1、Designation: D852 16Standard Test Method forSolidification Point of Benzene1This standard is issued under the fixed designation D852; 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 parenthese
2、s 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 the determination of the solidi-fication point of benzene.1.2 In determining the conformance of the test results usingthis method
3、to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafe
4、ty 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 specific hazardstatements, see Section 7.2. Referenced Documents2.1 AS
5、TM Standards:2D1015 Test Method for Freezing Points of High-PurityHydrocarbonsD1016 Test Method for Purity of Hydrocarbons from Freez-ing PointsD1193 Specification for Reagent WaterD3437 Practice for Sampling and Handling Liquid CyclicProductsD6809 Guide for Quality Control and Quality AssuranceProc
6、edures for Aromatic Hydrocarbons and Related Ma-terialsE1 Specification for ASTM Liquid-in-Glass ThermometersE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Met
7、hod2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. 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 soli
8、d phase.3.1.1.1 DiscussionSolidification point is distinguishedfrom freezing point which is described in Test Method D1015.An interpretation of mol percent purity in terms of freezingpoint is given in Test Method D1016.4. Summary of Test Method4.1 Solidification point is measured by noting the maxim
9、umtemperature 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 pointreaches that of pure benzene, the purer the sample.6. Apparatu
10、s6.1 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 InsulationDry absorbent cotton or glass wool.6.2 Benzene Container (thick walled), a glass
11、 test tube 18mm in outside diameter, 14 mm in inside diameter and 150 mmin length. The thick walled tube is only compatible with thethermistor.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommitt
12、ee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and TheirDerivatives.Current edition approved June 1, 2016. Published July 2016. Originally approvedin 1945. Last previous edition approved in 2013 as D852 13. DOI: 10.1520/D0852-16.2For referenced ASTM standards, visit the ASTM website, www.astm.o
13、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available 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.*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 States16.3 Ice Bath, a 1-L beaker, or similar suitable container,having an effective depth o
15、f at least 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
16、the smaller test tube.6.5 Temperature Measurement Device, either device de-scribed below has been found satisfactory.6.5.1 Thermometer, anASTM Benzene Freezing Point Ther-mometer having a range from 4.0 to 6.0C and conforming tothe requirements for Thermometer 112C as prescribed inSpecification E1.6
17、.5.2 Thermistor, in stainless steel housing with resistancegreater than 2K ohms at 25C. Calibration accuracy 0.01C.Drift in resistance equivalent to less than 60.01C/year.Thermistor shall be calibrated to cover the range it is used.6.6 Stirring Apparatus (Optional), the apparatus illustratedin Fig.
18、1 has been demonstrated to be an acceptable replace-ment for manually stirring the benzene solution.6.7 Ohmeter, capable of measuring resistance to the nearest0.1 ohm in the range 1000 to 10 000 ohms with directtemperature readout.7. Hazards7.1 Consult current OSHA regulations, suppliers SafetyData
19、Sheets, and local regulations for all materials used in thistest method.7.2 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system, kidney, and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive tomateri
20、als. Caution should be taken when handling mercury andmercury-containing products. See the applicable product lSafety Data Sheet (SDS) for details and EPAs website (http:/www.epa.gov/mercury/faq.htm) for additional information.Users should be aware that selling mercury or mercury-containing products
21、, or both, in your state may be prohibited bystate law.8. Sampling8.1 Sample the material in accordance with Practice D3437.FIG. 1 Benzene Solidification Point Apparatus Set UpD852 1629. Preparation of Apparatus9.1 Fit the benzene container with a two-hole stopper.Through one hole insert the tempera
22、ture 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 the benzene container (air jacketed), place a3.2-mm layer of dry absorbent cotto
23、n or glass wool in thebottom of the larger test tube and insert the inner container upto the lip into a stopper or annular ring that just fits into themouth of the air jacket.10. Calibration of Temperature Measuring Device10.1 Calibration of ASTM thermometer 112C is accom-plished with the small scal
24、e 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 D1193) and add just enough chilledType I or Type II water to make a slurry. Immerse thethermometer in the ice bath, allo
25、w 5 min for the system toreach equilibrium and read the thermometer. Solidificationpoint values are subsequently adjusted by adding (or subtract-ing) the number of degrees the thermometer is below (orabove) 0.00C.10.2 Calibration of the thermistor is performed by thethermistor manufacturer. Resistan
26、ce is converted to tempera-ture using an equation supplied by the manufacturer.11. Procedure11.1 Saturate the sample of benzene with water as follows: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 stir
27、ring apparatus (if any) into thebenzene container.11.3 When using the benzene container (air jacket), theoperator may cool the smaller test tube and contents 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
28、 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, 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-c
29、ooling before solidification startsand shall not be more than 0.7C below the maximum whenusing a thermometer. Record the maximum constant tempera-ture 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 do
30、es not remain constant at the maximum for at least15 s, the determination shall be repeated. The thermistor reading shouldremain constant to at least 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 wat
31、er-saturated benzene,the solidification point shall be corrected to the anhydrous basisby adding 0.09C to the observed maximum temperaturefollowing the minimum. Corrections for accuracy of thethermometer shall be made.13. Precision and Bias413.1 Thermometer PrecisionThe following criteria shouldbe u
32、sed to judge the acceptability of results obtained by thistest method when using a thermometer. The criteria weredetermined by measuring the solidification point of a sampletwelve times at one laboratory using a thermometer. The resultsof the intralaboratory study were calculated and analyzed usingP
33、ractice E691. Duplicate results in the same laboratory shouldnot be considered suspect unless they differ by more than0.04C.13.2 Thermistor PrecisionThe following criteria shouldbe used to judge the acceptability (95 % probability level) ofresults obtained by this test method when using a thermistor
34、.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. The results of the intralaboratory studywere calculated and analyzed using Practice E691.
35、13.2.1 Intermediate PrecisionResults in the same labora-tory 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 th
36、e time.13.2.2 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 between two test results obtained in different labo-ratories on the same material will be expected to excee
37、d thisvalue only 5 % of the time.13.3 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure, bias has notbeen determined.14. Quality Guidelines14.1 Laboratories shall have a quality control system inplace.14.1.1 Confirm the performance of the test instr
38、ument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.14.1.2 A quality control sample is a stable material isolatedfrom the production process and representative of the samplebeing analyzed.14.1.3 When QA/QC protocols are
39、already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.14.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD6809 or similar statistical quality control practices.4Supportin
40、g data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1028. ContactASTM CustomerService at serviceastm.org.D852 16315. Keywords15.1 benzene; solidification pointSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes
41、 to this standard since the last issue (D85213)that may impact the use of this standard. (Approved June 1, 2016.)(1) Footnote referring to a sole source supplier was removed.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mention
42、edin 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 at any time by the responsible technical committee and
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