ASTM_D_6504_-_11.pdf

Designation:D650411Standard Practice forOn-Line Determination of Cation Conductivity in High PurityWater1This standard is issued under the fixed designation D6504;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 practice describes continuous sample conditioningby hydrogen ion exchange and measurement by electrolyticconductivity.It is commonly known as cation conductivitymeasurement in the power industry although it is actually anindication of anion contamination in high purity water samples.Measurements are typically in a range less than 1 S/cm.1.2 The actual conductivity measurements are made usingTest Method D5391.1.3 This practice does not provide for separate determina-tion of dissolved carbon dioxide.Refer to Test Methods D2186and D4519.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 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 Standards:2D1066 Practice for Sampling SteamD1125 Test Methods for Electrical Conductivity and Resis-tivity of WaterD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2186 Test Methods for Deposit-Forming Impurities inSteamD3370 Practices for Sampling Water from Closed ConduitsD3864 Guide for On-Line Monitoring Systems for WaterAnalysisD4519 Test Method for On-Line Determination of Anionsand Carbon Dioxide in High Purity Water by CationExchange and Degassed Cation ConductivityD5391 Test Method for Electrical Conductivity and Resis-tivity of a Flowing High Purity Water SampleD5540 Practice for Flow Control and Temperature Controlfor On-Line Water Sampling and Analysis3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,refer to Test Methods D1125,Terminology D1129,and Practice D3864.3.2 Definitions of Terms Specific to This Standard:3.2.1 cation conductivity,nthe parameter obtained byconditioning a sample by passing it through a hydrogen formcation ion exchange resin column and then measuring itselectrolytic conductivity,on-line.3.2.2 specific conductivity,ndirect electrolytic conductiv-ity measurement of a power plant sample,usually dominatedby treatment chemicals,such as ammonia or amines.4.Summary of Practice4.1 The sample is passed continuously through a smallcation exchange column in the hydrogen form,which ex-changes all cations for H+.In this process,pH adjustingtreatment chemicals,such as ammonia and amines are re-moved.4.2 Measurement is made continuously on the conditionedsample with a process high purity conductivity analyzer/transmitter.4.3 Temperature conditioning of the sample and specializedcompensation of the measurement are used to minimizetemperature effects on the performance of the ion exchangeresin and the measurement.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits,Analysis of Water for Power Generation and Process Use,On-Line Water Analysis,and Surveillance of Water.Current edition approved May 1,2011.Published May 2011.Originallyapproved in 1999.Last previous edition approved in 2007 as D6504 07.DOI:10.1520/D6504-11.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.4 Few studies have been published on the performance ofcation conductivity measurement but one collaborative effortprovides some background(1).35.Significance and Use5.1 Cation conductivity provides one of the most sensitiveand dependable on-line means of detecting anionic contamina-tion in the boiler/steam cycle,such as chlorides,sulfates,nitrates,bicarbonates,and organic acids,such as formic andacetic.5.2 High sensitivity is provided by intentionally eliminatingthe pH adjusting treatment chemical(s),for example,ammoniaand amines,from the sample and converting remaining saltcontaminants into their acid forms which are approximatelythree times as conductive.5.3 Guidelines on cation conductivity limits for variouscycle chemistry and boiler types have been established byEP