SIST EN 16980-1:2021
(Main)Photocatalysis - Continuous flow test methods - Part 1: Determination of the degradation of nitric oxide (NO) in the air by photocatalytic materials
Photocatalysis - Continuous flow test methods - Part 1: Determination of the degradation of nitric oxide (NO) in the air by photocatalytic materials
This document describes a method for assessing the performance of photocatalytic inorganic materials contained in cement mortars and/or limes or ceramic-based matrices, paints or materials deposited as thin films or coatings on a variety of substrates for the photocatalytic abatement of nitric oxide in the gas phase. This method is not suitable for the assessment of samples to be applied with flow perpendicular to the surface or flow permeating the surface itself as polymeric and paper filters, honeycomb structures and suchlike.
The performance for the photocatalytic sample under test is evaluated by measuring the degradation rate of nitric oxide (NO) using the method described herein. The photocatalytic abatement rate is calculated from the observed rate by eliminating the effects of mass transfer. The intrinsic photocatalytic abatement rate is an intrinsic property of the material tested and makes it possible to distinguish the photocatalytic activities of various products with an absolute scale defined with physical and engineering meaning.
For the measurements and calculations described in this document the concentration of nitrogen oxides (NOx) is defined as the stoichiometric sum of nitric oxide (NO) and nitrogen dioxide (NO2).
Photokatalyse - Prüfverfahren mit kontinuierlichem Durchfluss - Teil 1: Bestimmung des Abbaus von Stickstoffmonoxid (NO) aus der Luft durch photokatalytische Werkstoffe
Dieses Dokument beschreibt ein Verfahren zur Bewertung der Leistung von photokatalytischen anorganischen Werkstoffen, enthalten in Zementmörtel und/oder Kalken oder aus Keramik bestehenden Grundsubstanzen, Farben oder Werkstoffen, die als dünne Filme oder Beschichtungen auf einer Vielzahl von Trägerwerkstoffen für die photokatalytische Beseitigung von Stickstoffmonoxid in der Gasphase vorkommen. Dieses Verfahren eignet sich weder für die Bewertung von Proben, die mit einem Fluss senkrecht zur Oberfläche verwendet werden, noch für Proben, wie Polymer und Papierfilter, Wabenstrukturen und dergleichen, bei denen der Fluss die Oberfläche durchdringt.
Die Leistung für die zu prüfende photokatalytische Probe wird durch die Messung der Abbaugeschwindigkeit von Stickstoffmonoxid (NO) mithilfe des hier beschriebenen Verfahrens bewertet. Die photokatalytische Minderungsgeschwindigkeit wird aus dem beobachteten Wert berechnet, indem die Auswirkungen des Stoffübergangs abgezogen werden. Die intrinsische photokatalytische Minderungsgeschwindigkeit ist eine intrinsische Eigenschaft des untersuchten Werkstoffs und macht es möglich, die photokatalytischen Aktivitäten verschiedener Produkte in einem absoluten Maßstab, bestimmt im physikalischen und technischen Sinn, zu unterscheiden.
Für die in diesem Dokument beschriebenen Messungen und Berechnungen, wird die Konzentration von Stickoxiden (NOx) als die stöchiometrische Summe von Stickstoffmonoxid (NO) und Stickstoffdioxid (NO2) definiert.
Photocatalyse - Méthodes d'essai en flux continu - Partie 1 : Mesure de la dégradation du monoxyde d'azote (NO) dans l'air par un matériau photocatalytique
Le présent document décrit une méthode d’évaluation de la performance des matériaux inorganiques photocatalytiques contenus dans les mortiers de ciment et/ou les chaux ou dans les matrices à base de céramique, les peintures ou les matériaux déposés sous forme de films minces ou de revêtements sur une variété de substrats pour la dégradation photocatalytique du monoxyde d’azote en phase gazeuse. Cette méthode ne convient pas pour l’évaluation des échantillons devant être utilisés avec un flux perpendiculaire à la surface ou traversant la surface, comme les filtres polymères et papier, les structures en nid d’abeille et autres éléments similaires.
La performance de l’échantillon photocatalytique étudié est évaluée en mesurant la vitesse de dégradation du monoxyde d’azote (NO) à l’aide de la méthode décrite ici. La vitesse de dégradation photocatalytique est calculée à partir de la vitesse observée en éliminant les effets du transfert de masse. La vitesse intrinsèque de dégradation photocatalytique est une propriété intrinsèque du matériau soumis à l’essai et elle permet de distinguer les activités photocatalytiques de divers produits au moyen d’une échelle absolue définie par des caractéristiques physiques et mécaniques.
Pour les mesurages et les calculs décrits dans le présent document, la concentration en oxydes d’azote (NOx) est définie comme la somme stœchiométrique du monoxyde d’azote (NO) et du dioxyde d’azote (NO2).
Fotokataliza - Metode preskušanja kontinuiranega pretoka - 1. del: Ugotavljanje razgradnje dušikovega oksida (NO) v zraku z materiali fotokatalize
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 16980-1:2021
01-november-2021
Nadomešča:
SIST-TS CEN/TS 16980-1:2017
Fotokataliza - Metode preskušanja kontinuiranega pretoka - 1. del: Ugotavljanje
razgradnje dušikovega oksida (NO) v zraku z materiali fotokatalize
Photocatalysis - Continuous flow test methods - Part 1: Determination of the degradation
of nitric oxide (NO) in the air by photocatalytic materials
Photokatalyse - Prüfverfahren mit kontinuierlichem Durchfluss - Teil 1: Bestimmung des
Abbaus von Stickstoffmonoxid (NO) aus der Luft durch photokatalytische Werkstoffe
Photocatalyse - Méthodes d'essai en flux continu - Partie 1 : Mesure de la dégradation
du monoxyde d'azote (NO) dans l'air par un matériau photocatalytique
Ta slovenski standard je istoveten z: EN 16980-1:2021
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
25.220.20 Površinska obdelava Surface treatment
SIST EN 16980-1:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 16980-1:2021
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SIST EN 16980-1:2021
EN 16980-1
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2021
EUROPÄISCHE NORM
ICS 13.040.20; 87.040; 87.060.20; 91.100.10 Supersedes CEN/TS 16980-1:2016
English Version
Photocatalysis - Continuous flow test methods - Part 1:
Determination of the degradation of nitric oxide (NO) in
the air by photocatalytic materials
Photocatylyse - Méthode d'essai en flux continu - Photokatalyse - Prüfverfahren mit kontinuierlichem
Partie 1 : Détermination de la dégradation du Durchfluss - Teil 1: Bestimmung des Abbaus von
monoxyde d'azote (NO) dans l'air par des matériaux Stickstoffmonoxid (NO) aus der Luft durch
photocatalytiques photokatalytische Werkstoffe
This European Standard was approved by CEN on 9 May 2021.
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 NORMALISATIO N
EUROPÄISCHES KOMITEE FÜR NORMUN G
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16980-1:2021 E
worldwide for CEN national Members.
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
Contents Page
European foreword . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviations . 5
3.1 Terms and definitions . 5
3.2 Abbreviations and symbols . 6
4 Principle . 8
5 Interferences . 8
6 Apparatus . 8
6.1 General . 8
6.2 Gas mixture preparation system . 8
6.3 Illumination and measuring system . 9
7 Sample preparation . 14
7.1 Precaution. 14
7.2 Sample characteristics . 15
7.3 Conditioning . 15
8 Measurement of concentrations . 15
8.1 General . 15
8.2 Measurement of the initial concentration of nitrogen oxides before entering the
photochemical reactor . 16
8.3 Conversion without sample . 16
8.4 Conversion in the dark and in the presence of sample . 17
8.5 Conversion under illumination in the presence of sample . 17
9 Calculation of photocatalytic degradation rate . 18
9.1 The observed rate of photocatalytic degradation . 18
9.2 Intrinsic rate of photocatalytic transformation . 19
10 Optional part for the use of different fan speeds . 19
10.1 General . 19
10.2 Conversion under illumination in the presence of sample at different fan speeds . 19
10.3 Calculation of photocatalytic degradation rate at different fan speeds . 20
11 Acceptability ranges of main test parameters . 21
12 Test report . 22
Annex A (informative) Typical trend of NO, NO and NO concentrations during a
2 x
photocatalytic test at nominal fan speed . 24
Annex B (informative) Typical trend of NO, NO and NO concentrations during a
2 x
photocatalytic test using different fan speeds . 25
Annex C (informative) Example of test for the control of mass transfer limitation . 26
Annex D (informative) Typical Ohmic response of the fan . 27
Bibliography . 28
2
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
European foreword
This document (EN 16980-1:2021) has been prepared by Technical Committee CEN/TC 386
“Photocatalysis”, the secretariat of which is held by AFNOR.
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 March 2022, and conflicting national standards shall be
withdrawn at the latest by March 2022.
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.
This document supersedes CEN/TS 16980-1:2016.
EN 16980-1:2021 includes the following significant technical changes with respect to
CEN/TS 16980-1:2016:
— 3.2
2
— addition of: “A sample illuminated surface area in m ”
— deletion of: “CIN concentration at reactor inlet” and “Fv,I fan flow at ith potential”
— modification of abbreviations: “F Flow” to “Q Flow”, “V0” to “U ”, “Vmin” to “U ”, “MM” to “M”
0 min
— 6.3 (before 6.2) Modification of Figure 2
— 7.1 updated sentence: “Samples shall be eventually preconditioned following the supplier advices.”
C ppmv ××M P
( )
−33
— 8.1 updated formula: C µ g m 10 ppmv× k
( )
R× T
— 12 (before 11):
— addition of: “a) international Standard used (including its year of publication)”;
“b) any deviations from the procedure”;
“c) the date of the test”;
— Annex A: change of figure “Typical trend of NO, NO and NO concentrations during a photocatalytic
2 x
test at nominal fan speed”
— Annex B: change of figure “Typical trend of NO, NO and NO concentrations during a photocatalytic
2 x
test at nominal fan speed”.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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
3
= =
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
4
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
1 Scope
This document specifies a method for assessing the performance of photocatalytic inorganic materials
contained in cement mortars and/or limes or ceramic-based matrices, paints or materials deposited as
thin films or coatings on a variety of substrates for the photocatalytic abatement of nitric oxide in the gas
phase. This method does not apply to the assessment of samples to be applied with flow perpendicular
to the surface or flow permeating the surface itself as polymeric and paper filters, honeycomb structures
and suchlike.
The performance for the photocatalytic sample under test is evaluated by measuring the degradation rate
of nitric oxide (NO) using the method specified herein. The photocatalytic abatement rate is calculated
from the observed rate by eliminating the effects of mass transfer. The intrinsic photocatalytic abatement
rate is an intrinsic property of the material tested and makes it possible to distinguish the photocatalytic
activities of various products with an absolute scale defined with physical and engineering meaning.
For the measurements and calculations described in this document the concentration of nitrogen oxides
(NO ) is defined as the stoichiometric sum of nitric oxide (NO) and nitrogen dioxide (NO ).
x 2
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.
CEN/TS 16599, Photocatalysis — Irradiation conditions for testing photocatalytic properties of
semiconducting materials and the measurement of these conditions
EN ISO 9169, Air quality — Definition and determination of performance characteristics of an automatic
measuring system (ISO 9169)
ISO 7996:1985, Ambient air — Determination of the mass concentration of nitrogen oxides —
Chemiluminescence method
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms, definitions and abbreviations 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 https://www.electropedia.org/
3.1.1
concentration of nitrogen oxides
NO
x
stoichiometric sum of nitric oxide (NO) and nitrogen dioxide (NO )
2
Note 1 to entry: For grade 999 nitrogen or air, the purity of the gas should be equal at least to 99,9 %.
5
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
3.1.2
photocatalyst
catalyst able to produce, upon absorption of light, chemical transformations of the reaction partners
Note 1 to entry: The excited state of the photocatalyst repeatedly interacts with the reaction partners forming
reaction intermediates and regenerates itself after each cycle of such interactions.
3.1.3
photocatalytic material
material in which or on which the photocatalyst is added by coating, impregnation, mixing, etc.
3.2 Abbreviations and symbols
2
A
sample illuminated surface area in m
C concentration
CSTR Continuous Stirred-Tank Reactor
IN
concentration of NO and NO at reactor inlet
C
2
OUT, DARK concentration of NO and NO at reactor outlet under stable conditions in the dark
2
C
(no illumination)
OUT, LIGHT
concentration of NO and NO at reactor outlet under stable conditions with illumination
2
C
(lamp on) without sample
IN
concentration of NO at reactor inlet
C
NO
IN
concentration of NO at reactor inlet
2
C
NO
2
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark
C
NO
(no illumination) without sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark
C 2
NO
2
(no illumination) without sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark
C
NO,S
(no illumination) in presence of sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark
C 2
NO ,S
2
(no illumination) in presence of sample
OUT, LIGHT concentration of NO at reactor outlet under stable conditions with illumination
C
NO
(lamp on) without sample
OUT, LIGHT
concentration of NO at reactor outlet under illumination of sample measured at fan
C
NO,0
speed at nominal voltage U
0
OUT, LIGHT concentration of NO at reactor outlet under stable conditions with illumination
2
C
NO
2 (lamp on) without sample
OUT, LIGHT
concentration NO at reactor outlet under illumination of sample measured at fan speed
2
C
NO ,0
2 nominal voltage U
0
0
intrinsic NO photocatalytic abatment rate
k
R
6
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
I irradiance
LED light emitting diodes
M molecular mass
n calculated nominal value
calc
P pressure in atmosphere
PTFE polytetrafluoroethylene
Q flow
Q nominal fan flow set by the manufacturer at the applied nominal potential U
v,0 0
fan flow at its applied potential (i = 0.n)
R ideal gas constant
RH gas relative humidity at 25 °C inside the reactor
U fan flow at its applied potential (i = 0.n)
v,i
dark
conversion of NO in the dark
η
NO
dark
conversion to NO in the dark
η 2
NO
2
PHOTO
conversion of NO under illumination without sample
η
NO,lamp
total
conversion of NO measured at each fan flow Q
v,i
η
NO ,i
total
conversion to NO measured at each fan flow Q
2 v,i
η
NO ,i
2
photo NO abatement rate at each fan flow Q
v,i
v
NO,i
photo NO photocatalytic production rate at each fan flow Q
2 v,i
v
NO ,i
2
photo NO abatement rate corresponds to NO abatement rate minus NO photocatalytic
x 2
v
NO ,i
x
production rate
photoCAT
NO photocatalytic degradation rate intrinsic to the surface of the material, after
v
NO
removing the mass transfer limitations
photoCAT NO photocatalytic degradation rate intrinsic to the surface of the material, after
x
v
NO
X
removing the mass transfer limitations
UV-A ultraviolet with wavelength (λ) situated between 315 nm and 400 nm (IUPAC)
U fan nominal operating potential (in Volt)
0
U fan minimum operating potential (in Volt) set by the manufacturer
min
S sample
T temperature in Kelvin
t time to reach the stability of NO concentration
stab
UV UltraViolet
7
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EN 16980-1:2021 (E)
V reactor net volume
r
4 Principle
The method consists in measuring the photocatalytic abatement of nitric oxide (NO) by photocatalytic
materials as specified in Clause 1 using a Continuous Stirred-Tank Reactor (CSTR) with flow tangential
to the sample. Information on the theory is reported in the specialized literature (Minero et al. 2013). The
residual NO and NOx concentration at the CSTR outlet is measured by a chemiluminescence analyser
accordingly to ISO 7996:1985.
The photocatalytic activity test is carried out using chromatographic grade air, also obtained by mixing
pure gases, to which NO is added in such an amount as to simulate a high degree of air pollution. The NO
concentration is set to (0,50 ± 0,05) ppmv.
5 Interferences
The measurement’s interferences are reported in the technical specifications of the chemiluminescence
analyser. As what is measured are all species that can be converted by reduction to NO, NO concentration
2
is here defined as [NO ] = [NO ]-[NO]. For interferences on chemiluminescence detection, see Winer et
2 x
al. (1974).
6 Apparatus
6.1 General
The test apparatus shall consist of the following main components.
6.2 Gas mixture preparation system
The system used for preparing the reaction mixture is shown in Figure 1.
The mass flow controllers, calibrated and traceable, shall ensure a maximum flow consistent with that
needed for a correct test execution. To ensure the necessary accuracy, the flow shall not exceed 90 % of
the rated full scale.
As an example, to obtain the gas mixture only gases of chromatographic grade or higher purity shall be
used. Instead of dry air cylinders, two separate cylinders of pure N and O can be used at the inlet of
2 2
mass-flow controllers, adjusted so as to produce a mixture consisting of 20,8 % of O and 79,2 % of N .
2 2
The NO concentration to flow #1 is set to (0,50 ± 0,05) ppmv.
8
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SIST EN 16980-1:2021
EN 16980-1:2021 (E)
a) Relative humidity is set by regulating the b) Relative humidity is set by regulating the
flow to U, which is downstream to F pressure before U and F
Key
S source of nitric oxide NO diluted in N
1 2
S cylinder of air (chromatographic grade) or, alternatively, individual cylinders of N and O
2 2 2
(chromatographic grade)
F flow controller with mass-flow controllers (2 or 3)
P pressure regulators with low-pressure manometers
U humidifier maintained at controlled temperature
F#1 flow entering the reactor
Figure 1 — Gas mixture preparation system
The humidification of the gas mixture can be obtained with two different configurations:
a) using two mass flow controllers regulating the flow to U, as in Figure 1 a;
b) using one mass flow controller regulating the pressure on U, as in Figure 1 b.
The gas mixture preparation system shall ensure a relative humidity of (40 ± 5) % inside the CSTR
reactor. The relative humidity shall be measured either inside the reactor R (see Figure 2) or
E
immediately at its outlet on flow 2 of Figure 2 by means of a hygro-thermometer.
6.3 Illumination and measuring system
6.3.1 General
The light source arrangement and the measuring system are shown in Figure 2.
9
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EN 16980-1:2021 (E)
Key
R reaction chamber, Continuous Stirred-Tank Reactor (CSTR) type
E
V fan
A power supply of fan V
N NO/NO chemiluminescence analyser
2
E processing/logging unit
L illumination system
1, 2, 3, 4 flow paths, with valves and tubing
Figure 2 — Illumination, reaction and measuring system
All parts of the test apparatus, including connections and pipes, which come into contact with the nitric
oxide mixture should be made of chemically inert materials. For pipes and connections PTFE is
recommended. The pipes of paths 1, 2, 3, 4 and the related connections shall have an outer diameter of
−3 −3
6 × 10 m (1/4”) and inner clearance of at least 4 × 10 m to avoid overpressures that can affect the gas
concentration inside the reactor.
Temperature should be measured and recorded inside the reactor during the test or immediately at its
outlet on flow 2 by means of a hygro-thermometer. The gas temperature inside the reaction chamber
should be (25 ± 5) °C.
6.3.2 Illumination system L
The illumination source shall consist of any lamp able to excite the photocatalyst (quartz mercury vapor
lamps, UV-A fluorescent lamps, Xenon lamps, LEDs, lamps consisting of a metal vapor element combined
with tungsten incandescence elements, etc.) as specified in the Technical Specification CEN/TS 16599.
The illumination system shall provide an average irradiance to the test sample surface within the range
2
of wavelengths that are mostly adsorbed by the photocatalyst, equal to (10,0 ± 0,5) W/m .
The geometry of the illumination system shall be such that uniform illumination of the sample surface is
ensured. The illumination is considered uniform if five independent measurements performed on the
surface (one in centre position and the other four in positions perpendicular to each other and next to
the edge of the sample) show a percentage variation compared to the average value of less than 10 %.
The control of the uniformity of illumination and average irradiance shall be repeated each time the
system geometry changes (position of the lamp or any filters or reflectors, sample position, etc.).
10
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EN 16980-1:2021 (E)
Irradiance shall be measured by placing a radiometric sensor inside the reaction chamber in the same
position occupied by the sample in order to measure real irradiance at its surface. A second measuring
sensor for the control of source stability can be positioned outside the reaction chamber, provided that it
has been calibrated with a reference radiometric sensor placed inside the reactor. Irradiance can be
measured continuously during the test or, alternatively, just before the beginning of the test and
immediately after its conclusion. The irradiance values shall be measured only after the lamp intensity
has stabilized as a result of its warming-up (typically 10 min after being turned on). The irradiance value
as measured shall be recorded as average value in the test report.
The radiometer used for the measurement shall have been previously calibrated by means of a
spectroradiometer, which in turn has been previously calibrated by means of standard sources.
In order to avoid decomposition by direct photolysis of NO, the integrated irradiance at λ < 340 nm shall
2
be less than 0,5 W/m . The direct NO photolysis rate shall be checked by performing the test using the
empty reactor, where standard NO concentration (0,5 ppmv) is introduced and the reactor outlet
concentration is measured according to 8.3, a). For example, in the case of a photocatalyst consisting of
pure TiO , the illumination system that uses a medium-pressure mercury lamp shall be such as to ensure
2
the surface of the sample receives a UV irradiance (λ < 400 nm) mainly composed of the line at 365 nm
2
of mercury, and an integrated irradiance for λ < 340 nm of less than 0,5 W/m .
The spectrum of the lamp used shall be acquired and reported in the test report, because the analysis
result depends significantly on the lamp type used.
6.3.3 Reaction chamber R
E
A schematic of the reaction chamber is given in Figure 3.
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EN 16980-1:2021 (E)
Dimensions in millimetres
Key
1, S sample 4 inflow
2 fan
3 outflow
3A gas output (alternative)
Figure 3 — Top view of the CSTR reaction chamber, with dimensional details and indication of
flows for thorough mixing and location of the sampling point
Other dimensional details of the reaction chamber with related sample positions are also shown in the
Figures 4 and 5 below.
The reaction chamber shall be built with NO inert materials, i.e. glass, polymethylmethacrylate or other
inert plastic materials. The chamber shall be gas-tight. On top, the chamber shall be provided with a flat
window that is transparent to the light emitted by the illumination system and vertically incident to the
sample. This flat window, transparent to the wavelengths used (e.g. made up of borosilicate glass for
λ ≥ 340 nm) shall be 3 mm to 4 mm thick to ensure sufficient strength and also removable to allow for
sample positioning.
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EN 16980-1:2021 (E)
Dimensions in millimetres
Key
HAC holes for air circulation
HF hole for a fan with Φ = 60 mm
1 top window
2 fan 60 mm nominal
3 gas outlet
4 gas inlet
Figure 4 — Side view (back of fan side) of the CSTR reactor
Dimensions in millimetres
Key
3 gas outlet
h distance to the surface of the sample
S sample on the support
th sample maximum thickness
max
NOTE The surface of the sample is at 50 mm ± 2 mm from the bottom.
Figure 5 — Side view (fan front side) of reactor CSTR, with indications of sample position
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The reaction chamber shall comply with the dimensions shown in Figures 3 to 5. Considering the volumes
3 3
occupied by internal barriers, fan, sample and sample support, the total net volume is 2,8 dm to 3,5 dm .
This volume is not critical. The gas flow is maintained constant throughout the whole test, and shall be
3 −1
equal to 1,6 dm min . It shall be at least 20 % higher than the sampling flow of the NO/NO analyser.
2
The max flow variation allowed is 10 %.
The fan ensures perfect mixing inside the reaction chamber. The fan is placed inside the reactor on a
support having a hole with diameter equal to the fan aperture and axial to the fan axis. The support has
3
lateral holes that ensure full air mixing inside the chamber. The fan shall provide nominal flows of 70 m
−1
h at the nominal supply voltage U .
0
Fans with external dimensions of 60 mm × 60 mm and thickness from 25 mm to 35 mm are suitable for
this purpose. The fan flow shall be varied by varying the supply voltage by an appropriate power supply
of continuous variable output voltage (see A of Figure 2).
The sample is positioned inside the reactor assuring that its surface is at the level of the fan axis, implying
a distance from the bottom of the reactor of 50 mm (see th in Figure 5). The sample can have any
max
thickness less than 50 mm. The correct positioning is ensured by a proper support.
6.3.4 NO/NO analyser
2
The analyser shall be calibrated according to the procedures described in ISO 7996 or according to
EN ISO 9169. The instrument's calibration can be performed using NO and/or NO mixtures at a known
2
and traceable concentration of either grade 999 nitrogen or air. For the measurement range adopted
during calibration, at least 4 standard gas mixtures shall be analysed, supported by the related calibration
certificates, with different NO contents in N (or in any other inert gas) with concentrations equal to
2
approx. 0,2 ppmv, 0,4 ppmv, 0,6 ppmv, 0,8 ppmv.
Alternatively, the concentrations needed to check the analyser calibration can be generated starting from
a single gas cylinder with traceable NO concentration and with the help of a calibrated flow controller
provided with calibration certificates for mass-flow controllers.
...
SLOVENSKI STANDARD
oSIST prEN 16980-1:2020
01-junij-2020
Fotokataliza - Metode preskušanja kontinuiranega pretoka - 1. del: Ugotavljanje
razgradnje dušikovega oksida (NO) v zraku z materiali fotokatalize
Photocatalysis - Continuous flow test methods - Part 1: Determination of the degradation
of nitric oxide (NO) in the air by photocatalytic materials
Photokatalyse - Prüfverfahren mit kontinuierlichem Durchfluss - Teil 1: Bestimmung des
Abbaus von Stickstoffmonoxid (NO) aus der Luft durch photokatalytische Werkstoffe
Photocatalyse - Méthodes d'essai en flux continu - Partie 1 : Mesure de la dégradation
du monoxyde d'azote (NO) dans l'air par un matériau photocatalytique
Ta slovenski standard je istoveten z: prEN 16980-1
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
25.220.20 Površinska obdelava Surface treatment
oSIST prEN 16980-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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DRAFT
EUROPEAN STANDARD
prEN 16980-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2020
ICS 13.040.20; 87.040; 87.060.20; 91.100.10 Will supersede CEN/TS 16980-1:2016
English Version
Photocatalysis - Continuous flow test methods - Part 1:
Determination of the degradation of nitric oxide (NO) in
the air by photocatalytic materials
Photocatalyse - Méthodes d'essai en flux continu - Photokatalyse - Prüfverfahren mit kontinuierlichem
Partie 1 : Mesure de la dégradation du monoxyde Durchfluss - Teil 1: Bestimmung des Abbaus von
d'azote (NO) dans l'air par un matériau Stickstoffmonoxid (NO) aus der Luft durch
photocatalytique photokatalytische Werkstoffe
This draft European Standard is submitted to CEN members for parallel enquiry. It has been drawn up by the Technical
Committee CEN/TC 386.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16980-1:2020 E
worldwide for CEN national Members.
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Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 5
3 Terms, definitions and abbreviations . 5
3.1 Terms and definitions . 5
3.2 Abbreviations . 5
4 Principle . 7
5 Interferences . 7
6 Apparatus . 7
6.1 General . 7
6.2 Gas mixture preparation system . 7
6.3 Illumination and measuring system: . 8
7 Sample preparation . 14
7.1 Precaution. 14
7.2 Sample characteristics . 14
7.3 Conditioning . 14
8 Measurement of concentrations . 15
8.1 General . 15
8.2 Measurement of the initial concentration of nitrogen oxides before entering the
photochemical reactor . 15
8.3 Conversion without sample . 15
8.4 Conversion in the dark and in the presence of sample . 16
8.5 Conversion under illumination in the presence of sample . 16
9 Calculation of photocatalytic degradation rate . 17
9.1 The observed rate of photocatalytic degradation . 17
9.2 Intrinsic rate of photocatalytic transformation . 18
10 Optional part . 18
10.1 Conversion under illumination in the presence of sample at different fan speeds . 18
10.2 Calculation of photocatalytic degradation rate at different fan speeds . 19
11 Acceptability ranges of main test parameters . 20
12 Test report . 21
Annex A (informative) Typical trend of NO, NO and NO concentrations during a
2 x
photocatalytic test at nominal fan speed . 23
Annex B (informative) Typical trend of NO, NO and NO concentrations during a
2 x
photocatalytic test using different fan speeds . 24
Annex C (informative) Example of test for the control of mass transfer conditions . 25
Annex D (informative) Typical Ohmic response of the fan . 26
Bibliography . 27
2
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European foreword
This document (prEN 16980-1:2020) has been prepared by Technical Committee CEN/TC 386
“Photocatalysis”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede CEN/TS 16980-1:2016.
3
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1 Scope
This document describes a method for assessing the performance of photocatalytic inorganic materials
contained in cement mortars and/or limes or ceramic-based matrices, paints or materials deposited as
thin films or coatings on a variety of substrates for the photocatalytic abatement of nitric oxide in the gas
phase. This method is not suitable for the assessment of samples to be applied with flow perpendicular
to the surface or flow permeating the surface itself as polymeric and paper filters, honeycomb structures
and suchlike.
The performance for the photocatalytic sample under test is evaluated by measuring the degradation rate
of nitric oxide (NO) using the method described herein. The photocatalytic abatement rate is calculated
from the observed rate by eliminating the effects of mass transfer. The intrinsic photocatalytic abatement
rate is an intrinsic property of the material tested and makes it possible to distinguish the photocatalytic
activities of various products with an absolute scale defined with physical and engineering meaning.
For the measurements and calculations described in this document the concentration of nitrogen oxides
(NO ) is defined as the stoichiometric sum of nitric oxide (NO) and nitrogen dioxide (NO ).
x 2
4
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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.
CEN/TS 16599:2014, Photocatalysis —Irradiation conditions for testing photocatalytic properties of
semiconducting materials and the measurement of these conditions
EN ISO 9169, Air quality — Definition and determination of performance characteristics of an automatic
measuring system (ISO 9169)
ISO 7996, Ambient air — Determination of the mass concentration of nitrogen oxides — Chemiluminescence
method
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following terms, definitions and abbreviations 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/
3.1.1
concentration of nitrogen oxides
NO
x
stoichiometric sum of nitric oxide (NO) and nitrogen dioxide (NO )
2
Note 1 to entry: For grade 999 nitrogen or air: the purity of the gas should be equal at least to 99,9 %.
3.1.2
photocatalyst
catalyst able to produce, upon absorption of light, chemical transformations of the reaction partners
Note 1 to entry: The excited state of the photocatalyst repeatedly interacts with the reaction partners forming
reaction intermediates and regenerates itself after each cycle of such interactions.
3.1.3
photocatalytic materials
materials in which or on which the photocatalyst is added by coating, impregnation, mixing, etc
3.2 Abbreviations
CSTR Continuous Stirred-Tank Reactor
IN
C concentration at reactor inlet
OUT,DARK
C concentration of NO and NO at reactor outlet under stable conditions in the dark (no
2
illumination)
OUT, light
concentration at reactor outlet under stable conditions with illumination (lamp on)
C
5
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IN
concentration of NO at reactor inlet
C
NO
IN
concentration of NO at reactor inlet
2
C
NO
2
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark (no
C
NO
illumination) without sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark (no
2
C
NO
2
illumination) without sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark (no
C
NO,S
illumination) in presence of sample
OUT,DARK
concentration of NO at reactor outlet under stable conditions in the dark (no
2
C
NO ,S
2
illumination) in presence of sample
OUT, LIGHT
concentration of NO at reactor outlet under stable conditions with illumination (lamp
C
NO
on) without sample
OUT, LIGHT
concentration of NO at reactor outlet under illumination of sample measured at fan
C
NO,0
speed at nominal voltage V
0
OUT, LIGHT
concentration NO at reactor outlet under illumination of sample measured at fan speed
2
C
NO ,0
nominal voltage V
0
2
F Flow
th
F fan flow at i applied potential (i = 0.n)
v,i
I irradiance
LED light emitting diodes
MM molecular mass
P pressure in atmosphere
PTFE Polytetrafluoroethylene
R ideal gas constant
RH gas relative humidity at 25 °C inside the reactor
dark
conversion of NO in the dark
η
NO
dark
conversion to NO in the dark
2
η
NO
2
PHOTO
conversion of NO under illumination without sample
η
NO,lamp
total
conversion of NO measured at each fan flow F
v,i
η
NO ,i
total
conversion to NO measured at each fan flow F
2 v,i
η
NO ,i
2
photo NO abatement rate at each fan flow F
v,i
r
NO,i
photo NO photocatalytic production rate at each fan flow F
2 v,i
r
NO ,i
2
6
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photo NO abatement rate corresponds to NO abatement rate minus NO photocatalytic
x 2
r
NO ,i
production rate
x
photoCAT NO photocatalytic degradation rate intrinsic to the surface of the material, after
r
NO
removing the mass transfer limitations
photoCAT NO photocatalytic degradation rate intrinsic to the surface of the material, after
x
r
NO
removing the mass transfer limitations
X
UV-A ultraviolet with wavelength (λ) situated between 315 nm and 400 nm (IUPAC)
V0 fan nominal operating potential (in Volt)
V fan minimum operating potential (in Volt) set by the manufacturer
min
S Sample
T temperature in Kelvin
t time to reach the stability of NO concentration
stab
UV UltraViolet
Vr Reactor net volume
4 Principle
The method consists in measuring the photocatalytic abatement of nitric oxide (NO) by photocatalytic
materials as specified in Clause 1 using a Continuous Stirred-Tank Reactor (CSTR) with flow tangential
to the sample. Information on the theory is reported in the specialized literature (Minero et al. 2013). The
residual NO and NOx concentration at the CSTR outlet is measured by a chemiluminescence analyser
(ISO 7996).
The photocatalytic activity test is carried out using chromatographic grade air, also obtained by mixing
pure gases, to which NO is added in such an amount as to simulate a high degree of air pollution. The NO
concentration is set to (0,50 ± 0,05) ppmv.
5 Interferences
The measurement’s interferences are reported in the technical specifications of the chemiluminescence
analyser. As what is measured are all species that can be converted by reduction to NO, NO concentration
2
is here defined as [NO ] = [NO ]-[NO]. For interferences on chemiluminescence detection, see Winer et al.
2 x
(1974).
6 Apparatus
6.1 General
The test apparatus shall consist of the following main components.
6.2 Gas mixture preparation system
The system used for preparing the reaction mixture is shown in Figure 1.
The mass flow controllers, calibrated and traceable, shall ensure a maximum flow consistent with that
needed for a correct test execution. To ensure the necessary accuracy, the flow shall not exceed 90 % of
the rated full scale.
As an example, to obtain the gas mixture only gases of chromatographic grade or higher purity shall be
used. Instead of dry air cylinders, two separate cylinders of pure N and O can be used at the inlet of
2 2
7
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mass-flow controllers, adjusted so as to produce a mixture consisting of 20,8 % of O and 79,2 % of N .
2 2
The NO concentration to flow #1 is set to (0,50 ± 0,05) ppmv.
a) Relative humidity is set by regulating the b) Relative humidity is set by regulating the
flow to U, which is downstream to F pressure before U and F
Key
S source of nitric oxide NO diluted in N
1 2
S2 cylinder of air (chromatographic grade) or, alternatively, individual cylinders of N2 and O2
(chromatographic grade)
F flow controller with mass-flow controllers (2 or 3)
P pressure regulators with low-pressure manometers
U humidifier maintained at controlled temperature
F#1 flow entering the reactor
Figure 1 — Gas mixture preparation system
The humidification of the gas mixture can be obtained with two different configurations:
a) using two mass flow controllers regulating the flow to U, as in Figure 1 left;
b) using one mass flow controller regulating the pressure on U, as in Figure 1 right.
The gas mixture preparation system shall ensure a relative humidity of (40 ± 5) % inside the CSTR
reactor. The relative humidity shall be measured either inside the reactor R (Figure 2) or immediately at
its outlet on flow 2 of Figure 2 by means of a hygro-thermometer.
6.3 Illumination and measuring system:
6.3.1 General:
The light source arrangement and the measuring system are shown in Figure 2.
8
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Key
R reaction chamber, Continuous Stirred-Tank Reactor (CSTR) type
V fan
A power supply of fan V
N NO/NO2 chemiluminescence analyser
E processing/logging unit
L illumination system
1, 2, 3, 4 flow paths, with valves and tubing
Figure 2 — Illumination, reaction and measuring system
All parts of the test apparatus, including connections and pipes, which come into contact with the nitric
oxide mixture shall be made of chemically inert materials. For pipes and connections PTFE is
recommended. The pipes of paths 1, 2, 3, 4 and the related connections shall have an outer diameter of
6 mm (1/4”) and inner clearance of at least 4 mm to avoid overpressures that may affect the gas
concentration inside the reactor.
Temperature shall be measured and recorded inside the reactor during the test or immediately at its
outlet on flow 2 by means of a hygro-thermometer. The gas temperature inside the reaction chamber
shall be (25 ± 5) °C.
6.3.2 Illumination system L:
The illumination source shall consist of any lamp able to excite the photocatalyst (quartz mercury vapor
lamps, UV-A fluorescent lamps, Xenon lamps, LEDs, lamps consisting of a metal vapor element combined
with tungsten incandescence elements, etc.) as specified in the Technical Specification CEN/TS 16599.
The illumination system shall provide an average irradiance to the test sample surface within the range
2
of wavelengths that are mostly adsorbed by the photocatalyst, equal to (10,0 ± 5 %) W/m .
The geometry of the illumination system shall be such that uniform illumination of the sample surface is
ensured. The illumination is considered uniform if 5 independent measurements performed on the
surface (one in centre position and the other four in positions perpendicular to each other and next to
the edge of the sample) show a percentage variation compared to the average value of less than 10 %.
The control of the uniformity of illumination and average irradiance shall be repeated each time the
system geometry changes (position of the lamp or any filters or reflectors, sample position, etc.).
Irradiance shall be measured by placing a radiometric sensor inside the reaction chamber in the same
position occupied by the sample in order to measure real irradiance at its surface. A second measuring
sensor for the control of source stability can be positioned outside the reaction chamber, provided that it
9
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has been calibrated with a reference radiometric sensor placed inside the reactor. Irradiance can be
measured continuously during the test or, alternatively, just before the beginning of the test and
immediately after its conclusion. The irradiance values shall be measured only after the lamp intensity
has stabilized as a result of its warming-up (typically 10 min after being turned on). The irradiance value
as measured shall be recorded as average value in the test report.
The radiometer used for the measurement shall have been previously calibrated by means of a
spectroradiometer, which in turn has been previously calibrated by means of standard sources.
In order to avoid decomposition by direct photolysis of NO, the integrated irradiance at λ < 340 nm shall
2
be less than 0,5 W/m . The direct NO photolysis rate shall be checked by performing the test using the
empty reactor, where standard NO concentration (0,5 ppmv) is introduced and the reactor outlet
concentration is measured according to 8.3, a). For example, in the case of a photocatalyst consisting of
pure TiO , the illumination system that uses a medium-pressure mercury lamp shall be such as to ensure
2
the surface of the sample receives a UV irradiance (λ < 400 nm) mainly composed of the line at 365 nm
2
of mercury, and an integrated irradiance for λ < 340 nm of less than 0,5 W/m .
The spectrum of the lamp used shall be acquired and reported in the test report, because the analysis
result depends significantly on the lamp type used.
6.3.3 Reaction chamber R:
A schematic of the reaction chamber is given in Figure 3.
10
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Dimensions in millimetres
Key
1, S sample 4 inflow
2 fan
3 outflow
3A gas output (alternative)
Figure 3 — Top view of the CSTR reaction chamber, with dimensional details and indication of
flows for thorough mixing and location of the sampling point
Other dimensional details of the reaction chamber with related sample positions are also shown in the
Figures 4 and 5 below.
The reaction chamber shall be built with NO inert materials, i.e. glass, polymethylmethacrylate or other
inert plastic materials. The chamber shall be gas-tight. On top, the chamber shall be provided with a flat
window that is transparent to the light emitted by the illumination system and vertically incident to the
sample. This flat window, transparent to the wavelengths used (e.g. made up of borosilicate glass for
λ ≥ 340 nm) shall be 3 mm to 4 mm thick to ensure sufficient strength and also removable to allow for
sample positioning.
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Dimensions in millimetres
Key
HAC holes for air circulation
HF hole for a fan with Φ = 60 mm
1 top window
2 fan 60 mm nominal
3 gas outlet
4 gas inlet
Figure 4 — Side view (back of fan side) of the CSTR reactor
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Dimensions in millimetres
Key
3 gas outlet
h distance to the surface of the sample
S sample
th sample on the support, any thickness, max 50mm
max
Figure 5 — Side view (fan front side) of reactor CSTR, with indications of sample position
The reaction chamber shall comply with the dimensions shown in Figures 3 to 5. Considering the volumes
3 3
occupied by internal barriers, fan, sample and sample support, the total net volume is 2,8 dm to 3,5 dm .
This volume is not critical. The gas flow is maintained constant throughout the whole test, and shall be
3 −1
equal to 1,6 dm min . It shall be at least 20 % higher than the sampling flow of the NO/NO analyser.
2
The max flow variation allowed is 10 %.
The fan ensures perfect mixing inside the reaction chamber. The fan is placed inside the reactor on a
support having a hole with diameter equal to the fan aperture and axial to the fan axis. The support has
3
lateral holes that ensure full air mixing inside the chamber. The fan shall provide nominal flows of 70 m
−1
h at the nominal supply voltage V .
o
Fans with external dimensions of 60 mm × 60 mm and thickness from 25 mm to 35 mm are suitable for
this purpose. The fan flow shall be varied by varying the supply voltage by an appropriate power supply
of continuous variable output voltage (see A of Figure 2).
2
6.3.4 NO/NO analyser
The analyser shall be calibrated according to the procedures described in ISO 7996 or according to
EN ISO 9169. The instrument's calibration can be performed using NO and/or NO mixtures at a known
2
and certified concentration of either grade 999 nitrogen or air. For the measurement range adopted
during calibration, at least 4 standard gas mixtures shall be analysed, supported by the related calibration
certificates, with different NO contents in N (or in any other inert gas) with concentrations equal to
2
approx. 0,2 ppmv, 0,4 ppmv, 0,6 ppmv, 0,8 ppmv.
Alternatively, the concentrations needed to check the analyser calibration can be generated starting from
a single gas cylinder with certified NO concentration and with the help of a calibrated flow controller
provided with calibration certificates for mass-flow controllers.
Adjustments and calibrations shall be always carried out when the measuring device is under steady
conditions.
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By comparing the measured NO concentration values and the related certified values it is possible to
obtain, for each concentration level, the corresponding analyser calibration condition, which can be
expressed in table form, as a calibration curve or a response factor.
If calibration provides a linear response as nitrogen oxide concentrations vary within the calibration
range, then a single level measurement can be adopted during the control of the instrument calibration
condition. The frequency of such control operations depends on the accuracy level desired in accordance
with the time drift of the instrumental signal typical of each NOx-analyser.
7 Sample preparation
7.1 Precaution
Samples shall be eventually preconditioned following the supplier advices.
7.2 Sample characteristics
2
The samples being analysed shall have a surface area of (64 ± 6) cm . For larger samples, use a mask. The
surface area value shall be carefully assessed being a parameter necessary for the normalization of the
test result.
The sample shall be positioned on a support made of borosilicate glass, polytetrafluoroethylene (PTFE)
or ceramic material that is not photocatalytically active, paying attention that its surface is as close as
possible to the level of the fan rotation axis and central to the free space between fan and reactor wall in
the lateral direction (see Figure 5). As to distance tolerances, the sample surface can be at a distance of
30 mm to 50 mm from the internal base, that is 60 mm to 40 mm from the inner surface of the upper
transparent window of the reactor. This means that the sample shall have a maximum usable thickness
of 50 mm. Solid samples of 50 mm thickness can be positioned in the reaction chamber without any
support.
The geometric surface area exposed to the gas flow can be square, rectangular or circular, provided that
the illumination uniformity conditions are met (see 6.3.2). The sample width in axial direction should not
2
exceed 120 mm. Typically a cylindrical sample has a surface area of (64 ± 6) cm (±10 %).
The required surface area can be achieved by combination of various samples, provided that they are
coplanar and the resulting surface meets the specifications above.
The surfaces of the tested sample other than those exposed orthogonally to the incident lightbeam, shall
be isolated from gas containing nitric oxide by means of a coating of commercial silicones, paraffin waxes,
inert polymer films or composite materials. The test shall be performed only after these protective films
have completely dried. All coatings shall withstand irradiance conditions for at least 6 h, shou
...
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