1、Designation: E2744 10 (Reapproved 2015)E2744 16Standard 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
2、 last 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 Scope*1.1 This test method describes the calibration or performance confirmation of the electronic pressure signals from
3、 thermalanalysis apparatus.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 There is no ISO standard equivalent to this test method.1.4 This standard does not purport to address all of the safety concerns, if any, assoc
4、iated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D5483 Test Method for Oxidation Induction Time of Lubricating
5、 Greases by Pressure Differential Scanning CalorimetryD6186 Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)D5720 Practice for Static Calibration of Electronic Transducer-Based Pressure Measurement Systems for Geotechnical PurposesD588
6、5 Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure Differential ScanningCalorimetryE473 Terminology Relating to Thermal Analysis and RheologyE537 Test Method for The Thermal Stability of Chemicals by Differential Scanning CalorimetryE1142 Terminology Relating to
7、Thermophysical PropertiesE1782 Test Method for Determining Vapor Pressure by Thermal AnalysisE1858 Test Methods for Determining Oxidation Induction Time of Hydrocarbons by Differential Scanning CalorimetryE2009 Test Methods for Oxidation Onset Temperature of Hydrocarbons by Differential Scanning Cal
8、orimetryE2161 Terminology Relating to Performance Validation in Thermal Analysis and Rheology3. Terminology3.1 Definitions:3.1.1 The technical terms used in this test method are defined in Terminologies E473, E1142, and E2161, including calibration,Celsius, differential scanning calorimetry, high pr
9、essure, 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 to zero pressure corresponding to empty space.3.2.1.1 DiscussionAbsolute pressure is atmospheric pressure plus gag
10、e pressure.3.2.2 atmospheric pressure, nthe pressure due to the weight of the atmosphere.1 This test method is under the jurisdiction ofASTM Committee E37 on Thermal Measurements and is the direct responsibility of Subcommittee E37.10 on Fundamental,Statistical and Mechanical Properties.Current edit
11、ion approved March 1, 2015Feb. 15, 2016. Published March 2015March 2016. Originally approved in 2010. Last previous edition approved in 20102015 asE2744 10. DOI:101520/E2744-10R15.10 (2015). DOI:101520/E2744-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Custo
12、mer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the
13、 previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary o
14、f Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2.1 DiscussionAtmospheric pressure varies with elevation above sea level, acceleration due to gravity and weather conditions. Sta
15、ndardatmospheric pressure is 101.325 kPa.3.2.3 barometer, nan instrument for measuring atmospheric pressure.3.2.4 gage pressure, npressure measured relative to atmospheric pressure.3.2.4.1 DiscussionZero gage pressure is equal to atmospheric pressure. Gage pressure is the difference between absolute
16、 pressure and atmosphericpressure.3.2.5 pressure, nthe force exerted to a surface per unit area.3.2.6 vacuum, npressure less than atmospheric pressure.4. Summary of Test Method4.1 The pressure (vacuum) signal generated by a thermal analyzer is compared to a gage whose performance is known andtraceab
17、le to a national metrology institute. The thermal analyzer may be said to be in conformance if the performance is withinestablished limits. Alternately, the pressure signal may be calibrated using a two-point calibration method.5. Significance and Use5.1 Most thermal analysis experiments are conduct
18、ed under ambient pressure conditions using isothermal or temperature timerate of change conditions where time or temperature is the independent parameter. Some experiments, however, are conductedunder reduced or elevated pressure conditions where pressure is an independent experimental parameter (Te
19、st Method E537).Oxidation Induction Times (Test Methods D5483, D5885, D6186, and E1858), Oxidation Onset Temperature (Test MethodE2009), and the Vapor Pressure (Test Method E1782) are other examples of experiments conducted under elevated or reducedpressure (vacuum) conditions. Since in these cases
20、pressure is an independent variable, the measurement system for this parametershall be calibrated to ensure interlaboratory reproducibility.5.2 The dependence of experimental results on pressure is usually logarithmic rather than linear.6. Apparatus6.1 Reference pressure gage with a range 1.2 times
21、the maximum value to be calibrated readable to within 0.1 % of the fullrange and performance of which has been verified using standards and procedures traceable to a national metrology institute (suchas the National Institute of Standards and Technology (NIST).NOTE 1To ensure an accurate pressure me
22、asurement, the reference pressure gage shall be placed as close as practical to the thermal analysis apparatusto be calibrated and connected to the thermal analysis apparatus with large diameter tubing such as 6.3 mm or larger especially for vacuum testing. Ensurethat there is no gas flow in the con
23、nection (for example, due to leaking) to provide a static pressure measurement.NOTE 2Additional information on pressure gages may be found in Practice D5720.6.2 A source of pressurized inert gas, typically nitrogen, with a pressure regulator, capable of adjusting the pressure suppliedto the apparatu
24、s from zero to 100 % of the gage pressure range to be calibrated, commonly 7 MPa.NOTE 3Since the calibration is performed under static flow conditions, the pressurizing gas delivery system to the thermal analysis apparatus shouldbe of small diameter (such as 1.6 mm diameter tubing) for safety consid
25、erations.NOTE 4Do not use a reactive gas such as oxygen unless all apparatus, tubing and test gage have been cleaned and are rated for oxygen service.6.3 The thermal analysis apparatus for which the pressure calibration is to be performed.6.4 Barometer capable of measuring atmospheric pressure reada
26、ble to 60.01 kPa (0.1 mm Hg).7. Hazards7.1 This test poses risks associated with high pressure operation. The thermal analysis apparatus, connecting tubing andmeasurement gages shall be designed to contain pressures in excess of two times the maximum allowable working pressure.Pressure relief shall
27、be provided at pressures no greater than 1.2 times the maximum allowable working pressure.8. Preparation of Apparatus8.1 Assemble the apparatus so that the calibration pressure gage is connected in parallel with the pressure transducer of theapparatus. That is, the instrument transducer and the cali
28、bration gage shall see the same static pressure (see Fig. 1). Equilibratethe thermal analysis apparatus pressure container, reference pressure gage and instrument transducer at ambient temperature.E2744 1629. Calibration9.1 Perform any pressure signal calibration procedures recommended by the manufa
29、cturer of the thermal analyzer as describedin the Operators Manual.10. Procedure10.1 Electronic pressure signals associated with thermal analysis apparatus measure gage pressure relative to atmosphericpressure. However, absolute pressure is most often required for thermal analysis experiments.Absolu
30、te pressure is the sum of gagepressure and atmospheric pressure. So knowledge of atmospheric pressure is required to obtain absolute pressure.10.2 Using a laboratory barometer, measure and record the atmospheric pressure (Patm) within one hour of the pressurecalibration in steps 10.4 10.6.NOTE 5Shou
31、ld a laboratory barometer be unavailable, local pressure may often be obtained by contacting the local weather service. This approachis not suitable for laboratories operating under negative gage pressure.10.3 Assemble the instrument to be calibrated, the reference pressure gage and the source of th
32、e pressurized gas according toschematic Fig. 1.10.4 With the thermal analysis exhaust valve open to atmospheric and the source shut-off valve shut off closed (see Fig. 1), setthe thermal analysis instrument indicated pressure to zero gage pressure.10.5 Close the thermal analyzer exhaust valve, open
33、the source of pressurized gas, and slowly increase the pressure regulatoruntil the reference pressure gage reads the maximum pressure to be calibrated (often 7.00 MPa). Close the source valve. Recordthis value as P2.NOTE 6Other calibration pressures may be used but shall be reported.10.6 Record the
34、indicated pressure on the thermal analyzer pressure measuring signal (or gage) as P3.10.7 Calculate the calibration constant (S) using Eq 2.10.8 Using the value of S from 10.7, calculate the percent conformity (C) using Eq 4 or a table of percent conformity values(see 11.4.1)11. Calculation11.1 For
35、the purpose of these procedures, it is assumed that the relationship between observed pressure (Po) and the actualpressure (P) is linear and governed by Eq 1:P 5Po3S (1)FIG. 1 Schematic Diagram of ApparatusE2744 163where:P = true gage pressure (kPa),Po = thermal analyzer observed gage pressure (kPa)
36、, 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 available decimal places in the measured value and in the value of S.11.3 Using the value of S from 11.2, the percent conformity o
37、f the pressure measurement of the instrument signal may becalculated by:C 5S 21.00000!3100% (3)11.4 Conformity may be estimated to one significant figure using the following criteria:11.4.1 If the value of S lies:11.4.1.1 Between 0.9990 and 0.9999 or between 1.0001 and 1.0010, then conformity is bet
38、ter than 0.1 %;11.4.1.2 Between 0.9900 and 0.9990 or between 1.0010 and 1.0100, then conformity is better than 1 %; and11.4.1.3 Between 0.9000 and 0.9900 or between 1.1000 and 1.0100, then conformity is better than 10 %.11.5 Using the determined value of S,Eq 1 may be used to calculate true gage pre
39、ssure (P) from an observed signal pressure(Po), provided that the measuring gage has been properly “zeroed.”11.6 Absolute pressure (Pa) may be obtained from Eq 4:Pa5Patm1P (4)where:Pa = absolute pressure (kPa), andPatm = atmospheric pressure (kPa).12. Report12.1 Report the following information:12.2
40、 Model number and description of the thermal analyzer used.12.3 The value of S determined in 10.7 reported to at least four places to the right of the decimal point.12.4 Conformity as determined in 10.8.13. Precision and Bias13.1 An interlaboratory study of pressure signal calibration was conducted
41、in 2009 in which a single organization made 6duplicated determinations on 5 different instruments for a total of 20 degrees of experimental freedom.13.2 Precision:13.2.1 Within laboratory variability may be described using the repeatability value (r) obtained by multiplying the repeatabilitystandard
42、 deviation by 2.8.The repeatability value estimates the 95 % confidence limit.That is, two results from the same laboratoryshould be considered suspect (95 % confidence level) if they differ by more than the repeatability value.13.2.2 The within laboratory repeatability standard deviation obtained f
43、or the measurement of pressure was 3.4 kPa. Therelative repeatability standard deviation was 0.098 %.13.2.3 The between laboratory variability may be described using the reproducibility value (R) obtained by multiplying thereproducibility standard deviation by 2.8. The reproducibility value estimate
44、s the 95 % confidence limit. This is, results obtainedfrom two different laboratories, operators or apparatus should be considered suspect (at the 95 % confidence level) if they differby more than the reproducibility value.13.2.4 The between laboratory reproducibility standard deviation obtained for
45、 the measurement of pressure was 6.2 kPa. Therelative reproducibility standard deviation was 0.18 %.13.3 Bias:13.3.1 Bias is the difference between the mean value obtained and an acceptable reference value. This test method reports biasas conformance.13.3.2 The mean value of pressure measured was 34
46、44.5 kPA gage compared to the reference value of 3447.5 kPa gage. Thiscorresponds to a bias of 3.0 Pa or 0.087 %.13.4 Bias is the difference between the mean value obtained and an acceptable reference value. This test methods reports biasas conformance.E2744 16413.5 The mean slope determined by this
47、 test method was S = 1.00087. This corresponds to a conformance value ofC = 0.0087 %.14. Keywords14.1 absolute pressure; atmospheric pressure; calibration; gage pressure; pressure; thermal analysisSUMMARY OF CHANGESCommittee E37 has identified the location of selected changes to this standard since
48、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 takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are ex
49、pressly 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 for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresp
