1、Designation: D6875 12Standard 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 year of l
2、ast 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 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 D852,D1015, D1016, D3799, D4493, and D6269.1.2 This test method is applicable to relatively pure com-po
4、unds 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 be roun
5、ded 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 standa
6、rd 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 statemen
7、t, see Section 8, Hazards.2. Referenced Documents2.1 ASTM Standards:2D852 Test Method for Solidification Point of BenzeneD1015 Test Method for Freezing Points of High-PurityHydrocarbonsD1016 Test Method for Purity of Hydrocarbons from Freez-ing PointsD3437 Practice for Sampling and Handling Liquid C
8、yclicProductsD3438 Practice for Sampling and Handling Naphthalene,Maleic Anhydride, and Phthalic AnhydrideD3799 Test Method for Purity of Styrene by Freezing PointMethod (Withdrawn 2000)3D3852 Practice for Sampling and Handling Phenol, Cresols,and Cresylic AcidD4297 Practice for Sampling and Handlin
9、g 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 Quality AssuranceProcedures for Aromatic Hydrocarbons and Related
10、Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Other Documents:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120043. Terminology3.1 Definitions:3.1.1 solidification point, nan empirical constant definedas the temperature at whi
11、ch the liquid phase of a substance isin approximate equilibrium with a relatively small portion ofthe solid phase.3.1.1.1 DiscussionSolidification point as distinguishedfrom freezing point is described in Test Method D1015.Aninterpretation of mole percent in terms of freezing point isgiven in Test M
12、ethod D1016.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved Dec. 1, 2012. Published January 2013. Originallyapproved in 2003. Last
13、previous edition approved in 2008 as D6875 08. DOI:10.1520/D6875-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM w
14、ebsite.3The last approved version of this historical standard is referenced onwww.astm.org.4Available 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.*A Summary of Changes section appears at the e
15、nd of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 The solidification point is measured by noting themaximum temperature reached during a cooling cycle after theappearance of a solid phase.
16、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. Apparatus6.1 Ohmmeter, capabl
17、e 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 steel wire bentinto a
18、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.6.5 Temperature Bat
19、h, 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 to cover the range
20、 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 regulations, suppliers
21、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 corrosivechemicals, or both.8.3 A fume hood should be
22、used when performing the testmethod on hazardous chemicals (OSHA 1910.1450 definition).9. Sampling and Handling9.1 Sample the material in accordance with PracticesD3437, D3438, D3852, and D4297.10. Preparation of Apparatus10.1 Fit the sample container with a two-hole stopper.Through one hole insert
23、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 two years.11.2 The thermist
24、or 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 oragreement with customer.12.
25、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 samplecontainer.12.3.2 A
26、dd 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.5The sole source of supply of the apparatus known to the committee at this timeis the Hart Scientific Model 1504, 220 N. 1300 Wes
27、t, 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 responsible technical committee,1which you may attend.6The sole source of supp
28、ly 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 International Headquarters. Your comments will receivecareful consideration a
29、t a meeting of the responsible technical committee,1whichyou may attend.D6875 12213.2 Insert the stopper with the thermistor and stirrer intothe sample container and adjust the thermistor so that it is about5 mm from the bottom.13.3 Place the sample container in the constant temperaturebath set at 5
30、 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 specimen continuously and observe the tem-perature readings closely. The temperature will fall to aminimum (super cool
31、ing), 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 rise to a maximum, increase the constant temperaturebath temperature slightly and repeat the solidification pointdet
32、ermination. Repeat increasing the temperature until a mini-mum temperature is observed and the temperature then rises toa maximum.14. Calculations14.1 Benzene results should be reported on an anhydrousbasis by adding 0.09C to the observed maximum temperaturefollowing the minimum.14.2 All other resul
33、ts 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 laboratory should not be
34、considered suspect unless they differ more than 0.04C. On the7Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1028.FIG. 1 Solidification Point Apparatus Set UpD6875 123basis of test error alone, the difference between the res
35、ultsobtained 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 each of twolaboratories should not be considered suspect unless they differby more than 0.05C. On the basis of test error alone, thedifference
36、 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 CyclohexaneBased on a single sample analyzed fivetimes in three different laboratories.16.2.1 RepeatabilityResults in the same laboratory shouldnot be con
37、sidered 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 same materialwill be expected to exceed this value only 5 % of the time.16.2.2 ReproducibilityResults submitted by each of twolaboratories sh
38、ould not be considered suspect unless they differby 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-XyleneBased on a single sample analy
39、zed 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 materialwill be expected to exceed
40、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-ratories on the same material
41、 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. Quality Guidelines17.1 Laboratories shall have a quality control system inplace.17.1.1 Confirm the pe
42、rformance of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.17.1.2 A quality control sample is a stable material isolatedfrom the production process and representative of the samplebeing analyzed.17.1.
43、3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.17.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD6809 or similar statistical quality c
44、ontrol practices.18. Keywords18.1 benzene; cyclohexane; p-Xylene; solidification pointSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue (D6875 08) that may impact the use of this standard. (Approved December 1, 2012.)(1) Added Guide
45、 D6809 to referenced methods in Section 2.(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 advised that d
46、etermination 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, either reapproved
47、 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. If you feel
48、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 reprin
49、ts (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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D6875 124
