ASTM_D_7278_-_21.pdf

Designation:D727821Standard Guide forPrediction of Analyzer Sample System Lag Times1This standard is issued under the fixed designation D7278;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.INTRODUCTIONLag time,as used in this guide,is the time required to transport a representative sample from theprocess tap to the analyzer.Sample system designs have infinite configurations so this guide gives theuser guidance,based on basic design considerations,when calculating the lag time of online sampledelivery systems.Lag time of the analyzer sample system is a required system characteristic whenperforming system validation in Practice D3764,D6122,or D8321 and in general the proper operationof any online analytical system.The guide lists the components of the system that need to beconsidered when determining lag time plus a means to judge the type of flow and need for multipleflushes before analysis on any sample.1.Scope*1.1 This guide covers the application of routine calculationsto estimate sample system lag time,in seconds,for gas,liquid,and mixed phase systems.1.2 This guide considers the sources of lag time from theprocess sample tap,tap conditioning,sample transport,pre-analysis conditioning and analysis.1.3 Lag times are estimated based on a prediction of flowcharacteristics,turbulent,non turbulent,or laminar,and thecorresponding purge requirements.1.4 Mixed phase systems prevent reliable representativesampling so system lag times should not be used to predictsample representation of a mixed phase stream.1.5 The values stated in inch-pound units are to be regardedas standard.Other units of measurement are included in thisstandard and Appendix X1 examples where normally seen inindustry.1.6 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed 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 Documents2.1 ASTM Standards:2D3764 Practice for Validation of the Performance of ProcessStream Analyzer SystemsD6122 Practice for Validation of the Performance of Multi-variate Online,At-Line,Field and Laboratory InfraredSpectrophotometer,and Raman Spectrometer Based Ana-lyzer SystemsD8321 Practice for Development and Validation of Multi-variate Analyses for Use in Predicting Properties ofPetroleum Products,Liquid Fuels,and Lubricants basedon Spectroscopic Measurements3.Terminology3.1 Definitions:3.1.1 continuous analyzer unit cycle time,nthe timeinterval required to replace the volume of the analyzer mea-surement cell.3.1.2 intermittent analyzer unit cycle time,nthe timeinterval between successive updates of the analyzer output.3.1.3 purge volume,nthe combined volume of the fullanalyzer sampling and conditioning systems.1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.25 on Performance Assessment and Validation of Process StreamAnalyzer Systems.Current edition approved Dec.1,2021.Published December 2021.Originallyapproved in 2006.Last previous edition approved in 2016 as D7278 16.DOI:10.1520/D7278-21.2For referenced ASTM standards,visit the ASTM 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 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 Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1?3.1.4 sample system lag time,nthe time required totransport a representative sample from the process tap to theanalyzer.3.1.4.1 DiscussionThis includes sample conditioning unitlag time and sample loop lag time described in Practice D3764.3.1.5 total analyzer system response time,nthe sum of theanalyzer unit response time and the analyzer sample system lagtime.3.2 Abbreviations:3.2.1 I.D.Internal Diameter3.2.2 LPMliters per minute3.2.3 SLPMstandard liters