SIST EN ISO 21877:2019

Stationary source emissions - Determination of the mass concentration of ammonia - Manual method (ISO 21877:2019)

This document specifies a manual method of measurement including sampling and different analytical methods for the determination of the mass concentration of ammonia (NH3) in the waste gas of industrial plants, for example combustion plants or agricultural plants. All compounds which are volatile at the sampling temperature and produce ammonium ions upon dissociation during sampling in the absorption solution are measured by this method, which gives the volatile ammonia content of the waste gas.
This document specifies an independent method of measurement, which has been validated in field tests in a NH3 concentration range of approximately 8 mg/m3 to 65 mg/m3 at standard conditions. The lower limit of the validation range was determined under operational conditions of a test plant. The measurement method can be used at lower values depending, for example, on the sampling duration, sampling volume and the limit of detection of the analytical method used.
NOTE 1    The plant, the conditions during field tests and the performance characteristics obtained in the field are given in Annex A.
This method of measurement can be used for intermittent monitoring of ammonia emissions as well as for the calibration and validation of permanently installed automated ammonia measuring systems.
NOTE 2    An independent method of measurement is called standard reference method (SRM) in EN 14181.

Emissionen aus stationären Quellen - Ermittlung der Massenkonzentration von Ammoniak - Manuelles Verfahren (ISO 21877:2019)

Dieses Dokument legt ein manuelles Messverfahren einschließlich der Probenahme und verschiedener Analyseverfahren zur Bestimmung der Massenkonzentration von Ammoniak (NH3) im Abgas von Industrieanlagen wie etwa Verbrennungsanlagen oder landwirtschaftlichen Anlagen fest. Alle Stoffe, die bei der Probenahmetemperatur flüchtig sind und bei der Zersetzung während der Probenahme in der Absorptionslösung Ammoniumionen bilden, werden mit diesem Verfahren gemessen, das daher den flüchtigen Ammoniakgehalt im Abgas bestimmt.
Dieses Dokument legt ein unabhängiges Messverfahren fest, das in Feldversuchen einem NH3 Konzentrationsbereich von ungefähr 8 mg/m3 bis 65 mg/m3 unter Normbedingungen validiert wurde. Die untere Grenze des Validierungsbereichs wurde durch die Betriebsbedingungen der untersuchten Anlage bestimmt. Das Messverfahren kann auch bei geringeren Werten in Abhängigkeit beispielsweise von der Probenahmedauer, des Probenvolumens und der Nachweisgrenze des Analyseverfahrens eingesetzt werden.
ANMERKUNG 1   Die Anlage, die Bedingungen der Feldversuche und die im Rahmen der Feldversuche ermittelten Verfahrenskenngrößen sind in Anhang A angegeben.
Dieses Messverfahren kann für die wiederkehrende Überwachung von Ammoniak-Emissionen sowie die Kalibrierung und Validierung dauerhaft eingebauter automatischer Ammoniak-Messeinrichtungen verwendet werden.
ANMERKUNG 2   Ein unabhängiges Messverfahren wird in EN 14181 als Standardreferenzverfahren (SRM, en: standard reference method) bezeichnet.

Émissions de sources fixes - Détermination de la concentration en masse de l’ammoniac dans les gaz de combustion - Méthode manuelle (ISO 21877:2019)

Le présent document spécifie une méthode manuelle de mesurage comprenant l'échantillonnage ainsi que différentes méthodes d'analyse pour la détermination de la concentration en masse de l'ammoniac (NH3) dans les effluents gazeux des installations industrielles, par exemple les installations de combustion ou les exploitations agricoles. Tous les composés volatils à la température d'échantillonnage et produisant des ions ammonium dans la solution d'absorption durant l'échantillonnage sont mesurés par cette méthode qui donne alors la teneur en ammoniac volatil des effluents gazeux.
Le présent document spécifie une méthode de mesure indépendante qui a été validée lors d'essais sur site dans une gamme de concentration en NH3 d'environ 8 mg/m3 à 65 mg/m3 dans des conditions normales. La limite inférieure de la gamme de validation a été déterminée dans les conditions opérationnelles d'une installation d'essai. La méthode de mesure peut être utilisée à des valeurs moins élevées, en fonction, par exemple, de la durée d'échantillonnage, du volume d'échantillonnage et de la limite de détection de la méthode d'analyse utilisée.
NOTE 1    L'installation, les conditions des essais sur site et les caractéristiques de performance obtenues sur le site sont indiquées à l'Annexe A.
Cette méthode de mesure peut être utilisée pour la surveillance intermittente des émissions d'ammoniac ainsi que pour l'étalonnage et la validation de systèmes de mesurage automatisés des concentrations en ammoniac.
NOTE 2    Une méthode de mesure indépendante est appelée « méthode de référence normalisée » (SRM) dans l'EN 14181.

Emisije nepremičnih virov - Določevanje masne koncentracije amoniaka - Ročna metoda (ISO 21877:2019)

Ta dokument določa ročno metodo merjenja, vključno z vzorčenjem in različnimi analitičnimi metodami, za določanje masne koncentracije amoniaka (NH3) v odpadnih plinih industrijskih obratov, na primer kurilnih naprav ali kmetijskih obratov. Po tej metodi se merijo vse spojine, ki so hlapne pri temperaturi vzorčenja in tvorijo amonijeve ione po razpadu v absorpcijski raztopini, kar daje vsebnost hlapnega amoniaka v odpadnih plinih. Ta dokument določa neodvisno metodo merjenja, ki je bila potrjena v terenskih preskusih do koncentracije NH3 približno 65 mg/m3 pri standardnih pogojih. To metodo merjenja je mogoče uporabljati za občasno spremljanje emisij amoniaka, pa tudi za umerjanje in potrjevanje stalno nameščenih avtomatiziranih merilnih sistemov za amoniak.

General Information

• Status: Published
• Public Enquiry End Date: 19-Jun-2018
• Publication Date: 10-Nov-2019
• ICS: 13.040.40 - Stationary source emissions
• Technical Committee: KAZ - Air quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 06-Nov-2019
• Due Date: 11-Jan-2020
• Completion Date: 11-Nov-2019
• Ref Project: EN ISO 21877:2019 - Stationary source emissions - Determination of the mass concentration of ammonia - Manual method (ISO 21877:2019)

Overview

EN ISO 21877:2019 - Stationary source emissions: Determination of the mass concentration of ammonia (NH3) - Manual method specifies a validated, manual (independent) method for sampling and analysis of ammonia in waste gases from industrial and agricultural plants. The method measures the volatile ammonia content (all compounds volatile at sampling temperature that yield ammonium ions in the absorption solution) and is intended for intermittent monitoring and for calibration/validation of permanently installed automated measuring systems (AMS). Field validation was performed in the range of approximately 8 mg/m3 to 65 mg/m3 (standard conditions), with the potential to measure lower concentrations depending on sampling duration, sample volume and analytical detection limits.

Key Topics and Requirements

• Scope and principle: Defines what is measured (volatile ammonia) and the basis of the manual absorption/analysis approach.
• Sampling systems: Requirements for sampling equipment including non‑isokinetic and isokinetic sampling options and related setup.
• Field operation: Measurement planning, sampling strategy, field blanks, leak tests, sample transport and storage.
• Analytical methods: Supported laboratory techniques described in informative annexes:
  • Spectrophotometry
  • Continuous Flow Analysis (CFA)
  • Ion chromatography
• Performance and validation: Performance characteristics for sampling and analysis, field validation data (Annex A) and examples of uncertainty budgets (Annex E).
• Uncertainty management: Guidance for establishing an uncertainty budget, including conversion to dry gas and reference oxygen concentrations (Annex F).
• Reporting: Required elements for the measurement report and documentation to support calibration/validation of AMS.

Applications and Who Uses It

This standard is directly applicable to:

• Environmental laboratories conducting emissions testing for ammonia (NH3).
• Industrial operators - combustion plants, waste incinerators, fertilizer production, agricultural facilities - needing intermittent monitoring or AMS validation.
• Regulatory bodies and compliance auditors assessing emission performance and verifying AMS calibration.
• Consultants and third‑party measurement teams performing independent reference measurements (Standard Reference Method / SRM).

Practical uses include intermittent stack testing, AMS calibration/validation per ISO 17179, emission inventory verification, and compliance testing where quantified NH3 slip or agricultural emissions are regulated.

Related Standards

• ISO 17179 (performance of automated ammonia measuring systems) - for AMS calibration/validation relationships.
• EN 14181 - concept of Standard Reference Method (SRM) for monitoring systems.
• Analytical method standards referenced: ISO 7150‑1, ISO 11732, ISO 14911.
• ISO/IEC Guide 98‑3 (GUM) - uncertainty of measurement guidance.

Keywords: EN ISO 21877:2019, ammonia emissions, NH3 measurement, stationary source emissions, manual method, sampling, spectrophotometry, ion chromatography, continuous flow analysis, AMS calibration, emission monitoring.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2019
Emisije nepremičnih virov - Določevanje masne koncentracije amoniaka - Ročna
metoda (ISO 21877:2019)
Stationary source emissions - Determination of the mass concentration of ammonia -
Manual method (ISO 21877:2019)
Emissionen aus stationären Quellen - Ermittlung der Massenkonzentration von
Ammoniak - Manuelles Verfahren (ISO 21877:2019)
Émissions de sources fixes - Détermination de la concentration en masse de l’ammoniac
dans les gaz de combustion - Méthode manuelle (ISO 21877:2019)
Ta slovenski standard je istoveten z: EN ISO 21877:2019
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 21877
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 13.040.40
English Version
Stationary source emissions - Determination of the mass
concentration of ammonia - Manual method (ISO
21877:2019)
Émissions de sources fixes - Détermination de la Emissionen aus stationären Quellen - Ermittlung der
concentration en masse de l'ammoniac dans les gaz de Massenkonzentration von Ammoniak - Manuelles
combustion - Méthode manuelle (ISO 21877:2019) Verfahren (ISO 21877:2019)
This European Standard was approved by CEN on 26 July 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21877:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 21877:2019) has been prepared by Technical Committee ISO/TC 146 "Air
quality" in collaboration with Technical Committee CEN/TC 264 “Air quality” the secretariat of which is
held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 21877:2019 has been approved by CEN as EN ISO 21877:2019 without any modification.

INTERNATIONAL ISO
STANDARD 21877
First edition
2019-08
Stationary source emissions —
Determination of the mass
concentration of ammonia — Manual
method
Émissions de sources fixes — Détermination de la concentration en
masse de l’ammoniac — Méthode manuelle
Reference number
ISO 21877:2019(E)
©
ISO 2019
ISO 21877:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
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Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 21877:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
5 Principle of the method of measurement . 5
6 Sampling system . 6
6.1 General . 6
6.2 Sampling equipment . 6
6.2.1 Non-isokinetic sampling . 6
6.2.2 Isokinetic sampling . . 7
6.3 Other equipment . 9
7 Performance characteristics . 9
7.1 General . 9
7.2 Performance characteristics of the sampling system . 9
7.3 Performance characteristics of the analysis .10
7.3.1 Sources of uncertainty .10
7.3.2 Performance criterion of analysis .10
7.4 Establishment of the uncertainty budget .11
8 Field operation .11
8.1 Measurement planning .11
8.2 Sampling strategy .11
8.3 Field blank .12
8.4 Leak test .12
8.5 Sampling .13
8.6 Sample transport and storage .13
9 Analytical determination .13
10 Calculation of the results .14
11 Measurement report .15
Annex A (informative) Validation of the method of measurement in the field .16
Annex B (informative) Description of the analytical method — Spectrophotometry .21
Annex C (informative) Description of the analytical method — Continuous flow analysis (CFA) .25
Annex D (informative) Description of the analytical method — Ion chromatography .28
Annex E (informative) Example of the calculation of the uncertainty budget .32
Annex F (informative) Calculation of the uncertainty associated with a mass concentration
expressed on dry gas and at an oxygen reference concentration .40
Bibliography .44
ISO 21877:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 1,
Stationary source emissions.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

ISO 21877:2019(E)
Introduction
Ammonia emissions arise to a large extent from agriculture. Industries such as chemical production
processes (e.g. fertilizer production plants) emit ammonia as well as power plants, cement factories and
waste incineration plants with SCR and non-SCR reactors with ammonia slip. The ammonia emissions
are measured and often controlled by legislation.
This document specifies an independent method of measurement for intermittent monitoring of
ammonia emissions as well as for the calibration and validation of automated ammonia measuring
systems.
This document can be used in conjunction with ISO 17179 which specifies performance characteristics
of automated measuring systems (AMS) for the determination of the mass concentration of ammonia in
waste gas. According to ISO 17179, permanently installed AMS for continuous monitoring of ammonia
emissions are calibrated and validated by comparison with an independent method of measurement.
The uncertainty of measured values obtained by permanently installed AMS for continuous monitoring
are determined by comparison measurements with an independent method of measurement as
part of the calibration and validation of the AMS. This ensures that the measurement uncertainty is
representative of the emission at a specific plant.
INTERNATIONAL STANDARD ISO 21877:2019(E)
Stationary source emissions — Determination of the mass
concentration of ammonia — Manual method
1 Scope
This document specifies a manual method of measurement including sampling and different analytical
methods for the determination of the mass concentration of ammonia (NH ) in the waste gas of
industrial plants, for example combustion plants or agricultural plants. All compounds which are
volatile at the sampling temperature and produce ammonium ions upon dissociation during sampling
in the absorption solution are measured by this method, which gives the volatile ammonia content of
the waste gas.
This document specifies an independent method of measurement, which has been validated in field
3 3
tests in a NH concentration range of approximately 8 mg/m to 65 mg/m at standard conditions. The
lower limit of the validation range was determined under operational conditions of a test plant. The
measurement method can be used at lower values depending, for example, on the sampling duration,
sampling volume and the limit of detection of the analytical method used.
NOTE 1 The plant, the conditions during field tests and the performance characteristics obtained in the field
are given in Annex A.
This method of measurement can be used for intermittent monitoring of ammonia emissions as well
as for the calibration and validation of permanently installed automated ammonia measuring systems.
NOTE 2 An independent method of measurement is called standard reference method (SRM) in EN 14181.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 7150-1, Water quality — Determination of ammonium — Part 1: Manual spectrometric method
ISO 11732, Water quality — Determination of ammonium nitrogen — Method by flow analysis (CFA and
FIA) and spectrometric detection
+ + + + 2+ 2+ 2+ 2+ 2+
ISO 14911, Water quality — Determination of dissolved Li , Na , NH , K , Mn , Ca , Mg , Sr and Ba
using ion chromatography — Method for water and waste water
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
ISO 21877:2019(E)
3.1
mass concentration
mass of a substance in an emitted waste gas divided by the volume of the emitted waste gas
Note 1 to entry: Mass concentration is often expressed as milligrams per cubic metre (mg/m ).
3.2
measurement site
place on the waste gas duct in the area of the measurement plane(s) (3.3) consisting of structures and
technical equipment, for example working platforms, measurement ports (3.4), energy supply
Note 1 to entry: Measurement site is also known as sampling site.
3.3
measurement plane
plane normal to the centre line of the duct at the sampling position
Note 1 to entry: Measurement plane is also known as sampling plane.
3.4
measurement port
opening in the waste gas duct along the measurement line (3.5), through which access to the waste gas
is gained
Note 1 to entry: Measurement port is also known as sampling port or access port.
3.5
measurement line
line in the measurement plane (3.3) along which the measurement points (3.6) are located, bounded by
the inner duct wall
Note 1 to entry: Measurement line is also known as sampling line.
3.6
measurement point
position in the measurement plane (3.3) at which the sample stream is extracted, or the measurement
data are obtained directly
Note 1 to entry: Measurement point is also known as sampling point.
3.7
isokinetic sampling
sampling at a rate such that the velocity and direction of the gas entering the sampling nozzle is the
same as that of the gas in the duct at the measurement point (3.6)
3.8
field blank
test sample obtained according to the field blank procedure
3.9
field blank value
result of a measurement performed according to the field blank procedure at the plant site and in the
laboratory
3.10
uncertainty of measurement
parameter associated with the result of a measurement, that characterises the dispersion of the values
that could reasonably be attributed to the measurand
2 © ISO 2019 – All rights reserved

ISO 21877:2019(E)
3.11
standard uncertainty
u
uncertainty of the result of a measurement expressed as a standard deviation
3.12
combined uncertainty
u
c
standard uncertainty (3.11) attached to the measurement result calculated by combination of several
standard uncertainties according to the principles laid down in ISO/IEC Guide 98-3 (GUM)
3.13
expanded uncertainty
U
quantity defining a level of confidence about the result of a measurement that may be expected to
encompass a specific fraction of the distribution of values that could reasonably be attributed to a
measurand
Uk=×u
c
Note 1 to entry: The value of the coverage factor k depends on the number of degrees of freedom and the level of
confidence. In this document a level of confidence of 95 % is used.
Note 2 to entry: The expression overall uncertainty is sometimes used to express the expanded uncertainty.
3.14
uncertainty budget
calculation table combining all the sources of uncertainty according to ISO 14956 or ISO/IEC Guide 98-3
in order to calculate the combined uncertainty of the method at a specified value
4 Symbols and abbreviated terms
For the purposes of this document, the following symbols apply.
a intercept of the calibration function
A peak area
b slope of the calibration function
c second order slope of the calibration function
c NH mass concentration at standard conditions
m 3
c NH mass concentration corrected to oxygen reference volume concentration
corr 3
c mass concentration expressed on dry basis
dry
c mass concentration expressed on wet basis
wet
E absorbance at wavelength λ
λ
+
instrument specific factor for converting the result determined for NH into a result for
f
NH and the unit mg/ml
f
N
+
factor for converting NH to NH ( f = 0,944)
4 3 N
ISO 21877:2019(E)
h volume fraction of the water vapour in the sample gas
m
k coverage factor
k coverage factor for a coverage probability of 95 %
0,95
m NH mass in the sample
s 3
o measured oxygen volume concentration in the duct
m
o oxygen reference volume concentration
ref
p atmospheric pressure at the measurement site
atm
p absolute pressure at the gas volume meter
m
p standard pressure, 101,3 kPa
ref
p relative pressure measured at the gas volume meter
rel
P coverage probability
R peak resolution for the peak pair (2,1)
2,1
t retention time for peak 1
R1
t retention time for peak 2
R2
T temperature of the sample gas at the gas volume meter
m
T standard temperature, 273 K
ref
u standard uncertainty
u combined uncertainty
c
u uncertainty contribution due to calibration
cal
u uncertainty contribution due to drift
dr
u uncertainty contribution due to calculation of the mean
mean
u uncertainty contribution due to reading
read
u relative standard uncertainty
rel
u uncertainty contribution due to repeatability standard deviation
rep
u uncertainty contribution due to resolution
res
u uncertainty contribution due to tolerance of the cylinder
tol
U expanded uncertainty
U expanded uncertainty for a coverage probability of 95 %
0,95
U relative expanded uncertainty for a coverage probability of 95 %
rel,0,95
v volume of the sample absorption solution
s
V measured volume of the sample gas at operating conditions
m
4 © ISO 2019 – All rights reserved

ISO 21877:2019(E)
V measured volume of the sample gas at standard conditions
m,ref
w peak width for peak 1
w peak width for peak 2
y measured value in units specific to the instrument
Z dilution factor
+
+
NH mass concentration in the calibration solution
β NH
()4
+
+
NH mass concentration in the sample absorption solution
β NH
() 4
s 4
λ wavelength
v number of degrees of freedom
For the purposes of this document, the following abbreviated terms apply.
AMS automated measuring system
DM water demineralised water
PE polyethylene
PP polypropylene
SRM standard reference method
5 Principle of the method of measurement
A representative sample is taken from the waste gas flow of the plant for a specified sampling duration
and a specified sample gas flow. Isokinetic sampling is necessary if the waste gas contains droplets.
The sampling probe is heated to a temperature that ensures evaporation of the droplets and avoids
condensation of water vapour in the sample gas. Particles, which can be separated at this temperature,
are deposited on a specified particle filter. For non-isokinetic sampling, the use of a particle filter inside
the waste gas duct, is preferred since it does not require separate heating. If a particle filter outside
the waste gas duct is used, then heating of the particle filter to a specified temperature is required to
establish representative conditions and to avoid condensation of water vapour in the sample gas.
All compounds which are volatile at the sampling temperature and produce ammonium ions upon
dissociation during sampling in the absorption solution are measured by this method, which therefore
gives the volatile ammonia content of the waste gas.
NOTE 1 In the presence of semi-volatile ammonia salts, the choice of the sampling temperature can have
influence on the gas/solid balance of the volatile ammonia content.
Ammonia (NH ) in the sample gas passing through the filter is collected in an absorption system
+
acidified with H SO . The mass of NH is determined after sampling by using one of the analytical
2 4 4
methods specified in Clause 9.
NOTE 2 For total ammonia determination, both particulate matter and gas are analysed. Analysis of
particulate matter is not part of this document.
The volume of the sample gas is determined during sampling, for example by using a gas volume meter.
The mass concentration is calculated as the quotient of the ammonia mass collected in the absorption
ISO 21877:2019(E)
solution in milligrams (mg) and the volume of the sample gas in cubic metres (m ) and expressed as
milligrams per cubic metre (mg/m ) of ammonia (NH ).
6 Sampling system
6.1 General
6.1.1 The sampling system shall allow for the extraction of the sample gas from the waste gas duct. It
consists in principle of:
— sampling probe;
— particle filter;
— absorption unit consisting of two absorbers;
— suction unit.
The sampling system shall meet the following requirements:
— the sampling probe shall be a heated tube with an inlet made of titanium, quartz glass, borosilicate
glass or PTFE;
— the particle filter shall be a quartz fibre plane filter, to be heated if used outside the waste gas duct;
— the absorbers shall be frit wash bottles (frit porosity: D1 or finer) for low flow sampling or impingers
for high flow sampling;
— the suction unit shall be composed of a pump, volume flow controller, gas volume meter with
thermometer and pressure gauge, and, if required, drying tower;
— all components of the sampling system coming in contact with the waste gas shall be made of
corrosion-resistant material.
The sampling system shall be designed such that the residence time of the sample gas between the inlet
of the sampling probe and the two absorbers is minimized.
The heating of the sample gas line down to the absorption unit shall be maintained at least 15 K above
the dew-point of the waste gas to avoid any water vapour condensation.
6.1.2 The following absorption materials are required for sampling:
6.1.2.1 Absorption solution: 0,05 M H SO solution (quality: analytical grade).
2 4
NOTE The concentration can be increased for high NH concentrations to reach the minimum collection
efficiency.
6.1.2.2 Demineralised water (DM water).
6.2 Sampling equipment
6.2.1 Non-isokinetic sampling
Non-isokinetic sampling may be carried out using a heated probe without nozzle. Figure 1 shows an
example of a sampling system for non-isokinetic sampling. The use of a particle filter inside the waste
gas duct, is preferred since it does not require separate heating. If a particle filter outside the waste
gas duct is used, then heating of the particle filter to a specified temperature is required to establish
representative conditions and to avoid condensation of water vapour in the sample gas and on the filter.
6 © ISO 2019 – All rights reserved

ISO 21877:2019(E)
Key
1 heated sampling probe
2a in-stack particle filter or
2b heated particle filter
3 absorber(s)
4 guard bottle (optional)
5 drying tower (only for dry gas volume meter)
6 pump
7 flow meter behind the filter or before the gas volume meter
8 gas volume meter
Figure 1 — Example of non-isokinetic sampling system
6.2.2 Isokinetic sampling
6.2.2.1 General
Isokinetic sampling is necessary if the waste gas contains droplets. The sampling probe shall be heated to
a specified temperature that ensures evaporation of the droplets and avoids condensation of water vapour
in the sample gas. The particle filter outside the waste gas duct shall be heated to the same temperature
to establish representative conditions and to avoid condensation of water vapour on the filter.
6.2.2.2 Isokinetic sampling with side stream
Isokinetic sampling often requires volume flow rates much higher than those which can be tolerated by
the absorbers used for gaseous compound collection. Therefore, downstream of the filter, only a part of
the gases is drawn through the absorber(s) through a secondary line, the main line and the secondary
line having their own gas metering systems and suction devices. The measurement of the flow in the
main line can be measured either by an orifice plate or any other appropriate device, placed behind the
filter and before the T piece or before the gas volume meter (see Figure 2).
ISO 21877:2019(E)
Key
1 heated sampling probe with nozzle
2 heated particle filter
3 absorber(s)
4 guard bottle (optional)
5 drying tower (only for dry gas volume meter)
6 pump
7 flow meter behind the filter or before the gas volume meter
8 gas volume meter
Figure 2 — Example of isokinetic sampling system with side stream
6.2.2.3 Isokinetic sampling without side stream
A sampling system without secondary line (side stream) can be used for isokinetic sampling as shown
in Figure 3.
NOTE An advantage of an isokinetic sampling without a side stream is that a flow rate proportional to the
local velocity at each measurement point can be maintained more easily when a non-homogeneity is detected in
the measurement section.
Key
1 heated sampling probe with nozzle
2 heated particle filter
3 absorber(s)
4 guard bottle (optional)
5 drying tower (only for dry gas volume meter)
6 pump
7 flow meter behind the filter or before the gas volume meter
8 gas volume meter
Figure 3 — Example of isokinetic sampling system without a side stream
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ISO 21877:2019(E)
6.3 Other equipment
The following other equipment are required.
6.3.1 Equipment for the determination of isokinetic sampling such as pressure, temperature and gas
composition measuring devices.
6.3.2 Containers for sample transport, such as bottles made of glass, PP, PE or other inert materials.
6.3.3 Pipettes, with suitable volumes.
6.3.4 Volumetric flasks, with nominal volumes of, for example, 50 ml, 100 ml and 1 000 ml.
7 Performance characteristics
7.1 General
Table 1 and Table 2 give an overview of the performance characteristics and the associated performance
criteria of the method of measurement.
The test laboratory implementing the method of measurement shall demonstrate that:
— the performance characteristics of the sampling system used meet the performance criteria given
in Table 1 and Table 2;
— the relative expanded uncertainty calculated by combining the values of selected performance
characteristics by means of an uncertainty budget does not exceed 20 % of the applicable assessment
standard, such as daily emission limit value or the lowest limit value specified for the plant by the
local authorities. This expanded uncertainty is calculated on dry basis and before correction to the
oxygen reference concentration.
The values of the selected performance characteristics shall be evaluated:
— for the sampling step by means of laboratory tests in order to determine the uncertainty of the
calibration of the equipment and by means of field tests in order to determine other parameters;
— for the analytical step by means of laboratory tests.
7.2 Performance characteristics of the sampling system
Table 1 shows the performance characteristics and performance criteria of the sampling system.
ISO 21877:2019(E)
Table 1 — Performance characteristics of the sampling system to be determined in the
laboratory (L) and in the field (F) and associated performance criteria
Performance characteristic L F Performance criterion
Determination of the volume of the absorption X ≤1,0 % of the volume of solution
solution
Gas volume meter:
b a a
— standard uncertainty of sample volume X ≤2,5 % of the volume of gas sample
c a a
— standard uncertainty of temperature X ≤1,0 % of the absolute temperature
c a a
— standard uncertainty of absolute pressure X ≤1,0 % of the absolute pressure
d, e
Absorption efficiency X ≥95 %
Leak in the sampling line X ≤2,0 % of the nominal flow rate
Field blank value X ≤10,0 % of assessment standard
a
Performance criteria corresponding to the uncertainty of calibration.
b
The uncertainty of the sampled volume is a combination of uncertainties due to calibration, drift (random drift, drift
between two calibrations) and resolution or reading.
c
The uncertainty of temperature and absolute pressure at the gas volume meter is a combination of uncertainties due to
calibration, drift (random drift, drift between two calibrations), resolution or reading, and standard deviation of the mean
when several values are used to get the result.
d
This characteristic is a quality assurance check to quantify the absorption efficiency in the first absorber; but it does
not quantify a possible loss of absorption, and therefore it is not included in calculation of expanded uncertainty.
e
If the criteria for the absorption efficiency for the first absorber cannot be met at very low concentrations, the
concentration in the second absorber shall be below the analytical limit of quantification.
7.3 Performance characteristics of the analysis
7.3.1 Sources of uncertainty
Main possible sources of uncertainty associated with the analysis are:
— performance characteristics of the analytical equipment;
— preparation of calibration standards: purity of stock standard solution, and ratio of dilutions;
— linearity of the calibration curve depending on the extent of working range;
— measurement of volume of aliquot solution injected for analysis (ratio of the total absorption solution
volume and the volume of the aliquot taken for injection);
— level of dilution, if a dilution of the absorption solution is necessary before analysis;
— interferences;
— repeatability.
7.3.2 Performance criterion of analysis
Because all the components of uncertainty attached to the analysis are difficult to identify and to
estimate, the test laboratory can determine the expanded uncertainty due to analysis by taking the
repeatability standard deviation determined in an interlaboratory test. A maximum performance
criterion is given in Table 2.
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ISO 21877:2019(E)
Table 2 — Performance characteristic of analytical procedure to be determined in the
laboratory (L) and associated performance criterion
Performance characteristic L Performance criterion
≤2,5 % of the measured value
+
(value of quantity of NH ions in the
Repeatability standard deviation X
+
solution; in milligrams of NH per
litre of solution)
7.4 Establishment of the uncertainty budget
An uncertainty budget shall be established to evaluate whether the method fulfils the requirements for
a maximum allowable expanded uncertainty.
The relative expanded uncertainty for this method of measurement shall not exceed 20 % of the
applicable assessment standard, for example, daily emission limit value or of the lowest limit value
fixed to the plant by the local authorities. This expanded uncertainty is calculated on dry basis and
before correction to the oxygen reference concentration.
The principle of calculation of the combined uncertainty is based on the law on propagation of
uncertainty laid down in ISO/IEC Guide 98-3 (GUM).
— Determine the standard uncertainties attached to the performance characteristics to be included in
the calculation of the uncertainty budget according to ISO/IEC Guide 98-3.
— Calculate the uncertainty budget by combining all the standard uncertainties according to
ISO/IEC Guide 98-3.
— Values of standard uncertainty that are less than 5 % of the maximum standard uncertainty may be
neglected.
— Calculate the combined uncertainty at the measured value, reported as a dry gas value at actual
concentration of oxygen.
Annex E shows an example of the calculation of an uncertainty budget.
NOTE When the concentration of a measured compound has to be expressed at an oxygen reference
concentration (such as 3 % or 11 %), the correction of oxygen can bring an additional uncertainty which can
be significant if the difference between the oxygen measured value and the oxygen reference value is too
large. Annex F provides information on the contribution of oxygen correction to the uncertainty linked to the
concentration.
8 Field operation
8.1 Measurement planning
Emission measurements at a plant shall be carried out such that the results are representative for the
emissions from this plant and comparable with results obtained for other comparable plants. Therefore,
measurements shall be planned in accordance with the applicable standards and requirements.
8.2 Sampling strategy
It is necessary to ensure that the gas concentrations measured are representative of the average
conditions inside the waste gas duct. Measurements may be performed at one representative
measurement point or at any measurement point, if the corresponding requirements on the
homogeneity of the distribution of NH or any other relevant component in the measurement plane are
fulfilled. In all other cases the measurements shall be performed as grid measurements. In that case,
ISO 21877:2019(E)
the minimum number of measurement points to be used and the locations of the measurement points
in the measurement plane for circular and rectangular ducts shall be selected in accordance with the
applicable standards.
NOTE 1 Requirements for the minimum number of measurement points to be used and the locations of the
measurement points in the measurement plane for circular and rectangular ducts are specified in, for example,
ISO 9096 or EN 15259.
Measurement ports shall be provided for access to the measurement points selected.
Isokinetic sampling in combination with a grid measurement is only required if droplets are present
in the sample gas, since these droplets can contain ammonia. In such cases, the sampling probe is to
be equipped with a nozzle with a defined cross-section and the volume flow that is drawn off is to
be controlled based on the gas velocity in the tip of the nozzle. Furthermore, the sample gas shall be
heated just after the inlet such that all droplets including the ammonia are evaporated (sampling probe,
filter, sample gas line) before reaching the absorber.
NOTE 2 Details on isokinetic sampling are given, for example, in ISO 9096 or EN 15259.
The flow rates in the main stream and in the side stream shall be proportional to the local velocity at
each measurement point.
8.3 Field blank
To check the sampling procedure, a field blank shall be taken at least before each measurement series
or at least once a day, following the whole measurement procedure specified in this document and
including the assembly of the equipment described in Clause 6 without the suction step, i.e. without
starting and operating the sample gas pump.
The average sample gas volume shall be used for calculation of the field blank value expressed in mg/m .
If the equipment in contact with the measured substance is cleaned and reused in the field, a field blank
shall also be taken after the measurement series. If several measurements are performed at the same
emission source, then one single field blank at the beginning and one at the end of the series shall be
performed.
The field blank value shall be less than 10,0 % of the assessment standard. If the calculated result of
measurement is less than the field blank value, the result of measurement shall be reported as less or
equal to the field blank value.
The field blank value shall not be subtracted from the result of measurement. However, it is necessary
to take into account the field blank value in the calculation of the uncertainty of the measured value
(see Annex E).
8.4 Leak test
Before starting the measurement, check that there is no significant leakage in the sampling system by
use of the following procedure or any other relevant procedure:
— assemble the complete sampling system, including charging the filter housing and absorbers;
— close the nozzle inlet;
— switch on the pump;
— after reaching minimum pressure read or measure the flow rate with an appropriate measuring
device;
— the leak flow rate shall not exceed 2,0 % of the expected sample gas flow rate used during
measurement.
Perform the leak test at the operating temperature unless this conflicts with safety requirements.
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ISO 21877:2019(E)
In addition, the integrity of the sampling system can also be tested during sampling by continuously
measuring the concentration of a suitable stack gas component (such as O ) directly in the stack and
downstream the sampling system. Any systematic difference between those concentrations indicates a
leak in the sampling system (taking into account that the oxygen level measured at both locations is on
the same basis, i.e. wet or dry gas).
8.5 Sampling
Ensure that the absorbers are filled with the required volume of absorbent. Insert the sampling probe
into the waste gas duct.
The sampling probe and the filter sh
...