ASTM E1860-2007 Standard Test Method for Elapsed Time Calibration Thermal Analyzers《消逝时间校正热分析仪的标准试验方法》.pdf

1、Designation: E 1860 07Standard Test Method forElapsed Time Calibration of Thermal Analyzers1This standard is issued under the fixed designation E 1860; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu

2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the calibration or perfor-mance confirmation of the elapsed-time signal from thermalanalyzers.1.2 SI units ar

3、e the standard.1.3 There is no ISO standard equivalent to this method.1.4 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-priate safety and health practices and determine the

4、 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3350 Specification for Polyethylene Plastics Pipe andFittings MaterialsD 3895 Test Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning CalorimetryD 4565 Test Methods for Physi

5、cal and Environmental Per-formance Properties of Insulations and Jackets for Tele-communications Wire and CableD 5483 Test Method for Oxidation Induction Time of Lu-bricating Greases by Pressure Differential Scanning Calo-rimetryE 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 487 Test

6、Method for Constant-Temperature Stability OfChemical MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1142 Terminology Relating to Thermophysical PropertiesE 1858 Test Method for Determining Oxidation InductionTime of Hydrocarbons by Differe

7、ntial Scanning Calorim-etryE 1868 Test Method for Loss-On-Drying by Thermo-gravimetryE 2161 Terminology Relating to Performance Validation inThermal Analysis3. Terminology3.1 Definitions:3.1.1 The technical terms used in this test method aredefined in Terminologies E 473, E 1142, and E 2161, includi

8、ngcalibration, conformance, relative standard deviation, and ther-mal analysis.4. Summary of Test Method4.1 The elapsed time signal generated by a thermal analyzeris compared to a clock (or timer) whose performance is knownand traceable to a national metrology institute. The thermalanalyzer may be s

9、aid to be in conformance, if the performanceof the thermal analyzer is within established limits. Alterna-tively, the elapsed time signal may be calibrated using a twopoint calibration method.5. Significance and Use5.1 Most thermal analysis experiments are carried out undertemperature ramp condition

10、s where temperature is the inde-pendent parameter. Some experiments, however, are carriedout under isothermal temperature conditions where the elapsedtime to an event is measured as the independent parameter.Isothermal Kinetics (Test Methods E 2070), Thermal Stability(Test Method E 487), Oxidative I

11、nduction Time (OIT) (TestMethods D 3895, D 4565, D 5483, E 1858, and SpecificationD 3350 and Loss-on-Drying (Test Method E 1868) are com-mon examples of these kinds of experiments.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility

12、 of Subcommittee E37.01 on ThermalTest Methods and Practices.Current edition approved March 1, 2007. Published April 2007. Originallyapproved in 1997. Last previous edition approved in 2002 as E 186002.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv

13、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Modern scientific instruments, including

14、 thermal ana-lyzers, usually measure elapsed time with excellent precisionand accuracy. In such cases, it may only be necessary toconfirm the performance of the instrument by comparison to asuitable reference. Only rarely will it may be required tocorrect the calibration of an instruments elapsed ti

15、me signalthrough the use of a calibration factor.5.3 It is necessary to obtain elapsed time signal conformityonly to 0.1 times the repeatability relative standard deviation(standard deviation divided by the mean value) expressed as apercent for the test method in which the thermal analyzer is tobe u

16、sed. For those test methods listed in Section 2 thisconformity is 0.1 %.6. Apparatus6.1 Timer or Stopwatch, with timing capacity of at least 3 h(10 800 s), a resolution of 0.1 s or better and an accuracy of 1.5s per day which performance has been verified using standardsand procedures traceable to a

17、 national metrology institute (suchas the National Institute of Standards and Technology (NIST).Such timers are available from most laboratory equipmentsuppliers.7. Calibration7.1 Perform any elapsed time signal calibration proceduresrecommended by the manufacturer of the thermal analyzer asdescribe

18、d in the Operators Manual.8. Procedure8.1 Obtain the instrument reaction time (I).8.1.1 Reset the timer and the elapsed time signal for thethermal analyzer to zero elapsed time.8.1.2 Simultaneously start the timer and the elapsed timesignal for the thermal analyzer. Allow them to run for 6 to 10s. S

19、imultaneously stop the timer and the elapsed time signal forthe thermal analyzer. Record the elapsed time from the timer ast1. Record the elapsed time from the thermal analyzer as t2.NOTE 1The elapsed time of the timer (t1) is equal to the elapsed timeof the thermal analyzer (t2) plus the instrument

20、 reaction time (I). Theinstrument reaction time is that required for the thermal analyzer toinitialize and terminate the thermal analysis experiment and may be up toseveral seconds. The instrument start up time does not affect the elapsedtime of the thermal analysis experiment since the experiment i

21、s exclusiveof this time.NOTE 2Data acquisition rate shall be set to the maximum available.NOTE 3Time measurements shall be recorded in seconds retaining allavailable digits.8.1.3 Calculate the instrument reaction time I by Eq 2 (9.2).8.2 Obtain the calibration constant (S).8.2.1 Reset the timer and

22、the elapsed time signal for thethermal analyzer to zero elapsed time.8.2.2 Simultaneously start the timer and the elapsed timesignal for the thermal analyzer. Allow them to run for aminimum of 10 000 s ( = 167 min = 2.8 h = 2 h, 47 min).Simultaneously stop the timer and the elapsed time signal forth

23、e thermal analyzer (see Note 2, Note 3, and Note 4). Recordthe elapsed time from the timer as tt. Record the elapsed timefrom the thermal analyzer as to.8.2.3 Calculate the value for S using Eq 3 (see 9.3).8.3 Using the values for I and S from 8.1.3 and 8.2.3,calculate the percent conformity (C) usi

24、ng Eq 4 or table ofpercent conformity values (see 9.4).9. Calculation9.1 For the purpose of these procedures, it is assumed thatthe relationship between observed elapsed time (to) and theactual elapsed time (t) is linear and is governed by Eq 1:t 5 toS (1)where:t = true experimental elapsed time (s)

25、,to= thermal analyzer observed elapsed time (s), andS = slope (nominal value = 1.00000).9.2 Using the values for t1and t2from 8.1, the instrumentreaction time (I) may be calculated by:I 5 t12 t2(2)9.3 Using the values for ttand tofrom 8.2, the calibrationconstant S may be calculated by:S 5 tt2 I!/to

26、(3)where:tt= observed time of reference timer.9.3.1 When performing this calculation, retain all availabledecimal places in the measured value and in the value of S.9.4 Using the value for S from 9.3, the percent conformityof the instrument elapsed time indicator may be calculated asfollows:C 5 1.00

27、000 2 S! 3 100 % (4)NOTE 4The percent conformity is usually a very small number andexpressing it as a percent value may be inconsistent with SI metricnotation. Because of its effect on the experiment and because of commonuse, it is expressed as a percent is this procedure.9.4.1 Conformity may be est

28、imated to one significant figureusing the following criteria:9.4.1.1 If S lies:Between 0.9999 and 1.0001, then conformity is better than 0.01 %,Between 0.9990 and 0.9999 or between 1.0001 and 1.0010, then conformity isbetter than 0.1 %, andBetween 0.9900 and 0.9990 or between 1.0010 and 1.0100, then

29、 conformity isbetter than 1 %.9.5 Using the determined value for S, Eq 1 may be used tocalculate the true elapsed time (t) from an observed elapsedtime (to).10. Report10.1 Report the following information:10.1.1 Model number and description of the Thermal Ana-lyzer used,10.1.2 The value of S as dete

30、rmined in 8.2.3 reported to atleast five places to the right of the decimal point, and10.1.3 Conformity as determined in 9.4.11. Precision and Bias11.1 An interlaboratory study of elapsed time calibrationwas conducted in 1996 that included participation by nineE1860072laboratories using instruments

31、from four manufacturers. Theresults were treated by Practice E 691.311.2 Precision:11.2.1 The mean value for the calibration constant wasS = 0.999853.11.2.2 The repeatability (within laboratory) standard devia-tion for S was 0.000034.11.2.2.1 Two values, each the mean of duplicate determina-tions wi

32、thin a single laboratory should be considered suspect ifthey differ by more than the 95 % repeatability limit r= 0.000095.11.2.3 The reproducibility (between laboratory) standarddeviation for S was 0.00024.11.2.3.1 Two values, each the mean of duplicate determina-tions in differing laboratories, sho

33、uld be considered suspect, ifthey differ by more than the 95 % reproducibility limitR = 0.00069.11.3 Bias:11.3.1 The measurement of conformity in this test method isa comparison of the calibration constant S with the theoreticalvalue of 1.000000 and provides an indication of bias.11.3.2 The mean val

34、ue for conformity was C = 0.015 %.11.3.3 Conformity was found to vary widely among instru-ment models but in no case exceeded C = 0.05 %. This value isfar better than the nominal conformity of 1 % required for mostthermal analysis experiments.12. Keywords12.1 calibration; elapsed time; thermal analy

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