🔥 Sulfur, chlorine, fluorine and bromine in solid recovered fuels (SRF) — combustion in an oxygen bomb — PN-EN 15408

Petrochemistry and fuels PN-EN 15408

Overview

WHAT THIS TEST IS (clause 1 of EN 15408:2011; the same scope on the PKN card). Determination of S, Cl, F and Br in solid recovered fuels of various origin and composition after combustion in an oxygen atmosphere. The method is applicable to contents above 0.025 g/kg — depending on the element and the determination technique — and for fluorine above 0.015 g/kg. Insoluble halides and sulfates present in the sample or formed during combustion are not completely determined. The standard gives recommendations on standardized methods for determining halides and sulfates in the solution after combustion.

WHAT FOR (introduction): during combustion, sulfur and halogens in SRF usually turn into sulfates and halides, which are largely responsible for corrosion and harmful emissions — that is why they are determined both in the production and in the combustion of the fuel. "Halogen content" in this standard is the sum of the halogens in organic and inorganic compounds that can be converted into halides by combustion and absorbed in an aqueous solution (definition 3.1 — empirical, valid only for this standard).

PRINCIPLE (clause 5). Two stages or an automatic analyser: • the sample is burnt in a bomb with oxygen under pressure; halogen and sulfur compounds turn into fluorides, chlorides, bromides and sulfates, absorbed in an absorption solution (water or 0.2 mol/l KOH); • Cl, F, S and Br are determined by ion chromatography according to EN ISO 10304-1, fluorine also according to ISO 10359-1 (ion-selective electrode); bromine preferably by ICP-MS according to EN ISO 17294-2, because after combustion it occurs in several oxidation states; chlorides can also be determined titrimetrically according to ISO 9297 (Mohr's method). For S and Cl, direct automatic methods may be used, and other methods — if it is shown that they give the same results (introduction).

ABSORPTION SOLUTION (7.5 and 9.3): for most applications water is sufficient; when the chlorine content exceeds 1 % or bromine is determined, an alkaline 0.2 mol/l KOH solution is more effective. 10 ml of the solution is added to the bomb. The presence of bromine or a high chlorine content can be checked beforehand by XRF analysis.

SAMPLE AND COMBUSTION (clause 9): • samples are stored according to Annex A; the test sample is prepared according to EN 15413, with a target particle size of 1 mm or less (finer with a smaller test portion); with an uneven distribution of chlorine-containing particles, e.g. 0.5 mm gives better repeatability (Annex C); • the result is given on a dry basis — moisture is determined separately; of the standards referenced in clause 2, EN 15414-3 concerns it (moisture in the general analysis sample); • test portion usually about 1 g, weighed to the nearest 0.1 mg: as a pellet, in a capsule or in a PE bag (with 20 % water or without), or with a combustion aid (e.g. benzoic acid); additives contribute heat, so the test portion is reduced — it is important not to exceed the permissible temperature rise in the bomb; • after combustion at least 10 min of equalization to room temperature; after opening, the residues are checked — if there is an unburnt part, the sample is rejected; the solution is transferred quantitatively to a tared bottle and made up with water to 100 ml. The robustness study (Annex C) showed that in its present form the method is not suitable for some samples — e.g. those containing pieces of tyres — because the pellet falls apart during combustion.

APPARATUS AND REAGENTS (clauses 6 and 7): a combustion bomb of stainless steel or another resistant material, with a safety valve and electric ignition — it may be a bomb for determining the calorific value; for samples with a high chlorine content — a chlorine-resistant bomb. Analytical balance (0.1 mg), ion chromatograph with conductivity suppression, titration apparatus, ICP-MS, automatic S and Cl analyser. Oxygen at least 99.99 %, water of grade 1 according to EN ISO 3696, carbonate-hydrogencarbonate eluent, 1000 mg/l standard solutions, a certified reference material similar to SRF for checking the absorption efficiency and a control mixture — the example from the standard: 4-fluoro-, 4-chloro-, 4-bromo- and 4-iodobenzoic acids, sulfanilic acid and cellulose, containing 1.13 g/kg F, 7.547 g/kg Cl, 1.656 g/kg Br, 2.132 g/kg I and 6.17 g/kg S.

SOURCES OF ERROR (clause 8): the container in which the sample was delivered and stored, and grinding (contamination of the sample). In fuels with a high content of sulfur bound to iron, the method may give different results.

EDITIONS (state of the PKN card on 25.09.2026). PN-EN 15408:2011 — English version, publication 21-07-2011, 18 pages, KT 144 Coke and Processed Solid Fuels, introduces EN 15408:2011 [IDT], without the "Wycofana" [Withdrawn] header; the catalogue has no Polish version. EN 15408:2011 replaced CEN/TS 15408:2006 and differs from it only editorially. At the publisher (the CEN catalogue run by iTeh, read on 25.09.2026): published 09-03-2011 (CEN/TC 343 "Solid recovered fuels"); stage 90.93 — decision to confirm after the systematic review (enquiry from 04-02-2025, closing 23-09-2026).

HOW ACCREDITATION SCOPES CITE THE STANDARD. Measurement of 25.09.2026 on the database of PL accreditation scopes (1310 laboratories with entries): 35 entries at 15 laboratories; notations "PN-EN 15408:2011" (25), "PN-EN 15408" without a year (9) and once with an en dash "PN–EN 15408:2011". THE SAME NUMBER, A DIFFERENT STANDARD: in 6 entries of one laboratory (AB 1787) PN-ISO/IEC 15408 stands — criteria for IT security evaluation (Common Criteria); we do not count those entries here. Subject of the test: solid recovered fuels (SRF) and alternative fuels (16 entries, most often together with waste), waste alone (8), solid biomass (2), plastics and packaging materials (1) and — in 8 entries of 6 laboratories — hard coal and other solid fuels. The scope of the standard speaks of solid recovered fuels; the other products are an extension of use by the laboratories. Methodology: total sulfur (8) and sulfur (4), fluorine (6), chlorine (4) and total chlorine (2), bromine (4), once iodine. Techniques: ion chromatography with conductometric detection (15) and other notations of ion chromatography (3), high-temperature combustion with IR detection (10) or TCD (2), titrimetric (1), potentiometric (1). The declared ranges in % have lower limits from 0.0001 % to 0.1 %, and upper ones from 0.0025 % to 10 %. In the same entries stand, among others, PN-EN ISO 10304-1:2009+AC:2012 (4), PN-EN ISO 21663 (3) and PN-EN ISO 16994 (2).

THE KEY OF THE "LABORATORIES" TAB: "PN-EN 15408" — 15 laboratories and 34 entries, without foreign entries; the tab does not catch the PN-ISO/IEC 15408 standard. The tab does not show the one entry with an en dash, but its laboratory is visible thanks to other entries.

WHAT WE DO NOT GIVE. We had a fragment of the text of EN 15408:2011 made available by the publisher: the foreword, the introduction and clauses 1–9.3. We do not have the further clauses (calculation, quality control, precision) or Annexes A–C (sample storage, robustness study). We do not give the formulae or the precision data.

Method principle

An SRF sample (about 1 g, particle size ≤ 1 mm) is burnt in a bomb in oxygen under pressure; the sulfates and halides are absorbed in 10 ml of water or 0.2 mol/l KOH, the solution is made up to 100 ml and Cl, F, S, Br are determined by ion chromatography (EN ISO 10304-1), F also with an electrode (ISO 10359-1), Br preferably by ICP-MS (EN ISO 17294-2). S and Cl may be determined with automatic analysers. Result on a dry basis.

Applications

• Solid recovered fuels (SRF) — control of sulfur and halogens in production and before combustion (corrosion, emissions)
• Classification and specification of fuels from waste (chlorine as a quality parameter)
• In accreditation scopes also applied to coal and waste — outside the scope of the standard, which concerns SRF

Key parameters

Standard

Standard number

PN-EN 15408:2011 (wersja angielska; wprowadza EN 15408:2011 [IDT])

Title (PL)

Stałe paliwa wtórne — Metody oznaczania zawartości siarki (S), chloru (Cl), fluoru (F) i bromu (Br)

Title (EN)

Solid recovered fuels — Methods for the determination of sulphur (S), chlorine (Cl), fluorine (F) and bromine (Br) content

Step-by-step procedure

1. Sample

   Storage according to Annex A; preparation according to EN 15413 to a particle size ≤ 1 mm; separate determination of moisture (the standard references EN 15414-3) — result on a dry basis.

2. Test portion

   About 1 g ± 0.1 mg: pellet, capsule, PE bag (with 20 % water or without) or with a combustion aid — then a smaller test portion.

3. Bomb

   10 ml of 0.2 mol/l KOH (or water when Cl < 1 % and Br is not determined); fill with oxygen according to the manufacturer's instructions.

4. Combustion

   Ignition; then equalization to room temperature; after opening check whether the combustion was complete — reject an unburnt sample.

   ⏱ Time: ≥ 10 min of equalization

5. Solution

   Transfer quantitatively to a tared 100 ml bottle and make up with water.

6. Determination

   Chlorides, fluorides, sulfates, bromides: EN ISO 10304-1, ISO 9297, ISO 10359-1 or EN ISO 17294-2. WE DO NOT GIVE the formulae.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Oxygen bomb — only experienced personnel, according to the manufacturer's instructions; oxygen at high temperature and under high pressure (clause 4)
• Do not exceed the permissible temperature rise in the bomb — with combustion aids, reduce the test portion
• KOH solution — corrosive; acid gases after combustion — open the bomb carefully, under an extraction hood

Frequently asked questions