ASTM_D_7726_-_11_2016e1.pdf

Designation:D772611(Reapproved 2016)1Standard Guide forThe Use of Various Turbidimeter Technologies forMeasurement of Turbidity in Water1This standard is issued under the fixed designation D7726;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.1NOTEEditorial corrections were made throughout in November 2016.1.Scope1.1 This guide covers the best practices for use of variousturbidimeter designs for measurement of turbidity in watersincluding:drinking water,wastewater,industrial waters,andfor regulatory and environmental monitoring.This guide cov-ers both continuous and static measurements.1.1.1 In principle there are three basic applications foron-line measurement set ups.The first is the bypass orslipstream technique;a portion of sample is transported fromthe process or sample stream and to the turbidimeter foranalysis.It is then either transported back to the sample streamor to waste.The second is the in-line measurement;the sensoris submerged directly into the sample or process stream,whichis typically contained in a pipe.The third is in-situ where thesensor is directly inserted into the sample stream.The in-situprinciple is intended for the monitoring of water during anystep within a processing train,including immediately before orafter the process itself.1.1.2 Static covers both benchtop and portable designs forthe measurement of water samples that are captured into a celland then measured.1.2 Depending on the monitoring goals and desired datarequirements,certain technologies will deliver more desirableresults for a given application.This guide will help the useralign a technology to a given application with respect to bestpractices for data collection.1.3 Some designs are applicable for either a lower or uppermeasurement range.This guide will help provide guidance tothe best-suited technologies based given range of turbidity.1.4 Modern electronic turbidimeters are comprised of manyparts that can cause them to produce different results onsamples.The wavelength of incident light used,detector type,detector angle,number of detectors(and angles),and opticalpathlength are all design criteria that may be different amonginstruments.When these sensors are all calibrated with thesample turbidity standards,they will all read the standards thesame.However,samples comprise of completely differentmatrices and may measure quite differently among thesedifferent technologies.1.4.1 This guide does not provide calibration informationbut rather will defer the user to the appropriateASTM turbiditymethod and its calibration protocols.When calibrated ontraceable primary turbidity standards,the assigned turbidityunits such as those used in Table 1 are equivalent.For example,a 1 NTU formazin standard is also equivalent in measurementmagnitude to a 1 FNU,a 1 FAU,and a 1 BU standard and soforth.1.4.2 Improved traceability beyond the scope of this guidemay be practiced and would include the listing of the make andmodel number of the instrument used to determine the turbidityvalues.1.5 This guide does not purport to cover all availabletechnologies for high-level turbidity measurement.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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.1.8 This guide does not purport to address all of the safetyconcerns,if any,associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatory1This guide is under the jurisdiction of ASTM Committee D19 on Water and isthe direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Nov.1,2016.Published November 2016.Originallyapproved in 2011.Last previous edition approved in 2011 as D7726 11.DOI:10.1520/D7726-11R16E01.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 limitations prior to use.Refer to the MSDSs for all chemicalsused in this procedure.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD3977 Test Methods for Determining Sediment Concentra-tion in Water SamplesD6698 Test Method for On-Line Measurement of TurbidityBelow 5 NTU in WaterD6855 Test Method for Determination of Turbidity Below 5NTU in Static ModeD7315 Test Method for Determination of Turbidity Above 1Turbidity Unit(TU)in Static Mode2.2 Other References:USGS National Field Manual for the Collecti