ASTM D6855-12
Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode

Standard No.
ASTM D6855-12
Release Date
2012
Published By
American Society for Testing and Materials (ASTM)
Status
Replace By
ASTM D6855-17
Latest
ASTM D6855-17(2023)
Scope

Turbidity is undesirable in drinking water, plant effluent waters, water for food and beverage processing, and for a large number of other water-dependent manufacturing processes. Removal is often accomplished by coagulation, settling, and filtration. Measurement of turbidity provides a rapid means of process control for when, how, and to what extent the water must be treated to meet specifications.

This test method is suitable to turbidity such as that found in drinking water, process water, and high purity industrial water.

When reporting the measured result, appropriate units should also be reported. The units are reflective of the technology used to generate the result, and if necessary, provide more adequate comparison to historical data sets.

Table 1 describes technologies and reporting results (see also Refs (1),(2),(3)). Those technologies listed are appropriate for the range of measurement prescribed in this method. Others may come available in the future. Fig. X5.1 provides a flow chart to aid in selection of the appropriate technology for low-level static turbidity applications.

If a design that falls outside of the criteria listed in Table 1 is used, the turbidity should be reported in turbidity units (TU) with a subscripted wavelength value to characterize the light source that was used.

TABLE 1 Applicable Technologies Available for Performing Static Turbidity Measurements Below 5 NTU

Design and
Reporting Unit 		Prominent ApplicationKey Design FeaturesTypical Instrument RangeSuggested Application
Nephelometric
non-ratio (NTU)		White light turbidimeters. Comply
with USEPA Method 180.1 (1)
for low level turbidity monitoring.		Detector centered at 90° relative
to the incident light beam. Uses
a white light spectral source.		0.020 to 40Regulatory reporting
of clean water
Ratio White Light
turbidimeters (NTRU)		Complies with ISWTR regulations and
Standard Method 2130B. (2)
Can be used for both
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 000Regulatory Reporting of
clean water
Nephelometric, 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) monochromatic light source.		0.012 to 10000 - 40 ISO 7027
Regulatory reporting
Nephelometric near-IR
turbidimeters.........

ASTM D6855-12 Referenced Document

  • ASTM D1129 Standard Terminology Relating to Water
  • ASTM D1192 Standard Guide for Equipment for Sampling Water and Steam in Closed Conduits
  • ASTM D1193 Standard Specification for Reagent Water
  • ASTM D2777 Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
  • ASTM D3370 Standard Practices for Sampling Water from Closed Conduits
  • ASTM D5847 Standard Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
  • ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

ASTM D6855-12 history

  • 2023 ASTM D6855-17(2023) Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode
  • 2017 ASTM D6855-17 Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode
  • 2012 ASTM D6855-12 Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode
  • 2010 ASTM D6855-10 Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode
  • 2003 ASTM D6855-03 Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode
Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode


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