1、Designation: D7315 17Standard Test Method forDetermination of Turbidity Above 1 Turbidity Unit (TU) inStatic Mode1This standard is issued under the fixed designation D7315; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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. Static refers to a sample that is removedfro
3、m its source and tested in an isolated instrument. (SeeSection 4.)1.2 This test method is applicable to the measurement ofturbidities greater than 1.0 turbidity unit (TU). The upper endof the measurement range was left undefined because differenttechnologies described in this test method can cover v
4、erydifferent ranges. The round robin study covered the range of04000 turbidity units because instrument verification in thisrange can typically be covered by standards that can beconsistently reproduced.1.3 Many of the turbidity units and instrument designscovered in this test method are numerically
5、 equivalent incalibration when a common calibration standard is appliedacross those designs listed in Table 1. Measurement of acommon calibration standard of a defined value will alsoproduce equivalent results across these technologies.1.3.1 In this test method calibration standards are oftendefined
6、 in NTU values, but the other assigned turbidity units,such as those in Table 1 are equivalent. For example,a1NTUformazin standard is alsoa1FNU,a1FAU,a1BU,andsoforth.1.4 This test method does not purport to cover all availabletechnologies for high-level turbidity measurement.1.5 This test method was
7、 tested on different natural watersand wastewater, and with standards that will serve as surro-gates to samples. It is the users responsibility to ensure thevalidity of this test method for waters of untested matrices.1.6 Depending on the constituents within a high-levelsample, the proposed sample p
8、reparation and measurementmethods may or may not be applicable. Those samples with thehighest particle densities typically prove to be the most difficultto measure. In these cases, and alternative measurementmethod such as the process monitoring method can be consid-ered.1.7 This standard does not p
9、urport 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 i
10、n this procedure.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization Tec
11、hnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD4411 Guide for Sampling Fluvial Sedime
12、nt in MotionD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD6855 Test Method for Determination of Turbidity Below 5NTU in Static ModeE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Referen
13、ced Standards:U.S. EPA Method 180.1 Methods for Chemical Analysis ofWater and Wastes, Turbidity3ISO 7027 Water QualityDetermination of Turbidity41This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorpholog
14、y, and Open-Channel Flow.Current edition approved July 1, 2017. Published July 2017. Originally approvedin 2007. Last previous edition approved in 2012 as D7315 12. DOI: 10.1520/D7315-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servicea
15、stm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from United States Environmental ProtectionAgency (EPA), WilliamJefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,http:/www.epa.gov.4Availa
16、ble from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO
17、 Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued b
18、y the World Trade Organization Technical Barriers to Trade (TBT) Committee.1USGS National Field Manual for the Collection of WaterQuality Data53. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminology D1129.3.2 Definitions of Terms Specific to This Stand
19、ard:3.2.1 attenuation, vthe amount of incident light that isscattered and absorbed before reaching a detector, which isgeometrically centered at 0 relative to the centerline of theincident light beam.3.2.1.1 DiscussionAttenuation is inversely proportional totransmitted signal.Attenuated Turbidity 5
20、Absorbed Light1Scattered LightThe application of attenuation in this test method is as adistinct means of measuring turbidity. When measuring inthe FAU or AU mode, the turbidity value is a combinationof scattered (attenuated) plus absorbed light. The scattered5Available from United Stated Geological
21、 Survey (USGS), 12201 Sunrise ValleyDrive, Reston, VA 20192, http:/www.usgs.gov.TABLE 1 Summary of Known Instrument Designs, Applications, Ranges, and Reporting UnitsDesign andReporting UnitProminent Application Key Design FeaturesTypicalInstrument RangeSuggestedApplication RangesNephelometric non-r
22、atio(NTU)White light turbidimeters. Complywith U.S. EPA Method 180.1 forlow level turbidity monitoring.Detector centered at 90 relativeto the incident light beam. Usesa white light spectral source.0.040 0.040 RegulatoryRatio White Light turbidime-ters (NTRU)Complies with ISWTR regulationsand Standar
23、d Method 2130B.Can be used for both low andhigh level measurement.Used a white light spectralsource. Primary detector cen-tered at 90. Other detectorslocated at other angles. An in-strument algorithm uses a com-bination of detector readings togenerate the turbidity reading.010 000 040 Regulatory010
24、000 otherNephelometric, near-IRturbidimeters, non-ratiometric (FNU)Complies with ISO 7027. Thewavelength is less susceptibleto color interferences. Appli-cable for samples with colorand good for low level monitor-ing.Detector centered at 90 relativeto the incident light beam. Usesa near-IR (780900 n
25、m) mono-chromatic light source.01000 040 Regulatory (non-US)01000 otherNephelometric near-IRturbidimeters, ratio metric(FNRU)Complies with ISO 7027. Appli-cable for samples with high lev-els of color and for monitoringto high turbidity levels.Uses a near-IR monochromaticlight source (780900 nm). Pri
26、-mary detector centered at 90.Other detectors located at otherangles. An instrument algorithmuses a combination of detectorreadings to generate the turbid-ity reading.010 000 040 Regulatory010 000 otherSurface Scatter Turbidimeters(NTU)Turbidity is determined throughlight scatter from or near thesur
27、face of a sample.Detector centered at 90 relativeto the incident light beam. Usesa white light spectral source.1010 000 1010 000Formazin Back Scatter (FBU) Not applicable for regulatory pur-poses. Best applied to high tur-bidity samples. Backscatter iscommon with but not all onlyprobe technology and
28、 is bestapplied in higher turbiditysamples.Uses a near-IR monochromaticlight source in the 780900 nmrange. Detector geometry isbetween 90 and 180 relativeto the incident light beam.10010 000+ 10010 000Backscatter Unit (BU) Not applicable for regulatory pur-poses. Best applied for sampleswith high le
29、vel turbidity.Uses a white light spectral source(400680 nm range). Detectorgeometry is between 90 and180 relative to the incident lightbeam.1010 000+ 10010 000+Formazin attenuation unit(FAU)May be applicable for some regu-latory purposes. This is com-monly applied with spectropho-tometers. Best appl
30、ied forsamples with high level turbid-ity.Detector is geometrically centeredat 0 relative to incident beam(attenuation). Wavelength is780900 nm.201000 201000 RegulatoryLight attenuation unit (AU) Not applicable for some regulatorypurposes. This is commonlyapplied with spectrophotom-eters.Detector is
31、 geometrically centeredat 0 relative to incident beam(attenuation). Wavelength is400680 nm.201000 201000Nephelometric Turbidity Multi-beam Unit (NTMU)Is applicable to EPA regulatorymethod GLI Method 2. Appli-cable to drinking water andwastewater monitoring applica-tions.Detectors are geometrically c
32、en-tered at 0 and 90. An instru-ment algorithm uses a combina-tion of detector readings, whichmay differ for turbidities varyingmagnitude.0.024000 040 Regulatory04000 otherD7315 172light is affected by particle size and is a positive response.The absorption due to color is a negative. The sum ofthes
33、e two entities results in the turbidity value in the re-spective units.3.2.2 calibration turbidity standard, na turbidity standardthat is traceable and equivalent to the reference turbiditystandard to within statistical errors; calibration turbidity stan-dards include commercially prepared 4000 NTU
34、Formazin,stabilized formazin (see 9.2.3), and styrenedivinylbenzene(SDVB) (see 9.2.4).3.2.2.1 DiscussionThese standards may be used to cali-brate the instrument. Calibration standards may be instrumentdesign specific. Calibration standards that exceed 10 000turbidity units are commercially available
35、.3.2.3 calibration verification standards, ndefined stan-dards used to verify the accuracy of a calibration in themeasurement range of interest.3.2.3.1 DiscussionThese standards may not be used toperform calibrations, only calibration verifications. Includedstandards are opto-mechanical light scatte
36、r devices, gel-likestandards, or any other type of stable liquid standard. Calibra-tion verification standards may be instrument design specific.3.2.4 nephelometric turbidity measurement, nThe mea-surement of light scatter from a sample in a direction that is at90 with respect to the centerline of t
37、he incident light path.3.2.4.1 DiscussionUnits are NTU (Nephelometric Turbid-ity Units). When ISO 7027 technology is employed units are inFNU (Formazin Nephelometric Units).3.2.5 ratio turbidity measurement, nthe measurement de-rived through the use of a nephelometric detector that serves asthe prim
38、ary detector and one or more other detectors used tocompensate for variation in incident light fluctuation, straylight, instrument noise, or sample color.3.2.6 reference turbidity standard, na standard that issynthesized reproducibly from traceable raw materials by theuser.3.2.6.1 DiscussionAll othe
39、r standards are traced back tothis standard. The reference standard for turbidity is formazin(see 9.2.2).3.2.7 seasoning, vthe process of conditioning labwarewith the standard to be diluted to a lower value.3.2.7.1 DiscussionThe process reduces contamination anddilution errors.3.2.8 stray light, nal
40、l light reaching the detector other thanthat which is scattered by the sample.3.2.8.1 DiscussionFor example: ambient light leakage,internal reflections and divergent light in optical systems. Forthis test method, stray light is likely to be negligible. Theinstrument design is intended to reduce or e
41、liminate stray light.3.2.9 surface scatter turbidimeter, nan instrument thatdetermines the turbidity through incident light scatter thatoccurs at or slightly below the surface of a water sample witha detection angle that is at 90 relative to the incident lightbeam.3.2.9.1 DiscussionInterferences are
42、 not as substantial asnephelometric non-ratio measurements.3.2.10 turbidimeter, nan instrument that measures lightscatter, caused by particulates within a sample and converts themeasurement to a turbidity value.3.2.10.1 DiscussionThe detected light is quantitativelyconverted to a numeric value that
43、is traced to a light-scatterstandard. See Table 1 for examples of designs.3.2.11 turbidity, nan expression of the optical propertiesof a sample that causes light rays to be scattered and absorbedrather than transmitted in straight lines through the sample.3.2.11.1 DiscussionTurbidity of water is cau
44、sed by thepresence of matter such as clay, silt, finely divided organicmatter, plankton, other microscopic organisms, organic acids,and dyes.4. Summary of Test Method4.1 The optical property expressed as turbidity is measuredby the scattering effect that constituents within a sample haveon light; th
45、e higher the quantity of scattered or attenuatedincident light, the higher the turbidity. In samples containingparticulate material, light scatter and attenuation will vary (1)due to size, shape and composition of the particles in the water,and (2) the wavelength of the incident light.4.2 This test
46、method is based upon a comparison of theamount of light scattered or attenuated by the sample with theamount of light scattered or attenuated by a reference suspen-sion. Lower turbidity values are typically determined by anephelometer, which measures light scatter from a sample in adirection that is
47、 at 90 with respect to the centerline of theincident light path. High-level turbidity determination can beperformed using many different technologies. It is criticalwhen reporting the measurement, traceability to the type oftechnology be used. Turbidity measurements are not oftenconsistent among dif
48、fering technologies.5. Significance and Use5.1 Turbidity at the levels defined in the scope of this testmethod are often monitored to help control processes, monitorthe health and biology of water environments and determinethe impact of changes in response to environmental events(weather events, flo
49、ods, etc.). Turbidity is often undesirable indrinking water, plant effluent waters, water for food andbeverage processing, and for a large number of other water-dependent manufacturing processes. Removal is often accom-plished by coagulation, sedimentation, and various levels offiltration. Measurement of turbidity provides an indicator ofcontamination, and is a vital measurement for monitoring thecharacteristics and or quality within the samples source orprocess.5.2 This test method does overlap Test Method D
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