ASTM D6855-03

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6855 – 03
Standard Test Method for
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Determination of Turbidity Below 5 NTU in Static Mode
This standard is issued under the fixed designation D6855; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ISO 7027 (The International Organization for Standardiza-
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tion) Water Quality—for the Determination of Turbidity
1.1 This test method covers the static determination of
turbidity in water (see 4.1).
3. Terminology
1.2 This test method is applicable to the measurement of
3.1 Definitions—For definitions of terms used in this
turbidities under 5.0 nephelometric turbidity units (NTU).
method refer to Terminology D1129.
1.3 This test method was tested on municipal drinking
3.2 Definitions:
water, ultra-pure water and low turbidity samples. It is the
3.2.1 calibration turbidity standard—a turbidity standard
user’s responsibility to ensure the validity of this test method
that is traceable and equivalent to the reference turbidity
for waters of untested matrices.
standard to within statistical errors, including commercially
1.4 This standard does not purport to address all of the
prepared 4000 NTU Formazin, stabilized formazin (see 9.2.3),
safety concerns, if any, associated with its use. It is the
and styrenedivinylbenzene (SDVB) (see 9.2.4). These stan-
responsibility of the user of this standard to establish appro-
dards may be used to calibrate the instrument.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Refer to the
NOTE 1—Calibration standards may be instrument specific.
MSDSs for all chemicals used in this procedure.
3.2.2 calibration verification standards—defined standards
used to verify the accuracy of a calibration in the measurement
2. Referenced Documents
range of interest. These standards may not be used to perform
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2.1 ASTM Standards:
calibrations, only calibration verifications. Included standards
D1129 Terminology Relating to Water
are opto-mechanical light scatter devices, gel-like standards, or
D1192 Guide for Equipment for SamplingWater and Steam
any other type of stable liquid standard.
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in Closed Conduits
NOTE 2—Calibration verification standards may be instrument specific.
D1193 Specification for Reagent Water
D2777 Practice for Determination of Precision and Bias of
3.2.3 nephelometric turbidity measurement—the measure-
Applicable Test Methods of Committee D19 on Water
ment of light scatter from a sample in a direction that is at 90°
D3370 Practices for Sampling Water from Closed Conduits
with respect to the centerline of the incident light path. Units
D5847 Practice for Writing Quality Control Specifications
are NTU (Nephelometric Turbidity Units); when ISO 7027
for Standard Test Methods for Water Analysis
technology is employed units are in FNU (Formazin Nephelo-
E691 Practice for Conducting an Interlaboratory Study to
metric Units).
Determine the Precision of a Test Method
3.2.4 ratio turbidity measurement—the measurement de-
2.2 Other Referenced Standards:
rived through the use of a nephelometric detector that serves as
USEPA Method 180.1 Methods for Chemical Analysis of
the primary detector and one or more other detectors used to
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Water and Wastes, Turbidity
compensate for variation in incident light fluctuation, stray
light, instrument noise, or sample color.
3.2.5 reference turbidity standard—a standard that is syn-
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thesized reproducibly from traceable raw materials by a skilled
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibility of Subcommittee D19.07 on Sediments, Geomor-
analyst. All other standards are traced back to this standard.
phology, and Open-Channel Flow.
The reference standard for turbidity is formazin (see 9.2.2).
Current edition approved Jan. 10, 2003. Published April 2003. DOI: 10.1520/
3.2.6 seasoning—the process of conditioning laboratory
D6855-03.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or glassware with the standard to be diluted to a lower value. The
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
process reduces contamination and dilution errors. SeeAppen-
Standards volume information, refer to the standard’s Document Summary page on
dix X2 for the suggested procedure.
the ASTM website.
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Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org.
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