ASTM_D_7725_-_12.pdf

Designation:D772512Standard Test Method for theContinuous Measurement of Turbidity Above 1 TurbidityUnit(TU)1This standard is issued under the fixed designation D7725;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 covers the online and inline determi-nation of high-level turbidity in water that is greater than 1.0turbidity units(TU)in municipal,industrial and environmentalusage.1.2 In principle there are three basic applications for on-linemeasurement set ups.This first is the slipstream(bypass)sample technique.For the slipstream sample technique aportion of sample is transported out of the process and throughthe measurement apparatus.It is then either transported back tothe process or to waste.The second is the in-line measurementwhere the sensor is brought directly into the process(seeFigure 8).The third basic method is for in-situ monitoring ofsample waters.This principle is based on the insertion of asensor into the sample itself as the sample is being processed.The in-situ use in this method is intended for the monitoring ofwater during any step within a processing train,includingimmediately before or after the process itself.1.3 This test method is applicable to the measurement ofturbidities greater than 1.0 turbidity unit(TU).The absoluterange is dictated by the technology that is employed.1.4 The upper end of the measurement range is left unde-fined because different technologies described in this methodcan cover very different ranges of turbidity.1.5 Many of the turbidity units and instrument designscovered in this method are numerically equivalent in calibra-tion when a common calibration standard is applied acrossthose designs listed in Table 1.Measurement of a commoncalibration standard of a defined value will also produceequivalent results across these technologies.This methodprescribes the assignment of a determined turbidity values tothe technology used to determine those values.Numericalequivalence to turbidity standards is observed between differ-ent technologies but is not expected across a common sample.Improved traceability beyond the scope of this method may bepracticed and would include the listing of the make and modelnumber of the instrument used to determine the turbidityvalues.1.5.1 In this method,calibration standards are often definedin NTU values,but the other assigned turbidity units,such asthose in Table 1 are equivalent.For example,a 1 NTUformazin standard is also a 1 FNU,a 1 FAU,a 1 BU,and soforth.1.6 This standard does not purport to cover all availabletechnologies for high-level turbidity measurement.1.7 This test method was tested on different waters,and withstandards that will serve as surrogates to samples.It is theusers responsibility to ensure the validity of this test methodfor waters of untested matrices.1.8 Those samples with the highest particle densities typi-cally prove to be the most difficult to measure.In these cases,the process monitoring method can be considered with ad-equate measurement protocols installed.1.9 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.Refer to the MSDSsfor all chemicals used in this procedure.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3864 Guide for On-Line Monitoring Systems for WaterAnalysisD6698 Test Method for On-Line Measurement of TurbidityBelow 5 NTU in Water1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is 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 Jan.1,2012.Published June 2012.DOI:10.1520/D772512.2For 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 D7315 Test Method for Determination of Turbidity Above 1Turbidity Unit(TU)in Static Mode3.Terminology3.1 DefinitionsFor definitions of terms used in thismethod refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 Calibration turbidity standard,nA turbidity stan-dard that