🌿 Sampling of solid recovered fuels (SRF) in production plants, from deliveries and from stock — development of a sampling plan (objectives, lot, number of increments, minimum sample and increment mass with shape factor), manual and mechanical methods from material streams, vehicles, ships and static lots, PN-EN ISO 21645

Environment PN-EN ISO 21645

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 21645:2021-09 (English version), in full (our translation of the Polish text on the card): “This document specifies methods for taking samples of solid recovered fuels, for example from production plants, from deliveries or from stock. It includes manual and mechanical methods. It is not applicable to solid recovered fuels that are formed by liquid or sludge, but it includes dewatered sludge”. We read the text of the standard in two samples: SIST EN ISO 21645:2021 (English text of EN ISO 21645:2021 — European foreword, endorsement notice, ISO foreword, introduction, Clause 1 and Clause 2) and ISO 21645:2021 in the French version (table of contents, foreword, introduction with Figure 1, Clauses 1–3 up to definition 3.42). We do not have further definitions (3.43 onwards), Clause 4 (symbols), 5 (principle), 6 (development of a sampling plan), 7 (implementation of the plan), 8 (handling and storage of samples), 9 (precision) or Annexes A–L — we know them only from the table of contents.

ACCORDING TO THE TEXT OF ISO 21645:2021 AND EN ISO 21645:2021 (forewords, introduction, Clauses 1–3.42, table of contents). The standard was prepared by ISO/TC 300 “Solid recovered materials, including solid recovered fuels” in collaboration with CEN/TC 343 “Solid recovered fuels” (secretariat SFS); EN ISO 21645:2021 supersedes EN 15442:2011, and the ISO text was approved as a European standard without modification. Introduction: testing SRF allows informed decisions about its further handling and use; before designing any sampling, its objectives must be clearly identified — they set the level of testing (e.g. full examination or routine test), the required level of confidence and the frequency of testing; the objectives and the sequence of operations are described in an overall sampling plan, after which actual sampling starts. The standard is based mainly on the work of CEN/TC 292 “Characterization of waste” (now in CEN/TC 444), in particular on EN 14899:2005 and CEN/TR 15310-1:2006. What distinguishes SRF samples from other wastes is that they are very often solid, but neither “granular” nor monolithic — often an almost fibrous material; therefore the statistical sampling formulae of EN 14899:2005 and of Annex D to CEN/TR 15310-1:2006 cannot be applied without amendment, and a “shape factor” f is needed in them. Figure 1 shows the links between the elements of a testing programme. Procedures are given for various processing streams and common storage conditions; the sampling technique depends on the type of SRF, the situation at the sampling location and the form of the material (e.g. pile, conveyor belt, truck) and on the (expected) degree of heterogeneity (e.g. single source, fuel blend, fuel mixture). The standard is intended mainly for laboratories, producers, suppliers and purchasers of SRF, but is also useful for authorities and inspection bodies; sampling of solid biofuels is described in ISO 18135 (separate entry in the database). References (2): ISO 21637 (terminology), ISO 21640 (specifications and classes; FDIS stage at the time of publication), SRF test standards — among others ISO 21644 (biomass), ISO 21654 (calorific value), ISO 21656 (ash), ISO 21660-3 (moisture in the general analysis sample), ISO 21663 (C, H, N, S), ISO 22167 (volatile matter), EN 15408 (S, Cl, F, Br), EN 15410 (major elements), EN 15411 (trace elements), EN 15415-1, -2, -3 (particle size), CEN/TS 15401 (bulk density), CEN/TR 15404 (ash melting behaviour), CEN/TS 15405 (density of pellets and briquettes), CEN/TS 15406 (bridging properties), CEN/TS 15412 (total aluminium), CEN/TS 15414-1 and -2 (total moisture), CEN/TS 15639 (durability of pellets). Selected definitions (3): increment — portion of SRF extracted from a lot or sub-lot in a single operation of the sampling device (3.9); lot — defined quantity of fuel whose quality is to be determined, may be divided into sub-lots (3.11, 3.40); laboratory sample — combined sample received by the laboratory (3.10); general analysis sample — sub-sample of a laboratory sample with a nominal top size of 1 mm or less (3.6); minimum increment mass and minimum sample mass — the smallest quantities preserving representativeness; the minimum sample mass is at least the increment mass times the number of increments and is directly related to the nominal top size (3.13, 3.14); d95 — the smallest sieve aperture through which at least 95 % by mass of the material passes (3.17); shape factor — correction of the minimum sample mass when the particles of a lot do not have a regular shape, e.g. spherical or cubic (3.33); distribution factor — correction for the particle size distribution (3.3); duplicate and replicate samples — for estimating sampling variability (3.5, 3.27); static lot — a lot not in motion or transported by a conveyor during sampling (3.37); random, stratified and stratified random sampling (3.26, 3.38, 3.39); solid recovered fuel — solid fuel for energy purposes according to ISO 21640, prepared from non-hazardous waste (3.34; Note 1 lists among others fuels from municipal waste, shredder light fraction, sewage sludge, end-of-life wood, meat and bone meal). Table of contents: Clause 6 covers objectives, definition of the lot and its size when sampling from a stream, from vehicles, from ships and from a static lot, the sampling procedure, the number of increments, the minimum sample mass, the minimum increment mass (separately for streams and for static lots, vehicles and ships), the planned increment and sample mass, the distribution of increments and the equipment; Clause 7 — steps before, during and after sampling; Clause 8 — handling and storage of samples; Clause 9 — precision; annexes: A — procedure for developing the plan, B — sampling plan, C — example plan, D — equipment, E — minimum sample mass, F — increment mass when sampling from a material stream, G — increment mass for static lots, vehicles and ships, H — implementation of the plan for a material stream, I — implementation of the plan for a static lot or vehicle, J — minimum sample mass required for analysis, K — precision, L — examples of stratified and stratified random sampling.

STATUS (catalogue card as of 03.10.2026). The card of PN-EN ISO 21645:2021-09 (English version, published 22-09-2021, 72 pages, price group W) has no “Withdrawn” header: Mining Sector, KT 144 Coke and Processed Solid Fuels, ICS 75.160.10, “Introduces: EN ISO 21645:2021 [IDT], ISO 21645:2021 [IDT]”, “Replaces: PN-EN 15442:2011 — Polish version, PN-EN 15442:2011 — English version”. The PKN search engine (query “PN-EN ISO 21645”, 03.10.2026) shows only this edition. ISO document: according to the iTeh catalogue (read 03.10.2026) ISO 21645:2021 has the status “Published”, stage 90.93 (confirmed in the systematic review). What changed for the result compared with PN-EN 15442:2011: we have not read the text of the previous edition and do not give the differences.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 03.10.2026). The number 21645 appears in 11 records at 7 laboratories: AB 054, AB 213, AB 550, AB 687, AB 829, AB 1127, AB 1785. In the current scopes on the PCA website (read 03.10.2026, issues from 06.03.2025 to 22.09.2026) all give “PN-EN ISO 21645:2021-09”; AB 054 writes “PN-ISO 21645:2021-09” in the item for waste (a designation without “EN”). The “Laboratories” tab (“PN-EN ISO 21645”) shows all 7 laboratories; checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA scopes). “Sampling for chemical and physical testing” of solid recovered fuels (SRF) and raw materials for the production of fuels from waste (AB 054, AB 213, AB 550, AB 687, AB 829) and of waste: among others codes 19 12 08, 19 12 10, 19 12 12, 20 01 11, 20 03 01, 20 03 02, 20 03 07, 20 03 99 (AB 1785), 19 12 10, 19 12 12, 20 01 38, 20 03 01 (AB 054), 19 01 and 19 12 (AB 550), waste from waste treatment and municipal waste (AB 213, AB 550, AB 1127). AB 1127 applies the standard “excluding Annexes F and H” — according to the table of contents these are the increment mass and the implementation of the plan when sampling from a material stream. AB 550 cites in one item, next to it, also PN-EN 15442:2011 “excluding Annexes E and G”, i.e. the edition that, according to the PKN card, the standard replaced.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Sample mass: SRF can be almost fibrous — a minimum sample mass calculated with formulae for granular materials without the shape factor f comes out too small, and the sample “meets the formula” without being representative (introduction, 3.33). Definition of the lot: the result refers to the lot or sub-lot for which sampling was planned — a lot defined differently for a stream, a vehicle, a ship and a pile (6.3 according to the table of contents) changes what the result refers to. Choice of standard: SRF is fuel from non-hazardous waste; solid biofuels are sampled according to ISO 18135 (introduction, 3.34). Liquids and sludges: SRF in the form of liquid or sludge is outside the scope, dewatered sludge is within it (1). Testing chain: sampling is the first link — for a quantity calculated from several determinations (e.g. calorific value as received), a sampling error passes into all components at once and is not revealed by any of the laboratory determinations.

WHAT WE DO NOT GIVE. We do not have Clauses 4–9 or the annexes: symbols, principle, formulae for the number of increments, the minimum sample and increment mass, values of the shape factor and distribution factor, ways of distributing increments, the description of equipment, rules for handling and storing samples or precision data — so we give none of these values.

Method principle

Sampling of SRF is carried out according to a plan developed before sampling: the objectives of testing determine the level of testing and confidence, the form of the material determines the definition of the lot (stream, vehicle, ship, static lot); then the number of increments, the minimum sample and increment mass, taking into account particle size and shape, and the distribution of increments are determined, the increments are taken manually or mechanically and combined into a laboratory sample.

Applications

• Solid recovered fuels (SRF) and raw materials for the production of fuels from waste — in production plants, deliveries and stock; 7 laboratories in PCA scopes
• Waste intended as fuel, among others codes 19 12 10, 19 12 12, 20 03 01 — in PCA scopes together with SRF
• Sampling plan for producers, suppliers, purchasers of SRF and inspection authorities (introduction)

Key parameters

Standard

Standard number

PN-EN ISO 21645:2021-09

Title (PL)

Stałe paliwa wtórne — Metody pobierania próbek

Title (EN)

Solid recovered fuels — Methods for sampling

Step-by-step procedure

1. Objectives and plan

   Define the objectives (level of testing, level of confidence, frequency) and develop the sampling plan according to Clause 6 and Annexes A–C. PN-EN ISO 21645:2021-09 current (PKN catalogue card as of 03.10.2026).

2. Lot

   Define the lot and its size according to the form of the material: stream, vehicle, ship or static lot (6.3).

3. Number and mass of increments

   Determine the number of increments, the minimum sample mass (with shape factor) and the minimum increment mass as well as the planned quantities (6.5–6.8, Annexes E–G — we do not have the formulae).

4. Sampling

   Distribute the increments in the lot (random, stratified or stratified random) and take them manually or mechanically (6.9, 6.10, 7, Annexes D, H, I).

5. Sample and record

   Combine the increments into a laboratory sample, describe the sampling in a record, store and transfer the sample according to Clause 8.

Required equipment and apparatus

Health and safety (OHS)

• Sampling from conveyors, piles and vehicles involves mechanical hazards and vehicle traffic — follow site rules; the part of the standard we read contains no separate safety requirements
• SRF is made from waste — personal protective equipment against dust and biological contamination

Frequently asked questions