🔥 Determination of mechanical durability of solid biofuel pellets — a test portion of (500 ± 10) g of pellets, after removal of particles smaller than 3.15 mm, is tumbled in a dust-tight stainless steel box with a baffle (300 × 300 × 125 mm) for 500 rotations at (50 ± 2) r/min, sieved through a sieve with round holes of 3.15 mm and the material remaining on the sieve is weighed; result in mass percent, two test portions, PN-EN ISO 17831-1

Petrochemistry PN-EN ISO 17831-1

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 17831-1:2025-10 (English version), in full: “This document specifies a method for determining the mechanical durability of pellets. Mechanical durability is a measure of the resistance of densified fuels towards shocks and/or abrasion as a consequence of handling and transportation processes”. We read the text of the current edition in the sample of ISO 17831-1:2025 (and SIST EN ISO 17831-1:2025) — only the title page, table of contents, foreword and introduction; the clauses with the procedure are outside it. We read the procedure in the text of the previous edition: ISO 17831-1:2015 (iTeh sample from the table of contents through Clauses 1–6 up to and including 7.2) and SIST EN ISO 17831-1:2016 (European foreword of EN ISO 17831-1:2015). All procedure figures in this entry come from the 2015 edition; Clauses 8–10 (calculation, performance characteristics, test report) and Annex A we did not read in any edition.

ACCORDING TO THE TEXT OF ISO 17831-1:2025 (foreword, introduction). The second edition was prepared by ISO/TC 238 “Solid biofuels and pyrogenic biochar” in collaboration with CEN/TC 335; it replaced the 2015 edition after technical revision. Main changes according to the foreword: the introduction was changed, a reference to ISO 21945 was added, the description of sample preparation was changed to give more practical guidance on the test portions, and the description of sieving was replaced with a reference to ISO 5370. Introduction: densified biomass fuels are usually divided into pellets with a diameter generally not greater than 25 mm and briquettes with a larger diameter (ISO 17225-1); mechanical durability is an important parameter for assessing the tendency of pellets or briquettes to form a new fine fraction through abrasion during handling; because of the different particle dimensions, different apparatus are needed for pellets and for briquettes (Part 2 of the series — briquettes).

ACCORDING TO THE TEXT OF ISO 17831-1:2015 (Clauses 1–7.2). The first edition was prepared by ISO/TC 238 “Solid biofuels”; EN ISO 17831-1:2015 superseded EN 15210-1:2009 and was prepared under a mandate of the European Commission. Scope (1): test method for the mechanical durability of pellets — a measure of the resistance of densified fuels to shocks and/or abrasion as a result of handling and transport. References (2): ISO 14780 (sample preparation), ISO 16559 (terminology), ISO 18134-1 and -2 (moisture by the oven dry method), ISO 18135 (sampling). Principle (4): the test portion is subjected to controlled shocks by collision of pellets with each other and with the walls of a rotating test chamber; the durability is calculated from the mass of the portion after sieving off particles smaller than 3.15 mm and the mass after tumbling. Apparatus (5.1): dust-tight box with an internal baffle for mixing and a drive; smooth interior, protruding rivets and bolts kept to a minimum and rounded; of stainless steel (1.5 ± 0.1) mm, internal dimensions: width (300 ± 3) mm, height (300 ± 3) mm, depth (125 ± 1.3) mm; baffle of stainless steel (1.5 ± 0.1) mm, length (230 ± 2.3) mm, width (50 ± 1.0) mm, fixed diagonally on one of the 300 mm × 300 mm faces and protruding (50 ± 1.0) mm into the interior, with rounded edges; the box rotates at a constant speed of (50 ± 2) r/min, driven by a motor through pulleys or a gear without vibration, with a rotation counter (it may switch off the motor after a set number). Sieve (5.2): round holes of 3.15 mm, for hand sieving (ISO 3310-2), recommended diameter 400 mm or more. Balance (5.3): reading 0.1 g, capacity 2 kg. Preparation (6): laboratory sample of at least 2 kg, taken according to ISO 18135 and prepared according to ISO 14780, divided into four equal parts; one is used for the determination of total moisture according to ISO 18134-1 or -2; the other three are sieved separately to remove particles smaller than 3.15 mm — by hand, with about 5–10 circular movements, at a recommended sieve load below 0.8 g/cm2 of surface (e.g. 1.0 kg on a sieve with a diameter of 400 mm); the three parts may be combined and divided into two test portions. Tumbling (7.1): test portion (500 ± 10) g — for pellets with a diameter above 12 mm (500 ± 50) g is permitted — weighed to the nearest 0.1 g, tumbled in the box at (50 ± 2) r/min for 500 rotations, then sieved by hand; the same for the second portion. Sieving (7.2): after tumbling so as not to produce a new fine fraction — about 5–10 circular movements, sieve load below 0.8 g/cm2; sieving must be complete; the material remaining on the sieve is weighed for each portion, and the durability is calculated according to Clause 8.

STATUS (catalogue cards as of 03.10.2026). The card of PN-EN ISO 17831-1:2025-10 (English version, published 08-10-2025, 20 pages, price group K) has no “Withdrawn” header: Mining Sector, KT 144 Coke and Processed Solid Fuels, ICS 75.160.40, “Introduces: EN ISO 17831-1:2025 [IDT], ISO 17831-1:2025 [IDT]”, “Supersedes: PN-EN ISO 17831-1:2016-02 — English version”. The card of PN-EN ISO 17831-1:2016-02 (English version) — “Withdrawn” 08-10-2025, “Replaced by: PN-EN ISO 17831-1:2025-10”; it itself superseded PN-EN 15210-1:2010. What changed for the result: according to the foreword of the 2025 edition the description of portion preparation was changed and the description of sieving was replaced with a reference to ISO 5370; whether the figures changed (portion, number of rotations, sieve) and how the changes affect the result, we do not know, because we did not read these clauses of the 2025 edition.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read 03.10.2026). The number 17831-1 appears in 9 records at 6 laboratories: AB 053, AB 081, AB 300, AB 313, AB 550, AB 743. In the current scopes on the PCA website (read 03.10.2026, issues from 03.12.2025 to 22.09.2026) five laboratories give “PN-EN ISO 17831-1:2025-10”, and AB 081 (issue no. 26 of 03.12.2025) — the withdrawn edition “PN-EN ISO 17831-1:2016-02”. The “Laboratories” tab (“PN-EN ISO 17831-1”) shows the same 6 laboratories; checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (PCA items). Solid fuels — solid biomass, solid biofuels; item “Mechanical durability” or “Mechanical durability of pellets”, weighing method (AB 300 — “gravimetric method”). Ranges: (90.0–99.5) % (AB 053, AB 550, AB 743), (90.0–99.0) % (AB 300), (85.8–99.5) % (AB 313), (75.0–99.5) % (AB 081). Next to it in the same scopes there are, among others, fines content according to PN-EN ISO 18846:2016-11 (AB 300) and according to PN-EN ISO 5370:2023-08 (AB 550) and sampling according to PN-EN ISO 18135:2017-06 (AB 743).

WHERE A SEEMINGLY CORRECT RESULT IS EASY. At preparation: a portion from which particles smaller than 3.15 mm were not sieved off before the test already contains a fine fraction, which after tumbling passes through the sieve and lowers the result, although the pellets did not break (4, 6); an overloaded sieve (above 0.8 g/cm2) does not sieve accurately (6, 7.2). At tumbling: the number of rotations (500) and the speed (50 ± 2) r/min are part of the definition of the result — a different apparatus or a different number of rotations is a different quantity (5.1, 7.1). At sieving after tumbling: too vigorous sieving itself produces a new fine fraction and lowers the result, and incomplete sieving raises it (7.2). At the result: a value citing the 2016-02 edition (AB 081) comes from a withdrawn edition — according to the foreword of the 2025 edition, preparation and sieving are described in it differently than in the 2015 edition — we did not check the comparability of results from both editions; moisture is determined in parallel on a separate part of the sample (6).

WHAT WE DO NOT GIVE. Clauses 8–10 (formula, precision, test report) and Annex A we did not read in any edition, and Clauses 1–10 of the 2025 edition — not at all; we therefore do not give the calculation formula, precision, the ISO 5370 requirements for sieving, or whether the 2025 edition changed the portion and the number of rotations. We also do not give classification requirements for pellets (ISO 17225), because we did not read their text.

Method principle

Pellets from which the fine fraction has been sieved off are subjected to controlled shocks in a rotating box with a baffle — they collide with each other and with the walls, and part of them breaks and abrades. After tumbling the fine fraction (particles smaller than 3.15 mm) is separated on a sieve; mechanical durability is the mass of pellets remaining on the sieve related to the mass of the portion before tumbling, in percent.

Applications

• Solid biomass pellets — resistance to shocks and abrasion during handling and transport (Clause 1)
• Assessment of the tendency of pellets to form a new fine fraction through abrasion (introduction, 2025 edition)
• Solid fuels: solid biomass and solid biofuels — in the accreditation scopes of 6 laboratories at PCA

Key parameters

Standard

Standard number

PN-EN ISO 17831-1:2025-10

Title (PL)

Biopaliwa stałe — Oznaczanie wytrzymałości mechanicznej peletów i brykietów — Część 1: Pelety

Title (EN)

Solid biofuels — Determination of mechanical durability of pellets and briquettes — Part 1: Pellets

Step-by-step procedure

1. Sample

   At least 2 kg according to ISO 18135 and ISO 14780, division into four parts, one for moisture. PN-EN ISO 17831-1:2025-10 current (PKN catalogue card as of 03.10.2026); steps according to the 2015 edition.

2. Removal of the fine fraction

   Sieve three parts separately through the 3.15 mm sieve, 5–10 circular movements, load < 0.8 g/cm2; combine and divide into two portions.

3. Tumbling

   Portion (500 ± 10) g, weighed to the nearest 0.1 g; 500 rotations at (50 ± 2) r/min.

4. Sieving after tumbling

   Without producing a new fine fraction, to completion; weigh the pellets remaining on the sieve. Repeat for the second portion.

5. Result

   Durability in % from the mass before and after tumbling (Clause 8 — formula outside the sample read).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Moving parts of the tester (box, drive) — guards and switching off before opening the door; the standard in the part read contains no separate warnings
• Pellet dust is combustible — clean up without dispersing the dust

Frequently asked questions