5、be rounded off “to the nearest unit”in the last right hand digit used in expressing the specificationlimit, in accordance with the “rounding-off method” of PracticeE29.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This
6、 standard does not purport to address all of thesafety 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. For a specifichazard s
7、tatement, see Section 8, Hazards.2. Referenced Documents2.1 ASTM Standards:2D 852 Test Method for Solidification Point of BenzeneD 1015 Test Method for Freezing Points of High-PurityHydrocarbonsD 1016 Test Method for Purity of Hydrocarbons fromFreezing PointsD 3437 Practice for Sampling and Handling
8、 Liquid CyclicProductsD 3438 Practice for Sampling and Handling Naphthalene,Maleic Anhydride, and Phthalic AnhydrideD 3799 Test Method for purity of Styrene by Freezing PointMethod3D 3852 Practice for Sampling and Handling Phenol,Cresols, and Cresylic AcidD 4297 Practice for Sampling and Handling Bi
9、sphenol A(4,48 -Isopropylidinediphenol)D 4493 Test Method for Solidification Point of Bisphenol A(4,48-Isopropylidenediphenol)D 6269 Test Method for Solidification Point of p-Xylene3E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Other Documents:
10、OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120043. Terminology3.1 Definitions:3.1.1 solidification point, nan empirical constant definedas the temperature at which the liquid phase of a substance isin approximate equilibrium with a relatively small portion ofthe solid phase.3.1.1.1 Discus
11、sionSolidification point as distinguishedfrom freezing point is described in Test Method D 1015.Aninterpretation of mole percent in terms of freezing point isgiven in Test Method D 1016.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals an
12、d is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved Oct. 1, 2008. Published November 2008. Originallyapproved in 2003. Last previous edition approved in 2003 as D 6875 - 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcont
13、act ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington
14、, DC 20401, http:/www.access.gpo.gov.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 The solidification point is measured by noting themaximum temperature reached during a cooling cycle after theappearanc
15、e of a solid phase.5. Significance and Use5.1 This test method may be used for process control duringthe manufacture of organic chemicals described in Section 1,for setting specifications, for development and research work,and to determine if contamination was introduced duringshipment.6. Apparatus6
16、.1 Ohmmeter, capable of measuring resistance to the near-est 0.1 ohm in the range of 1000 to 10 000 ohms with directtemperature readout.56.2 Specimen Container, thick walled test tube with 18 mmoutside diameter and 14 mm inside diameter and 150 mm long.6.3 Stirrer, consisting of a 1-mm stainless ste
17、el wire bentinto a circular form at right angles to the shaft so it will movefreely in the annular space between the thermistor and the wallof the test tube.6.4 Stirring Apparatus (Optional)The apparatus illus-trated in Fig. 1 has been demonstrated to be an acceptablereplacement for manual stirring.
18、6.5 Temperature Bath, capable of being controlled at 5 61C below the expected solidification point.6.6 Thermistor, in stainless steel housing with resistancegreater than 2K ohms at 25C. Calibration accuracy 60.01C.Drift in resistance equivalent to less than 60.01C/year.Thermistor shall be calibrated
19、 to cover the range it is used.67. Reagents and Materials7.1 Cooling Media:7.1.1 Water is recommended for solidification points be-tween 4 and 30C.7.2 Drying Agents:7.2.1 3A Molecular Sieve, in the form of a powder orcylindrical granules about 3 mm in diameter.8. Hazards8.1 Consult current OSHA regu
20、lations, suppliers MaterialSafety Data Sheets, and local regulations for all materials usedin this procedure.8.2 Appropriate personal protection equipment such asgloves, safety glasses, a long rubber apron, and a full faceshield should be worn when handling hot or corrosive chemi-cals, or both.8.3 A
21、 fume hood should be used when performing the testmethod on hazardous chemicals (OSHA 1910.1450 definition).9. Sampling and Handling9.1 Sample the material in accordance with PracticesD 3437, D 3438, D 3852, and D 4297.10. Preparation of Apparatus10.1 Fit the sample container with a two-hole stopper
22、.Through one hole insert the thermistor. Through the other holeinsert the shaft of the stirrer. (See Fig. 1).10.2 Set temperature bath at 5 6 1C. below the expectedsolidification point of the sample.11. Calibration of Thermistor11.1 Thermistor should be calibrated by the factory at aminimum every tw
23、o years.11.2 The thermistor may be checked by determining the icepoint of water 0.00C.12. Sample Preparation12.1 Solids at Room TemperatureMelt the entire sampleby heating it to about 10C above its solidification point andswirl it for homogeneity.12.2 Drying SamplesIf required by specifications orag
24、reement with customer.12.2.1 p-Xylene should be dried before testing by placingabout 100 g of the material in a 400 mL Erlenmeyer flask andadding about 50 g of 3A molecular sieve.12.3 Benzene is a special case and should be saturated withwater as follows:12.3.1 Place 7 to 8 mL of the specimen in the
25、 samplecontainer.12.3.2 Add 1 drop of water to the specimen.12.3.3 Shake the sample tube vigorously.13. Procedure13.1 Place 7 to 8 mL of the specimen from step 12.2 or 12.3in the sample container.13.2 Insert the stopper with the thermistor and stirrer intothe sample container and adjust the thermist
26、or so that it is about5 mm from the bottom.13.3 Place the sample container in the constant temperaturebath set at 5 6 1C below the expected solidification point. Inthe case of cyclohexane, the constant temperature bath shouldbe set about 0.3C below the expected solidification point.13.4 Stir the spe
27、cimen continuously and observe the tem-perature readings closely. The temperature will fall to aminimum (super cooling), then rise to a maximum. Record themaximum temperature.13.5 If distinct minimum and maximum points are notevident, the determination shall be repeated. If the temperaturedoes not r
28、ise to a maximum, increase the constant temperaturebath temperature slightly and repeat the solidification pointdetermination. Repeat increasing the temperature until a mini-mum temperature is observed and the temperature then rises toa maximum.5The sole source of supply of the apparatus known to th
29、e committee at this timeis the Hart Scientific Model 1504, 220 N. 1300 West, P.O. Box 460, Pleasant Grove,UT 84062. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the resp
30、onsible technical committee,1which you may attend.6The sole source of supply of the apparatus known to the committee at this timeis GE Thermometrics, type CSP A727X-CSP60BA252M, 967 Windfall Rd. St.Marys, PA 15857. If you are aware of alternative suppliers, please provide thisinformation to ASTM Int
31、ernational Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.D687508214. Calculations14.1 Benzene results should be reported on an anhydrousbasis by adding 0.09C to the observed maximum temperaturefollowing the mini
32、mum.14.2 All other results should be reported as observed.15. Report15.1 Results shall be reported to the nearest 0.01C.16. Precision and Bias16.1 Benzene7Based on seven labs analyzing threesamples on two different days.16.1.1 Intermediate Precision (formerly calledRepeatability)Results in the same
33、laboratory should not beconsidered suspect unless they differ more than 0.04C. On thebasis of test error alone, the difference between the resultsobtained in the same laboratory on the same material will beexpected to exceed this value only 5 % of the time.16.1.2 ReproducibilityResults submitted by
34、each of twolaboratories should not be considered suspect unless they differby more than 0.05C. On the basis of test error alone, thedifference between two test results obtained in different labo-ratories on the same material will be expected to exceed thisvalue only 5 % of the time.16.2 CyclohexaneB
35、ased on a single sample analyzed fivetimes in three different laboratories.16.2.1 RepeatabilityResults in the same laboratory shouldnot be considered suspect unless they differ more than 0.015C.On the basis of test error alone, the difference between theresults obtained in the same laboratory on the
36、 same materialwill be expected to exceed this value only 5 % of the time.16.2.2 ReproducibilityResults submitted by each of twolaboratories should not be considered suspect unless they differ7Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research
37、 Report RR: D16-1028.FIG. 1 Solidification Point Apparatus Set UpD6875083by more than 0.06C. On the basis of test error alone, thedifference between two test results obtained in different labo-ratories on the same material will be expected to exceed thisvalue only 5 % of the time.16.3 p-Xylene8Based
38、 on a single sample analyzed fivetimes in six laboratories.16.3.1 RepeatabilityResults in the same laboratory shouldnot be considered suspect unless they differ more than 0.026C.On the basis of test error alone, the difference between theresults obtained in the same laboratory on the same materialwi
39、ll be expected to exceed this value only 5 % of the time.16.3.2 ReproducibilityResults submitted by each of twolaboratories should not be considered suspect unless they differby more than 0.035C. On the basis of test error alone, thedifference between two test results obtained in different labo-rato
40、ries on the same material will be expected to exceed thisvalue only 5 % of the time.16.4 BiasSince there is no accepted reference materialsuitable for determining the bias for this procedure, bias hasnot been determined.17. Keywords17.1 benzene; cyclohexane; p-Xylene; solidification pointASTM Intern
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42、heir own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand shoul
43、d be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Stand
44、ards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).8Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D16-1027.D6875084
