1、Designation: D6875 12D6875 18Standard Test Method forSolidification Point of Industrial Organic Chemicals byThermistor1This standard is issued under the fixed designation D6875; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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*1.1 This test method covers a general procedure for determining the solidification point of most organic chemicals
3、 havingappreciable heats of fusion and solidification points between 4 and 41C.NOTE 1Other test methods for determining freeze point and solidification point of aromatic hydrocarbons includeTest Methods D852, D1015, D1016,D3799, D4493, and D6269.1.2 This test method is applicable to relatively pure
4、compounds only. Solidification point depression is dependent on impurityconcentrations.1.3 The following applies to all specified limits in this test method: for purposes of determining conformance with applicablespecifications using this test method, an observed value or a calculated value shall be
5、 rounded off “to the nearest unit” in the lastright hand digit used in expressing the specification limit, in accordance with the “rounding-off method” of Practice E29.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 Th
6、is standard does not purport 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 safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior t
7、o use. For a specific hazard statement, see Section 8, Hazards.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations
8、 issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D852 Test Method for Solidification Point of BenzeneD1015 Test Method for Freezing Points of High-Purity HydrocarbonsD1016 Test Method for Purity of Hydrocarbons from Freezin
9、g PointsD3437 Practice for Sampling and Handling Liquid Cyclic ProductsD3438 Practice for Sampling and Handling Naphthalene, Maleic Anhydride, and Phthalic AnhydrideD3799 Test Method for Purity of Styrene by Freezing Point Method (Withdrawn 2000)3D3852 Practice for Sampling and Handling Phenol, Cres
10、ols, and Cresylic AcidD4297 Practice for Sampling and Handling Bisphenol A(4,4 -Isopropylidinediphenol)D4493 Test Method for Solidification Point of Bisphenol A(4,4-Isopropylidenediphenol)D6269 Test Method for Solidification Point of p-Xylene (Withdrawn 2004)3D6809 Guide for Quality Control and Qual
11、ity Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications2.2 Other Documents:OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.120041 This test method is under the jurisdiction of A
12、STM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the directresponsibility of Subcommittee D16.04 on Instrumental Analysis.Current edition approved Dec. 1, 2012Jan. 1, 2018. Published January 2013January 2018. Originally approved in 2003. Last pr
13、evious edition approved in 20082012 asD6875 08.D6875 12. DOI: 10.1520/D6875-12.10.1520/D6875-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Documen
14、t Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.This document
15、is not an ASTM standard and is intended only to provide the user of an ASTM 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 appro
16、priate. In all cases only the current versionof the standard as published 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 Stat
17、es13. Terminology3.1 Definitions:3.1.1 solidification point, nan empirical constant defined as the temperature at which the liquid phase of a substance is inapproximate equilibrium with a relatively small portion of the solid phase.3.1.1.1 DiscussionSolidification point as distinguished from freezin
18、g point is described in Test Method D1015. An interpretation of mole percent interms of freezing point is given in Test Method D1016.4. Summary of Test Method4.1 The solidification point is measured by noting the maximum temperature reached during a cooling cycle after the appearanceof a solid phase
19、.5. Significance and Use5.1 This test method may be used for process control during the manufacture of organic chemicals described in Section 1, forsetting specifications, for development and research work, and to determine if contamination was introduced during shipment.6. Apparatus6.1 Ohmmeter, ca
20、pable of measuring resistance to the nearest 0.1 ohm in the range of 1000 to 10 000 ohms with directtemperature readout.6.2 Specimen Container, thick walled test tube with 18 mm outside diameter and 14 mm inside diameter and 150 mm long.6.3 Stirrer, consisting of a 1-mm stainless steel wire bent int
21、o a circular form at right angles to the shaft so it will move freelyin the annular space between the thermistor and the wall of the test tube.6.4 Stirring Apparatus (Optional)The apparatus illustrated in Fig. 1 has been demonstrated to be an acceptable replacementfor manual stirring.6.5 Temperature
22、 Bath, capable of being controlled at 5 6 1C below the expected solidification point.6.6 Thermistor, in stainless steel housing with resistance greater than 2K ohms at 25C. Calibration accuracy 60.01C. Driftin resistance equivalent to less than 60.01C/year. Thermistor shall be calibrated to cover th
23、e range it is used.7. Reagents and Materials7.1 Cooling Media:7.1.1 Water is recommended for solidification points between 4 and 30C.7.2 Drying Agents:7.2.1 3A Molecular Sieve, in the form of a powder or cylindrical granules about 3 mm in diameter.8. Hazards8.1 Consult current OSHA regulations, supp
24、liers Material Safety Data Sheets, and local regulations for all materials used inthis procedure.8.2 Appropriate personal protection equipment such as gloves, safety glasses, a long rubber apron, and a full face shield shouldbe worn when handling hot or corrosive chemicals, or both.8.3 A fume hood s
25、hould be used when performing the test method on hazardous chemicals (OSHA 1910.1450 definition).9. Sampling and Handling9.1 Sample the material in accordance with Practices D3437, D3438, D3852, and D4297.10. Preparation of Apparatus10.1 Fit the sample container with a two-hole stopper. Through one
26、hole insert the thermistor. Through the other hole insert theshaft of the stirrer. (See Fig. 1).10.2 Set temperature bath at 5 6 1C. below the expected solidification point of the sample.11. Calibration of Thermistor11.1 Thermistor should be calibrated by the factory at a minimum every two years.11.
27、2 The thermistor may be checked by determining the ice point of water 0.00C.D6875 18212. Sample Preparation12.1 Solids at Room TemperatureMelt the entire sample by heating it to about 10C above its solidification point and swirlit for homogeneity.12.2 Drying SamplesIf required by specifications or a
28、greement with customer.12.2.1 p-Xylene should be dried before testing by placing about 100 g of the material in a 400 mL Erlenmeyer flask and addingabout 50 g of 3A molecular sieve.12.3 Benzene is a special case and should be saturated with water as follows:12.3.1 Place 7 to 8 mL of the specimen in
29、the sample container.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 12.3 in the sample container.13.2 Insert the stopper with the thermistor and stirrer into the sample container and adjust the th
30、ermistor so that it is about 5mm from the bottom.13.3 Place the sample container in the constant temperature bath set at 5 6 1C below the expected solidification point. In thecase of cyclohexane, the constant temperature bath should be set about 0.3C below the expected solidification point.13.4 Stir
31、 the specimen continuously and observe the temperature readings closely. The temperature will fall to a minimum(super cooling), then rise to a maximum. Record the maximum temperature.FIG. 1 Solidification Point Apparatus Set UpD6875 18313.5 If distinct minimum and maximum points are not evident, the
32、 determination shall be repeated. If the temperature does notrise to a maximum, increase the constant temperature bath temperature slightly and repeat the solidification point determination.Repeat increasing the temperature until a minimum temperature is observed and the temperature then rises to a
33、maximum.14. Calculations14.1 Benzene results should be reported on an anhydrous basis by adding 0.09C to the observed maximum temperaturefollowing the minimum.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.
34、1 Benzene5Based on seven labs analyzing three samples on two different days.16.1.1 Intermediate Precision (formerly called Repeatability)Results in the same laboratory should not be considered suspectunless they differ more than 0.04C. On the basis of test error alone, the difference between the res
35、ults obtained in the samelaboratory on the same material will be expected to exceed this value only 5 % of the time.16.1.2 ReproducibilityResults submitted by each of two laboratories should not be considered suspect unless they differ bymore than 0.05C. On the basis of test error alone, the differe
36、nce between two test results obtained in different laboratories on thesame material will be expected to exceed this value only 5 % of the time.16.2 CyclohexaneBased on a single sample analyzed five times in three different laboratories.16.2.1 RepeatabilityResults in the same laboratory should not be
37、 considered suspect unless they differ more than 0.015C. Onthe basis of test error alone, the difference between the results obtained in the same laboratory on the same material will beexpected to exceed this value only 5 % of the time.16.2.2 ReproducibilityResults submitted by each of two laborator
38、ies should not be considered suspect unless they differ bymore than 0.06C. On the basis of test error alone, the difference between two test results obtained in different laboratories on thesame material will be expected to exceed this value only 5 % of the time.16.3 p-XyleneBased on a single sample
39、 analyzed five times in six laboratories.16.3.1 RepeatabilityResults in the same laboratory should not be considered suspect unless they differ more than 0.026C. Onthe basis of test error alone, the difference between the results obtained in the same laboratory on the same material will beexpected t
40、o exceed this value only 5 % of the time.16.3.2 ReproducibilityResults submitted by each of two laboratories should not be considered suspect unless they differ bymore than 0.035C. On the basis of test error alone, the difference between two test results obtained in different laboratories onthe same
41、 material will be expected to exceed this value only 5 % of the time.16.4 BiasSince there is no accepted reference material suitable for determining the bias for this procedure, bias has not beendetermined.17. Quality Guidelines17.1 Laboratories shall have a quality control system in place.17.1.1 Co
42、nfirm the performance of the test instrument or test method by analyzing a quality control sample following theguidelines of standard statistical quality control practices.17.1.2 Aquality control sample is a stable material isolated from the production process and representative of the sample beinga
43、nalyzed.17.1.3 When QA/QC protocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity of test results.17.1.4 When there are no QA/QC protocols established in the testing facility, use the guidelines described in Guide D6809 orsimilar statis
44、tical quality control practices.18. Keywords18.1 benzene; cyclohexane; p-Xylene; solidification point5 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D16-1028. Contact ASTM CustomerService at serviceastm.org.D6875 184SUMMARY OF
45、 CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue (D6875 08) 12) that may impact the use of this standard. (Approved DecemberJanuary 1, 2012.)2018.)(1) Added Guide D6809 to referenced methods in Section 2.Footnotes 5 and 6 which referred to s
46、ole suppliers of the ohmmeterand thermistor were removed.(2) Added Section 17 Quality Control.(3) Renumbered sections.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly
47、 advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their 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, ei
48、ther reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend
49、. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, 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). P
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