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ASTM E2040-08 (Reapproved 2014)

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ASTM E2040-08 (Reapproved 2014)

Designation E2040 − 08 Reapproved 2014Standard Test Method forMass Scale Calibration of Thermogravimetric Analyzers1This standard is issued under the fixed designation E2040; 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 parentheses indicates the year of last reapproval. Asuperscript epsilon 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 mass or weight scale of thermo-gravimetric analyzers and is applicable to commercial andcustom-built 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 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 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1142 Terminology Relating to Thermophysical Properties3. Terminology3.1 DefinitionsSpecific technical terms used in this testmethod are defined in Terminologies E473 and E1142.4. Summary of Test Method4.1 The mass signal generated by a thermogravimetricanalyzer is compared to the mass of a reference materialtraceable to a national reference laboratory.Alinear correlationusing two calibration points is used to relate the mass orweight signal generated by the thermogravimetric analyzerand that of the reference material.5. Significance and Use5.1 This test method calibrates or demonstrates conformityof thermogravimetric apparatus at ambient conditions. Mostthermogravimetry analysis experiments are carried out undertemperature ramp conditions or at isothermal temperaturesdistant from ambient conditions. This test method does notaddress the temperature effects on mass calibration.5.2 In most thermogravimetry experiments, the masschange is reported as weight percent in which the observedmass at any time during the course of the experiment is dividedby the original mass of the test specimen. This method ofreporting results assumes that the mass scale of the apparatusis linear with increasing mass. In such cases, it may benecessary only to confirm the performance of the instrument bycomparison to a suitable reference.5.3 When the actual mass of the test specimen is recorded,the use of a calibration factor to correct the calibration of theapparatus may be required, on rare occasions.6. Apparatus6.1 The essential equipment required to provide the mini-mum thermogravimetric analytical capability for this testmethod includes the following6.1.1 Thermobalance, composed of a furnace;atempera-ture sensor;abalance to measure the specimen mass with aminimum capacity within the range to be calibrated and asensitivity of 61 g; and a means of maintaining the specimen/container under atmospheric control of the gas to be used at apurge rate between 10 to 100 6 5 mL/min.NOTE 1Excessive purge rates should be avoided as this may introducenoise due to buoyancy effects and temperature gradients.6.1.2 Temperature Controller, capable of maintaining ambi-ent temperature to 61K.6.1.3 A Data Collection Device, to provide a means ofacquiring, storing, and displaying measured or calculatedsignals, or both. The minimum output signals required forthermogravimetric analysis are mass, temperature, and time.6.1.4 Containers pans, crucibles, etc., which are inert tothe specimen and which will remain gravimetrically stable.1This test method is under the jurisdiction ofASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on Calo-rimetry and Mass Loss.Current edition approved March 15, 2014. Published April 2014. Originallyapproved in 1999. Last previous edition approved in 2008 as E2040 – 08. DOI10.1520/E2040-08R14.2For referenced ASTM standards, visit the website www.astm.org, or contactASTM Customer service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standard’s Document Summary page on the ASTMwebsite.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Reagents and Materials7.1 A reference material of known mass, which is traceableto a national standards laboratory, such as the National Instituteof Standards and Technology NIST. Such mass referencematerials are available from most general laboratory equipmentsuppliers.7.2 The mass of the reference material should correspond tothe working range of the analysis. For most work, the massmaximum should be 25 to 50 greater than the material beingexamined.8. Calibration and Standardization8.1 Perform any mass signal calibration procedures recom-mended by the manufacturer of the thermogravimetric analyzeras described in the operator’s manual.9. Procedure9.1 Prepare the thermogravimetric analyzer for operationunder the test conditions to be used for the characterization oftest specimens, including loading an empty specimen containerand initiating a purge gas. The temperature to be used isambient.9.2 Tare the apparatus by setting the mass of the emptyspecimen container to 0.00 mg.9.3 Open the apparatus, place the reference material into thespecimen container, and reassemble the apparatus under thetest conditions to be used for the characterization of the testspecimens.9.4 Record the mass observed by the apparatus as mo.9.5 Record the mass of the reference material from itscertificate as ms, retaining all available decimal places in themeasured value.9.6 Calculate and report the value for the slope S andconformity C using Eq 2 and Eq 3.10. Calculation10.1 For the purpose of this test method, it is assumed thatthe relationship between observed mass mo and the referencemass ms is linear and governed by the slope SofEq 1ms5 mo3 S 110.2 By using the mass values taken from 9.4 and 9.5,calculate S using Eq 2S 5 ms/mo2NOTE 2When performing this calculation, retain all available decimalplaces in the calculated value.10.3 Using the value of S from 10.2, the percent conformityof the instrument mass scale, C, may be calculated using Eq 3C 5 1.00000 2 S 3100 3NOTE 3The percent conformity usually is 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, its expression as a percent is used in this procedure.10.3.1 Conformity may be estimated to one significantfigure using the following table of criteria10.3.1.1 If S is between 0.9999 and 1.0001, then conformityis better than 0.01 .10.3.1.2 If S is between 0.9990 and 0.9999 or between1.0001 and 1.0010, then conformity is better than 0.1 .10.3.1.3 If S is between 0.9900 and 0.9990 or between1.0010 and 1.0100, then conformity is better than 1 .10.3.1.4 If S is between 0.9000 and 0.9900 or between1.0100 and 1.1000, then conformity is better than 10 .10.4 Report the value of S and the conformity, C.10.5 Using the determined value of S from Eq 2, Eq 1 maybe used to calculate the true corrected mass m from anobserved mass mo.11. Report11.1 The report shall include the following information11.1.1 Details and description, including the manufacturerand instrumental model number, where applicable, of thethermogravimetric analyzer.11.1.2 The value of S as determined in 10.2, reported to atleast four places to the right of the decimal point.11.1.3 The conformity, C, as determined in 10.3.11.1.4 The specific dated version of this test method used.12. Precision and Bias12.1 An interlaboratory study was conducted in 1998 thatincluded participation by seven laboratories using instrumentsfrom a single manufacturer TA Instruments. The results weretreated by Practice E691.12.2 Precision12.2.1 The mean value for the calibration constant was S 0.99818.12.2.2 The repeatability within laboratory standard devia-tion for S was 0.00047.12.2.3 Two values, each the mean of duplicated determina-tions within a single laboratory, should be considered suspect ifthey differ by more than 95 repeatability limit r 0.0013.12.2.4 The reproducibility between laboratory standarddeviation for S was 0.0030.12.2.5 Two values, each the mean of duplicated determina-tions in differing laboratories, should be considered suspect ifthey differ by more than 95 reproducibility limit R 0.0084.12.3 Bias12.3.1 The measurement of conformity in this test method isa comparison of the calibration constant S with the theoreticalvalue of 1.0000000 and provides an indication of bias.12.3.2 The mean value for conformity was C 0.18 .12.3.3 Conformity was found to vary widely among instru-ment models but in no case exceeded C 0.66 . This valueis far better than the nominal conformity of 1 required formost thermal analysis experiments.13. Keywords13.1 calibration; conformity; mass; thermogravimetry; ther-mogravimetric analyzerE2040 − 08 20142ASTM 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 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 for additional standardsand should be addressed to ASTM International Headquarters. Your comments 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.This 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 websitewww.astm.org. Permission rights to photocopy the standard may also be secured from the ASTM website www.astm.org/COPYRIGHT/.E2040 − 08 20143

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