ASTM D6855 - 17

    Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode

    Active Standard ASTM D6855 | Developed by Subcommittee: D19.07

    Book of Standards Volume: 11.01


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    Significance and Use

    5.1 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.

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

    5.3 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.

    5.3.1 Table 1 describes technologies and reporting results (see also Refs (1-3)6). Those technologies listed are appropriate for the range of measurement prescribed in this test 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.

    5.3.2 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.

    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 the 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 test method uses calibration standards are defined 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. Units are numerically equivalent with respect to the calibration standard. For example, a 1.0 NTU formazin standard 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 establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Refer to the MSDSs for all chemicals used in this test method.

    1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D1129 Terminology Relating to Water

    D1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits

    D1193 Specification for Reagent Water

    D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water

    D3370 Practices for Sampling Water from Closed Conduits

    D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis

    D7315 Test Method for Determination of Turbidity Above 1 Turbidity Unit (TU) in Static Mode

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method


    ICS Code

    ICS Number Code 19.100 (Non-destructive testing)

    UNSPSC Code

    UNSPSC Code


    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D6855-17

    Citation Format

    ASTM D6855-17, Standard Test Method for Determination of Turbidity Below 5 NTU in Static Mode, ASTM International, West Conshohocken, PA, 2017, www.astm.org

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