1、Designation: E2744 161Standard Test Method forPressure Calibration of Thermal Analyzers1This standard is issued under the fixed designation E2744; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEResearch report information was editorially added to 13.1 in January 2018.1. Scope*1.1 This test method describes the calibration or perfor-mance con
3、firmation of the electronic pressure signals fromthermal analysis apparatus.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 There is no ISO standard equivalent to this test method.1.4 This standard does not purport to ad
4、dress all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was dev
5、eloped in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Do
6、cuments2.1 ASTM Standards:2D5483 Test Method for Oxidation Induction Time of Lubri-cating Greases by Pressure Differential Scanning Calorim-etryD6186 Test Method for Oxidation Induction Time of Lubri-cating Oils by Pressure Differential Scanning Calorimetry(PDSC)D5720 Practice for Static Calibration
7、 of ElectronicTransducer-Based Pressure Measurement Systems forGeotechnical PurposesD5885 Test Method for Oxidative Induction Time of Poly-olefin Geosynthetics by High-Pressure Differential Scan-ning CalorimetryE473 Terminology Relating to Thermal Analysis and Rhe-ologyE537 Test Method for The Therm
8、al Stability of Chemicalsby Differential Scanning CalorimetryE1142 Terminology Relating to Thermophysical PropertiesE1782 Test Method for Determining Vapor Pressure byThermal AnalysisE1858 Test Methods for Determining Oxidation InductionTime of Hydrocarbons by Differential Scanning Calorim-etryE2009
9、 Test Methods for Oxidation Onset Temperature ofHydrocarbons by Differential Scanning CalorimetryE2161 Terminology Relating to Performance Validation inThermal Analysis and Rheology3. Terminology3.1 Definitions:3.1.1 The technical terms used in this test method aredefined in Terminologies E473, E114
10、2, and E2161, includingcalibration, Celsius, differential scanning calorimetry, highpressure, linearity, oxidative induction time, thermal analysis,and vapor pressure.3.2 Definitions of Terms Specific to This Standard:3.2.1 absolute pressure, npressure measured relative tozero pressure corresponding
11、 to empty space.3.2.1.1 DiscussionAbsolute pressure is atmospheric pres-sure plus gage pressure.3.2.2 atmospheric pressure, nthe pressure due to theweight of the atmosphere.3.2.2.1 DiscussionAtmospheric pressure varies with el-evation above sea level, acceleration due to gravity andweather condition
12、s. Standard atmospheric pressure is101.325 kPa.3.2.3 barometer, nan instrument for measuring atmo-spheric pressure.3.2.4 gage pressure, npressure measured relative to atmo-spheric pressure.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct respo
13、nsibility of Subcommittee E37.10 onFundamental, Statistical and Mechanical Properties.Current edition approved Feb. 15, 2016. Published March 2016. Originallyapproved in 2010. Last previous edition approved in 2015 as E2744 10 (2015).DOI:101520/E2744-16E01.2For referenced ASTM standards, visit the A
14、STM 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 website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr
15、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommen
16、dations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.4.1 DiscussionZero gage pressure is equal to atmo-spheric pressure. Gage pressure is the difference betweenabsolute pressure and atmospheric pressure.3.2.5 pressure, nthe force exerted to a surface per un
17、itarea.3.2.6 vacuum, npressure less than atmospheric pressure.4. Summary of Test Method4.1 The pressure (vacuum) signal generated by a thermalanalyzer is compared to a gage whose performance is knownand traceable to a national metrology institute. The thermalanalyzer may be said to be in conformance
18、 if the performanceis within established limits. Alternately, the pressure signalmay be calibrated using a two-point calibration method.5. Significance and Use5.1 Most thermal analysis experiments are conducted underambient pressure conditions using isothermal or temperaturetime rate of change condi
19、tions where time or temperature is theindependent parameter. Some experiments, however, are con-ducted under reduced or elevated pressure conditions wherepressure is an independent experimental parameter (TestMethod E537). Oxidation Induction Times (Test MethodsD5483, D5885, D6186, and E1858), Oxida
20、tion Onset Tem-perature (Test Method E2009), and the Vapor Pressure (TestMethod E1782) are other examples of experiments conductedunder elevated or reduced pressure (vacuum) conditions. Sincein these cases pressure is an independent variable, the mea-surement system for this parameter shall be calib
21、rated to ensureinterlaboratory reproducibility.5.2 The dependence of experimental results on pressure isusually logarithmic rather than linear.6. Apparatus6.1 Reference pressure gage with a range 1.2 times themaximum value to be calibrated readable to within 0.1 % of thefull range and performance of
22、 which has been verified usingstandards and procedures traceable to a national metrologyinstitute (such as the National Institute of Standards andTechnology (NIST).NOTE 1To ensure an accurate pressure measurement, the referencepressure gage shall be placed as close as practical to the thermal analys
23、isapparatus to be calibrated and connected to the thermal analysis apparatuswith large diameter tubing such as 6.3 mm or larger especially for vacuumtesting. Ensure that there is no gas flow in the connection (for example,due to leaking) to provide a static pressure measurement.NOTE 2Additional info
24、rmation on pressure gages may be found inPractice D5720.6.2 A source of pressurized inert gas, typically nitrogen,with a pressure regulator, capable of adjusting the pressuresupplied to the apparatus from zero to 100 % of the gagepressure range to be calibrated, commonly 7 MPa.NOTE 3Since the calibr
25、ation is performed under static flowconditions, the pressurizing gas delivery system to the thermal analysisapparatus should be of small diameter (such as 1.6 mm diameter tubing)for safety considerations.NOTE 4Do not use a reactive gas such as oxygen unless all apparatus,tubing and test gage have be
26、en cleaned and are rated for oxygen service.6.3 The thermal analysis apparatus for which the pressurecalibration is to be performed.6.4 Barometer capable of measuring atmospheric pressurereadable to 60.01 kPa (0.1 mm Hg).7. Hazards7.1 This test poses risks associated with high pressureoperation. The
27、 thermal analysis apparatus, connecting tubingand measurement gages shall be designed to contain pressuresin excess of two times the maximum allowable workingpressure. Pressure relief shall be provided at pressures nogreater than 1.2 times the maximum allowable working pres-sure.8. Preparation of Ap
28、paratus8.1 Assemble the apparatus so that the calibration pressuregage is connected in parallel with the pressure transducer of theapparatus. That is, the instrument transducer and the calibrationgage shall see the same static pressure (see Fig. 1). Equilibratethe thermal analysis apparatus pressure
29、 container, referencepressure gage and instrument transducer at ambient tempera-ture.9. Calibration9.1 Perform any pressure signal calibration procedures rec-ommended by the manufacturer of the thermal analyzer asdescribed in the Operators Manual.10. Procedure10.1 Electronic pressure signals associa
30、ted with thermalanalysis apparatus measure gage pressure relative to atmo-spheric pressure. However, absolute pressure is most oftenrequired for thermal analysis experiments. Absolute pressure isthe sum of gage pressure and atmospheric pressure. Soknowledge of atmospheric pressure is required to obt
31、ainabsolute pressure.10.2 Using a laboratory barometer, measure and record theatmospheric pressure (Patm) within one hour of the pressurecalibration in steps 10.4 10.6.NOTE 5Should a laboratory barometer be unavailable, local pressuremay often be obtained by contacting the local weather service. Thi
32、sapproach is not suitable for laboratories operating under negative gagepressure.10.3 Assemble the instrument to be calibrated, the referencepressure gage and the source of the pressurized gas accordingto schematic Fig. 1.10.4 With the thermal analysis exhaust valve open toatmospheric and the source
33、 shut-off valve closed (see Fig. 1),set the thermal analysis instrument indicated pressure to zerogage pressure.10.5 Close the thermal analyzer exhaust valve, open thesource of pressurized gas, and slowly increase the pressureregulator until the reference pressure gage reads the maximumpressure to b
34、e calibrated (often 7.00 MPa). Close the sourcevalve. Record this value as P2.NOTE 6Other calibration pressures may be used but shall be reported.E2744 161210.6 Record the indicated pressure on the thermal analyzerpressure measuring signal (or gage) as P3.10.7 Calculate the calibration constant (S)
35、using Eq 2.10.8 Using the value of S from 10.7, calculate the percentconformity (C) using Eq 4 or a table of percent conformityvalues (see 11.4.1)11. Calculation11.1 For the purpose of these procedures, it is assumed thatthe relationship between observed pressure (Po) and the actualpressure (P) is l
36、inear and governed by Eq 1:P 5 Po 3 S (1)where:P = true gage pressure (kPa),Po = thermal analyzer observed gage pressure (kPa), andP = calibration constant (nominal value 1.00000).11.2 The calibration constant S is determined by Eq 2:S 5P2P3(2)NOTE 7When performing this calculation, retain all avail
37、able decimalplaces in the measured value and in the value of S.11.3 Using the value of S from 11.2, the percent conformityof the pressure measurement of the instrument signal may becalculated by:C 5 S 2 1.00000! 3100% (3)11.4 Conformity may be estimated to one significant figureusing the following c
38、riteria:11.4.1 If the value of S lies:11.4.1.1 Between 0.9990 and 0.9999 or between 1.0001 and1.0010, then conformity is better than 0.1 %;11.4.1.2 Between 0.9900 and 0.9990 or between 1.0010 and1.0100, then conformity is better than 1 %; and11.4.1.3 Between 0.9000 and 0.9900 or between 1.1000 and1.
39、0100, then conformity is better than 10 %.11.5 Using the determined value of S, Eq 1 may be used tocalculate true gage pressure (P) from an observed signalpressure (Po), provided that the measuring gage has beenproperly “zeroed.”11.6 Absolute pressure (Pa) may be obtained from Eq 4:Pa 5 Patm1P (4)wh
40、ere:Pa = absolute pressure (kPa), andPatm = atmospheric pressure (kPa).12. Report12.1 Report the following information:12.2 Model number and description of the thermal analyzerused.12.3 The value of S determined in 10.7 reported to at leastfour places to the right of the decimal point.12.4 Conformit
41、y as determined in 10.8.13. Precision and Bias13.1 An interlaboratory study of pressure signal calibrationwas conducted in 2009 in which a single organization made 6FIG. 1 Schematic Diagram of ApparatusE2744 1613duplicated determinations on 5 different instruments for a totalof 20 degrees of experim
42、ental freedom.313.2 Precision:13.2.1 Within laboratory variability may be described usingthe repeatability value (r) obtained by multiplying the repeat-ability standard deviation by 2.8. The repeatability valueestimates the 95 % confidence limit. That is, two results fromthe same laboratory should b
43、e considered suspect (95 %confidence level) if they differ by more than the repeatabilityvalue.13.2.2 The within laboratory repeatability standard devia-tion obtained for the measurement of pressure was 3.4 kPa.The relative repeatability standard deviation was 0.098 %.13.2.3 The between laboratory v
44、ariability may be describedusing the reproducibility value (R) obtained by multiplying thereproducibility standard deviation by 2.8. The reproducibilityvalue estimates the 95 % confidence limit. This is, resultsobtained from two different laboratories, operators or apparatusshould be considered susp
45、ect (at the 95 % confidence level) ifthey differ by more than the reproducibility value.13.2.4 The between laboratory reproducibility standard de-viation obtained for the measurement of pressure was 6.2 kPa.The relative reproducibility standard deviation was 0.18 %.13.3 Bias:13.3.1 Bias is the diffe
46、rence between the mean value ob-tained and an acceptable reference value. This test methodreports bias as conformance.13.3.2 The mean value of pressure measured was3444.5 kPA gage compared to the reference value of3447.5 kPa gage. This corresponds to a bias of 3.0 Pa or0.087 %.13.4 Bias is the diffe
47、rence between the mean value obtainedand an acceptable reference value. This test methods reportsbias as conformance.13.5 The mean slope determined by this test method wasS = 1.00087. This corresponds to a conformance value ofC = 0.0087 %.14. Keywords14.1 absolute pressure; atmospheric pressure; cal
48、ibration;gage pressure; pressure; thermal analysisSUMMARY OF CHANGESCommittee E37 has identified the location of selected changes to this standard since the last issue (E2744 10 (2015) that may impact the use of this standard. (Approved Feb. 15, 2016.)(1) Revised 10.4 and 10.5.ASTM International tak
49、es 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 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, either reapproved or withdrawn. Your comments are invited either for revision of this standard or f
