ISO 18283:2006
(Main)Hard coal and coke — Manual sampling
Hard coal and coke — Manual sampling
ISO 18283:2006 defines the basic terms used in manual sampling of hard coal and coke and describes the general principles of sampling. ISO 18283:2006 specifies procedures and requirements for establishing a manual sampling scheme, methods of manual sampling, sampling equipment, handling and storage of samples, sample preparation and a sampling report. ISO 18283:2006 applies to manual sampling from fuels in movement. Guidelines for manual sampling from fuels in stationary situations are given, but this method of sampling does not provide a representative test sample and the sampling report shall state this. ISO 18283:2006 does not include sampling of brown coals and lignites, sampling from coal seams or mechanical sampling of coal and coke.
Houille et coke — Échantillonnage manuel
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18283
First edition
2006-09-15
Hard coal and coke — Manual sampling
Houille et coke — Échantillonnage manuel
Reference number
ISO 18283:2006(E)
©
ISO 2006
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ISO 18283:2006(E)
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ISO 18283:2006(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Establishing a sampling scheme . 5
4.1 General. 5
4.2 Sampling methods. 6
4.3 Design of the sampling scheme. 6
4.4 Precision of sampling. 9
4.5 Checking the overall precision for the lot by calculation and selection of sampling
scheme. 23
4.6 Determination of acquired precision by replicate sampling . 23
4.7 Size analysis. 24
5 Methods of sampling. 25
5.1 General. 25
5.2 Sampling by time interval . 25
5.3 Sampling by mass interval . 25
5.4 Stratified random sampling . 26
5.5 Extracting the increment. 26
5.6 Fuel in motion . 27
5.7 Moisture/common sample . 29
5.8 Different fuels. 30
5.9 Random selection of increments . 30
6 Sampling equipment. 31
6.1 General. 31
6.2 Examples . 32
7 Handling and storage of samples . 39
7.1 Sample size . 39
7.2 Time. 39
7.3 Divided sample. 39
7.4 Containers . 39
7.5 Moisture loss/breakage or degradation. 40
7.6 Identification/labelling. 41
8 Sample preparation . 41
8.1 General. 41
8.2 Constitution of a sample. 41
8.3 Division . 42
8.4 Reduction . 52
8.5 Mixing. 53
8.6 Air-drying. 53
8.7 Coal — Preparation of test samples . 54
8.8 Coke — Preparation of test samples . 61
9 Packing and marking of samples and sampling report. 64
Annex A (informative) Example of calculation of precision, mass of increments, number of sub-
lots and number of increments per sub-lot. 66
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ISO 18283:2006(E)
Annex B (informative) Methods of sampling large fuels and fuels from stationary lots. 69
Bibliography . 71
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ISO 18283:2006(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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 18283 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 4,
Sampling.
This first edition of ISO 18283 cancels and replaces ISO 1988:1975 and ISO 2309:1980, which have been
technically revised.
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ISO 18283:2006(E)
Introduction
Mechanical sampling from moving streams is the preferred method for sampling fuels. However, often
mechanical facilities are not available. Moreover, for sized coal or coke, mechanical sampling can be a
problem because of (size) degradation by the sampling system.
The fundamental requirements of sampling are that all particles of the fuel in the lot are accessible to the
sampling instrument and that each individual particle has an equal probability of being selected and included
in the sample.
When sampling manually, conditions are often far from ideal. The methods described in this International
Standard are intended to obtain the most representative sample that can be achieved. Manual sampling
should only be applied if no possibility for mechanical sampling exists.
The purpose of taking and preparing a sample of fuel is to provide a test sample that, when analysed,
provides test results representative of the lot sampled.
The first stage of sampling, known as primary sampling, is the taking from positions distributed over the entire
lot of an adequate number of fuel portions known as primary increments. The primary increments are then
combined into a sample, either “as taken” or after having been divided, in order to reduce the mass of the
sample to a manageable size. From this sample, the required number and types of test samples are prepared
by a series of processes jointly known as sample preparation.
In devising a sampling procedure, it is also essential to guard against bias in the taking of increments. Bias
can arise from
a) incorrect location/timing of increments,
b) incorrect delimitation and extraction of increments,
c) loss of integrity of increments after extraction.
Methods for measuring bias are described in this International Standard.
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INTERNATIONAL STANDARD ISO 18283:2006(E)
Hard coal and coke — Manual sampling
CAUTION — Sampling can involve hazardous materials, operations, equipment and situations.
However, it is beyond the scope of this International Standard to address all of the safety problems
associated with the use of this International Standard. It is, therefore, the responsibility of the parties
concerned to establish appropriate safety and health practices and to determine the applicability of
regulatory limitations prior to use.
1 Scope
ISO 18283 defines the basic terms used in manual sampling of hard coal and coke and describes the general
principles of sampling. It specifies procedures and requirements for establishing a manual sampling scheme,
methods of manual sampling, sampling equipment, handling and storage of samples, sample preparation and
a sampling report.
This International Standard applies to manual sampling from fuels in movement. Guidelines for manual
sampling from fuels in stationary situations are given in Annex B, but this method of sampling does not
provide a representative test sample and the sampling report shall state this.
ISO 18283 does not include sampling of brown coals and lignites, which is described in ISO 5069-1 and
ISO 5069-2, nor sampling from coal seams, for which guidance is given in ISO 14180. Mechanical sampling of
coal and coke is covered in ISO 13909 (all parts).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 579, Coke — Determination of total moisture
ISO 589:2003, Hard coal — Determination of total moisture
ISO 687, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 13909-7, Hard coal and coke — Mechanical sampling — Part 7: Methods for determining the precision of
sampling, sample preparation and testing
ISO 13909-8, Hard coal and coke — Mechanical sampling — Part 8: Methods of testing for bias
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ISO 18283:2006(E)
3 Terms and definitions
For the purposes of this document, the following definitions apply.
3.1
air-drying
process of bringing the moisture content of the sample near to equilibrium with the atmosphere in the area in
which further reduction and division of the sample are to take place
NOTE Air-drying to equilibrium with the atmosphere applies to coal. Drying of coke is generally to facilitate sample
preparation.
3.2
bias
systematic error that leads to the average value of a series of results being persistently higher or persistently
lower than those that are obtained using a reference sampling method
3.3
common sample
sample collected for more than one intended use
3.4
continuous sampling
taking of a sample from each consecutive sub-lot so that increments are taken at uniform intervals whenever
the fuel is handled at the point of sampling
3.5
divided increment
part obtained from the division of the increment in order to decrease its mass
NOTE Such division can be done with or without prior size reduction.
3.6
fixed-mass division
method of sample division in which the mass retained is predetermined and independent of the mass of the
feed
3.7
fixed-ratio division
method of sample division in which the division ratio is predetermined, i.e. the mass of sample retained is a
fixed proportion of the mass of the feed
3.8
fuel
hard coal or coke
3.9
general analysis test sample
sample prepared to pass a sieve of nominal size of openings 212 µm in accordance with ISO 3310-1, used for
the determination of most chemical and some physical characteristics
3.10
increment
portion of fuel extracted in a single operation of the sampling device
3.11
intermittent sampling
taking of samples from only certain sub-lots of fuel
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ISO 18283:2006(E)
3.12
lot
defined quantity of fuel for which the quality is to be determined
NOTE A lot can be divided into sub-lots.
3.13
manual sampling
extraction of increments by human effort
3.14
mass-basis sampling
taking of increments whereby the position of each increment to be extracted from the stream of fuel is
measured by a mass interval of stream flow and the increment mass is fixed
3.15
mechanical sampling
extraction of increments by mechanical means
3.16
moisture sample
sample taken specifically for the purpose of determining total moisture
NOTE For coke, this sample can also be used for general analysis.
3.17
nominal top size
aperture size of the smallest sieve in the range included in the R 20 Series (see ISO 565, square hole) on
which not more than 5 % of the sample is retained
3.18
physical sample
sample taken specifically for the determination of physical characteristics, e.g. physical strength indices or
size distribution
3.19
precision
closeness of agreement between independent test results obtained under stipulated conditions
NOTE 1 This is often defined using an index of precision, such as 2 standard deviations.
NOTE 2 A determination might be made with great precision and the standard deviation of a number of determinations
on the same sub-lot might, therefore, be low; but such results are accurate only if they are free from bias.
3.20
primary increment
increment extracted at the first stage of sampling, prior to any sample division and/or sample reduction
3.21
random sampling
extracting of increments at random mass or time intervals
3.22
replicate sampling
extracting, at intervals, of increments that are combined in rotation into different containers to give two or more
samples of approximately equal mass
3.23
sample
quantity of fuel, representative of a larger mass for which the quality is to be determined
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ISO 18283:2006(E)
3.24
sample division
process in sample preparation whereby the sample is divided into representative, separate portions
3.25
sample preparation
process of bringing samples to the condition required for analysis or testing
NOTE Sample preparation covers mixing, particle size reduction, sample division and sometimes air-drying of the
sample and may be performed in several stages
3.26
sample reduction
process in sample preparation whereby the particle size of the sample is reduced by crushing or grinding
3.27
size analysis sample
sample taken specifically for particle size analysis
3.28
standard deviation
square root of the variance
3.29
stratified random sampling
extracting of an increment at random within the mass interval or time interval determined for mass-basis
sampling or time-basis sampling respectively
3.30
sub-lot
part of a lot for which a test result is required
3.31
systematic sampling
extracting of increments at uniform mass or time intervals according to a predetermined plan
3.32
test sample
sample which is prepared to meet the requirements of a specific test
3.33
time-basis sampling
extracting of increments whereby the position of each increment to be collected from the stream of fuel is
measured by a time interval and the increment mass is proportional to the flow rate at the time the increment
is taken
3.34
unit mass
quantity of material, which is defined by the sampling process (usually the primary increment)
3.35
variance
measure of dispersion, which is the sum of the squared deviations of observations from their average divided
by one less than the number of observations
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ISO 18283:2006(E)
4 Establishing a sampling scheme
4.1 General
4.1.1 Sampling
The preferred method for manual sampling of fuels is during handling: e.g. (un)loading of ships, barges,
wagons, trucks or during formation of or reclaiming from stockpiles. For safety and practical reasons, manual
sampling of moving streams is sometimes not possible.
NOTE Manual sampling in stationary situations (see Annex B) refers to static lots, where no formation of or
reclaiming from piles/heaps takes place.
Increments should be collected by trained samplers. Instructions should be as complete and as simple as
possible; in particular, the position of sampling and the times at which increments are taken should be
specified and not left to the personal judgement of the sampler. These instructions, which should preferably be
set out in writing, should be prepared by the sampling supervisor from the information given in this
International Standard.
4.1.2 Sampling scheme
The general procedure for establishing a sampling scheme is as follows.
a) Define the quality parameters to be determined and the types of samples required.
b) Define the lot.
c) Select or assume the required overall precision for the lot (see 4.4.2).
d) Determine or assume the variability of the fuel (see 4.4.5 and, if relevant, 4.4.6) and the variance of
preparation and testing (see 4.4.7).
e) Ascertain the nominal top size of the fuel for the purpose of determining the mass of increment and
sample (see 4.4.9 and 4.4.10).
The nominal top size should initially be ascertained by consulting the consignment details or by visual
estimation and should be verified by preliminary test work.
f) Select the sampling device (see Clause 6).
g) Establish the number of sub-lots and the number of increments per sub-lot required to attain the desired
precision (see 4.5).
h) Determine the method of combining the increments into samples and the method of sample preparation
(see Clause 8).
i) Define the sampling interval in terms of time or mass (see Clause 5).
j) Determine where to take the increments (see Clause 5).
4.1.3 Parameters
In order to ensure that the result obtained is to the required precision, the following parameters are
considered:
a) variability of the fuel;
b) number of samples to be taken from the lot;
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ISO 18283:2006(E)
c) number of increments comprising each sample;
d) mass of sample relative to nominal top size.
4.1.4 Sampling methods
In this International Standard, the following sampling methods are considered:
a) continuous sampling;
b) intermittent sampling.
4.2 Sampling methods
4.2.1 Continuous sampling
In continuous sampling, every sub-lot is sampled and the number of increments collected from each sub-lot
shall be determined in accordance with 4.4.8.2. There are as many sample results for the lot as there are sub-
lots. Each sub-lot should be approximately the same size; however, for practical reasons sometimes sub-lots
of different sizes are used. The mean result for the lot should be of the required precision, but if it is desired to
check that the required precision has been attained, it is possible to do this by using the procedures of
replicate sampling (see 4.6).
4.2.2 Intermittent sampling
If fuel of the same source and quality is sampled frequently, it can be satisfactory to collect increments from
some of the sub-lots but not from others. This is called intermittent sampling. The same number of increments
shall be taken from every sub-lot that is sampled (see 4.4.8.3). The sub-lots to be sampled shall be chosen at
random, unless it can be demonstrated that no bias, for example as a result of time-dependent variance, is
introduced by choosing sub-lots systematically. Such demonstration shall be repeated from time to time and at
random intervals. There are as many sample results per lot as there are sub-lots sampled, but because some
sub-lots are not sampled, it is not possible to say whether the average of these results has the required
precision for the lot unless information about the variation between sub-lots is available (see 4.4.4 and 4.4.6).
If the variation between sub-lots is too large, it can be necessary to introduce continuous sampling to achieve
the desired precision. Use of intermittent sampling shall be agreed between contracting parties and shall be
recorded in the sampling report.
4.3 Design of the sampling scheme
4.3.1 General
The basic first step in the design of a sampling scheme is a review of the requirements for operations in order
to draw up instructions for the sampling operator(s). The instructions should cover all sampling problems likely
to be encountered.
It is important that the sampling operator receive instructions that are simple, easily understood and capable
of only one interpretation. These instructions, which should be set out in writing, should be prepared by the
sampling supervisor after inspecting the sampling site and referring to the information given in this
International Standard. The following items in the following list and described in 4.3.2 to 4.3.6 should be
considered by the supervisor when compiling instructions:
a) fuel to be sampled and considerations for sampling;
b) bias of results;
c) precision of results;
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ISO 18283:2006(E)
d) lot size and number of sub-lots;
e) method of sampling;
f) requirements for test samples;
g) number of increments;
h) mass of sample.
4.3.2 Fuel to be sampled and considerations for sampling
The first stage in the design of the scheme is to identify the fuel to be sampled. Samples can be required for
technical evaluation, process control, quality control and for commercial reasons by both the producer and/or
seller and the customer. It is essential to ascertain exactly at what stage in the fuel-handling process the
sample is required and, as far as practicable, to design the scheme accordingly. In some instances, however,
it can prove impracticable to obtain samples at the point preferred and, in such cases, a more practicable
alternative is required, provided a representative sample can be taken.
The following identifications are indispensable for the design of a manual sampling scheme:
a) fuel properties, e.g. fines, lumpy and, more specifically, the nominal top size; furthermore, whether dry,
wet or free flowing;
b) location and the handling system;
c) transport means/carriers;
d) where to sample in the handling process, taking into account contract terms and the practicability for
sampling;
e) human safety risks.
4.3.3 Division of lots
The lot may be sampled as a whole, resulting in one sample, or divided into a number of sub-lots resulting in a
sample from each. A lot may be sampled as a whole or as a series of sub-lots each to a maximum of 10 000 t,
e.g. fuel despatched or delivered over a period of time, a ship load, a train load, a wagon load, or fuel
produced during a certain period, e.g. a shift.
Such division into a number of sub-lots can be necessary to
a) achieve the required precision (calculated by the procedure in 4.5),
b) maintain the integrity of the sample, e.g. avoiding bias that can result from the loss of moisture due to
standing or of calorific value due to oxidation,
c) create convenience when sampling lots over a long period, e.g. on a shift basis,
d) keep sample masses manageable, taking into account the maximum lifting capacity,
e) distinguish different components of a mixture of fuels, e.g. different coal types within one lot.
4.3.4 Bias of results
It is of particular importance in sampling to ensure as far as possible that the parameter to be measured is not
altered by the sampling and sample preparation process or by subsequent storage prior to testing. This can
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ISO 18283:2006(E)
require, in some circumstances, a limit on the mass of the primary increment, the divided sample and the test
sample to maintain integrity (see 4.4.9 and 4.4.10).
It can be necessary, when collecting samples for moisture determination from lots over an extended period, to
limit the standing time of samples by dividing the lot into a number of sub-lots. For establishing the loss of
integrity of the sample, a bias test can be carried out to compare a series of reference samples immediately
after extraction with samples after standing for the normal time to establish moisture or calorific value loss
(see ISO 13909-8).
Bias testing for manual sampling can be performed according to the same principles as for mechanical
sampling using a reference method to judge a manual sampling practice (ISO 13909-8).
4.3.5 Precision of results
After the overall precision of the lot has been decided, the number of sub-lots and the number of increments
per sub-lot collected shall then be determined as described in 4.4.8 and the reference mass of the primary
increments shall be determined as described in 4.4.9.
For single lots, the quality variation shall be assumed as the worst
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