# PD CEN TS 16010-2013

BSI Standards Publication Plastics — Recycled plastics — Sampling procedures for testing plastics waste and recyclates PD CEN/TS 16010:2013National foreword This Published Document is the UK implementation of CEN/TS 16010:2013. The UK participation in its preparation was entrusted to Technical Committee PRI/89, Plastics recycling. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. © The British Standards Institution 2013 Published by BSI Standards Limited 2013 ISBN 978 0 580 75314 5 ICS 13.030.50; 83.080.01 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 28 February 2013. Amendments issued since publication Amd. No. Date Text affected PUBLISHED DOCUMENT PD CEN/TS 16010:2013 TECHNICAL SPECIFICATION SPÉCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 16010 January 2013 ICS 13.030.50; 83.080.01 English Version Plastics - Recycled plastics - Sampling procedures for testing plastics waste and recyclates Plastiques - Plastiques recyclés - Procédures d échantillonnage pour l essai des déchets de plastiques et des recyclats Kunststoffe - Kunststoff-Rezyklate - Probenahmeverfahren zur Prüfung von Kunststoffabfall und Rezyklaten This Technical Specification (CEN/TS) was approved by CEN on 22 October 2012 for provisional application. The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 16010:2013: E PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 2 Contents Page Foreword 3 Introduction .4 1 Scope 5 2 Normative references 5 3 Terms and definitions .5 4 Symbols and abbreviations 7 5 Calculating the probability that a given set of samples is representative.7 6 Sampling from non homogeneous material streams .9 7 Procedures for the determination of material characteristics through sampling . 10 Annex A (normative) Procedures for the determination of material characteristics through sampling 13 Annex B (informative) Principal development of standard deviation s as a function of number of samples n . 16 Annex C (informative) Development of factor t of the Student distribution for different levels of confidence . 17 Bibliography . 18 PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 3 Foreword This document (CEN/TS 16010:2013) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the secretariat of which is held by NBN. 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 Technical Specification is one part of a series of CEN publications on Plastics Recycling that is structured as follows: EN 15342, Plastics — Recycled Plastics — Characterization of polystyrene (PS) recyclates EN 15343, Plastics — Recycled Plastics — Plastics recycling traceability and assessment of conformity and recycled content EN 15344, Plastics — Recycled Plastics — Characterisation of Polyethylene (PE) recyclates EN 15345, Plastics — Recycled Plastics — Characterisation of Polypropylene (PP) recyclates EN 15346, Plastics — Recycled plastics — Characterisation of poly(vinyl chloride) (PVC) recyclates EN 15347, Plastics — Recycled Plastics — Characterisation of plastics wastes EN 15348, Plastic — Recycled plastics — Characterization of poly(ethylene terephthalate) (PET) recyclates CEN/TR 15353, Plastics — Recycled plastics — Guidelines for the development of standards for recycled plastics CEN/TS 16011, Plastics — Recycled plastics — Sample preparation According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 4 Introduction Recycling of plastics waste is one type of material recovery process intended to save resources (virgin raw materials, water, energy), while minimising harmful emissions into air, water and soil as well as their impacts on human health. The environmental impact of recycling should be assessed over the whole life cycle of the recycling system (from the waste generation point to the disposal of final residues). To ensure that recycling constitutes the best environmental option for treating the available waste, some prerequisites should preferably be met: the recycling scheme being contemplated should generate lower environmental impacts than alternative recovery options; existing or potential market outlets should be identified that will secure a sustainable industrial recycling operation; the collection and sorting schemes should be properly designed to deliver recyclable plastics waste fractions fitting reasonably well with the available recycling technologies and with the (changing) needs of the identified market outlets, preferably at minimum costs for society. This Technical Specification has been produced in accordance with the guidance produced by CEN on Environmental Aspects and in accordance with CEN/TR 15353, Plastics — Recycled plastics — Guidelines for the development of standards for recycled plastics. NOTE CEN/TR 15353 considers the general environmental aspects which are specific to the recycling process. This Technical Specification is intended to serve two purposes. 1. To provide a guide to plastic recyclers and others that enables a calculation to be made of the risk of inaccuracy presented by a chosen sampling regime. This will help to inform decisions about sampling that can also be influenced by factors such as the supply record of a supplier or the reliability of a process. This is covered in Clause 5. 2. To define the sampling procedures to be followed to characterise the material being sampled. These procedures may be followed where a particular level of accuracy is required, or where the sampling is in support of the resolution of a dispute. This is covered in Clause 7 and Annex A. It is not the intention of this Technical Specification to develop new sampling methods. PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 5 1 Scope This Technical Specification specifies a system for sampling procedures for testing plastics waste and recyclates which take into account the specifics of the plastics waste and recyclates. It is intended to cover all stages of the plastic recycling process. The sampling procedures include the statistical specifics of the plastic waste and the behaviour of recyclates. The sampling method should produce a representative testing sample. Differences can arise due to: the mixture of plastics; the origin (e.g. green dot in Germany, or electronic/automotive industry); the previous use of the plastic material; the residual contents (e.g. of containers); inert, residual or moisture content on or in the material. This Technical Specification is without prejudice to any existing legislation. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. CEN/TR 15353:2007, Plastics — Recycled plastics — Guidelines for the development of standards for recycled plastics CEN/TS 16011, Plastics — Recycled plastics — Sample preparation EN ISO 472:2001, Plastics — Vocabulary (ISO 472:1999) ISO 11648-1:2003, Statistical aspects of sampling from bulk materials — Part 1: General principles ISO 11648-2:2001, Statistical aspects of sampling from bulk materials — Part 2: Sampling of particulate materials 3 Terms and definitions For the purposes of this document, the terms, definitions and abbreviated terms given in EN ISO 472:2001, in CEN/TR 15353:2007 and the following apply. NOTE The terms used are confined to the field of bulk sampling. 3.1 bulk material amount of material within which component parts are not initially distinguishable on the macroscopic level [SOURCE: ISO 11648-1:2003] PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 6 3.2 sample combination of a set of increments of material taken from a lot, intended to supply information, and possibly serve as a basis for a decision concerning the lot or the process by which it has been produced [SOURCE: ISO 8656-1:1988] 3.3 increment quantity of bulk material taken in one action by a sampling device [SOURCE: ISO 11648-1:2003] 3.4 laboratory sample sample intended to be used for an inspection or for laboratory tests [SOURCE: ISO 8656-1:1988] 3.5 test sample sample taken from the laboratory sample and prepared in a suitable manner for subjection to particular tests Note 1 to entry: Test samples might be prepared, for example, for the determination of particle size distribution, moisture content, chemical composition, physical or other properties. See also CEN/TS 16011. [SOURCE: ISO 8656-1:1988] 3.6 central limit theorem fundamental theorem of probability and statistics, stating that the distribution of the mean of a random sample from a population with finite variance is approximately normally distributed when the sample size is large, regardless of the shape of the population s distribution Note 1 to entry: If x 1, x 2, …., x n are independent measurements (i.e. a random sample of size n), from a population where the mean of x is µ, and the standard deviation of x is σ, then: The distribution of = n x x x n 2 1 + + + .has mean and standard deviation given by: µ = µ and σ = n σWhen n is sufficiently large, then the distribution of is approximately normal. 3.7 Student s t-distribution t-distribution probability distribution that is effective in the problem for estimating the mean of a normally distributed population when the sample size is small 3.8 duration length of sample time when sampling from a continuous stream 3.9 plastics waste plastics fraction of waste PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 7 3.10 waste material or object which the holder discards, or intends to discard, or is required to discard [SOURCE: ISO 15270:2008] 4 Symbols and abbreviations n number of single samples, number of measurements x n independent single measured value arithmetic mean (average value, average) s standard deviation of samples σ standard deviation of population µ is the real value of the true mean of the known distribution t the value of the Student deviation for different levels of confidence 5 Calculating the probability that a given set of samples is representative 5.1 General In everyday circumstances plastics recyclers require sampling for two basic purposes: to provide input quality control and to verify the quality of the output recycled plastic. Although the physical properties of input and output materials might be very different, the underlying statistical principles are the same. The samples taken shall be sufficiently representative of the batch to satisfy the user of the sample information that it is relevant for his purpose. The sampling regime will be based on a number of factors including: the physical form and homogeneity of the material being sampled; the level of confidence in the consistency and reliability of the material being sampled; the consequences of the sample not being representative. The purpose of this section is to provide a tool for the plastic recycler to use to calculate the effectiveness of his chosen sampling routine or, conversely, to calculate the risk associated with a particular sampling regime. Sample sizes are often small, and the population standard deviation ( σ) is usually unknown. The population standard deviation ( σ) can be replaced with the sample standard deviation (s). To be more conservative in the analysis, the t-distribution may be used rather than the normal distribution. When sample sizes are large the results are the same (Central Limit Theorem). Many common statistical procedures require data to be approximately normal, but the Central Limit Theorem enables these procedures to be applied to populations that are strongly non-normal. How large the sample size shall be depends on the shape of the original distribution. If the population s distribution is symmetric, a sample size of 5 might yield a good approximation; if the population s distribution is strongly asymmetric, a larger sample size is necessary (50 or more). Sampling error is in effect n 1 and this gives a guide to the limit of detection in that it would be possible to miss a 10 % component by taking a sample of 100 pieces. It is also important to recognise that the sampling error is based on the particles as sampled. If these particles have an average mass of 10 g then a sample of 1 kg is needed to get a 10 % error and 100 kg to get a 1 % error. PD CEN/TS 16010:2013CEN/TS 16010:2013 (E) 8 5.2 Power and sample size Power is the likelihood of identifying a significant difference (effect) when one truly exists. Errors are referred to as Type 1 and Type 2 errors. A Type 1 error results in rejecting good material and a Type 2 error results in accepting bad material. The easiest way to improve power is to