⛽ Moisture content of hard coal and coke — gravimetric method (PN-80/G-04511)
In short
Gravimetric determination of moisture in solid fuels: free moisture, moisture in the analysis sample and — by calculation — total moisture. The test is performed according to PN-G-04511:1980 (wersja polska); STATUS (state of the PKN card on 22-09-2026): WITHDRAWN — the "Data wycofania" [withdrawal date] row: 24-01-2012. The card has NO "Zastąpiona przez" [Replaced by] field: the catalogue does not indicate a successor. The procedure comprises 6 steps; it is used for: Testing the quality of solid fuels placed on the market — determination of total moisture content according to item 8 of the annex to the regulation, Recognising the citation "PN-80/G-04511" encountered in accreditation scopes and in fuel quality certificates, Assessment of the documentation of a laboratory citing a withdrawn standard that is still indicated by a legal act in force.
At a glance
- Standard: PN-G-04511:1980 (wersja polska)
- Category: Petrochemistry and fuels
- Procedure steps: 6
- STATUS (state of the PKN card on 22-09-2026): WITHDRAWN — the "Data wycofania" [withdrawal date] row: 24-01-2012. The card has NO "Zastąpiona przez" [Replaced by] field: the catalogue does not indicate a successor
- Does the withdrawal mean that it must not be applied: NO. Item 8 of the annex to the regulation on methods of testing the quality of solid fuels still indicates it — withdrawal by PKN does not remove the standard from the legal act, and in a regulated test it is the act that decides
- WHAT KIND of citation this is — two different mechanisms, often confused: this is NOT a "mandatory standard" in the old sense. The obligation to apply Polish Standards was introduced by separate regulations on the obligation to apply PN, and it DISAPPEARED with the Standardisation Act of 2002 (the last such act for food — Journal of Laws 1997 item 535 — was deemed repealed as of 01-01-2003). Here a different mechanism, still alive, is at work: A SECTORAL ACT INDICATES A SPECIFIC STANDARD AS THE TEST METHOD in a specific regulated test. The effect is narrower but binding — it concerns testing the quality of solid fuels placed on the market, not the application of the standard in general
Overview
WHAT THIS STANDARD COVERS. The scope on the PKN catalogue card lists the types of moisture and their definitions: free moisture of coal, moisture of air-dried coal, total moisture of coal, moisture in the analysis sample of coal, total moisture of coke and semi-coke from hard coal, and moisture in the analysis sample of coke and semi-coke. Hard coal that does not oxidise at temperatures up to 110 °C is defined separately — this distinction determines the drying conditions.
STATUS OF THE DOCUMENT AND THE THING THAT IS MOST IMPORTANT HERE FOR THE READER. The PKN catalogue card (reading of 22.09.2026) has the "Wycofana" [Withdrawn] header and the row "Data wycofania: 24-01-2012" [withdrawal date]; it does NOT have a "Zastąpiona przez" [Replaced by] row — the catalogue does not indicate a successor. Nevertheless, the standard is INDICATED BY A LEGAL ACT IN FORCE: item 8 of the annex to the Regulation of the Minister of Energy of 27 September 2018 on methods of testing the quality of solid fuels lists it for the determination of total moisture content. WITHDRAWAL BY PKN DOES NOT REMOVE THE STANDARD FROM THE LEGAL ACT — in testing the quality of solid fuels it is the act that decides what may be applied, so the sentence "the standard has been withdrawn, so it should not be applied" would be false here.
SINCE WHEN THERE HAVE BEEN THREE DOCUMENTS, NOT TWO. The wording of item 8 changed in December 2023. Until 8 December 2023 the item listed TWO documents: "PN-G-04511:1980 albo PN-ISO 589:2006" [albo = or]. The Regulation of the Minister of Climate and Environment of 7 December 2023 (Journal of Laws 2023 item 2661, promulgated 8.12.2023, in force 9.12.2023) replaced them with the wording: "PN-G-04511:1980, PN-ISO 589:2006 albo PN-G-04611:2020" [albo = or]. This has a practical consequence when reading older documentation: AN ACCREDITATION SCOPE FROM BEFORE 9 DECEMBER 2023 DESCRIBES A STATE IN WHICH THERE WERE TWO BASES — a laboratory citing two documents is then not making a mistake, but reflecting the legal state of its time.
A NOTE ON THE CONSOLIDATED TEXT, WHICH IS EASY TO FALL FOR. The consolidated text of the regulation (Journal of Laws 2021 item 1366) is from July 2021 and DOES NOT CONTAIN the amendment of December 2023 — in item 8 it shows two documents instead of three. Anyone who relies on the consolidated text will describe the state of three years ago. We checked this in the register of acts: the basic act Journal of Laws 2018 item 1893 has two entries in the "Akty zmieniające" [amending acts] field — Journal of Laws 2019 item 1258 (concerns items 6.1–6.3, caking capacity; included in the consolidated text) and Journal of Laws 2023 item 2661 (items 5.3, 6.2, the sieve table and item 8; NOT INCLUDED).
THREE DOCUMENTS ARE NOT THE SAME TEST THREE TIMES. Item 8 speaks of TOTAL MOISTURE and permits three bases, but these documents differ in character: PN-G-04611:2020-06 bears the title "Węgiel kamienny, koks i półkoks z węgla kamiennego oraz karbonizat — Oznaczanie zawartości wilgoci — METODY UPROSZCZONE" [Hard coal, coke and semi-coke from hard coal and char — Determination of moisture content — SIMPLIFIED METHODS] and does not replace either of the others (the card has no "Zastępuje" [Replaces] field). The equivalence is therefore LEGAL — the act permits each of the three — not technical. WHETHER AND BY HOW MUCH THE RESULTS DIFFER BETWEEN THESE METHODS, WE HAVE NOT ESTABLISHED: we did not have the texts of any of the three standards, all of them are available for a fee.
DO LABORATORIES TREAT THESE DOCUMENTS AS ALTERNATIVES — A MEASUREMENT, NOT A SUPPOSITION. Our own measurement on the database of accreditation scopes (22-09-2026, 17 h; counted over all forms of notation, taking both numbering schemes into account): only PN-80/G-04511 — 69 entries in 26 laboratories; only PN-ISO 589:2006 — 98 entries in 40 laboratories; only PN-G-04611 — 57 entries in 19 laboratories; 04511 together with 589 — 15 entries; 04511 together with 04611 — 20; 589 together with 04611 — 7; all three at once — 4 entries in 3 laboratories. EACH OF THE THREE DOCUMENTS APPEARS ON ITS OWN, AND IN LARGE NUMBERS, while mixed combinations account for 46 entries out of 270. The distribution of methodologies is the same in all groups ("zawartość wilgoci w próbce analitycznej" [moisture content in the analysis sample], "zawartość wilgoci całkowitej" [total moisture content], "zawartość wilgoci przemijającej" [free moisture content], "zawartość wilgoci całkowitej z obliczeń" [total moisture content, calculated]). This is a picture of an ALTERNATIVE, not of a division of activities — and it agrees with the wording of the act, which links these three documents with the conjunction "albo" [or].
WHERE A CORRECTLY PERFORMED TEST GIVES A TOO LOW RESULT. In the determination of moisture, the most dangerous thing is what is not visible in the procedure: water lost BETWEEN SAMPLING AND THE FIRST WEIGHING. The drying will proceed correctly, the masses will be read without reservation, the calculation will come out in accordance with the formula, and the result will be lower by as much as evaporated on the way — and there is nothing to compare it with, because at the moment the sample is received nobody knows its original mass. That is why the transport conditions and the tightness of the container are part of the method, not an organisational matter. WITH TOTAL MOISTURE OBTAINED BY CALCULATION, the effect is one level worse: the error enters a COMPONENT (the free moisture), and the final result looks correct, because the formula will be calculated without reservation.
WHAT WE DO NOT GIVE. We did not have the text of the standard — PKN makes it available for a fee (9 pages, Mining Sector, Technical Body KT 220, ICS 75.160.10). WE DO NOT GIVE: drying temperatures and times, requirements for the dishes and the oven, the conditions for coal that oxidises at temperatures up to 110 °C, the method of calculating the results or the precision of the method. All of this is the content of the standard and must be taken from its text. Nor have we checked whether work is under way on amending the list in item 8 — we checked only the register of PROMULGATED acts.
Method principle
The fuel sample is dried under specified conditions and weighed before and after drying; the loss of mass relative to the mass of the sample gives the moisture content. The standard distinguishes free moisture (removed when the sample is brought to the air-dried state), moisture in the analysis sample, and total moisture, which in the two-stage determination is obtained BY CALCULATION from the previous two. The method of performance, the apparatus and the calculations are specified by the text of the standard, which we do not quote.
Applications
- Testing the quality of solid fuels placed on the market — determination of total moisture content according to item 8 of the annex to the regulation
- Recognising the citation "PN-80/G-04511" encountered in accreditation scopes and in fuel quality certificates
- Assessment of the documentation of a laboratory citing a withdrawn standard that is still indicated by a legal act in force
- Reading older reports in which total moisture was given as a quantity calculated from two determinations
Key parameters
| Parameter | Value |
|---|---|
| STATUS (state of the PKN card on 22-09-2026) | WITHDRAWN — the "Data wycofania" [withdrawal date] row: 24-01-2012. The card has NO "Zastąpiona przez" [Replaced by] field: the catalogue does not indicate a successor |
| Does the withdrawal mean that it must not be applied | NO. Item 8 of the annex to the regulation on methods of testing the quality of solid fuels still indicates it — withdrawal by PKN does not remove the standard from the legal act, and in a regulated test it is the act that decides |
| WHAT KIND of citation this is — two different mechanisms, often confused | this is NOT a "mandatory standard" in the old sense. The obligation to apply Polish Standards was introduced by separate regulations on the obligation to apply PN, and it DISAPPEARED with the Standardisation Act of 2002 (the last such act for food — Journal of Laws 1997 item 535 — was deemed repealed as of 01-01-2003). Here a different mechanism, still alive, is at work: A SECTORAL ACT INDICATES A SPECIFIC STANDARD AS THE TEST METHOD in a specific regulated test. The effect is narrower but binding — it concerns testing the quality of solid fuels placed on the market, not the application of the standard in general |
| Legal basis of the indication (wording in force) | item 8 of the annex: "PN-G-04511:1980, PN-ISO 589:2006 albo PN-G-04611:2020" [albo = or] — since 9 December 2023 (Journal of Laws 2023 item 2661) |
| Previous wording — relevant for older scopes | until 8 December 2023: "PN-G-04511:1980 albo PN-ISO 589:2006" [albo = or] — TWO documents. An accreditation scope from before this date describes a different legal state and is not erroneous for that reason |
| The consolidated text trap | the consolidated text Journal of Laws 2021 item 1366 is from July 2021 and does NOT contain the amendment of December 2023 — in item 8 it shows two documents. The register of acts gives two amendments for Journal of Laws 2018 item 1893: Journal of Laws 2019 item 1258 (included) and Journal of Laws 2023 item 2661 (not included) |
| Form of the number used in accreditation scopes | "PN-80/G-04511" as the WHOLE value of the field — 75 entries in 21 laboratories; the same notation as the BEGINNING of the value (followed by a clause number: "pkt. 2.2.1", "pkt 2.3.1", "p. 2.4.1.7a" [pkt, p. = clause]) — 95 entries in 25 laboratories, AND IT IS THIS SECOND NUMBER THAT THE LABORATORIES TAB SHOWS, because it searches by prefix; counting all forms of notation of the number — 109 entries in 27 laboratories. The form from the card ("PN-G-04511:1980") occurs in 10 entries at 3 laboratories, of which in 2 as the whole value of the field. The laboratories tab for this entry searches by the former (measurement of 22-09-2026, 17 h) |
| Form of the number in the legal act — different from the scopes | the regulation writes "PN-G-04511:1980", that is, the form from the card. A laboratory copying the designation directly from the provision will get a notation that two entries out of 75 use in the scopes |
| Types of moisture covered by the standard | free, in air-dried coal, total of coal, in the analysis sample of coal, and total and analytical of coke and semi-coke from hard coal (according to the scope on the card) |
| Total moisture — a CALCULATED quantity, not a measured one | in the two-stage determination it arises from two measurements: free moisture and moisture in the analysis sample. The comparability of results therefore depends on the methodologies of BOTH COMPONENTS, not on the formula — and it must not be judged after checking the formula alone |
| Where an error gives a seemingly correct result | water lost BETWEEN SAMPLING AND THE FIRST WEIGHING. Drying, weighing and calculation proceed without reservation, and the result is too low; at the moment the sample is received, there is nothing to compare its mass with |
| Joint citations in scopes (measurement of 22-09-2026, 17 h) | only 04511 — 69 entries / 26 laboratories; only PN-ISO 589 — 98 / 40; only PN-G-04611 — 57 / 19; 04511+589 — 15; 04511+04611 — 20; 589+04611 — 7; all three — 4 entries / 3 laboratories |
| What follows from this — an alternative, not a division of activities | each of the three documents appears ON ITS OWN and in large numbers, and the distribution of methodologies is the same in each group. This is a picture of equivalence, consistent with the conjunction "albo" [or] in the act |
| Legal versus technical equivalence | PN-G-04611:2020-06 is SIMPLIFIED METHODS (that is its title) and does not replace the others — its card has no "Zastępuje" [Replaces] field. The act permits each of the three; whether the results are comparable, we HAVE NOT ESTABLISHED |
| The standard most often cited with it outside item 8 | PN-ISO 11722:2009 (moisture in the analysis sample, drying in a nitrogen atmosphere) — 2 entries. Card without the "Wycofana" [Withdrawn] header (reading of 22-09-2026) |
| Numerical values from the text of the standard | WE DO NOT GIVE THEM — we did not have the text (9 pages, KT 220, ICS 75.160.10). This concerns drying temperatures and times, requirements for the apparatus (including dishes and cooling of the sample), the conditions for coal oxidising at up to 110 °C and the precision of the method |
Standard
- Standard number
- PN-G-04511:1980 (wersja polska)
- Title (PL)
- Paliwa stałe — Oznaczanie zawartości wilgoci
- Title (EN)
- Solid fuels — Determination of moisture content
Step-by-step procedure
-
Checking which basis applies to the given test
When testing the quality of solid fuels placed on the market, the basis is indicated by item 8 of the annex to the regulation: since 9 December 2023, PN-G-04511:1980, PN-ISO 589:2006 or PN-G-04611:2020. The withdrawal of PN-G-04511 by PKN (24-01-2012) does not change this.
-
Sampling and securing the sample
Place the sample in an airtight container and limit the time between sampling and the first weighing. THIS IS WHERE AN ERROR ARISES THAT IS NOT VISIBLE LATER: water lost at this stage makes the result too low, while the subsequent operations proceed correctly.
-
Determination of free moisture
Bringing the sample to the air-dried state and determining the loss of mass. The conditions (temperature, time, method of spreading the sample) are the content of the standard and we do not quote them.
-
Preparation and determination of moisture in the analysis sample
The analysis sample is dried under the conditions given in the standard and weighed. For coal that oxidises at temperatures up to 110 °C, the standard provides for a separate procedure — this distinction is defined separately in it.
-
Calculation of total moisture
In the two-stage determination, total moisture is calculated from the free moisture and the moisture in the analysis sample. We do not quote the formula. THE RESULT IS A CALCULATED QUANTITY: a change in the methodology of either component changes it without any change in the formula.
-
Recording the result with the basis and the type of moisture stated
In the report, state which document was applied (the three are equivalent within the meaning of the provision) and which moisture is meant — free, in the analysis sample or total, and for the latter also that it was obtained by calculation.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Laboratory drying oven with temperature control | The drying conditions (temperature, time, atmosphere) are the content of the standard and we do not quote them — they must be taken from its text | — |
| Balance | The method is gravimetric (regulation, item 8). The required weighing accuracy HAS NOT BEEN ESTABLISHED — we did not have the text of the standard | — |
| Airtight sample container | An element of the method, not of work organisation: water lost before the first weighing makes the result too low and leaves no trace in the subsequent procedure | — |
| Other equipment | NOT ESTABLISHED — we do not give the dishes, the method of cooling the sample after drying or the requirements for the apparatus, because we did not have the text of the standard | — |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Not established | — | The method is gravimetric (regulation, item 8) — the sample is dried and weighed. Whether the standard provides for any reagents, WE HAVE NOT ESTABLISHED — we did not have the text of the standard |
Health and safety (OHS)
- Coal dust is combustible and explosive as a suspension — limit dusting when crushing and pouring the sample
- The drying oven operates at elevated temperature; the sample removed after drying is hot
- With coals prone to self-heating, do not leave the crushed sample in the oven for longer than the standard provides
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-G-04511:1980 (wersja polska) — “Solid fuels — Determination of moisture content”.
How does this method work?
The fuel sample is dried under specified conditions and weighed before and after drying; the loss of mass relative to the mass of the sample gives the moisture content. The standard distinguishes free moisture (removed when the sample is brought to the air-dried state), moisture in the analysis sample, and total moisture, which in the two-stage determination is obtained BY CALCULATION from the previous two.
What is the measuring range and accuracy?
STATUS (state of the PKN card on 22-09-2026): WITHDRAWN — the "Data wycofania" [withdrawal date] row: 24-01-2012. The card has NO "Zastąpiona przez" [Replaced by] field: the catalogue does not indicate a successor; Does the withdrawal mean that it must not be applied: NO. Item 8 of the annex to the regulation on methods of testing the quality of solid fuels still indicates it — withdrawal by PKN does not remove the standard from the legal act, and in a regulated test it is the act that decides; WHAT KIND of citation this is — two different mechanisms, often confused: this is NOT a "mandatory standard" in the old sense. The obligation to apply Polish Standards was introduced by separate regulations on the obligation to apply PN, and it DISAPPEARED with the Standardisation Act of 2002 (the last such act for food — Journal of Laws 1997 item 535 — was deemed repealed as of 01-01-2003). Here a different mechanism, still alive, is at work: A SECTORAL ACT INDICATES A SPECIFIC STANDARD AS THE TEST METHOD in a specific regulated test. The effect is narrower but binding — it concerns testing the quality of solid fuels placed on the market, not the application of the standard in general; Legal basis of the indication (wording in force): item 8 of the annex: "PN-G-04511:1980, PN-ISO 589:2006 albo PN-G-04611:2020" [albo = or] — since 9 December 2023 (Journal of Laws 2023 item 2661).
How long does the test take?
The procedure comprises 6 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Laboratory drying oven with temperature control, Balance, Airtight sample container, Other equipment.
Where is this test used?
Testing the quality of solid fuels placed on the market — determination of total moisture content according to item 8 of the annex to the regulation; Recognising the citation "PN-80/G-04511" encountered in accreditation scopes and in fuel quality certificates; Assessment of the documentation of a laboratory citing a withdrawn standard that is still indicated by a legal act in force; Reading older reports in which total moisture was given as a quantity calculated from two determinations.
What safety precautions apply?
Coal dust is combustible and explosive as a suspension — limit dusting when crushing and pouring the sample; The drying oven operates at elevated temperature; the sample removed after drying is hot; With coals prone to self-heating, do not leave the crushed sample in the oven for longer than the standard provides.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-80/G-04511.