🌿 Sampling of waste gases for automatic analysers — extractive systems and in situ measurement (the basis of the determinations of NOx, SO₂, CO, O₂)

Environment PN-ISO 10396

Overview

STATUS (PKN card as of 23.09.2026): STANDARD WITHDRAWN. PN-ISO 10396:2001, Polish version, published 27-03-2001, 17 pages, KT 280 Air Quality, ICS 13.040.40, "Implements: ISO 10396:1993 [IDT]" — withdrawn on 15-11-2022; the card has no "Replaced by" row, so it names no successor in the PKN catalogue. In the accreditation scopes it remains a widely cited standard (below: 287 entries at 59 laboratories by the beginning of the record). The description in this entry is based on the preview of ISO 10396:2007 — an international edition NEWER than ISO 10396:1993, which the Polish standard implements; how the two editions differ in content we HAVE NOT ESTABLISHED.

In scopes of accreditation an item of the type „tlenki azotu w gazach odlotowych — analizatory automatyczne, PN-ISO 10396" [nitrogen oxides in waste gases — automatic analysers, PN-ISO 10396] is sometimes misleading, because the standard does not describe the determination of NOx itself, only the manner of taking the sample for the automated determination of gas concentrations. It is a condition of the correctness of every measurement with an analyser: if the sample is not representative or changes its composition on the way to the instrument, the result is worthless irrespective of the class of the analyser.

The standard covers two approaches. In extractive sampling the gas is conditioned before being led to the instruments — aerosols, dust and other interfering substances are removed. In non-extractive sampling the measurement is made on the spot, in situ, so no conditioning beyond the filtration of the retainable materials at the end of the probe is needed. In situ systems measure either across the duct or the stack, or at a point inside the duct.

The key concepts of the standard translate directly into measuring practice. The integrity of the sample is the maintenance of its representativeness by the elimination of leaks and of physical and chemical reactions in the gas on the way from the inlet to the instrument. The stratification of the gas is a state in which the concentration at any point differs from the mean over the cross-section by more than 10 % — this is the definition which decides whether a measurement at a single point may be regarded as reliable at all. A wet waste gas is a stream at the point of saturation or below it, which may contain droplets of water. A highly reactive component is a pollutant which may react, forming other chemical compounds — and for that reason the choice of the materials of the measuring line is not a formality.

Apparatus: the primary filter is made of a suitable alloy (for example cast stainless steel), borosilicate glass, silica, ceramic or another suitable material; a filter retaining particles larger than 10 µm is recommended, and in some systems a secondary filter is also needed. The filter may be placed outside the duct or at the end of the probe — in the latter case a deflector plate is recommended, which prevents the build-up of dust on the face of the filter and its blocking. Contamination of the filter with dust has to be avoided where the condensate could react with the gases and falsify the result. For the periodic cleaning of the filter a blow-back with compressed air is used — necessarily heated, clean and dry, so as not to contaminate the probe and not to cause condensation in the system.

Calibration: the standard uses the concept of a calibration gas mixture of a known, reliable and stable composition, with which the response of an automated measuring system can be checked and with which it should be calibrated. The Polish regulation on the requirements concerning the carrying out of measurements of emissions (consolidated text Dz.U. 2023 item 1706, § 13) permits until 1 January 2030 reference methodologies based both on the earlier and on the new editions of the standards EN 14789, EN 14792 and EN 15058, whereby in measurements with portable automated measuring systems it requires analysers with a certificate confirming the fulfilment of the requirements of the standard implementing EN 15267-3.

HOW MANY LABORATORIES REACH FOR THE INTERNATIONAL DOCUMENT — TWO, NOT THREE AND NOT FOUR. The number has to be given together with the way it was obtained, because with this particular standard the natural pattern gives a result TWICE TOO HIGH. Reading of 23.09.2026 on the working copy of the scope database: the record without the PN prefix — "ISO 10396:2007" — is held by TWO laboratories, AB 994 and AB 1624, 19 entries in total. A pattern searching for the string "ISO 10396" without an anchor before it, on the other hand, shows 24 entries at FOUR laboratories — but the two additional ones, AB 875 and AB 1488, cite the Polish standard written with the hyphen omitted ("PN ISO 10396:2001"), not the international document. Conclusion for the reader: reaching for ISO directly is the practice of TWO laboratories, not a phenomenon of the community — and that is how it should be treated when referring to this entry.

TEN FORMS OF THE RECORD AND ONE LABORATORY INVISIBLE TO THE SEARCH. The core "10396" occurs in the scopes in ten different forms (form = the whole value of the element in the reference-document column). The main form "PN-ISO 10396:2001" — 281 occurrences at 59 laboratories; next "ISO 10396:2007" (19 at 2), the same Polish standard with the test procedure PB/LBP/08 appended (4 at 1), "PN-ISO-10396:2001" with a superfluous hyphen (2), "P N-ISO 10396:2001" with a split PN element (2), "PN ISO 10396:2001" without a hyphen (2), "PN-ISO 10396:2001 ←" with an arrow from the table layout (2), and three lines in which the Polish standard stands AFTER another designation (PN-EN 14789, PN-EN 14792, PN-EN 15058 — one each). The sum adds up: 281 + 19 + 4 + 2 + 2 + 2 + 2 + 3 = 315.

THREE FIGURES FOR THE REACH OF THE POLISH STANDARD, THREE DIFFERENT QUESTIONS. By the BEGINNING of the string, i.e. the way the "Laboratories" tab on this page searches: 287 entries / 59 laboratories. Allowing a space instead of the hyphen in the "PN-ISO" element: 292 / 60. By all Polish forms, including the split "P N-ISO": 296 / 60. The sixtieth laboratory is AB 875 — it cites the Polish standard ONLY in the form without the hyphen, so it will not appear in the tab of this page, although it has the standard. The difference between the first and the third figure is nine entries and one laboratory, and it lies entirely in how the prefix is written, not in the content of the test.

Method principle

The standard gives guidelines for the representative sampling of gases in a duct and covers extractive and non-extractive methods. In extractive sampling the gas is conditioned — aerosols, dust and other interfering substances are removed — before it is led to the measuring instruments. In non-extractive sampling the measurements are made on the spot, so beyond the filtration of the retainable materials at the end of the probe no conditioning is required. The representativeness of the sample is assessed taking into account the nature of the source, the location of the sampling point and other factors; a stratification of the stream (a difference of the concentration at a point with respect to the mean over the cross-section greater than 10 %) excludes any inference from a point measurement. The measuring line is built of materials matched to the physical and chemical properties of the gas (the recommendations are in an annex to the standard), with a filter retaining particles above 10 µm, where necessary with a secondary filter, and with a probe matched to the composition of the gas; the integrity of the sample is ensured by the elimination of leaks and of physical and chemical reactions between the inlet and the instrument. The response of an automated measuring system is checked and calibrated with calibration gas mixtures of a known, reliable and stable composition.

Applications

• Measurements of the emission of NOx, SO₂, CO and oxygen with automatic analysers in boiler houses, heating plants and industrial installations
• Permanently installed automated monitoring systems (AMS) — the sampling for a continuous system
• Measurements with portable automated measuring systems in the course of the periodic control of emissions
• Choice of the sampling point and checking of the stratification of the stream before a series of measurements
• Design and acceptance of the measuring line: probe, filters, heated lines, conditioning system

Key parameters

Standard

Standard number

PN-ISO 10396:2001 (wersja polska; wprowadza ISO 10396:1993 [IDT])

Title (PL)

Emisja ze źródeł stacjonarnych — Pobieranie próbek do automatycznego pomiaru stężenia składników gazowych

Title (EN)

Stationary source emissions — Sampling for the automated determination of gas concentrations

Step-by-step procedure

1. Assessment of the source and choice of the sampling point

   Recognise the nature of the source and choose the location of the measuring point taking into account the factors influencing the representativeness of the sample indicated in the standard.

2. Checking of the stratification

   Check whether the stream is not stratified — if the concentration at a point differs from the mean over the cross-section by more than 10 %, a measurement at a single point is not reliable and multi-point sampling has to be used or the place changed.

3. Choice of the materials and construction of the line

   Match the materials of the probe, of the filters and of the lines to the physical and chemical properties of the gas (the recommendations are in an annex to the standard), paying attention to highly reactive components and to a wet gas with droplets of water.

4. Filtration

   Mount a primary filter retaining particles above 10 µm — outside the duct or at the end of the probe; when it is mounted on the probe use a deflector plate protecting the face of the filter against the build-up of dust. Where necessary add a secondary filter.

5. Conditioning (extractive system)

   In an extractive system remove aerosols, dust and other interfering substances before the gas is led to the analyser; keep the lines at a temperature preventing condensation.

6. Checking of the tightness and of the integrity of the sample

   Check the tightness of the line; eliminate the places at which physical and chemical reactions in the gas could take place between the inlet and the instrument.

7. Calibration and checking of the response

   Set the zero and check the response of the analyser with calibration gas mixtures of a known and stable composition; carry out the calibration according to the recommendations of the standard and of the manufacturer of the analyser.

8. Measurement and blow-back

   Carry out the measurement, periodically blowing back the filter with heated, clean and dry compressed air. After the series check the drift of the zero and of the sensitivity.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Work at a stack and at a flue gas duct — protection against a fall from a height is required, as is an arrangement with the operator of the installation.
• The waste gas is hot and toxic (CO, NOx, SO₂) — the probe and the lines are scalding hot, and a leak in a room threatens poisoning.
• Secure the cylinders of calibration gases against being knocked over; check the dates of the verification of the pressure reducers.
• Carry out the blow-back with compressed air carefully — a sudden ejection of dust from the probe threatens injury to the eyes.
• It is not permitted to work at an installation without the knowledge of its operator — changes of the load of the boiler during a measurement are dangerous and spoil the result.

Frequently asked questions