EN ISO 7027:1999
(Main)Water quality - Determination of turbidity (ISO 7027:1999)
Water quality - Determination of turbidity (ISO 7027:1999)
Migrated from Progress Sheet (TC Comment) (2000-07-10): N 315: New TD (980916)
Wasserbeschaffenheit - Bestimmung der Trübung (ISO 7027:1990)
Diese Internationale Norm legt vier Verfahren zur Bestimmung der Trübung von Wasser fest. Zwei halbquantitative Verfahren, die Beispielsweise für Feldmessungen eingesetzt werden: a) Verfahren mit dem Durchsichtigkeitßylinder (geeignet für reine und leicht verschmutzte Wässer); b) Verfahren, die auf der Erkennbarkeit von Sichtscheiben beruhen (besonders geeignet für Oberflächenwässer).
Quantité de l'eau - Détermination de la turbidité (ISO 7027:1990)
La présente Norme internationale prescrit quatre méthodes de détermination de la turbidité de l'eau.Deux méthodes semi-quantitatives utilisés, par exemple, sur le terrain, sont spécifiées:a) méthode faisant appel à un tube d'évaluation de la transparence (applicable aux eaux pures et aux eaux de faible turbidité);b) méthode faisant appel à un disque d'évaluation de la transparence (applicable notamment aux eaux de surface).Deux méthodes quantitatives faisant appel à des turbidimètres optiques sont spécifiées:c) méthode par mesurage de la lumière diffusée, applicable aux eaux de faible turbidité (par exemple eaux de boisson);La turbidité mesurée selon cette méthode est exprimée en unités néphélométriques formazine (FNU), normalement dans la gamme entre 0 FNU et 40 FNU. Selon les caractéristiques de l'appareillage, elle peut être également utilisée pour des eaux de plus forte turbidité.d) méthode par mesurage de l'atténuation de la lumière incidente, plus appropriée aux eaux de forte turbidité (par exemple eaux résiduaires ou polluées).La turbidité mesurée selon cette méthode est exprimée en unités d'atténuation formazine (FAU), normalement dans la gamme entre 40 FAU et 4 000 FAU.
Kakovost vode - Ugotavljanje motnosti (ISO 7027:1999)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2000
1DGRPHãþD
SIST EN 27027:1996
Kakovost vode - Ugotavljanje motnosti (ISO 7027:1999)
Water quality - Determination of turbidity (ISO 7027:1999)
Wasserbeschaffenheit - Bestimmung der Trübung (ISO 7027:1990)
Quantité de l'eau - Détermination de la turbidité (ISO 7027:1990)
Ta slovenski standard je istoveten z: EN ISO 7027:1999
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 7027
Third edition
1999-12-15
Water quality — Determination of turbidity
Qualité de l'eau — Détermination de la turbidité
Reference number
ISO 7027:1999(E)
©
ISO 1999
ISO 7027:1999(E)
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ii © ISO 1999 – All rights reserved
ISO 7027:1999(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions.1
4 Sampling and samples.2
5 Semiquantitative methods of turbidity measurement.2
5.1 Measurement using the transparency testing tube.2
5.2 Measurement using the transparency testing disk .2
6 Quantitative methods of turbidity measurement using optical turbidimeters.3
6.1 General principles .3
6.2 Reagents.4
6.3 Measurement of diffuse radiation .5
6.4 Measurement of attenuated radiation.6
Annex A (informative) Results of an interlaboratory collaborative trial to evaluate the suitability of a
synthetic polymer for use as a secondary standard to formazine in turbidity measurements.8
Bibliography.10
© ISO 1999 – All rights reserved iii
ISO 7027:1999(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 7027 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee
SC 2, Physical, chemical, biochemical methods.
This third edition cancels and replaces the second edition (ISO 7027:1990), which has been technically revised.
Annex A of this International Standard is for information only.
iv © ISO 1999 – All rights reserved
ISO 7027:1999(E)
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 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 should be investigated whether, and to what extent, particular problems will require the specification of additional
marginal conditions.
© ISO 1999 – All rights reserved v
INTERNATIONAL STANDARD ISO 7027:1999(E)
Water quality — Determination of turbidity
1 Scope
This International Standard specifies four methods for the determination of turbidity of water.
Two semiquantitative methods, employed for example in field work, are specified:
a) measurement of turbidity using the transparency testing tube (applicable to pure and lightly polluted water);
b) measurement of turbidity using the transparency testing disk (especially applicable to surface water).
Two quantitative methods, using optical turbidimeters, are specified:
c) measurement of diffuse radiation, applicable to water of low turbidity (for example drinking water);
Turbidity measured by this method is expressed in formazin nephelometric units (FNU); results typically range
between 0 FNU and 40 FNU. Depending on the instrument design, it may also be applicable to waters of
higher turbidity.
d) measurement of the attenuation of a radiant flux, more applicable to highly turbid waters (for example waste or
polluted waters).
Turbidity measured by this method is expressed in formazin attenuation units (FAU); results typically range
between 40 FAU and 4000 FAU.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3864:1984, Safety colours and safety signs.
ISO 5667-3:1994, Water quality — Sampling — Part 3: Guidance on the preservation and handling of samples.
CIE Publication No. 17:1987, International Lighting Vocabulary.
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in CIE Publication No. 17 and the
following apply.
3.1
turbidity
reduction of transparency of a liquid caused by the presence of undissolved matter
© ISO 1999 – All rights reserved 1
ISO 7027:1999(E)
4 Sampling and samples
Maintain all containers that come into contact with the sample in a scrupulously clean condition. Wash with
hydrochloric acid or surfactant cleaning solution.
Collect samples in glass or plastics bottles, and carry out the determinations as soon as possible after collection. If
storage is unavoidable, store the samples in a cool, dark room but for not longer than 24 h. If the samples have
been stored cool, allow them to come to room temperature before measurement. Prevent contact between the
sample and air, and avoid unnecessary changes in the temperature of the sample.
5 Semiquantitative methods of turbidity measurement
5.1 Measurement using the transparency testing tube
5.1.1 Apparatus
5.1.1.1 Transparency testing tube, consisting of a colourless glass tube 600 mm � 10 mm long and of
internal diameter 25 mm � 1 mm, graduated in divisions of 10 mm.
5.1.1.2 Shield, close-fitting, to protect the transparency testing tube from lateral light.
5.1.1.3 Print sample to place under the tube (5.1.1.1), consisting of black print on a white background (height
of characters 3,5 mm; line width 0,35 mm) or a test mark (for example, a black cross on white paper), provided
with the apparatus.
5.1.1.4 Constant light source, 3 W low voltage tungsten lamp, to illuminate the print sample or test mark
(5.1.1.3).
5.1.2 Procedure
It is absolutely essential that tests conducted according to this International Standard be carried out by suitably
qualified staff.
Thoroughly mix the sample and transfer it to the transparency testing tube (5.1.1.1). Steadily lower the sample level
until the print sample or test mark (5.1.1.3) is clearly recognizable as viewed from above. Read the liquid height
from the graduations on the tube.
5.1.3 Expression of results
Report the measured liquid height, to the nearest 10 mm, together with the apparatus used (name of the
manufacturer).
5.2 Measurement using the transparency testing disk
NOTE This method is intended primarily for testing bodies of water in situ.
5.2.1 Apparatus
5.2.1.1 Transparency testing disk made of cast bronze and coated with white (see ISO 3864) plastics,
attached to a chain or rod.
NOTE A typical design comprises a disk of diameter 200 mm with six holes, each of diameter 55 mm, on a circle of
diameter 120 mm.
2 © ISO 1999 – All rights reserved
ISO 7027:1999(E)
5.2.2 Procedure
It is absolutely essential that tests conducted according to this standard be carried out by suitably qualified staff.
Lower the disk, on its chain or rod, into the water until the disk is barely visible when viewed from above. Measure
the length of immersed chain or rod. Repeat the test several times.
Ensure that no interference arises from reflection at the water surface.
5.2.3 Expression of results
Report the depth of immersion.
For values less than 1 m, report the result to the nearest 10 mm. For values greater than 1 m, report the result to
the nearest 0,1 m.
6 Quantitative methods of turbidity measurement using optical turbidimeters
6.1 General principles
It is absolutely essential that tests conducted according to this International Standard be carried out by suitably
qualified staff.
A water sample coloured by dissolved substances is a homogeneous system that only attenuates radiation passing
through the sample. A water sample containing undissolved substances attenuates the incident radiation, and in
addition the insoluble particles which are present diffuse the radiation unequally in all directions. The forward
diffusion of radiation by the particles affects the attenuation so that the common spectral attenuation coefficient�(�)
is the sum of the spectral diffusion coefficient s(�) and the spectral absorption coefficient�(�):
�(�)= s(�)+�(�) (1)
To obtain the spectral diffusion coefficient s(�) alone, the spectral absorption coefficient �(�) needs to be known. In
order to determine the spectral absorption coefficient of the dissolved substance, the undissolved substances can,
in some cases, be removed by filtration, but this may cause interferences. Therefore, it is necessary to report the
results of the determination of turbidity in comparison to a calibration standard.
The intensity of the diffuse radiation depends upon the wavelength of the incident radiation, the measurement
angle, and the shape, optical characteristics and particle size distribution of the particles suspended in the water.
In measurements of the attenuation of transmitted radiation, the measured value depends upon the aperture angle
� of the radiant efficiency arriving
...
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