🌿 Determination of the methane (CH4) concentration in waste gas from stationary sources by an automatic method with a flame ionisation detector (FID) equipped with a catalytic converter that oxidizes all organic compounds except methane — extractive system (FID and sampling system), continuous measurement with permanently installed systems or intermittent measurement, in dry and wet gases; principles, performance criteria and quality assurance procedures; conversion to standard conditions, dry gas and reference oxygen; PN-EN ISO 25140:2011

Environment PN-EN ISO 25140

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of ISO 25140:2010 (first edition, English text) — PN-EN ISO 25140:2011 adopts EN ISO 25140:2010 and ISO 25140:2010 as identical (PKN search): contents, foreword, introduction, Clauses 1–4 and Clause 5 up to 5.1.1 — the sample ends on page 6. We do not read the rest of the apparatus and principles of operation (5), performance criteria and their determination (6), measurement procedure (7), quality assurance and control (8), test report (9) or Annexes A (operational gases), B (procedures of the general performance test and ongoing control), C (safety measures) and D (results of comparison tests); we know the titles from the contents.

ACCORDING TO THE TEXT OF ISO 25140:2010. The standard was prepared by ISO/TC 146 “Air quality”, Subcommittee SC 1 “Stationary source emissions”. Introduction: methane (CH4) is a gas of relevance to the climate (greenhouse gas); sources include cattle breeding, rice cultivation, extraction and transport of natural gas, landfills, composting plants, the use of biogas and natural gas and biomass firing. Scope (1): principle, performance criteria and QA/QC procedures of an automatic method for measuring methane in waste gas from stationary sources by flame ionisation detection; dry or wet waste gases; continuous monitoring with permanently installed systems and intermittent measurements; the standard supplements general requirements of e.g. EN 15267-3, EN 14181 and EN 15259; it does not specify an independent method — the method for calibration and validation of permanently installed systems is given in ISO 25139 (in EN 14181 called the standard reference method SRM). References (2): ISO 9169:2006, ISO 14956, ISO 20988. Definitions (3): among others AMS (a system attached to a duct measuring and recording the mass concentrations of methane continuously or intermittently), analyser, mass concentration (usually in mg/m³), independent reading (two readings separated by at least four response times), individual reading (averaged over a time equal to the response time), adjustment, calibration (relationship with an independent method applied simultaneously at the same point), interference, zero, span and reference gases, span point (often around 80 % of the upper limit of the range or near the emission limit value), response time as the sum of lag time (to 10 % of the change) and rise time (10–90 %) or fall time (90–10 %), lack of fit, residence time of the gas from the probe inlet to the measuring cell, period of unattended operation, standard and expanded uncertainty. Symbols (4): e.g. molecular mass of methane 16 g/mol and of water 18 g/mol, molar volume 22.4 l/mol; methane concentrations at standard conditions (wet gas), at reference conditions of water vapour (dry gas) and at reference oxygen; sums of positive and negative effects of interferents. Method (5.1.1): the extractive system consists of the FID and the associated sampling system; the FID measures the ionisation current of organically bound carbon in a hydrogen flame, depending on the number of C–H bonds broken in the flame, the type of chain (straight or branched) and the presence of other elements; the FID responds strongly to organic compounds and less to CO, CO2, NO and H2O; to determine methane alone the FID is equipped with a catalytic converter oxidizing all organic compounds except methane — it must be protected against poisoning by sulfur, nitrogen and chlorine compounds, and to avoid memory effects and delays the converter should be close to the FID and heated.

STATUS (as of 03.10.2026). The PKN search engine (query “PN-EN ISO 25140”, 03.10.2026) lists PN-EN ISO 25140:2011 — English version, “Introduces: EN ISO 25140:2010 [IDT], ISO 25140:2010 [IDT]”, without a withdrawal note; there is no Polish version in the results.

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 25140 appears in 4 records at 2 laboratories: AB 550 and AB 833 (2 each). In the current PCA documents (read 03.10.2026; AB 833 issue no. 25 of 30.07.2026, AB 550 issue no. 33 of 22.09.2026) the number appears at the same 2 laboratories; in every document the number of page markers equals the number of PDF pages, without repetitions; a search of all PCA documents downloaded from BIP on 03.10.2026 found no laboratories outside the database copy. The form “PN-EN ISO 25140:2011” at both. None of these items is suspended (the word “zawieszonego” in the AB 550 document refers to suspended particulate matter). The “Laboratories” tab (query “PN-EN ISO 25140”) shows both laboratories — checked by a tab query on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). AB 550: waste gas — CH4 concentration by continuous measurement with flame ionisation detection (HFID) (0.3–11) mg/m³ and CH4 emission by calculation. AB 833: waste gas — methane concentration by continuous flame ionisation detection (FID) (1.0–50) mg/m³ and CH4 emission by calculation.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Converter: poisoned by sulfur, nitrogen or chlorine compounds, the converter stops oxidizing other organic compounds and the FID measures them together with methane — the result rises although there is no more methane (5.1.1). Memory effects: a contaminated tube system in the instrument shifts the signal — hence the converter close to the FID and heated (5.1.1). Readings: independent readings must be separated by at least four response times (3.5) — faster readings are not independent. Conditions: concentration in wet gas at standard conditions, in dry gas and at reference oxygen are three different numbers (4). Calibration: ISO 25140 is not an independent method — a permanently installed system is calibrated with the method of ISO 25139 (1, 3.9). PN edition: the PKN catalogue has only the English version PN-EN ISO 25140:2011.

WHAT WE DO NOT GIVE. We do not quote the description of the sampling system, criteria and procedures for determining performance characteristics, the measurement procedure, frequency of checks, operational gases, safety measures or results of comparison tests — they lie outside the sample. We do not summarize ISO 25139, EN 14181, EN 15259, EN 15267-3, ISO 9169, ISO 14956 or ISO 20988 in this entry. We do not give emission limit values for methane.

Method principle

Waste gas is drawn by an extractive system to an analyser with a flame ionisation detector. Before the detector the gas passes through a heated catalytic converter that oxidizes all organic compounds except methane, so the ionisation current in the hydrogen flame comes from methane. The signal is converted into the mass concentration of methane from calibration with reference gases and — where needed — to standard conditions, dry gas and reference oxygen.

Applications

• Methane in waste gas from stationary sources — dry and wet gases (1)
• Continuous monitoring with permanently installed systems and intermittent measurement of methane emissions (1)
• Sources named in the introduction: landfills, composting plants, biogas, natural gas, biomass firing (introduction)
• Waste gas — 4 accreditation scope records of 2 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN ISO 25140:2011

Title (PL)

Emisja ze źródeł stacjonarnych — Automatyczna metoda oznaczania stężenia metanu z zastosowaniem detekcji płomieniowo-jonizacyjnej (FID)

Title (EN)

Stationary source emissions — Automatic method for the determination of the methane concentration using flame ionisation detection (FID)

Step-by-step procedure

1. System

   FID with converter and sampling system (5.1.1). PN-EN ISO 25140:2011 — no withdrawal note (PKN, 03.10.2026).

2. Performance characteristics

   Determination of characteristics in the general performance test (6, Annex B — outside the sample).

3. Measurement

   Continuous or intermittent; independent readings at least four response times apart (3.5; Clause 7 outside the sample).

4. Conversion

   Standard conditions, dry gas, reference oxygen (4; calculations outside the sample).

5. Quality control

   Ongoing control and calibration with the independent method ISO 25139 (1; Clause 8 outside the sample).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The FID operates with a hydrogen flame; safety measures are given in normative Annex C (outside the sample; title from the contents)

Frequently asked questions