SIST EN 14780:2011
(Main)Solid biofuels - Sample preparation
Solid biofuels - Sample preparation
This Standard describes methods for reducing combined samples to laboratory samples and laboratory samples to sub-samples and general analysis samples, and is applicable to solid biofuels that are either:
- Fine and regularly-shaped particulate materials, particle size up to about 10 mm that can be sampled using a scoop or pipe, for example: sawdust, olive stones and wood pellets;
- coarse or irregularly-shaped particulate materials, particle size up to about 200 mm that can be sampled using a fork or shovel, for example: wood chips and nut shells, forest residue chips and loose straw;
- large pieces with nominal top size above 200 mm;
The methods described in this Standard may be used for sample preparation, for example, when the samples are to be tested for bulk density, durability, particle size distribution, moisture content, ash content, ash melting behaviour, calorific value, chemical composition and impurities. The methods are not intended to be applied to the very large samples required for the testing of bridging properties.
Feste Biobrennstoffe - Probenherstellung
Diese Europäische Norm legt Verfahren zur Reduktion von Gesamtproben (oder Einzelproben) auf Laboratoriumsproben und von Laboratoriumsproben auf Teilproben und allgemeine Analysenproben fest und gilt für feste Biobrennstoffe. Die in dieser Europäische Norm festgelegten Verfahren dürfen bei der Probenvorbereitung angewendet werden, zum Beispiel, wenn Proben im Hinblick auf Energiegehalt, Wasser- und Aschegehalt, Schüttdichte, mechanische Festigkeit, Partikelgrößenverteilung, Ascheschmelzverhalten, chemische Zusammensetzung und Verunreinigungen zu prüfen sind. Die Verfahren sind nicht dafür vorgesehen, auf sehr große Proben angewendet zu werden, die zur Prüfung der Neigung zur Brückenbildung erforderlich sind.
Biocombustibles solides - Préparation des échantillons
La présente Norme européenne décrit les méthodes permettant de réduire les échantillons composites (ou les prélèvements élémentaires) en échantillons pour laboratoire et les échantillons pour laboratoire en sous échantillons et en échantillons pour analyse générale. Elle s’applique aux biocombustibles solides.
Les méthodes décrites dans la présente Norme européenne peuvent être utilisées pour la préparation d’échantillons devant, par exemple, être soumis à des essais portant sur le pouvoir calorique, le taux d’humidité, la teneur en cendres, la masse volumique apparente, la durabilité, la distribution granulométrique des particules, la fusibilité de cendre, la composition chimique et les impuretés. Ces méthodes ne visent pas à s’appliquer aux très grands échantillons utilisés pour évaluer les propriétés de pontage.
Trdna biogoriva - Priprava vzorcev
Ta standard določa metode za zmanjševanje združenih vzorcev v laboratorijske vzorce in laboratorijskih vzorcev v podvzorce ter splošne preskusne vzorce ter velja za trdna biogoriva, ki so lahko:
- drobni delci pravilnih oblik z velikostjo do približno 10 mm, ki se lahko vzorčijo z zajemalko ali cevjo, na primer: žagovina, olivne koščice in lesni peleti;
- grobi delci ali delci nepravilnih oblik z velikostjo do približno 200 mm, ki se lahko vzorčijo z vilami ali lopato, na primer: lesni sekanci in lupine oreškov, sekanci gozdnih ostankov in nevezana slama;
- veliki delci z nazivno največjo velikostjo nad 200 mm;
Metode, opisane v tem standardu, se lahko uporabljajo za pripravo vzorcev, na primer pri preskusu vzorcev za volumensko gostoto, trajnost, porazdelitev velikosti delcev, vsebnost vlage, vsebnost pepela, karakterizacijo tališča pepela, kalorično vrednost, kemično sestavo in nečistoče. Metode niso primerne za uporabo pri zelo velikih vzorcih, potrebnih za preskušanje premostitvenih lastnosti.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Trdna biogoriva - Priprava vzorcevFeste Biobrennstoffe - ProbenherstellungBiocombustibles solides - Préparation des échantillonsSolid biofuels - Sample preparation75.160.10Trda gorivaSolid fuelsICS:Ta slovenski standard je istoveten z:EN 14780:2011SIST EN 14780:2011en,fr,de01-september-2011SIST EN 14780:2011SLOVENSKI
STANDARDSIST-TS CEN/TS 14780:20051DGRPHãþD
SIST EN 14780:2011
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14780
June 2011 ICS 75.160.10 Supersedes CEN/TS 14780:2005English Version
Solid biofuels - Sample preparation
Biocombustibles solides - Préparation des échantillons
Feste Biobrennstoffe - Probenherstellung This European Standard was approved by CEN on 5 May 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14780:2011: ESIST EN 14780:2011
EN 14780:2011 (E) 2 Contents
Foreword .3Introduction .41Scope .52Normative references .53Terms and definitions .54Symbols and abbreviations .65Principles of correct sample reduction .66Apparatus .77Sample reduction – general principles . 108Methods for sample division . 129Method for reducing laboratory samples to sub-samples and general analysis samples . 1510Storage and labelling . 1711Performance characteristics . 17Annex A (informative)
Precision in relation to division method . 18Bibliography . 24 SIST EN 14780:2011
EN 14780:2011 (E) 3 Foreword This document (EN 14780:2011) has been prepared by Technical Committee CEN/TC 335 “Solid biofuels”, the secretariat of which is held by SIS. 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 December 2011, and conflicting national standards shall be withdrawn at the latest by December 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes CEN/TS 14780:2005. This document differs from CEN/TS 14780:2005 mainly as follows: a) results of interlaboratory tests are supplemented as informative annexes; b) new definitions for sampling are introduced; c) a method for determining the minimum number of increments for sampling is included; d) the whole document is restructured and editorially revised; e) decision schemes are updated; f) updated normative references are included. 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. SIST EN 14780:2011
EN 14780:2011 (E) 4 Introduction
Biofuels are a major source of renewable energy. European Standards are needed for production, trade and use of solid biofuels. For sampling and sample preparation of biofuels the following European Standards can be used: EN 14778, Solid biofuels – Sampling EN 14780, Solid biofuels – Sample preparation This European Standard can be used in regard to production, controlling and analysis of solid biofuels in general.
SIST EN 14780:2011
EN 14780:2011 (E) 5 1 Scope This European Standard describes methods for reducing combined samples (or increments) to laboratory samples and laboratory samples to sub-samples and general analysis samples and is applicable to solid biofuels. The methods described in this European Standard may be used for sample preparation, for example, when the samples are to be tested for calorific value, moisture content, ash content, bulk density, durability, particle size distribution, ash melting behaviour, chemical composition, and impurities. The methods are not intended to be applied to the very large samples required for the testing of bridging properties. 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. EN 14588:2010, Solid biofuels — Terminology, definitions and descriptions EN 14774-1, Solid biofuels — Determination of moisture content — Oven dry method — Part 1: Total moisture — Reference method EN 14774-2, Solid biofuels — Determination of moisture content — Oven dry method — Part 2: Total moisture — Simplified procedure 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 14588:2010 and the following apply. 3.1 combined sample sample consisting of all the increments taken from a sub-lot NOTE The increments may be reduced by division before being added to the combined sample. 3.2 general analysis sample sub-sample of a laboratory sample having a nominal top size of 1 mm or less and used for a number of chemical and physical analyses 3.3 increment portion of fuel extracted in a single operation of the sampling device 3.4 laboratory sample combined sample or a sub-sample of a combined sample for use in a laboratory 3.5 lot defined quantity of fuel for which the quality is to be determined NOTE See also sub-lot. 3.6 moisture analysis sample sample taken specifically for the purpose of determining total moisture according to EN 14774-1 and EN 14774-2 SIST EN 14780:2011
EN 14780:2011 (E) 6 3.7 nominal top size aperture size of the sieve used in CEN, method for determining the particle size distribution of solid fuels, through which at least 95 % by mass of the material passes 3.8 particle size-reduction reduction of the nominal top size of a sample or sub-sample 3.9 sample quantity of material, representative of a larger quantity for which the quality is to be determined 3.10 sample division division of a sample or sub-sample to a appropriate size. This usually always leads to a mass reduction of a sample or sub-sample 3.11 size analysis sample sample taken specifically for the purpose of determining particle size distribution
3.12 sub-lot
part of a lot for which a test result is required 3.13 sub-sample portion of a sample 3.14 test portion sub-sample either of a laboratory sample or a test sample 3.15 test-sample laboratory sample after an appropriate preparation made by the laboratory 4 Symbols and abbreviations Mp
is the moisture loss, in percentage msample,1 is the initial mass of the sample, g msample,2 is the mass of the sample after pre-drying, g W
is the width and is at least 2,5 times the nominal top size of the material 5 Principles of correct sample reduction The main purpose of sample preparation is that a sample is reduced to one or more test portions that are in general smaller than the original sample. The main principle for sample reduction is that the composition of the sample as taken on site shall not be changed during each stage of the sample preparation. Each sub sample shall be representative of the original sample. To reach this goal every particle in the sample before sample division shall have an equal probability of being included in the sub-sample following sample division. Two basic methods are used during the sample preparation. These methods are: sample division; particle size-reduction of the sample. SIST EN 14780:2011
EN 14780:2011 (E) 7 CAUTION — Avoid loss of moisture and fine particles during milling and other operations. Because of the risk of changes in the moisture content (loss of moisture), a sub-sample (moisture analysis sample) shall be separated at the earliest possible stage of the sample preparation procedure. As an alternative, a separate moisture analysis sample may be taken. The sample reduction shall be carried out by a procedure that does not conflict with requirements of EN 14774-1 or EN 14774-2. For materials that have to be examined for moisture content, care shall be taken to avoid any significant heat build-up and risk of drying.
6 Apparatus 6.1 Apparatus for sample division 6.1.1 General Sample division is the process of reducing the mass of the sample without reducing the size of the particles. This subclause gives some suitable apparatus for this purpose. To determine the correct use of each apparatus for different purposes refer to Clause 8. 6.1.2 Riffle boxes A riffle box shall have an equal number of slots and at least 6 at each side (preferably more if possible), with adjacent slots directing material into different sub-samples, and the width of the slots shall be at least 2,5 times the nominal top size of the material to be riffled (see Figure 1).
Key 1 W - slot width is at least 2,5 times the nominal top size of the material Figure 1 — Example of a riffle box 6.1.3 Rotary sample dividers The inner dimensions of the equipment where the sample is fed shall be at least 2,5 times as wide as the nominal top size of the material to be processed. The rotary sample divider shall have a feeder device adjusted, so that the number of compartments multiplied by the number of rotations shall not be less than 120 while the sample is being divided. See Figure 2 for an example of a rotating divider.
SIST EN 14780:2011
EN 14780:2011 (E) 8
Key 1 feeder 2 funnel 3 rotating receivers 4 divided sample Figure 2 — Example of a rotary sample divider 6.1.4 Shovels and scoops A shovel or scoop are tools used for manual sample division. They shall have a flat bottom, with edges raised high enough to prevent particles rolling off, and be at least 2,5 times as wide as the nominal top size of the material to be processed. See Figures 3 and 4 for examples of a scoop and a shovel respectively.
Key 1 W
width of the scoop Figure 3 — Example of a scoop SIST EN 14780:2011
EN 14780:2011 (E) 9
Figure 4 — Example of a shovel
NOTE For very large sample sizes, it is more practical to use a push dozer or bulldozer or any other heavy machinery that has a large "scoop" with raised edges. 6.2 Apparatus for particle size-reduction CAUTION — When analysing metals, take care that there is no contamination from the sample preparation or reduction equipment. 6.2.1 Coarse cutting mill or wood crusher Coarse cutting mills are used for cutting materials into lengths of about 10 mm to 30 mm (depending on the biofuel and the analyses to be performed). Drying of the material during coarse cutting should be avoided, by limiting heat production and air flow through the material. The equipment shall be designed so that it does not lose dust or contaminate the material with pieces of metal, and shall be easy to clean.
NOTE To prevent losses of moisture during particle size reduction a grinder with as low a grinding speed as possible is preferred.
6.2.2 Cutting mill Cutting mills are used for reducing the nominal top size of materials used as biofuels from about 10 mm to
30 mm down to about 1 mm or less (depending on the biofuel and the analyses to be performed). The mill shall be provided with screens of various aperture sizes covering this range, including an appropriate sieve to control the nominal top size of the material produced. Other apparatus may be used provided that they are designed so that they do not get blocked with the material that is being processed. Avoid the use of cutting mills whose cutting faces contain significant quantities of an element that is to be determined in the analysis.
NOTE Cross beater mills can be used without any excessive dusting, when fitted with dust filters (like a filter sock) between the mill and the receiving container. They are suitable for final grinding of hard, wood type materials after the pre-grinding with cutting type mills.
SIST EN 14780:2011
EN 14780:2011 (E) 10 6.2.3 Axe An axe is used for cutting wood logs or coarse material down to maximum 30 mm thickness or suitable size to be processed in a cutting mill provided with a 30 mm sieve. 6.2.4 Hand saw A hand saw is used to saw off wood logs or coarse material down to maximum 30 mm thickness or suitable size to be processed in a cutting mill provided with a 30 mm sieve. NOTE A chain saw may contaminate the sample by chain oil and should therefore not be used. A saw machine should not be used for size reduction to avoid the risk of losing moisture in the sample as a result of heat caused by friction. 6.3 Sieves A wire-mesh sieve with an aperture size of 1,00 mm is required to check the nominal top size of general analysis samples. A wire-mesh sieve with an aperture size of 0,25 mm will be required if sub-samples with this nominal top size are required. 6.4 Balance A balance is required that is capable of determining the mass of samples to an accuracy of 0,1 % of the sample mass, and the mass of sub-samples to an accuracy of 0,1 % of the sub-sample mass. 7 Sample reduction – general principles For every sample division stage to be carried out it is important that a sufficient mass of material is retained, otherwise the sub-samples produced or the test portions to be taken may not be representative of the original sample. Table 1 gives a guideline for minimum masses to be retained after each sample division stage, depending on the nominal top size of the material. In addition to the minimum masses stated in Table 1, it shall be ensured that the mass after a sample division stage is sufficiently large for the actual test or tests to be performed. Supplementary requirements concerning the masses of the test portions are given in European Standards for test methods of solid biofuels. SIST EN 14780:2011
EN 14780:2011 (E) 11 Table 1 — Guideline for minimum masses to be retained during sample division stages Nominal top size (mm) Minimum mass(g) 200 150 100 63 50 45 40 30 10 5 1 0,25 120000 50000 15000 4000 2000 1500 1000 500 150 100 50 10
NOTE This guideline does not take in to account: particle size distribution, shape of a particle, density of a particle, etc. Figure 5 summarises the range of steps that can be taken during sample reduction. SIST EN 14780:2011
EN 14780:2011 (E) 12
NOTE List of optional sub-sample extractions may not be exhaustive
Figure 5 —
Flow sheet for sample preparation and optional extraction of sub-samples
8 Methods for sample division 8.1 General Combined samples may be divided into two or more laboratory samples and laboratory samples are in general further divided in sub-samples (test-portions). This clause describes the methods and procedures for sample division. For every division step the mass of retained material given in Table 1 shall be taken into account.
8.2 Riffling g) This may be used for materials that can be passed through the riffle without bridging. It is not suitable for straw, bark, or other materials containing elongated particles, or for wet and/or sticky materials. Brittle materials should be handled with care to avoid the production of fine materials. Place the whole of the SIST EN 14780:2011
EN 14780:2011 (E) 13 combined sample into one of the containers of the riffle so that it is evenly distributed throughout the container. Place the other two containers in position under the riffle. Pour the contents of the first container down the centre line of the riffle. Pour the biofuel sufficiently slowly to avoid bridging occurring. Do not move the container from side to side (this would cause the end slots to receive less biofuel). Discard the biofuel that falls into one of the containers, chosen at random. Repeat the riffling process until a sub-sample of the required mass is obtained. See Figure 1 for an example of a riffle box. 8.3 Strip mixing This may be used for all materials, and will be a convenient method when a combined sample is to be divided into a small number of laboratory samples. Place the whole combined sample on a clean, hard surface and homogenise it by mixing with a shovel, and form into a strip at least 20 times as long as it is wide. Distribute the sample along the length of the strip as evenly as possible working randomly from end to end. Building up the strip with several layers will increase the quality of the division. Obtain a laboratory sample by taking at least 20 increments from locations evenly spaced along the length of the strip. Take each increment by inserting two plates vertically into the strip and removing all the material from between the plates. The two plates should be inserted the same distance a
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Trdna biogoriva - Priprava vzorcevFeste Biobrennstoffe - ProbenherstellungBiocombustibles solides - Préparation des échantillonsSolid biofuels - Sample preparation75.160.10Trda gorivaSolid fuelsICS:Ta slovenski standard je istoveten z:FprEN 14780kSIST FprEN 14780:2011en,fr,de01-januar-2011kSIST FprEN 14780:2011SLOVENSKI
STANDARD
kSIST FprEN 14780:2011
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN 14780
November 2010 ICS 75.160.10 Will supersede CEN/TS 14780:2005English Version
Solid biofuels - Sample preparation
Biocombustibles solides - Préparation des échantillons
Feste Biobrennstoffe - Probenherstellung This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/TC 335.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. FprEN 14780:2010: EkSIST FprEN 14780:2011
FprEN 14780:2010 (E)
2 Contents
1 Scope .4 2 Normative references .4 3 Terms and definitions .4 4 Symbols and abbreviations .5 5 Principles of correct sample reduction .5 6 Apparatus .6 7 Sample reduction – general principles .9 8 Methods for sample division . 11 9 Method for reducing laboratory samples to sub-samples and general analysis samples . 14 10 Storage and labelling . 16 11 Performance characteristics . 16 Annex A (informative)
Precision in relation to division method . 17
kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
3Foreword This document (FprEN 14780:2010) has been prepared by Technical Committee CEN/TC 335 “Solid biofuels”, the secretariat of which is held by SIS. This document is currently submitted to the Unique Acceptance Procedure. This document will supersede CEN/TS 14780:2005 Introduction
Biofuels are a major source of renewable energy. European Standards are needed for production, trade and use of solid biofuels. For sampling and sample preparation of biofuels the following European Standards can be used: EN 14778, Solid biofuels – Sampling.
EN 14780, Solid biofuels – Sample preparation. This European Standard can be used in regard to production, controlling and analysis of solid biofuels in general.
kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
4 1 Scope This European Standard describes methods for reducing combined samples (or increments) to laboratory samples and laboratory samples to sub-samples and general analysis samples and is applicable to solid biofuels. The methods described in this European Standard may be used for sample preparation, for example, when the samples are to be tested for calorific value, moisture content, ash content, bulk density, durability, particle size distribution, ash melting behaviour, chemical composition, and impurities. The methods are not intended to be applied to the very large samples required for the testing of bridging properties. 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. EN 14588, Solid biofuels – Terminology, definitions and descriptions.
EN 14774-1, Solid biofuels – Determination of moisture content – Oven dry method – Part 1: Total moisture – Reference method. EN 14774-2, Solid biofuels – Determination of moisture content – Oven dry method – Part 2: Total moisture – Simplified procedure. CEN/TS 15149-1, Solid biofuels – Methods for the determination of particle size distribution – Part 1: Oscillating screen method using sieve apertures of 3,15 mm and above. EN 15149-2, Solid biofuels – Methods for the determination of particle size distribution – Part 2: Vibrating screen method using sieve apertures of 3,15 mm and below. EN 14778, Solid Biofuels – Sampling. 3 Terms and definitions For the purposes of this European Standard, the terms and definitions given in EN 14588 and the following apply. 3.1 combined sample sample consisting of all the increments taken from a sub-lot NOTE The increments may be reduced by division before being added to the combined sample. 3.2 general analysis sample sub-sample of a laboratory sample having a nominal top size of 1 mm or less and used for a number of chemical and physical analyses 3.3 increment portion of fuel extracted in a single operation of the sampling device 3.4 laboratory sample combined sample or a sub-sample of a combined sample for use in a laboratory 3.5 lot defined quantity of fuel for which the quality is to be determined kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
5NOTE See also sub-lot. 3.6 Sample division division of a sample or sub-sample to a appropriate size. This usually always leads to a mass reduction of a sample or sub-sample 3.7 moisture analysis sample sample taken specifically for the purpose of determining total moisture according to EN 14774-1 and EN 14774-2 3.8 nominal top size aperture size of the sieve used in the CEN/TS 15149-1 and CEN/TS 15149-2, method for determining the particle size distribution of solid biofuels, through which at least 95 % by mass of the material passes 3.9 sample quantity of material, representative of a larger quantity for which the quality is to be determined 3.10 size analysis sample sample taken specifically for the purpose of determining particle size distribution
3.11 particle size-reduction reduction of the nominal top size of a sample or sub-sample 3.12 sub-lot
part of a lot for which a test result is required 3.13 sub-sample portion of a sample 3.14 test portion sub-sample of a laboratory sample consisting of the quantity of material required for a single execution of a test method 3.15 test-sample laboratory sample after an appropriate preparation made by the laboratory 4 Symbols and abbreviations Mp
is the moisture loss, in percentage msample,1 is the initial mass of the sample, g msample,2 is the mass of the sample after pre-drying, g W
is the width and is at least 2,5 times the nominal top size of the material 5 Principles of correct sample reduction The main purpose of sample preparation is that a sample is reduced to one or more test portions that are in general smaller than the original sample. The main principle for sample reduction is that the composition of the sample as taken on site shall not be changed during each stage of the sample preparation. Each sub sample shall be representative of the original sample. To reach this goal every particle in the sample before sample division shall kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
6 have an equal probability of being included in the sub-sample following sample division. Two basic methods are used during the sample preparation. These methods are: sample division; particle size-reduction of the sample. CAUTION — Avoid loss of moisture and fine particles during milling and other operations. Because of the risk of changes in the moisture content (loss of moisture), a sub-sample (moisture analysis sample) shall be separated at the earliest possible stage of the sample preparation procedure. As an alternative, a separate moisture analysis sample may be taken. The sample reduction shall be carried out by a procedure that does not conflict with requirements of EN 14774-1 or EN 14774-2. For materials that have to be examined for moisture content, care must be taken to avoid any significant heat build-up and risk of drying.
6 Apparatus 6.1 Apparatus for sample division Sample division is the process of reducing the mass of the sample without reducing the size of the particles. This paragraph gives some suitable apparatus for this purpose. To determine the correct use of each apparatus for different purposes refer to Clause 8. 6.1.1 Riffle boxes A riffle box should have an equal number of slots and at least 6 at each side (preferably more if possible), with adjacent slots directing material into different sub-samples, and the width of the slots shall be at least 2,5 times the nominal top size of the material to be riffled (see Figure 1).
Figure 1 — Example of a riffle box Key 1 W - slot width is at least 2,5 times the nominal top size of the material 6.1.2 Rotary sample dividers The inner dimensions of the equipment where the sample is fed shall be at least 2,5 times as wide as the nominal top size of the material to be processed. The rotary sample divider shall have a feeder device adjusted, so that the kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
7number of compartments multiplied by the number of rotations shall not be less than 120 while the sample is being divided. See Figure 2 for an example of a rotating divider.
Figure 2 — Example of a rotary sample divider Key 1 feeder 2 funnel 3 rotating receivers 4 divided sample 6.1.3 Shovels and scoops A shovel or scoop are tools used for manual sample division. They shall have a flat bottom, with edges raised high enough to prevent particles rolling off, and be at least 2,5 times as wide as the nominal top size of the material to be processed. See Figures 3 and 4 for examples of a scoop and a shovel respectively.
kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
8
Key 1 W
width of the scoop Figure 3 — Example of a scoop
Figure 4 — Example of a shovel
NOTE For very large sample sizes, it is more practical to use a push dozer or bulldozer or any other heavy machinery that has a large "scoop" with raised edges. kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
96.2 Apparatus for particle size-reduction CAUTION — When analysing metals, take care that there is no contamination from the sample preparation or reduction equipment. 6.2.1 Coarse cutting mill or wood crusher Coarse cutting mills are used for cutting materials into lengths of about 10 mm to 30 mm (depending on the biofuel and the analyses to be performed). Drying of the material during coarse cutting should be avoided, by limiting heat production and air flow through the material. The equipment shall be designed so that it does not lose dust or contaminate the material with pieces of metal, and shall be easy to clean.
NOTE To prevent losses of moisture during particle size reduction a grinder with as low a grinding speed as possible is preferred.
6.2.2 Cutting mill Cutting mills are used for reducing the nominal top size of materials used as biofuels from about 10 mm to
30 mm down to about 1 mm or less (depending on the biofuel and the analyses to be performed). The mill shall be provided with screens of various aperture sizes covering this range, including an appropriate sieve to control the nominal top size of the material produced. Other apparatus may be used provided that they are designed so that they do not get blocked with the material that is being processed. Avoid the use of cutting mills whose cutting faces contain significant quantities of an element that is to be determined in the analysis.
NOTE Cross beater mills can be used without any excessive dusting, when fitted with dust filters (like a filter sock) between the mill and the receiving container. They are suitable for final grinding of hard, wood type materials after the pre-grinding with cutting type mills.
6.2.3 Axe An axe is used for cutting wood logs or coarse material down to maximum 30 mm thickness or suitable size to be processed in a cutting mill provided with a 30 mm sieve. 6.2.4 Hand saw A hand saw is used to saw off wood logs or coarse material down to maximum 30 mm thickness or suitable size to be processed in a cutting mill provided with a 30 mm sieve. NOTE A chain saw may contaminate the sample by chain oil and should therefore not be used. A saw machine should not be used for size reduction to avoid the risk of losing moisture in the sample as a result of heat caused by friction. 6.3 Sieves A wire-mesh sieve with an aperture size of 1,00 mm is required to check the nominal top size of general analysis samples. A wire-mesh sieve with an aperture size of 0,25 mm will be required if sub-samples with this nominal top size are required. 6.4 Balance A balance is required that is capable of determining the mass of samples to an accuracy of 0,1 % of the sample mass, and the mass of sub-samples to an accuracy of 0,1 % of the sub-sample mass. 7 Sample reduction – general principles For every sample division stage to be carried out it is important that a sufficient mass of material is retained, otherwise the sub-samples produced or the test portions to be taken may not be representative of the original sample. Table 1 gives a guideline for minimum masses to be retained after each sample division stage, depending on the nominal top size of the material. In addition to the minimum masses stated in Table 1, it must be ensured that the mass after a sample division stage is sufficiently large for the actual test or tests to be performed. kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
10Supplementary requirements concerning the masses of the test portions are given in European Standards for test methods of solid biofuels. Table 1 — Guideline for minimum masses to be retained during sample division stages Nominal top size (mm) Minimum mass(g) 200 150 100 63 50 45 40 30 10 5 1 0,25 120000 50000 15000 4000 2000 1500 1000 500 150 100 50 10
NOTE This guideline does not take in to account: particle size distribution, shape of a particle, density of a particle, etc. Figure 5 summarises the range of steps that can be taken during sample reduction. kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
11Particlesizereductionto< 1 mm material(9.6)Mixing(9.1) ifrequiredand/orsampledivision< 1 mm material(9.7)Particlesizereductionto<0,25 mm material(9.8) Analysissample materialforanalyses wherethe < 1 mm materialdo notsufficeGeneralanalysissamplePredry/equilibrateifrequired(9.3)Sub-samplefordeterminationof particlesizedistributionParticlesizereductionifrequiredto< 31,5 mm bycoarsecutting(9.4)Mixing(9.1) ifrequiredand/orsample division<31,5 mm material(9.5)Sub-samplefordeterminationof totalmoisturecontentCombinedsampleMixingifrequired(9.1) and/orinitialsampledivisionof the laboratorysample (9.2)Sub-samplesfordeterminationof bulk density, durabilityof pellets and briquettes, moistureanalysissamplePreparationstepsOptionalextractionof sub-samplesParticlesizereductionto< 1 mm material(9.6)Mixing(9.1) ifrequiredand/orsampledivision< 1 mm material(9.7)Particlesizereductionto<0,25 mm material(9.8) Analysissample materialforanalyses wherethe < 1 mm materialdo notsufficeGeneralanalysissamplePredry/equilibrateifrequired(9.3)Sub-samplefordeterminationof particlesizedistributionParticlesizereductionifrequiredto< 31,5 mm bycoarsecutting(9.4)Mixing(9.1) ifrequiredand/orsample division<31,5 mm material(9.5)Sub-samplefordeterminationof totalmoisturecontentCombinedsampleMixingifrequired(9.1) and/orinitialsampledivisionof the laboratorysample (9.2)Sub-samplesfordeterminationof bulk density, durabilityof pellets and briquettes, moistureanalysissamplePreparationstepsOptionalextractionof sub-samples NOTE List of optional sub-sample extractions may not be exhaustive
Figure 5 —
Flow sheet for sample preparation and optional extraction of sub-samples
8 Methods for sample division Combined samples may be divided into two or more laboratory samples and laboratory samples are in general further divided in sub-samples (test-portions). This clause describes the methods and procedures for sample division. For every division step the mass of retained material given in table 1 shall be taken into account.
8.1 Riffling This may be used for materials that can be passed through the riffle without bridging. It is not suitable for straw, bark, or other materials containing elongated particles, or for wet and/or sticky materials. Brittle materials should be handled with care to avoid the production of fine materials. Place the whole of the combined sample into one of the containers of the riffle so that it is evenly distributed throughout the container. Place the other two containers in position under the riffle. Pour the contents of the first container down the centre line of the riffle. Pour the biofuel sufficiently slowly to avoid bridging occurring. Do not move the container from side to side (this would cause the end kSIST FprEN 14780:2011
FprEN 14780:2010 (E)
12slots to receive less biofuel). Discard the biofuel that falls into one of the containers, chosen at random. Repeat the riffling process until a sub-sample of the required mass is obtained. See Figure 1 for an example of a riffle box. 8.2 Strip mixing This may be used for all materials, and will be a convenient method when a combined sample is to be divided into a small number of laboratory samples. Place the whole combined sample on a clean, hard surface and homogenise it by mixing with a shovel, and form into a strip at least 20 times as long as it is wide. Distribute the sample along the length of the strip as evenly as possible working randomly from end to end. Building up the strip with several layers will increase the quality of the division.
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