ASTM_D_6855_-_12.pdf

Designation:D685512Standard Test Method forDetermination of Turbidity Below 5 NTU in Static Mode1This standard is issued under the fixed designation D6855;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.Scope*1.1 This test method covers the static determination ofturbidity in water(see 4.1).1.2 This test method is applicable to the measurement ofturbidities under 5.0 nephelometric turbidity units(NTU).1.3 This test method was tested on municipal drinkingwater,ultra-pure water and low turbidity samples.It is theusers responsibility to ensure the validity of this test methodfor waters of untested matrices.1.4 This test method uses calibration standards are definedin NTU values,but other assigned turbidity units are assumedto be equivalent.1.5 This test method assigns traceable reporting units to thetype of respective technology that was used to perform themeasurement.Units are numerically equivalent with respect tothe calibration standard.For example,a 1.0 NTU formazinstandard is also equal to a 1.0 FNU standard,a 1.0 FNRUstandard and so forth.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 and health practices and determine the applica-bility of regulatory limitations prior to use.Refer to theMSDSs for all chemicals used in this procedure.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits(Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Referenced Standards:USEPA Method 180.1 Methods for Chemical Analysis ofWater and Wastes,Turbidity4ISO 7027(The International Organization for Standardiza-tion)Water Qualityfor the Determination of Turbidity53.Terminology3.1 DefinitionsFor definitions of terms used in thismethod refer to Terminology D1129.3.2 Definitions:3.2.1 calibration turbidity standard,nAturbidity standardthat is traceable and equivalent to the reference turbiditystandard to within statistical errors;calibration turbidity stan-dards include commercially prepared 4000 NTU Formazin,stabilized formazin(see 9.2.3),and styrenedivinylbenzene(SDVB)(see 9.2.4).3.2.1.1 Discussionthese standards may be used to cali-brate the instrument.NOTE1Calibration standards may be instrument specific.3.2.2 calibration verification standards,nDefined stan-dards used to verify the accuracy of a calibration in themeasurement range of interest.3.2.2.1 Discussionthese standards may not be used toperform calibrations,only calibration verifications.Includedstandards are opto-mechanical light scatter devices,gel-likestandards,or any other type of stable liquid standard.NOTE2Calibration verification standards may be instrument specific.3.2.3 nephelometric turbidity measurement,nThe mea-surement of light scatter from a sample in a direction that is at90 with respect to the centerline of the incident light path.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved June 1,2012.Published June 2012.Originallyapproved in 2003.Last previous edition approved in 2010 as D6855 10.DOI:10.1520/D6855-12.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from United States Environmental Protection Association(EPA),Ariel Rios Bldg.,1200 Pennsylvania Ave.,NW,Washington,DC 20460.5Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.*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 States1 3.2.3.1 Discussionunits are NTU(Nephelometric Turbid-ity Units);when ISO 7027 technology is employed units are inFNU(Formazin Nephelometric Units).3.2.4 ratio turbidity measurement,nThe measurementderived through the use of a nephelometric detector that servesas the primary detector and one or more other detectors used tocompensate for variati