EN ISO 5667-1:2022

SLOVENSKI STANDARD
01-september-2022
Nadomešča:
SIST EN ISO 5667-1:2007
SIST EN ISO 5667-1:2007/AC:2007
Kakovost vode - Vzorčenje - 1. del: Navodilo za načrtovanje programov in tehnik
vzorčenja (ISO 5667-1:2020)
Water quality - Sampling - Part 1: Guidance on the design of sampling programmes and
sampling techniques (ISO 5667-1:2020)
Wasserbeschaffenheit - Probenahme - Teil 1: Anleitung zur Erstellung von
Probenahmeprogrammen und Probenahmetechniken (ISO 5667-1:2020)
Qualité de l'eau - Échantillonnage - Partie 1: Recommandations relatives à la conception
des programmes et des techniques d’échantillonnage (ISO 5667-1:2020)
Ta slovenski standard je istoveten z: EN ISO 5667-1:2022
ICS:
13.060.45 Preiskava vode na splošno Examination of water in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 5667-1
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2022
EUROPÄISCHE NORM
ICS 13.060.45 Supersedes EN ISO 5667-1:2006, EN ISO 5667-
1:2006/AC:2007
English Version
Water quality - Sampling - Part 1: Guidance on the design
of sampling programmes and sampling techniques (ISO
5667-1:2020)
Qualité de l'eau - Échantillonnage - Partie 1: Wasserbeschaffenheit - Probenahme - Teil 1: Anleitung
Recommandations relatives à la conception des zur Erstellung von Probenahmeprogrammen und
programmes et des techniques d'échantillonnage (ISO Probenahmetechniken (ISO 5667-1:2020)
5667-1:2020)
This European Standard was approved by CEN on 21 February 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5667-1:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 5667-1:2022) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2022, and conflicting national standards shall
be withdrawn at the latest by August 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 5667-1:2006, EN ISO 5667-1:2006/AC:2007.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 5667-1:2020 has been approved by CEN as EN ISO 5667-1:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 5667-1
Third edition
2020-12
Water quality — Sampling —
Part 1:
Guidance on the design of sampling
programmes and sampling techniques
Qualité de l'eau — Échantillonnage —
Partie 1: Recommandations relatives à la conception des programmes
et des techniques d’échantillonnage
Reference number
ISO 5667-1:2020(E)
©
ISO 2020
ISO 5667-1:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 5667-1:2020(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General safety precautions . 1
4.1 Safety of Personnel . 1
4.2 General environmental considerations . 2
5 Design of sampling programmes . 2
5.1 General . 2
5.2 Sampling personnel . 3
5.3 Broad objectives for the design of sampling programmes . 3
5.4 Specific considerations in relation to variability . 5
5.5 Identifying the sampling location . 5
6 Characteristics and conditions affecting sampling . 6
6.1 General . 6
6.2 Variations from normal sampling conditions . 7
7 Standards for sampling from water . 7
7.1 General standards in the 5667 series . 7
7.2 Standards outside the 5667 series that provide guidance on sampling
programmes in specific areas . 8
7.3 Standards within the ISO 5667 series providing specific guidance on the sampling
of a range waters . 9
8 Time and frequency of sampling .13
8.1 General .13
8.2 Water quality management programmes .13
8.3 Quality characterization programmes .13
8.4 Programmes for investigation of causes of contamination .13
8.5 Statistical considerations .14
8.5.1 Establishment of sampling programmes .14
8.5.2 Random and systematic variations of water quality .14
8.6 Duration of sampling occasion and composite samples .15
9 Flow measurements and situations justifying flow measurements for water quality
purposes .15
9.1 General .15
9.2 Direction of flow .16
9.3 Velocity of flow .16
9.4 Discharge rate .16
9.5 Flow profile .16
9.6 Cross-sectional area .17
9.7 Justification for flow measurements in water quality control management.17
9.7.1 Treatment plant loads .17
9.7.2 Dilution effects (flux calculations) . .17
9.7.3 Mass flow calculations .17
9.7.4 Transport of contaminants and rates of recovery .17
9.7.5 Flow-related parameters .17
9.7.6 Groundwaters .18
9.8 Methods available for flow measurement .18
10 Current sampling techniques .19
10.1 General .19
10.2 Spot samples .19
10.3 Periodic samples (discontinuous) .20
ISO 5667-1:2020(E)
10.3.1 Periodic samples taken at fixed time-intervals (time-dependent) or
constant time constant volume (C.T.C.V.) .20
10.3.2 Periodic samples taken at fixed flow-intervals (volume-dependent) or
constant time variable volume variable time (C.T.V.T.) .20
10.3.3 Periodic samples taken at fixed flow-intervals (flow-dependent) or
constant volume variable volume sampling (C.V.V.V.) .20
10.4 Continuous samples .20
10.4.1 Continuous samples taken at fixed flow rates (time-continuous samples) .20
10.4.2 Continuous samples taken at variable flow rates (flow-continuous samples) .20
10.5 Series sampling .20
10.6 Composite samples.21
10.7 Large-volume samples .21
11 Passive sampling .21
12 Sampling equipment for physical or chemical characteristics .22
12.1 General .22
12.2 Sampling containers .22
12.2.1 General.22
12.2.2 Types of sample container .23
12.3 Equipment for spot sampling .24
12.4 Sampling equipment for sediments .24
12.4.1 Grab or dredge sampling .24
12.4.2 Core samplers .24
12.5 Sampling equipment for dissolved gases and volatile materials .24
12.6 Sampling equipment for radioactivity characteristics .25
12.7 Sampling equipment for biological and microbiological characteristics .25
12.8 Automatic sampling equipment .25
12.9 Sampling equipment for passive sampling .26
12.10 Sampling equipment for suspended sediments .26
13 Quality assurance and quality control of environmental water sampling and handling .26
13.1 General .26
13.2 Sources of contamination .27
13.3 Control or prevention of contamination .27
14 Transport to, and storage of samples at, the depot or laboratory .28
15 Sample identification and records .28
15.1 General .28
15.2 Data management .29
15.3 Samples that might be used for legal purposes .29
Annex A (informative) Diagrams illustrating types of periodic and continuous samples .30
Annex B (informative) Diagrams illustrating types of field paperwork and labels etc .33
Annex C (informative) Alternative and emerging sampling techniques .35
Annex D (informative) Preparation of sampling equipment.37
Bibliography .38
iv © ISO 2020 – All rights reserved

ISO 5667-1:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 6,
Sampling management.
This third edition cancels and replaces the second edition (ISO 5667-1:2006), which has been technically
revised. The main changes compared to the previous edition are as follows:
— incorporation of updated references;
— addition of a section on variation from normal sampling conditions;
— expansion of Clause 7 on sampling from specific types of water;
— introduction of a clause on passive sampling;
— incorporation of sample container provisions in Clause 12;
— expansion of Clause 15 to address data management;
— addition of annexes on field documentation, emerging sampling techniques, preparation of sampling
equipment.
A list of all parts in the ISO 5667 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
INTERNATIONAL STANDARD ISO 5667-1:2020(E)
Water quality — Sampling —
Part 1:
Guidance on the design of sampling programmes and
sampling techniques
1 Scope
This document sets out the general principles for, and provides guidance on, the design of sampling
programmes and sampling techniques for all aspects of sampling of water (including waste waters,
sludges, effluents, suspended solids and sediments).
It does not include detailed instructions for specific sampling situations, which are covered in the
various other parts of ISO 5667 and in ISO 19458.
2 Normative references
There are no normative references.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 General safety precautions
Attention is drawn to the requirements of national and/or regional health and safety regulations.
The following are general examples of safety considerations.
4.1 Safety of Personnel
The enormously wide range of conditions encountered in sampling water bodies and bottom sediments
can subject sampling personnel to a variety of safety and health risks. Precautions should be taken
to avoid inhalation of toxic gases and ingestion of toxic materials through the nose, mouth and skin.
Personnel responsible for the design of sampling programmes and for carrying out sampling operations
should ensure that sampling personnel are informed of the necessary precautions to be taken in
sampling operations.
Weather conditions should be taken into account in order to ensure the safety of personnel and
equipment and it is essential that life jackets and lifelines should be worn when sampling large masses
of water. Before sampling from ice-covered waters, the location and extent of weak ice should be
carefully checked. If self-contained underwater breathing apparatus or other diving equipment is used,
it should always be checked and maintained in accordance with relevant ISO or national standards to
ensure reliability.
ISO 5667-1:2020(E)
Boats or platforms used for sampling purposes should be capable of being maintained in a stable
condition. In all waters, precautions should be taken in relation to commercial ships and fishing
vessels; for example, the correct signal flags should be flown to indicate the nature of the work being
undertaken.
Sampling from unsafe sites, such as unstable river banks, should be avoided wherever possible. If this
is not possible, the operation should be conducted by a team using appropriate precautions rather than
by a single operator. Wherever possible, sampling from bridges should be used as a substitute for bank
sampling unless bank conditions are the specific subject of the sampling study.
Safe access to sampling sites in all weather is essential for frequent routine sampling. Where relevant,
precautions should be taken where additional natural hazards are present, such as fauna or flora, that
can endanger the health or safety of personnel.
Hazardous materials (e.g. bottles containing concentrated acids) should be properly labelled.
If instruments or other items of equipment are to be installed on a river bank for sampling
purposes, locations that are susceptible to flooding or vandalism should be avoided or appropriate
precautions taken.
Many other situations arise during the sampling of water when special precautions should be taken
to avoid accidents. For example, some industrial effluents can be corrosive or can contain toxic or
flammable materials. The potential dangers associated with contact with sewage should also not be
overlooked; these can be gaseous, microbiological, radiological, virological or zoological, such as from
amoebae or helminthes.
Gas protection equipment, breathing apparatus, resuscitation apparatus and other safety equipment
should be available when sampling personnel need to enter sampling locations containing hazardous
atmospheres. In addition, the concentration of oxygen and of any likely toxic or asphyxiating vapour or
gas likely to be present should be measured before personnel enter enclosed spaces.
In the sampling of steam and hot discharges, special care is necessary, and recognized sampling
techniques designed to remove hazards should be applied.
The handling of radioactive samples requires special care, and the special techniques required should
be strictly applied.
The use of electrically operated sampling equipment in or near water can present special electrocution
hazards. Work procedures, site design and equipment maintenance should be planned so as to minimize
these hazards. Where appropriate, specific materials and equipment, e.g. ‘Atmosphere Explosible’
equipment, should be used.
4.2 General environmental considerations
Whilst working in the field environmental protection should be observed. In any sampling activity
there should be measures taken to avoid environmental impacts on the sampling site surroundings and
the working space.
Measures should be designed to avoid any harm to flora and fauna when installing equipment using
machinery (subsoil compaction) or when developing the access and egress form the site.
5 Design of sampling programmes
5.1 General
Whenever a volume of water, suspended solids, bottom sediment or sludge is to be characterized, it is
generally impossible to examine the whole and it is therefore necessary to take samples.
2 © ISO 2020 – All rights reserved

ISO 5667-1:2020(E)
Samples are collected and examined primarily for the following reasons:
a) to determine the concentration of associated physical, chemical, microbiological, biological and
radiological parameters in space and time;
b) with bottom sediments, to obtain a visual indication of their nature;
c) to estimate the flux of material;
d) to assess trends over time or over space;
e) for conformance with, or attainment of, criteria, standards or objectives.
Sampling programmes, the outcome of which will be estimates of summary statistics and trends,
should be designed in full awareness of the issues of statistical sampling error and the techniques by
which these errors are quantified and how they are used to take decisions.
The samples collected should be as representative as possible of the whole to be characterized, and all
precautions should be taken to ensure that, as far as possible, the samples do not undergo any changes
in the interval between sampling and analysis (see ISO 5667-3 for additional guidance). The sampling
of multiphase systems, such as water containing suspended solids or immiscible organic liquids, can
present special problems and in such cases, specific advice should be sought (see Clause 6).
5.2 Sampling personnel
Attention is drawn to the fact that certification and accreditation of the sampling process and the
individuals implementing it may be required or recommended at national level. Also refer to 7.1.6,
ISO 5667-14 and ISO 5667-24.
5.3 Broad objectives for the design of sampling programmes
Before any sampling programme is devised, it is very important that the objectives of the programme
are carefully established since they are the major factors in determining the position of sampling sites,
frequency of sampling, duration of sampling, sampling procedures, subsequent treatment of samples
and analytical requirements. The degree of accuracy and precision necessary for the estimation of
water quality concentrations sought should also be taken into account, as should the manner in which
the results are to be expressed and presented, for example, as concentrations or mass loads, maximum
and/or minimum values, arithmetic means, median values, etc. The sampling programme should be
designed to be capable of estimating the error in such values as affected by statistical sampling error
and errors in chemical analysis.
Additionally, a list of parameters of interest should be compiled and the relevant analytical procedures
consulted since these might give guidance on precautions to be observed during sampling and
subsequent handling (general guidance on handling of samples is given in ISO 5667-3).
It can often be necessary to carry out a preliminary sampling and analysis programme before the
final objectives can be defined. It is important to take into account all relevant data from previous
programmes at the same or similar locations and other information on local conditions. Previous
personal experience of similar programmes or situations can also be very valuable when setting up
a new programme for the first time. Putting sufficient effort in time and money into the design of a
proper sampling programme is a good investment that will ensure that the required information is
obtained both efficiently and economically; failure to put proper effort into this aspect can result in
either failure of the programme to achieve its objectives and/or over-expenditure of time and money.
Three broad objectives can be distinguished as follows (these are covered in more detail in 8.2, 8.3
and 8.4):
— quality control measurements within water or waste water treatment plants used to decide when
short-term process corrections are required;
ISO 5667-1:2020(E)
— quality characterization measurements used to estimate quality, perhaps as part of a research
project, for setting and measuring performance targets against regulatory targets, for long-term
control purposes or to indicate long-term trends;
— identification and control of sources of contamination.
The purpose of the programme can change from quality characterization to quality control and vice-
versa. For example, a longer-term programme for nitrate characterization might become a short-term
quality control programme requiring increased frequency of sampling as the nitrate concentration
approaches a critical value.
No single sampling study can satisfy all possible purposes. It is therefore important that specific
sampling programmes are optimized for specific study purposes, such as the following:
a) to determine the suitability of water for an intended use and, if necessary, to assess any treatment
or control requirements, for example, to examine borehole water for cooling, boiler feed or process
purposes or, if a natural spring, as a possible source of water intended for human consumption;
b) to study the effect of waste discharges, including accidental spillages, on a receiving water;
c) to assess the performance and control of water, sewage and industrial effluent plants, for example
1) to assess the variations and long-term changes in load entering a treatment works,
2) to determine the efficiency of each stage in a treatment process,
3) to provide evidence of quality of treated water,
4) to control the concentration of treated substances including those which can constitute a
health hazard or which can inhibit a bacteriological process, and
5) to control substances which can damage the fabric of plant or equipment;
d) to study the effects of fresh and saline water flows on estuarine conditions in order to provide
information on mixing patterns and associated stratification with variations in tides and
freshwater flow;
e) to identify and quantify products lost from industrial processes; this information is required
when product balances across the plant are to be assessed and when effluent discharges are to be
measured;
f) to establish the quality of boiler water, steam condensate and other reclaimed water, enabling its
suitability for a particular intended purpose to be assessed;
g) to control the operation of industrial cooling water systems; this enables the use of water to be
optimized and, at the same time, the problems associated with scale formation and corrosion to be
minimized;
h) to study the effects of atmospheric contaminants on the quality of rainwater; this provides useful
information on air quality and also indicates if problems are likely to arise, for example, on exposed
electrical contacts;
i) to assess the effect of inputs from the land on water quality from naturally occurring materials, or
contamination by fertilizers, pesticides and chemicals used in agriculture, or both;
j) to assess the effect of the accumulation and release of substances by bottom sediments on the
aquatic biota in the water mass or bottom sediment;
k) to study the effect of abstraction, river regulation and river-to-river transfers on natural water-
courses; for example, varying proportions of waters of different quality can be involved in river
regulation and the quality of the resulting blend can fluctuate;
4 © ISO 2020 – All rights reserved

ISO 5667-1:2020(E)
l) to assess changes in water quality which occur in distribution systems for water for human
consumption; these changes can occur for a number of reasons, for example, contamination,
introduction of water from a new source, biological growths, deposition of scale or dissolution
of metal;
m) to gather information for compiling pollution load estimations of river catchment areas as well as
information about the significance of different pollution sources:
n) to assess the effect of anthropogenic changes (global warming, ocean acidification, eutrophication,
dust storms, etc.) on the water quality in marine environments and long term variations in
biogeochemical cycling and spatio-temporal distribution of environmentally important components
(nutrients, dissolved gases, contaminants, suspended solids, etc).
On some occasions, the conditions can be sufficiently stable and the forms of variability understood
for the required information and the accompanying estimates of errors to be obtained from a simple
sampling programme. But, in most locations, quality characteristics are subject to continuous variations
in time and space and, ideally, assessment should also be continuous. However, this is often very costly
and in many situations impossible to achieve. In the absence of continuous low-error monitoring, and
in the use of data collected by sampling, it is vital to take account of sampling error. When considering
sampling programmes, the special considerations given in 5.4 should be borne in mind.
5.4 Specific considerations in relation to variability
Sampling programmes can be complex in situations and locations where wide, rapid and continuous
variations occur in characteristics such as the concentrations of parameters of interest. These variations
can be caused by such factors as extreme changes in temperature, flow patterns or plant operating
conditions (as well as in things like chemical analysis). The design of any sampling programme should
take this variability into account, either by means of continuous assessment (see Figure A.1) (although
this is often very costly and in many situations impossible to achieve), or by taking into account the
following recommendations.
a) The programme should be set in terms of the requirements of techniques that allow the estimation
of statistical sampling error.
b) Sampling should be avoided at or near boundaries of systems unless those conditions are of special
interest.
c) Care should be taken to eliminate or minimize any changes in the concentration of parameters of
interest that might be produced by the sampling process itself, and to ensure that changes during
the period between sampling and analysis are avoided or minimized. For detailed guidance on
these issues, reference should be made to ISO 5667-14.
d) Composite sampling may be used to give the best indication of the average composition over a
period of time, provided that the parameter being measured is stable during the period of sampling
and examination. Data derived from composite sampling should be considered a specific data type
in databases so that this type of data is not confused with discrete samples. It should be borne in
mind that composite samples are of little value in determining transient peak conditions.
In situations of extreme variability of flow, or concentration, or both (for example, intermittent plant
effluents), there may be a benefit in studying the discharge or flow parameters to ascertain whether a
pattern is evident, before committing to a particular sampling programme.
5.5 Identifying the sampling location
Depending on the objectives to be achieved (see 5.3), the sampling network can be anything from a
single site to, for example, an entire river catchment. A basic river network can comprise sampling
sites at the tidal limit, major tributaries at its confluence and major discharges of sewage or industrial
effluent.
ISO 5667-1:2020(E)
In designing water quality sampling networks, it is usual to make provision for the measurement of
flow at key stations (see Clause 9).
Identifying the sampling location enables comparative samples to be taken. In most river sampling
situations, sampling locations can readily be fixed by reference to physical features on the river bank.
On uncovered estuarine and coastal shores, sampling locations can similarly be related to an easily
recognizable static object. For sampling from a boat or ship in these situations, instrumental methods
(e.g. global positioning system) for location identification should be used. Map references or other
standard forms of reference can be valuable in achieving this.
6 Characteristics and conditions affecting sampling
6.1 General
Flow can change from streamlined to turbulent and vice-versa. Ideally, samples should be taken from
turbulent, well-mixed liquids and whenever possible, turbulence should be induced in flows that are
streamlined, except where samples for the determination of dissolved gases and volatile materials and
volatile materials are to be collected, the concentration of which can be altered by induced turbulence.
Sampling staff should ensure that “reverse flow”, which can occur from other parts of the system, does
not produce contamination at the sampling point.
Discrete “slugs” of material can occur at any time, for example, dissolved contaminants, solids, volatile
materials or oily surface layers. These should be captured within any sampling programme designed to
produce valid and representative samples.
Where sampling from pipes is carried out, the liquids to be sampled should be pumped through pipes of
adequate size and at linear velocities high enough to maintain turbulent flow characteristics. Horizontal
pipe runs should be avoided. When sampling heterogeneous liquids, pipes with a minimum nominal
bore of 25 mm should be used.
When liquids which are corrosive or abrasive are being s
...