1、Designation: D 852 02Standard Test Method forSolidification Point of Benzene1This standard is issued under the fixed designation D 852; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthe
2、ses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope *1.1 This test method covers the determination of the solidi-fication point of benzene.1.2 In determining the conformance of the test results usingthis met
3、hod to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E 29.1.3 This 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-p
4、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 7.2. Referenced Documents2.1 ASTM Standards:D 1015 Test Method for Freezing Points of High-PurityHydrocarbons2D 1016 Test Method for Purity of Hydroca
5、rbons fromFreezing Points2D 1193 Specification for Reagent Water3D 3437 Practice for Sampling and Handling Liquid CyclicProducts4E 1 Specification for ASTM Thermometers5E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications6E 691 Practice for Conducting a
6、n Interlaboratory Study toDetermine the Precision of a Test Method62.2 Other Document:OSHA Regulations, 29CFR, paragraphs 1910.1000 and1910.120073. Terminology3.1 Definitions:3.1.1 solidification pointan empirical constant defined asthe temperature at which the liquid phase of a substance is inappro
7、ximate equilibrium with a relatively small portion of thesolid phase.3.1.1.1 DiscussionSolidification point is distinguishedfrom freezing point which is described in Test Method D 1015.An interpretation of mol percent purity in terms of freezingpoint is given in Test Method D 1016.4. Summary of Test
8、 Method4.1 Solidification point is measured by noting the maximumtemperature reached during a controlled cooling cycle after theappearance of a solid phase.5. Significance and Use5.1 This test method may be used as a criteria for determin-ing the purity of benzene. The closer the solidification poin
9、treaches that of pure benzene, the purer the sample.6. Apparatus6.1 Benzene Container (Air Jacketed):6.1.1 Inner Container, a test tube 15 mm in outside diameterand 125 mm in length.6.1.2 Air Jacket, a standard test tube 25 mm in outsidediameter and 150 mm in length.6.1.3 Insulation Dry absorbent co
10、tton or glass wool.6.2 Benzene Container (thick walled), a glass test tube 18mm in outside diameter, 14 mm in inside diameter and 150 mmin length. The thick walled tube is only compatible with thethermistor.6.3 Ice Bath, a 1-L beaker, or similar suitable container,having an effective depth of at lea
11、st 127 mm and filled withchipped or shaved ice.6.4 Stirrer, consisting of a 1-mm wire (copper or stainlesssteel) or a 2-mm glass rod with one end bent into a circularform at right angles to the shaft so that it will move freely inthe annular space between the thermometer stem and the wallof the smal
12、ler test tube.6.5 Temperature Measurement Device, either device de-scribed below has been found satisfactory.6.5.1 Thermometer, an ASTM Benzene Freezing Point1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibili
13、ty ofSubcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane, and TheirDerivatives.Current edition approved Aug. 10, 2002. Published October 2002. Originallypublished as D 852 45. Last previous edition D 852 00e1.2Annual Book of ASTM Standards, Vol 05.01.3Annual Book of ASTM Standards, Vol 11.
14、01.4Annual Book of ASTM Standards, Vol 06.04.5Annual Book of ASTM Standards, Vol 14.03.6Annual Book of ASTM Standards, Vol 14.02.7Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1*A Summary of Changes section app
15、ears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Thermometer having a range from 4.0 to 6.0C and conform-ing to the requirements for Thermometer 112C as prescribed inSpecification E 1.6.5.2 Thermistor,
16、Type CSP with accuracy of 0.01 C witha nominal resistance at 2500 s at 25C. The thermistor shall beequipped with an ohm meter capable of reading resistance tothe nearest 0.1 s.6.6 Stirring Apparatus (Optional), the apparatus illustratedin Fig. 1 has been demonstrated to be an acceptable replace-ment
17、 for manually stirring the benzene solution.7. Hazards7.1 Consult the latest OSHA regulations, suppliers MaterialSafety Data Sheets, and local regulations for all materials usedin this test method.8. Sampling8.1 Sample the material in accordance with PracticeD 3437.9. Preparation of Apparatus9.1 Fit
18、 the benzene container with a two-hole stopper.Through one hole insert the temperature measurement device.The thermometer should be inserted up to the 4.0C mark. Thethermistor should be inserted so as to contact the benzenesolution. Through the other hole insert the shaft of the stirrer.9.2 If using
19、 the benzene container (air jacketed), place a18-in. (3.2-mm) layer of dry absorbent cotton or glass wool inthe bottom of the larger test tube and insert the inner containerup to the lip into a stopper or annular ring that just fits into themouth of the air jacket.10. Calibration of Temperature Meas
20、uring Device10.1 Calibration of ASTM thermometer 112C is accom-plished with the small scale etched on the lower portion of thethermometer. Prepare an ice bath by filling a small Dewar flaskwith crushed ice made from Type I or Type II water (asspecified in Specification D 1193) and add just enough ch
21、illedType I or Type II water to make a slurry. Immerse theFIG. 1 Benzene Solidification Point Apparatus Set UpD852022thermometer in the ice bath, allow 5 min for the system toreach equilibrium and read the thermometer. Solidificationpoint values are subsequently adjusted by adding (or subtract-ing)
22、the number of degrees the thermometer is below (orabove) 0.00C.10.2 Calibration of the thermistor is performed by thethermistor manufacturer. Resistance is converted to tempera-ture using an equation supplied by the manufacturer.11. Procedure11.1 Saturate the sample of benzene with water as follows:
23、Place 7 to 8 mL of the sample in the benzene container, add 1drop of water, and shake the tube and contents vigorously.11.2 Place the stopper and stirring apparatus (if any) into thebenzene container.11.3 When using the benzene container (air jacket), theoperator may cool the smaller test tube and c
24、ontents rapidly toabout 6C in the ice bath, while stirring. Wipe dry the outsideof the smaller test tube and insert it into the larger test tube.Place the assembled tubes in the ice bath.11.4 Stir the benzene continuously and observe the tempera-ture closely. The temperature will fall to a minimum,
25、then riseto a maximum, remain constant at this maximum for approxi-mately 15 s, and then fall again (Note 1). The minimumtemperature is due to super-cooling before solidification startsand shall not be more than 0.7C below the maximum whenusing a thermometer. Record the maximum constant tempera-ture
26、 observed to the nearest 0.01C and designate it as “wet”(Note 1).NOTE 1If distinct minimum and maximum points are not evident, orif the temperature does not remain constant at the maximum for at least 15s, the determination shall be repeated. The thermistor reading shouldremain constant to at least
27、two places to the right of the decimal.12. Report12.1 Results shall be reported on the anhydrous basis. Sincethe determination is actually made on water-saturated benzene,the solidification point shall be corrected to the anhydrous basisby adding 0.09C to the observed maximum temperaturefollowing th
28、e minimum. Corrections for accuracy of thethermometer shall be made.13. Precision and Bias813.1 Thermometer PrecisionThe following criteriashould be used to judge the acceptability of results obtained bythis test method when using a thermometer. The criteria weredetermined by measuring the solidific
29、ation point of a sampletwelve times at one laboratory using a thermometer. Duplicateresults in the same laboratory should not be considered suspectunless they differ by more than 0.04C.13.2 Thermistor PrecisionThe following criteria shouldbe used to judge the acceptability (95 % probability level) o
30、fresults obtained by this test method when using a thermistor.The criteria were derived from an interlaboratory study be-tween six laboratories. Three different samples were analyzedin triplicate on two different days using a thermistor and a thickwalled glass test tube.13.2.1 Intermediate Precision
31、 Results in the same labo-ratory should not be considered suspect unless they differ morethan 0.04C. On the basis of test error alone, the differencebetween two results obtained in the same laboratory on thesame material will be expected to exceed this value only 5 %of the time.13.2.2 Reproducibilit
32、yResults 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 between two test results obtained in different labo-ratories on the same material will be expected to exceed thisvalue only5%ofthetime.
33、13.3 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure, bias has notbeen determined.14. Keywords14.1 benzene; solidification pointSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last date of
34、 issue(D 852 - 00e1) that may impact the use of this standard.(1) Correction of bath temperature and generalization oftemperature measuring device in Fig. 1.2) Addition of new Precision statements for thermometer andthermistor.ASTM International takes no position respecting the validity of any paten
35、t rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly 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 a
36、t 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 should be addressed to ASTM International Headquarters. Your commen
37、ts 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 Standards, at the address shown below.8Supporting data are availabl
38、e for ASTM International Headquarters. RequestRR: D161028.D852023This 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).D852024
