ISO 7027-1:2016 水質—濁度の測定—パート1：定量的方法 | ページ 2

Foreword

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The committee responsible for this document is ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods.

This first edition of ISO 7027-1, together with ISO 7027-2, cancels and replaces ISO 7027:1999, which has been technically revised.

ISO 7027 consists of the following parts, under the general title Water quality — Determination of turbidity:

• Part 1: Quantitative methods

The following part is under preparation:

• Part 2: Semi-quantitative methods

Introduction

Measurements of turbidity can be affected by the presence of dissolved light-absorbing substances (substances imparting colour). Such effects can be minimized, however, by performing measurements at wavelengths greater than 800 nm. Only carbon black and a blue colour, which can be found in certain polluted waters, slightly affects measurements of turbidity in this region of the spectrum. Air bubbles can also interfere with measurements, but such interference can be minimized by careful handling of the samples.

It is to be investigated whether and to what extent, particular problems will require the specification of additional marginal conditions.

1 Scope

This part of ISO 7027 specifies two quantitative methods using optical turbidimeters or nephelometers for the determination of turbidity of water:

• a) nephelometry, procedure for measurement of diffuse radiation, applicable to water of low turbidity (for example drinking water);
• b) turbidimetry, procedure for measurement of the attenuation of a radiant flux, more applicable to highly turbid waters (for example waste waters or other cloudy waters).

Turbidities measured according to the first method are presented as nephelometric turbidity units (NTU). The results typically range between <0,05 NTU and 400 NTU. Depending on the instrument design, it can also be applicable to waters of higher turbidity. There is numerical equivalence of the units NTU and formazin nephelometric unit (FNU).

Turbidity measured by the second method is expressed in formazin attenuation units (FAU), results typically range between 40 FAU and 4 000 FAU.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in CIE Publication No. 17 and the following apply.

Bibliography