🌿 Guidance on measuring velocity and volume flow rate of gas in emission ducts according to EN ISO 16911-1 — three measurement objectives with different uncertainty requirements (periodic measurements and isokinetics, calibration of automated flow meters, other EU ETS measurements), criteria for 2D Pitot tubes taken from US EPA Method 2G, L-type Pitot tube for swirl assessment and a corrected uncertainty budget example, CEN/TR 17078

Environment CEN/TR 17078

Overview

WHAT THIS DOCUMENT COVERS. This is a CEN Technical Report, not a standard: it contains no measurement method of its own and — as it says itself in 5.1.2 — does not repeat text, tables or figures of EN ISO 16911-1:2013 but only refers to its clauses, so it cannot be applied without a copy of the standard. Scope (Clause 1) in full: the report “provides guidance only on the application of the European Standard EN ISO 16911-1:2013” and “does not provide guidance on the application of EN ISO 16911-2:2013” (automated flow meters). We read the text in the iTeh sample of SIST-TP CEN/TR 17078:2017 (text of CEN/TR 17078:2017, English): from the title page through the European foreword, contents, introduction and Clauses 1–5 up to and including 6.8.1. Outside the sample remain 6.8.2–6.18 (duct cross-section area, performance characteristics and requirements, site survey, measurement plane and number of points, checks before measurement — leak tightness, S-type Pitot tube, repeatability at a point, swirl — quality control, calculation with wall-effect correction, uncertainty), Clauses 7–9 (guidance on Annexes A and F of the standard) and Annexes A and B of the report (example procedures: degree of swirl, leak check of the S-type tube). We also checked an earlier sample of the final draft FprCEN/TR 17078:2016 — the text of Clauses 1–5 is the same there.

ACCORDING TO THE TEXT OF CEN/TR 17078:2017 (Clauses 1–5, 6.1–6.8.1). The report was prepared by CEN/TC 264 “Air quality” (secretariat DIN) under a mandate from the European Commission and EFTA; it was produced at the request of national mirror committees for clarification of how certain requirements of EN ISO 16911-1:2013 are to be understood. Adoption of the report in whole or in part may be decided by the regulatory authorities of individual Member States (5.1.1). Normative references (2): EN 14181, EN 15259:2007, EN ISO 16911-1:2013, EN ISO 16911-2:2013, ISO 10780. The report points out an error in Formula (F.10) of the uncertainty example in Annex F of the standard and recommends replacing that example with the example in Clause 8 of the report (5.1.2). The standard applies to installations covered by the Industrial Emissions Directive 2010/75/EU and to installations covered by the emissions trading Directive 2003/87/EC that must or have chosen to use the measurement-based methodology under Commission Regulation (EU) No 601/2012 (MRR) (5.2.1). The requirements of the standard were set for the most stringent objective — EU ETS tier 4, ±2.5 % — although the standard also covers less demanding objectives such as support of isokinetic sampling; the level of quality control should depend on the uncertainty requirements of the objective and may be reduced for less demanding objectives (5.2.2). Under the Industrial Emissions Directive velocity and volume flow are measured in periodic monitoring for compliance or for reporting when mass emissions are determined, and for control of isokinetic conditions during manual sampling of pollutants (5.3.1). In the EU ETS automated flow meters are subject to quality assurance according to EN 14181 and the corresponding EN standards, i.e. the requirements of EN ISO 16911-2, and their calibration is carried out with one of the techniques of EN ISO 16911-1 (5.3.2). Table 1 (after Regulation 601/2012) gives the maximum permissible uncertainty of measurement-based methods: CO2 sources — ±10 % (tier 1), ±7.5 % (2), ±5 % (3), ±2.5 % (4); N2O sources — ±10 %, ±7.5 %, ±5 %, no tier 4. An emission source is treated as tier 4 when it emits more than 5000 tonnes of CO2 equivalent per year or contributes more than 10 % of the annual emissions of the whole installation; the permissible uncertainty is the combined uncertainty of the concentration analyser and the flow meter expanded to a 95 % confidence interval, so with equal shares of both components about ±1.8 % falls to the flow (5.3.2). Characterisation of the flow profile at the measurement plane may be required before a new flow meter is installed; calibration of a flow meter for other regulatory reasons is also within the scope of the standard (5.3.3). For 2D Pitot tubes the standard refers to US EPA Method 2G, and the report takes over its main requirements (Table 2): calibration acceptance criterion of the probe ±3° at 0° (yaw and pitch angles) — prior to use; width of the reference scribe line ≤ 1.6 mm; diameter of the tubing connecting the probe and the pressure readout ≥ 3.2 mm; uncertainty of the yaw-angle measuring device ≤ ±1°; horizontal straightness check < 5° — before field measurement; rotational position check of the angle measuring device ±1° before and ±2° after measurement; calibration acceptance of the angle device ±2° against a known angle of a triangular block. A laboratory wishing to use 2D tubes should meet the full set of requirements of US EPA Method 2G; these requirements do not apply to manual S-type Pitot tubes, which are described in the standard itself (6.5.2). For determining swirl at the measurement plane the standard provides S-type, 3D or 2D Pitot tubes; the report additionally recommends the L-type Pitot tube (6.6.2). The report groups measurement objectives differently from the standard — according to the recommended quality control (6.7.1): objective 1 — periodic monitoring for compliance according to EN 15259 or reporting with determination of mass emissions, and control of isokinetic conditions during manual sampling; objective 2 — calibration of automated flow meters according to EN 14181 and EN ISO 16911-2 or flow profile characterisation, for the EU ETS or other requirements; objective 3 — other periodic measurements required by the EU ETS Directive. For the clauses on the principle, tracer methods and plant thermal input (6.5.1, 6.6.3–6.6.5) and on the choice of technique (6.7.2, 6.7.3) the report states “no guidance required”.

STATUS (as of 03.10.2026). In the iTeh catalogue (read on 03.10.2026) CEN/TR 17078:2017 has the status “Published”, publication date 22.03.2017, stage 60.60, committee CEN/TC 264, working group WG 23 (manual and automatic measurement of velocity and volumetric flow in ducts) and mandate M/401. In the PKN search engine (terms “CEN/TR 17078” and “TR 17078”, 03.10.2026) the document is not found — the results contain only standards of the EN ISO 17078 series on a different subject, so we give no Polish designation or title; the Polish title in this entry is our translation. In four records laboratories write “CEN/TR 17078:2017-03” — the month matches the month of CEN publication (March 2017). The standard EN ISO 16911-1 is described in a separate entry “Velocity and volumetric flow rate of gases in ducts — Pitot tube (manual reference method)”.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read on 03.10.2026). The number 17078 with the prefix “CEN/TR” appears in 15 records at 11 laboratories: AB 073, AB 322, AB 409, AB 412, AB 746, AB 833, AB 835, AB 875, AB 994, AB 1382, AB 1642. In the current PCA documents (read on 03.10.2026, issues from 07.05.2025 to 02.10.2026) the number appears in 13 items of the same 11 laboratories — there are more records because at AB 875 one cell with the standard covers three rows (sampling, concentration and emission of dust). The report never stands alone: ten laboratories write it under EN ISO 16911-1 (AB 409 as “PN-EN 16911-1:2013-07”, without “ISO”), and AB 875 — under PN-EN 13284-1:2018-02 (sampling and concentration of dust). The “Laboratories” tab searches by the beginning of the value, and the report is always in second place, so for the term “CEN/TR 17078” it shows 0 laboratories; for the term “PN-EN ISO 16911-1” — 20, among them nine of the eleven (without AB 409 and AB 875). Checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). All items concern waste gases, mostly in the part “Periodic measurements of emissions to air from stationary sources performed for the regulated area”. Velocity and volume flow rate of gas by the differential pressure method for differential pressures above 5 Pa: AB 073, AB 322, AB 746, AB 833, AB 994; “for dynamic pressures > 5 Pa”: AB 835, and volume flow rate only: AB 409 (dynamic pressures) and AB 1642; above 10 Pa: AB 412 and AB 1382. Velocity by the anemometric method: AB 322 — range (1.0–6) m/s and AB 833 — (0.5–10) m/s. AB 875 cites the report for sampling for dust concentration and for dust concentration by the gravimetric method, range (0.5–50) mg/m3, together with PN-EN 13284-1:2018-02 — i.e. for objective 1 of the report (control of isokinetic conditions). In the database copy the report is assigned at AB 073 to dust concentration; in the current PCA document it stands at velocity and volume flow rate. At AB 746 part of the scope is suspended (bold italics) — the item with the report does not belong to it.

WHERE A SEEMINGLY CORRECT RESULT IS EASY. When choosing quality control: the requirements of EN ISO 16911-1 were set for EU ETS tier 4 (±2.5 %, about ±1.8 % for the flow alone), and the report allows them to be reduced for less demanding objectives — but only when the measurement objective (1, 2 or 3 of 6.7.1) is named before the measurement; simplified control applied to the calibration of a flow meter for the EU ETS gives a result with no visible error that does not meet the required uncertainty. With 2D tubes: the requirements in Table 2 are only a selection from US EPA Method 2G — the report requires its full set. When calculating uncertainty: the example in Annex F of the standard contains an error in Formula (F.10); a budget built following that example repeats the error, and the report recommends the example in its own Clause 8 (5.1.2). On the measurement itself and the calculation (measurement plane, leak tightness, wall-effect correction, standard conditions) the report speaks in 6.10–6.16, which we have not read — we refer to the entry on EN ISO 16911-1 by the name given above.

WHAT WE DO NOT GIVE. We have not read 6.8.2–6.18, Clauses 7–9 or Annexes A and B of the report, so we do not give the recommended requirements for the individual measurement objectives (the content of the tables in 6.9), the number of measurement points, the criteria of the leak, repeatability and swirl checks, the uncertainty budget example or the content of the corrected Formula (F.10). Nor do we state whether the report has been adopted in Poland as a PKN document or which parts of it a Polish regulatory authority has adopted — this is not in the sources read.

Method principle

The report introduces no method of its own: velocity at points of the measurement plane is measured with the techniques of EN ISO 16911-1 (Pitot tubes of various types or an anemometer), and volume flow rate is determined from the mean velocity and the cross-section area. The report assigns to each of the three measurement objectives — periodic monitoring and isokinetic control, calibration of automated flow meters and profile characterisation, other periodic EU ETS measurements — a recommended level of quality control, takes over criteria for 2D Pitot tubes from US EPA Method 2G, adds the L-type tube for swirl assessment and replaces the uncertainty budget example of Annex F of the standard.

Applications

• Waste gases from stationary sources — matching the requirements of EN ISO 16911-1 to the objective of velocity and volume flow measurement (1, 5.2, 6.7.1)
• Installations covered by Directive 2010/75/EU and EU ETS installations using the measurement-based methodology under Regulation 601/2012 (5.2.1)
• Waste gases: velocity and volume flow rate of gas, differential pressure and anemometric methods, and dust sampling and concentration — in the accreditation scopes of 11 laboratories in PCA

Key parameters

Standard

Standard number

CEN/TR 17078:2017

Title (PL)

Emisja ze źródeł stacjonarnych — Wytyczne dotyczące stosowania EN ISO 16911-1 (tłumaczenie robocze tytułu; dokument istnieje w wersji angielskiej)

Title (EN)

Stationary source emissions — Guidance on the application of EN ISO 16911-1

Step-by-step procedure

1. Naming the measurement objective

   Before the measurement assign the task to objective 1, 2 or 3 of 6.7.1 — the recommended level of quality control depends on it. CEN/TR 17078:2017 “Published” in the CEN catalogue (read on 03.10.2026).

2. Required uncertainty

   For the EU ETS establish the tier of the source (Table 1); at tier 4 about ±1.8 % falls to the flow — then the full requirements of EN ISO 16911-1 apply.

3. Choice and check of the probe

   S-type tube — according to the standard; 2D tube — the full set of US EPA 2G requirements (Table 2 gives the main ones); for swirl assessment the report also allows the L-type tube.

4. Measurement and calculation

   According to EN ISO 16911-1 and 6.10–6.16 of the report (plane, leak tightness, repeatability, swirl, wall-effect correction) — we have not read these clauses and do not give them.

5. Uncertainty budget

   Not following the example in Annex F of the standard (error in Formula F.10), but the example in Clause 8 of the report (5.1.2).

Required equipment and apparatus

Health and safety (OHS)

• Measurements are made on stacks and ducts of operating installations — work at height, hot and toxic gases at open sampling ports; the report gives no safety rules in the part read
• Leak checking and reconnecting probe tubing on a duct under overpressure risk gas escape — we have not read the report’s requirements (6.12.2)

Frequently asked questions