1、Designation:D685510D685512 Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode 1 This standard is issued under the xed designation D6855; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last
2、revision.Anumber in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval. 1. Scope* 1.1 This test method covers the static determination of turbidity in water (see 4.1). 1.2 This test method is applicable to th
3、e measurement of turbidities under 5.0 nephelometric turbidity units (NTU). 1.3 This test method was tested on municipal drinking water, ultra-pure water and low turbidity samples. It is the users responsibility to ensure the validity of this test method for waters of untested matrices. 1.4 This tes
4、t method uses calibration standards are dened in NTU values, but other assigned turbidity units are assumed to be equivalent. 1.5 This test method assigns traceable reporting units to the type of respective technology that was used to perform the measurement.Unitsarenumericallyequivalentwithrespectt
5、othecalibrationstandard.Forexample,a1.0NTUformazinstandard is also equal to a 1.0 FNU standard, a 1.0 FNRU standard and so forth. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establ
6、ish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Refer to the MSDSs for all chemicals used in this procedure. 2. Referenced Documents 2.1 ASTM Standards: 2 D1129Terminology Relating to Water D1192Guide for Equipment for Sampling Wate
7、r and Steam in Closed Conduits (Withdrawn 2003) 3 D1193Specication for Reagent Water D2777Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water D3370Practices for Sampling Water from Closed Conduits D5847Practice for Writing Quality Control Specication
8、s for Standard Test Methods for Water Analysis E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 2.2 Other Referenced Standards: USEPA Method 180.1Methods for Chemical Analysis of Water and Wastes, Turbidity 4 ISO 7027(The International Organization for
9、 Standardization) Water Qualityfor the Determination of Turbidity 5 3. Terminology 3.1 DenitionsFor denitions of terms used in this method refer to Terminology D1129. 3.2 Denitions: 3.2.1 calibration turbidity standardstandard, naA turbidity standard that is traceable and equivalent to the reference
10、 turbidity standard to within statistical errors, including errors; calibration turbidity standards include commercially prepared 4000 NTU Formazin, stabilized formazin (see 9.2.3), and styrenedivinylbenzene (SDVB) (see 9.2.4). These standards may be used to calibrate the instrument. 1 This test met
11、hod is under the jurisdiction ofASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology, and Open-Channel Flow. Current edition approved June 15, 2010June 1, 2012. Published August 2010June 2012. Originally approved in 2003. Last previous editi
12、on approved in 20032010 as D685503.D685510. DOI: 10.1520/D6855-10.10.1520/D6855-12. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to the standards Document Summary page on the ASTM we
13、bsite. 3 The last approved version of this historical standard is referenced on www.astm.org. 4 Available from United States Environmental Protection Association (EPA), Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460. 5 Available from American National Standards Institute (ANSI),
14、25 W. 43rd St., 4th Floor, New York, NY 10036. This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because it may not be technically possible to adequately depict all changes accurately
15、,ASTM recommends that users consult prior editions as appropriate. In all cases only the current version of the standard as published by ASTM is to be considered the official document. *ASummary of Changes section appears at the end of this standard Copyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959. United States 13.2.1.1 Discussion these standards may be used to calibrate the instrument. NOTE 1Calibration standards may be instrument specic. 3.2.2 calibration verication standardsstandards, ndenedDenedstandardsusedtoverifytheaccuracyofacalibratio
17、nin themeasurementrangeofinterest.Thesestandardsmaynotbeusedtoperformcalibrations,onlycalibrationverications.Included standards are opto-mechanical light scatter devices, gel-like standards, or any other type of stable liquid standard. 3.2.2.1 Discussion these standards may not be used to perform ca
18、librations, only calibration verications. Included standards are opto-mechanical light scatter devices, gel-like standards, or any other type of stable liquid standard. NOTE 2Calibration verication standards may be instrument specic. 3.2.3 nephelometricturbiditymeasurementmeasurement,ntheThemeasurem
19、entoflightscatterfromasampleinadirection that is at 90 with respect to the centerline of the incident light path. Units are NTU (Nephelometric Turbidity Units); when ISO 7027 technology is employed units are in FNU (Formazin Nephelometric Units). 3.2.3.1 Discussion units are NTU (Nephelometric Turbi
20、dity Units); when ISO 7027 technology is employed units are in FNU (Formazin Nephelometric Units). 3.2.4 ratio turbidity measurementmeasurement, ntheThe measurement derived through the use of a nephelometric detector that serves as the primary detector and one or more other detectors used to compens
21、ate for variation in incident light uctuation, stray light, instrument noise, or sample color. 3.2.5 reference turbidity standardstandard, naAstandard that is synthesized reproducibly from traceable raw materials by askilledanalyst.Allotherstandardsaretracedbacktothisstandard.Thereferencestandardfor
22、turbidityisformazin(seetheuser. 9.2.2). 3.2.5.1 Discussion all other standards are traced back to this standard. The reference standard for turbidity is formazin (see 9.2.2). 3.2.6 seasoningseasoning, vtheThe process of conditioning laboratory glassware labware with the standard to be diluted to a l
23、ower value. The process reduces contamination and dilution errors. See Appendix X2 for the suggested procedure. 3.2.6.1 Discussion the process reduces contamination and dilution errors. See Appendix X2 for the suggested procedure. 3.2.7 stray lightlight, nallAll light reaching the detector other tha
24、n that contributed by the sample. For example: ambient light leakage, internal reections and divergent light in optical systems. 3.2.7.1 Discussion for example: ambient light leakage, internal reections and divergent light in optical systems. 3.2.8 turbidimeterturbidimeter, nanAn instrument that mea
25、sures light scatter using a nephelometric detector. Examples includephotoelectricnephelometersandratiophotoelectricnephelometers.causedbyparticulateswithinasampleandconvertsthe measurement to a turbidity value. 3.2.8.1 Discussion the detected light is quantitatively converted to a numeric value that
26、 is traced to a light-scatter standard. 3.2.9 turbidityturbidity, nanAn expression of the optical properties of a sample that causes light rays to be scattered and absorbed rather than transmitted in straight lines through the sample. Turbidity of water is caused by the presence of suspended and dis
27、solved matter such as clay, silt, nely divided organic matter, plankton, other microscopic organisms, organic acids, and dyes. D685512 23.2.9.1 Discussion turbidity of water is caused by the presence of suspended and dissolved matter such as clay, silt, nely divided organic matter, plankton, other m
28、icroscopic organisms, organic acids, and dyes. 4. Summary of Test Method 4.1 The optical property expressed as turbidity is measured by the scattering effect that suspended particulate material have on light; the higher the intensity of scattered light, the higher the turbidity. In samples containin
29、g particulate material, the manner in whichsampleinterfereswithlighttransmittanceisrelatedtothesize,shapeandcompositionoftheparticlesinthewater,andalso to the wavelength of the incident light. 4.2 Themethodisbaseduponacomparisonoftheintensityoflightscatteredbythesamplewiththeintensityoflightscattere
30、d by a reference suspension. Turbidity values are determined by a nephelometer, which measures light scatter from a sample in a direction that is at 90 with respect to the centerline of the incident light path. 5. Signicance and Use 5.1 Turbidity is undesirable in drinking water, plant effluent wate
31、rs, water for food and beverage processing, and for a large numberofotherwater-dependentmanufacturingprocesses.Removalisoftenaccomplishedbycoagulation,settling,andltration. Measurement of turbidity provides a rapid means of process control for when, how, and to what extent the water must be treated
32、to meet specications. 5.2 Thistestmethodissuitabletoturbiditysuchasthatfoundindrinkingwater,processwater,andhighpurityindustrialwater. 5.3 When reporting the measured result, appropriate units should also be reported. The units are reective of the technology used to generate the result, and if neces
33、sary, provide more adequate comparison to historical data sets. 5.3.1 Table 1 describes technologies and reporting results (see also Refs(1),(2),(3). 6 Those technologies listed are appropriate 6 The boldface numbers in parentheses refer to the list of references at the end of this standard. TABLE 1
34、 Applicable Technologies Available for Performing Static Turbidity Measurements Below 5 NTU Design and Reporting Unit Prominent Application Key Design Features Typical Instrument RangeSuggested Application Nephelometric non-ratio (NTU) White light turbidimeters. Comply with USEPA Method 180.1 (1) fo
35、r low level turbidity monitoring. Detector centered at 90 relative to the incident light beam. Uses a white light spectral source. 0.020 to 40 Regulatory reporting of clean water Ratio White Light turbidimeters (NTRU) Complies with ISWTR regulations and Standard Method 2130B. (2) Can be used for bot
36、h low and high level measurement. Used a white light spectral source. Primary detector centered at 90. Other detectors located at other angles. An instrument algorithm uses a combination of detector readings to generate the turbidity reading. 0.020 to10 000 Regulatory Reporting of clean water Nephel
37、ometric, near-IR turbidimeters, non-ratiometric (FNU) Complies with ISO 7027. The wavelength is less susceptible to color interferences. Applicable for samples with color and good for low level monitoring. Detector centered at 90 relative to the incident light beam. Uses a near-IR (780-900 nm) monoc
38、hromatic light source. 0.012 to 1000 0 - 40 ISO 7027 Regulatory reporting Nephelometric near-IR turbidimeters, ratio metric (FNRU) Complies with ISO 7027. Applicable for samples with high levels of color and for monitoring to high turbidity levels. Uses a near-IR monochromatic light source (780-900
39、nm). Primary detector centered at 90. Other detectors located at other angles. An instrument algorithm uses a combination of detector readings to generate the turbidity reading. 0.012 to 10 000 0 - 40 ISO 7027 Regulatory reporting Nephelometric Turbidity Multibeam Unit (NTMU) Is applicable to EPA re
40、gulatory method GLI Method 2. (2) Applicable to drinking water and wastewater monitoring applications. Detectors are geometrically centered at 0 and 90. An instrument algorithm uses a combination of detector readings, which may differ for turbidities varying magnitude. 0.012 to 4000 0 to 40 Reportin
41、g for EPA and ISO compliance mNTU Is applicable to reporting of clean waters and lter performance monitoring. Very sensitive to turbidity changes in low turbidity samples. (3) Nephelometric method involving a laser-based light source at 660-nm and a high sensitivity photo-multplier tube (PMT) detect
42、or for light scattered at 90. 1000 mNTU = 1 NTU 5 to 5000 mNTU or 0.005 to 5.000 NTU 0-5000 mNTU, for EPA compliance reporting on drinking water systems D685512 3for the range of measurement prescribed in this method. Others may come available in the future. Fig. X5.1 provides a ow chart to aid in s
43、election of the appropriate technology for low-level static turbidity applications. 5.3.2 IfadesignthatfallsoutsideofthecriterialistedinTable1isused,theturbidityshouldbereportedinturbidityunits(TU) with a subscripted wavelength value to characterize the light source that was used. 6. Interferences 6
44、.1 Forthisapplication,bubbles,colorandlargeparticles,althoughtheycauseturbidity,mayresultininterferencesinmeasured turbidity as determined by this method. Bubbles cause a positive interference and color typically causes a negative interference. Dissolved material that imparts a color to the water ma
45、y cause errors in pure nephelometric readings,unless the instrument has special compensating features to reduce these interferences. Certain turbulent motions also create unstable reading conditions of nephelometers. 6.2 Color is characterized by absorption of specic wavelengths of light. If the wav
46、elengths of incident light are signicantly absorbed, a negative interference will result unless the instrument has special compensating features. 6.3 Scratches, nger marks, or dirt on the walls of the sample cell may give erroneous readings. Sample cells should be kept scrupulously clean both inside
47、 and outside and discarded when they become etched or scratched. The sample cells must not be handled where the light strikes them when positioned in the instrument well. 6.3.1 Sample cell caps and liners must also be scrupulously clean to prevent contamination of the sample. 6.4 Ideally,thesameinde
48、xedsamplecellshouldbeusedrstforstandardizationfollowedbyunknown(sample)determination. Ifthisisnotpossible,thensamplecellsmustbematched.Refertotheinstrumentmanualforinstructionsonmatchingsamplecells. NOTE 3Indexing of the sample cell to the instrument well is accomplished by placing a mark on the top
49、 of the sample cell and a similar mark on the upper surface of the well so that the sample cell can be placed in the well in an exact position each time. NOTE 4Sample cells can be matched by rst lling with dilution water (see 8.2).Allow the sample cell to stand for 5 to 10 min to allow for bubbles to vacate the sample. This is followed by cleaning and polishing the outside of the cell. Cells are then measured on the same turbidimeter and should read no different than 0.01 NTU. 6.5 Condensation of optical eleme
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