CEN/TS 16976:2016
(Main)Ambient air - Determination of the particle number concentration of atmospheric aerosol
Ambient air - Determination of the particle number concentration of atmospheric aerosol
This Technical Specification describes a standard method for determining the particle number concentration in ambient air in a range up to about 107 cm–3 for averaging times equal to or larger than 1 min. The standard method is based on a Condensation Particle Counter (CPC) operated in the counting mode and an appropriate dilution system for concentrations exceeding the counting mode range. It also defines the performance characteristics and the minimum requirements of the instruments to be used. The lower and upper sizes considered within this document are 7 nm and a few micrometres, respectively. This document describes sampling, operation, data processing and QA/QC procedures including calibration parameters.
Außenluft - Bestimmung der Partikelanzahlkonzentration des atmosphärischen Aerosols
Diese Technische Spezifikation stellt ein Standardverfahren zur Bestimmung der Partikelanzahl-konzentration in Außenluft im Bereich bis etwa 107 cm−3 für Mittelungszeiten von mindestens 1 min auf. Das Standardverfahren basiert auf einem im Zählmodus betriebenen Kondensationspartikelzähler (en: condensation particle counter, CPC), gegebenenfalls mit geeignetem Verdünnungssystem, falls die Konzentrationen den Bereich des Zählmodus überschreiten. Weiterhin werden Leistungskenngrößen und Mindestanforderungen für die zu verwendenden Geräte definiert. Der betrachtete Partikelgrößenbereich reicht von 7 nm bis zu einigen Mikrometern. Diese Technische Spezifikation beschreibt Probenahme, Betrieb des Geräts, Datenverarbeitung und QA/QC-Maßnahmen, einschließlich der Kalibrierparameter.
Air ambiant - Détermination de la concentration en nombre de particules de l'aérosol atmosphérique
La présente Spécification technique décrit une méthode normalisée de détermination de la concentration en nombre de particules dans l’air ambiant sur une plage allant jusqu’à environ 107 cm-3, pour des durées de calcul des moyennes supérieures ou égales à 1 min. La méthode normalisée repose sur un compteur de particules à noyaux de condensation (CPC) fonctionnant en mode comptage et sur un système de dilution approprié pour les concentrations excédant la plage du mode comptage. Elle définit également les caractéristiques de performance et les exigences minimales relatives aux instruments à utiliser. Les tailles de particules minimale et maximale considérées dans le présent document sont, respectivement, de 7 nm et quelques micromètres. Le présent document décrit le prélèvement, le fonctionnement, le traitement des données et les procédures d’assurance qualité et de contrôle qualité, y compris les paramètres d’étalonnage.
Zunanji zrak - Določevanje številčne koncentracije delcev atmosferskih aerosolov
Ta dokument opisuje standardno metodo za določevanje številčne koncentracije delcev v zunanjem zraku na območju do približno 10 na kvadrat 7 cm-3 za čase povprečenja, ki so dolgi največ 1 minuto. Standardna metoda temelji na kondenzacijskem števcu delcev (CPC), ki deluje v načinu štetja, in ustreznem sistemu redčenja za koncentracije, ki presegajo obseg načina štetja. Določa tudi lastnosti zmogljivosti in minimalne zahteve instrumentov, ki jih je treba uporabiti. Spodnje in zgornje velikosti, obravnavane tem dokumentu, so 7 nm in nekaj mikrometrov. Ta dokument opisuje vzorčenje, delovanje, obdelavo podatkov ter postopke zagotavljanja in nadzora kakovosti, vključno z umerjanjem.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2017
=XQDQML]UDN'RORþHYDQMHãWHYLOþQHNRQFHQWUDFLMHGHOFHYDWPRVIHUVNLKDHURVRORY
Ambient air - Determination of the particle number concentration of atmospheric aerosol
Außenluft - Bestimmung der Partikelanzahlkonzentration des atmosphärischen Aerosols
Air ambiant - Détermination de la concentration en nombre de particules de l'aérosol
atmosphérique
Ta slovenski standard je istoveten z: CEN/TS 16976:2016
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TS 16976
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
August 2016
TECHNISCHE SPEZIFIKATION
ICS 13.040.20
English Version
Ambient air - Determination of the particle number
concentration of atmospheric aerosol
Air ambiant - Détermination de la concentration en Außenluft - Bestimmung der
nombre de particules de l'aérosol atmosphérique Partikelanzahlkonzentration des atmosphärischen
Aerosols
This Technical Specification (CEN/TS) was approved by CEN on 26 June 2016 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 16976:2016 E
worldwide for CEN national Members.
Contents Page
European Foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Atmospheric aerosol . 8
5 Description of the method . 9
5.1 Sampling and conditioning . 9
5.1.1 Sampling . 9
5.1.2 Drying . 10
5.1.3 Dilution . 11
5.2 Determination of the number concentration with a CPC . 11
5.2.1 Condensation growth . 11
5.2.2 Optical detection . 13
6 CPC performance criteria and test procedures . 14
6.1 General . 14
6.2 General requirements of the CPC . 14
6.3 Test conditions . 15
6.4 Performance characteristics and criteria . 15
6.5 Test procedures . 16
6.5.1 Inlet flow rate accuracy . 16
6.5.2 Number concentration measurement range . 16
6.5.3 Number concentration detection limit . 16
6.5.4 Linearity and slope of response . 16
6.5.5 Detection efficiency curve at low particle size . 17
6.5.6 Upper particle size detection limit . 17
6.5.7 Zero count rate . 17
6.5.8 Response time . 17
6.5.9 Dependence of flow rate on supply voltage . 17
6.5.10 Accuracy of temperature and pressure sensor calibration . 18
6.5.11 Effect of failure of mains voltage . 18
7 Performance criteria and test procedures for the sampling and conditioning system . 18
7.1 General requirements . 18
7.2 Performance characteristics and criteria . 18
7.3 Diffusion losses . 19
7.4 Relative humidity . 19
7.5 Dilution factor . 19
7.6 Primary sampling flow . 19
8 Measurement procedure . 20
8.1 Measurement planning . 20
8.2 Environmental operating conditions . 20
8.3 Initial installation . 20
8.4 Initial checks on site. 20
8.5 Data processing and reporting . 21
9 Quality control, quality assurance and measurement uncertainty . 21
9.1 General. 21
9.2 Frequency of calibrations, checks and maintenance . 21
9.2.1 General. 21
9.2.2 Maintenance of CPC . 22
9.2.3 Calibration of CPC plateau region and linearity . 22
9.2.4 Determination of CPC low size cut-off . 22
9.2.5 CPC zero check . 22
9.2.6 Number concentration check . 23
9.2.7 CPC flow rate calibration . 23
9.2.8 Temperature and pressure sensor calibration . 23
9.2.9 CPC internal diagnostics . 23
9.2.10 Sample system maintenance . 23
9.2.11 Relative humidity sensor . 23
9.2.12 Dilution factor (where applicable) . 23
9.2.13 Leak check . 23
9.3 Measurement uncertainty . 24
9.3.1 General. 24
9.3.2 CPC plateau detection efficiency . 24
9.3.3 CPC detection efficiency drift. 24
9.3.4 Flow determination . 25
9.3.5 Correction to standard temperature and pressure . 25
9.3.6 Sampling losses due to diffusion to walls . 25
9.3.7 Dilution factor (where applicable) . 25
9.3.8 Calculation of overall uncertainty . 25
Annex A (normative) Determination of diffusion losses in sampling lines . 27
Annex B (informative) Example of the calculation of diffusion losses in a sampling system . 29
B.1 Description of the sampling system . 29
B.2 Air properties and diffusion coefficient . 30
B.3 Losses in the primary sampling tube . 30
B.4 Losses in the secondary sampling tube and the dryer . 31
B.5 Overall sampling losses . 31
Annex C (informative) Data reporting . 32
C.1 Motivation . 32
C.2 Level 0 (annotated raw data) . 32
C.3 Level 1 (data processed to final physical property, potential corrections applied, original
temporal resolution) . 33
C.4 Level 2 (hourly averages, including measures of variability) . 33
C.5 GAW WDCA Condensation Particle Counter Level 0 (raw data) file format example (system
without sample dilution): . 35
C.6 Line-by-line explanations: . 35
Annex D (informative) Uncertainty calculation (example) . 47
D.1 General. 47
D.2 CPC plateau detection efficiency . 47
D.3 CPC detection efficiency drift . 47
D.4 Flow determination . 47
D.5 Correction to standard temperature and pressure . 47
D.6 Sampling losses due to diffusion to walls . 47
D.7 Dilution factor (where applicable) . 48
D.8 Calculation of overall uncertainty . 48
Annex E (informative) Atmospheric aerosols in Europe . 49
E.1 General . 49
E.2 Mean concentrations . 49
E.3 Examples of measurements. 50
Annex F (informative) Dilution systems . 53
F.1 Background . 53
F.2 Criteria for dilution systems . 53
F.3 Operation principles of dilution systems . 53
F.3.1 General . 53
F.3.2 Dilution systems with partial flow filtration . 54
F.3.3 Dilution systems with external clean air supply . 54
Annex G (informative) Laminar flow. 56
European Foreword
This document (CEN/TS 16976:2016) has been prepared by Technical Committee CEN/TC 264 “Air quality”,
the secretariat of which is held by DIN.
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 organisations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus,
Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Introduction
There is a growing awareness of the significance of aerosol particles with diameters of D < 1 µm for human
health as well as for their climatic impact. To assess air quality, it appears necessary to supplement
gravimetrically determined mass concentrations such as PM or PM with a measurement of the particle
10 2.5
number concentration. Since ultrafine particles with diameters of D < 0,1 µm make an almost insignificant
contribution to the mass of atmospheric aerosol particles, they can best be detected with counting measuring
methods of sufficient sensitivity.
As particle measurement instrumentation allows determining either the particle number concentration or the
particle number size distribution two Technical Specifications will be established:
— one dealing with the determination of the single parameter number concentration (a measure of “total”
number concentration),
— one dealing with the determination of number concentration within a limited number of size ranges.
Clauses 5 and 6 contain general information about the method and the expected properties of the aerosol to
be measured.
Clause 7 sets out the performance criteria for CPCs. Specifically, these are the relevant performance
characteristics of CPC instruments (without any sampling system), the respective criteria that shall be met,
and a description of how the tests shall be carried out. In general these tests are expected to be carried out by
test houses or CPC manufacturers rather than users, and could form the basis for type testing of CPCs in
future.
Clause 8 sets out the performance criteria and test procedures for the sampling and conditioning system (e.g.
dilution). These may be applied by manufacturers of sampling systems, test houses or users (network
operators).
Clause 9 sets out requirements for the installation, initial checks and calibrations, and operation of a CPC and
sampling system at a monitoring site, including routine maintenance, data processing (including use of QA/QC
data) and reporting. In general these will be the responsibility of users (network operators), though
calibrations requiring test aerosols shall only be carried out by suitably qualified laboratories.
Clause 10 sets out Quality Assurance and Quality Control procedures, i.e. the ongoing checks and calibrations
that are required on the CPC and sampling system during operation at a monitoring site. It is expected that
these will be the responsibility of users (network operators), though calibrations requiring test aerosols shall
only be carried out by suitably qualified laboratories. The main sources of measurement uncertainty are
described.
1 Scope
This Technical Specification describes a standard method for determining the particle number concentration
7 –3
in ambient air in a range up to about 10 cm for averaging times equal to or larger than 1 min. The standard
method is based on a Condensation Particle Counter (CPC) operated in the counting mode and an appropriate
dilution system for concentrations exceeding the counting mode range. It also defines the performance
characteristics and the minimum requirements of the instruments to be used. The lower and upper sizes
considered within this document are 7 nm and a few micrometres, respectively. This document describes
sampling, operation, data processing and QA/QC procedures including calibration parameters.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 27891, Aerosol particle number concentration — Calibration of condensation particle counters
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
actual flow rate
volumetric flow rate of an individual instrument, measured at its inlet under the actual air conditions
3.2
aerosol
a multi-phase system of solid and/or liquid particles suspended in a gas, ranging in particle size from
0,001 µm to 100 µm
3.3
calculation flow rate
flow rate which directly relates count rate and particle number concentration
Note 1 to entry: This flow rate is used for instrument internal calculation of the particle number concentration. It
depends on the instrument type and may be nominal, factory-certified or actual inlet flow rate. It may also include a
calibration factor unless the total inlet flow is analysed.
3.4
coincidence error
error that occurs with counting measuring methods when two or more particles are counted simultaneously
as a single particle
Note 1 to entry: Coincidence error is related to particle number concentration, flow velocity through the sensing
zone and size of sensing zone.
3.5
detection efficiency
ratio of the particle number concentration determined by the measuring instrument to the reference particle
number concentration of the aerosol at the instrument's inlet
Note 1 to entry: The detection efficiency depends on particle size and may depend on particle number
concentration.
3.6
factory-certified flow rate
volumetric flow rate of an individual instrument at the time of factory calibration, measured at its inlet under
the actual air conditions, and documented on a check out certificate
3.7
nominal flow rate
volumetric flow rate indicated on the instrument specification sheet by the manufacturer
Note 1 to entry: The nominal flow rate is that flow rate, which a specific CPC model is designed for by the
manufacturer. The real flow rate of individual instruments may differ from the nominal flow due to manufacturing
tolerances.
3.8
number size distribution
frequency distribution of the particle number concentration represented as a function of particle size
3.9
particle
small piece of matter with defined physical boundary
Note 1 to entry: The phase of a particle can be solid, liquid, or between solid and liquid and a mixture of any of the
phases.
[SOURCE: ISO 27891:2015, modified]
3.10
particle number concentration
number of particles related to the unit volume of the carrier gas
Note 1 to entry: For the exact particle number concentration indication, information on the gaseous condition
(temperature and pressure) or the reference to a standard volume indication is necessary.
[SOURCE: ISO 27891:2015]
4 Atmospheric aerosol
Atmospheric aerosols are strongly dependent on their local and regional sources. Especially, the size
distribution in number and mass, as well as the size-resolved chemical composition are highly variable.
Aerosol particles are either emitted directly (primary aerosols) or formed by nucleation and condensation
from pre-cursor gases (secondary aerosol). Combustion processes lead to both primary and secondary
aerosols.
Mass-wise, the global direct emission of aerosol particles is dominated by sea salt, biological material as well
as by desert and volcanic dust. These particles are generally larger than 1 µm. Anthropogenic emissions in
this size range play a minor role on a global scale. Submicrometer natural aerosols consist mainly of marine
sulfate, biogenic organics, and wildfire carbonaceous particles. Submicrometer anthropogenic aerosols are
complex mixtures of primary and secondary particles, consisting mainly of sulfate, nitrate, organics and
elemental carbon.
Particle number concentrations of atmospheric aerosols cover several orders of magnitude. While remote
marine or free tropospheric aerosols have number concentrations as low as tens or a few hundred per cubic
centimetre, anthropogenically influenced aerosols can contain a few thousand up to one million particles per
cubic centimetre. The number concentration of the anthropogenic aerosol over land, especially in urban areas
is dominated by particles in the size range smaller than 0,1 µm. Major sources for high number concentrations
in this size range are regional new particle formation and local combustion processes. Average background
concentrations in an urban area are several tens of thousands of particles per cubic centimetre.
For details see Annex E.
5 Description of the method
5.1 Sampling and conditioning
5.1.1 Sampling
The measurement of atmospheric aerosols will always necessitate sampling and the transport of the sample
to the measuring instrument. Moreover, in certain cases the sample has to be processed in terms of
temperature, relative humidity and particle concentration in order to adapt the aerosol to the measuring
instrument's permissible operating conditions.
The information given on this issue in this document refers to stationary ambient monitoring sites. For mobile
applications (e.g. measurements from aircraft), additional considerations have to be taken into account.
The measuring instruments shall be accommodated in a protected environment in controlled conditions
(temperature 15 °C to 30 °C).
The sampling location depends on the measurement task. If the undisturbed atmospheric aerosol is to be
measured, air intake should take place 5 m to 10 m above the ground level. Buildings, vegetation or the
topography of the terrain may make an even higher sampling point necessary. By contrast, the measurement
of aerosols close to the source (e.g. traffic) calls for much lower sampling points (1,5 m to 4 m above the
ground, see Directive 2008/50/EC [1]).
The design of the intake port should permit representative sampling regardless of the direction of the wind
for a broad range of wind velocities. However, this is not a critical condition for the small particles measured
by the CPC. Steps shall be taken to avoid soiling of the sampling lines by particles larger than 10 µm. For this
purpose a PM10 or PM2.5 inlet can be used (see Figure 1).
Key
1 PM sampling inlet
2 Primary sampling tube
3 Secondary sampling tube
Figure 1 — Basic design of the aerosol intake port
The sample should ideally be fed via a vertical primary sampling tube without bends to the measuring
instruments. Since gas measuring methods have fundamentally different requirements regarding sampling,
gas and aerosol sampling should be conducted independently of each other.
)
To reduce diffusion loss, it is necessary to intake aerosol with the aid of a pump at a primary flow rate (Qtot
much higher than the secondary flow rate (Q ). The CPC should sample isoaxially in the central area from
CPC
this volumetric flow via a secondary sampling tube that is as short as possible. Flow in the primary sampling
tube should be laminar in order to prevent additional particle loss due to turbulence. Ideally, a Reynolds
number of about Re = 2000 shall be aimed for (see 7.2).
The diffusion losses in the sampling system for smallest relevant particle size of 7 nm shall be less than 30 %
(see 7.2).
The intake port and lines shall be made of a conductive, corrosion-resistant material with a low surface
roughness (e.g. stainless steel) and electrically earthed. This prevents chemical changes to the aerosol and
particle losses due to electrostatic effects. Flexible tubing of electrically conductive material may also be used
for small connections or short distances. The length of flexible tubing should be below 50 cm.
The inlet and the flow-splitter of the sampling system shall be checked regularly to detect obstructions, e.g. by
insects, and cleaned, if necessary.
5.1.2 Drying
Aerosols with a high relative humidity (mist in extreme cases) should be dried, as the size of particles of
hygroscopic materials is strongly influenced by humidity. The requirement is to keep the relative humidity of
the primary flow at the CPC inlet lower than 40 % (see 7.2). The relative humidity at the inlet of the CPC shall
be monitored.
With respect to the temperature conditions three cases are to be distinguished:
— In case the room temperature is higher than 22 °C no aerosol dryer is needed if the ambient dew point
temperature never exceeds 10 °C.
— If the dew point temperature is between 10 °C and the room temperature, the secondary flow shall be
dried.
— In case that the dew point temperature is above the room temperature, the primary flow shall be dried
before entering the room. Additional drying of the secondary flow may be necessary.
There are three recommended methods to dry the aerosol:
— Aerosol diffusion dryer based on silica; ®
— Membrane dryer (e.g. Nafion dryer);
— Dilution with dry particle-free air (only for high concentrations, see 5.1.3). In this case the exact dilution
ratio shall be known in order to calculate the correct concentrations.
NOTE Heating is not recommended as this may change the aerosol (significant evaporation of volatile components
above 40 °C).
5.1.3 Dilution
Preferably the CPC selected to measure at any particular site will have a concentration range in counting
mode (with or without coincidence correction) that covers the expected concentrations. When this is not
possible or the CPC would rely on photometric mode the sample shall be diluted with particle-free air.
The dilution step may introduce a high uncertainty which shall be estimated and specified in the report.
Where dilution is not required this step should be avoided.
The minimum requirement with respect to accuracy of the dilution factor is given in 7.2, operation principles
of suitable dilution systems are presented in Annex F.
5.2 Determination of the number concentration with a CPC
5.2.1 Condensation growth
In a CPC, particles are enlarged by condensation growth and then subjected to optical detection by scattered
light.
To incite the condensation growth of particles of a given diameter, a certain minimum saturation ratio with
respect to a condensable vapour must be present in accordance with the Kelvin Formula (1):
4⋅⋅σ M
S= exp
ρ⋅R⋅⋅Td
(1)
Where
S is the saturation ratio (ratio of current vapour pressure to saturation vapour pressure);
σ is the surface tension of the vapour substance;
M is the molar mass of the vapour substance (relative molecular mass);
ρ is the density of the vapour substance in its condensed state;
R is the general gas constant;
T is the absolute temperature;
d is the Kelvin equivalent diameter.
Particle shape, surface structure and affinity of the particle material to the vapour phase are important factors
influencing the Kelvin equivalent diameter.
NOTE The Kelvin equivalent diameter (with respect to the vapour substance) of an aerosol particle is defined as the
diameter of a pure vapour substance drop that would start to grow at the same supersaturation as the particle in
question.
Figure 2 shows the principle of a continuous flow CPC. The aerosol enters a heated saturator (3) in which it is
saturated with the vapour substance at a constant temperature. Typical vapour substances used in CPCs are
alcohols, e.g. n-butanol. It then flows into a cooled condenser (6) where the vapour condenses on the particles
forming spherical droplets that consist mainly of the vapour substance and have a diameter of typically a few
micrometres. These particles can be easily detected and counted optically.
The temperatures of the saturator and the condenser are important operating parameters that influence the
smallest detectable particle size.
Key
1 Aerosol inlet
2 Vapour substance reservoir
3 Heated saturator
4 Nanoparticle (not true to scale)
5 Thermoelectric cooling and heating device
6 Condenser
7 Droplet (not true to scale)
8 Light source
9 Illumination optics
10 Receiving optics
11 Photodetector
12 Aerosol outlet
Figure 2 — Principle of a continuous flow CPC (see ISO 27891)
5.2.2 Optical detection
The droplets produced by the condensation process are then transported through a light beam. The light
scattered by the droplets is collected by a receiving optic under a defined solid angle (receiver aperture) and
guided onto a detector (e.g. photodiode). If the particle number concentration is low enough, the droplets
cross the light beam one after the other, thus producing single electrical pulses at the detector output. From
the count rate of these pulses and the calculation flow rate the total number concentration of the droplets can
be determined. This number concentration is equal to the number concentration of the primary particles
(condensation nuclei) with a size larger than the Kelvin diameter determined by the supersaturation achieved
in the instrument.
For higher particle number concentrations more than one particle may cross the light beam at the same time
(coincidence). This results in the coincidence error, which leads to a measured value lower than the actual
concentration.
For even higher concentrations the detector cannot distinguish single pulses but measures the light scattered
by the whole population of particles in the sensing volume as an analogue signal (photometric mode). Since in
the ideal case droplet growth due to condensation yields the same size independently of the size of the
condensation nuclei and since the optical properties of the droplets are determined essentially by the
condensing material, there is in principle a linear relationship between this photometer signal and the
particle number concentration which can be determined by calibration. On the other hand very high particle
number concentrations lead to a depletion of the vapour concentration by the condensation process. This
leads not only to nonlinearity of the calibration curve but also influences the lower detection limit for particle
size.
The use of the photometric mode is not allowed in the standard method.
6 CPC performance criteria and test procedures
6.1 General
This clause sets out the performance criteria for the CPC. In general the tests described in 6.3 are expected to
be carried out by test houses or CPC manufacturers to validate an instrument design, and could form the basis
for type approval of CPCs in future.
6.2 General requirements of the CPC
1) The performance criteria all refer to the counting mode of the CPC, including counting with coincidence
correction, after any pre-determined calibration factors have been applied.
2) The CPC shall have no internal flow splitting, which is not accessible to an external flow rate check, or
internal dilution to avoid unnecessary sources of measurement uncertainty.
3) The working fluid shall be n-butanol.
4) The instrument shall produce concentration data averaged over a data reporting interval of 1 min.
5) The instrument's internal clock shall be externally synchronizable.
6) The instrument shall enable the following parameters to be recorded in 1 min time intervals:
— Date, start time and end time of each reported concentration
— Calculation flow rate
–3
— Raw concentration (count rate divided by the calculation flow rate), in cm
–3
— Concentration with internal coincidence correction (based on the calculation flow rate), in cm
— Saturator temperature, in K
— Condenser temperature, in K
— Temperature and absolute pressure at the point of flow rate measurement
— Warning and error flags:
• Signal quality out of tolerance
• Too high concentration
• Flow problems
• Saturator or condenser temperature out of range
• Butanol liquid level too low
• Light source malfunction
6.3 Test conditions
Before operating the CPC, the operating instructions of the manufacturer shall be followed, particularly with
regard to the set-up of the equipment, the quality and quantity of consumable products necessary, and the
CPC warm up time.
During the laboratory tests for each individual performance characteristic, the temperature of the air
surrounding the instrument shall be between 20 °C and 23 °C, except for the tests in 6.5.1, 6.5.4 and 6.5.5,
which are carried out at two temperatures (15 °C and 30 °C).
6.4 Performance characteristics and criteria
Table 1 lists the performance criteria of the CPC which shall be met in the performance tests specified in 6.5.
Table 1 — CPC performance criteria
Performance characteristic Criteria Clause
1 Actual flow rate ≤ 5 % difference to the nominal flow rate 6.5.1
≤ 2 % difference to the factory-certified flow rate
2 Number concentration measurement 6.5.2
range –3
≤ 100 cm (based on at least 1500 particle
Lower limit counts)
–3
Upper limit ≥ 10 000 cm (including coincidence correction)
Dynamic range at least 3 orders of magnitude
3 Number concentration detection limit < lower limit of number concentration 6.5.3
measurement range
4 Concentration response 6.5.4
Slope 1 ± 0,05
Linearity all residuals < 4 % of the measured value
5 Detection efficiency at low particle size D = 7 nm ± 0,7 nm 6.5.5
D < 14 nm
6 Detection efficiency (at intermediate > 95 % at (50 ± 10) nm 6.5.4
particle sizes)
7 Upper particle size detection limit > 90 % detection efficiency at 1000 nm ± 100 nm 6.5.6
–1
8 Zero count rate < 1 min 6.5.7
9 Response time t < 5 s 6.5.8
rise
t < 5 s
fall
t −t
rise fall
<10 %
t
rise
or < 0,5 s
10 Dependence of flow rate on supply ≤ 5 % 6.5.9
voltage
11 Accuracy of temperature and pressure T ≤ 3 K 6.5.10
sensor calibration
P ≤ 1 kPa
12 Effect of failure of mains voltage Instrument parameters shall be secured against 6.5.11
loss. On return of mains voltage, the instrument
shall automatically resume functioning.
6.5 Test procedures
6.5.1 Inlet flow rate accuracy
The CPC inlet flow rate shall be measured using a calibrated reference flow meter at two temperatures (15 °C
and 30 °C) and at atmospheric pressure above 900 hPa.
The pressure dependence shall be checked at two pressures (atmospheric pressure above 900 hPa and the
second pressure at least 200 hPa lower) and at a temperature between 20 °C and 23 °C.
The reference flow meter shall measure with a relative expanded uncertainty (95 % confidence) of ≤ 2 % at
the controlled flow rate. At each temperature at least 10 consecutive measurements shall be taken over a
minimum period of 1 h. For each temperature, the mean of the measurement results shall be compared with
the factory-certified flow rate as specified by the manufacturer, and the relative difference shall meet the
criteria in Table 1.
6.5.2 Number concentration measurement range
The instrument shall demonstrably cover the range given in Table 1 within its counting mode (with or
without coincidence correction).
6.5.3 Number concentration detection limit
The detection limit for the number concentration is the value that can be distinguished with a statistical
certainty of 95 % from the concentration indicated on the basis of the instrument's zero count rate. The zero
count rate states the number of indicated count events per unit of time that are not caused by particles. The
detection limit shall be lower than the lower limit of the number concentration measurement range given in
Table 1.
6.5.4 Linearity and slope of response
Linearity of response is determined by comparing the number concentrations determined by the CPC under
test and the reference instrument at various particle number concentrations. An aerosol electrometer or a
CPC can be used as reference instrument. This instrument shall meet the requirements of ISO 27891.
Following the ISO 27891 procedure for detection efficiency, using silver particles sized (40 ± 10) nm
produced by the evaporation/condensation method, the instrument response sh
...
Frequently Asked Questions
CEN/TS 16976:2016 is a technical specification published by the European Committee for Standardization (CEN). Its full title is "Ambient air - Determination of the particle number concentration of atmospheric aerosol". This standard covers: This Technical Specification describes a standard method for determining the particle number concentration in ambient air in a range up to about 107 cm–3 for averaging times equal to or larger than 1 min. The standard method is based on a Condensation Particle Counter (CPC) operated in the counting mode and an appropriate dilution system for concentrations exceeding the counting mode range. It also defines the performance characteristics and the minimum requirements of the instruments to be used. The lower and upper sizes considered within this document are 7 nm and a few micrometres, respectively. This document describes sampling, operation, data processing and QA/QC procedures including calibration parameters.
This Technical Specification describes a standard method for determining the particle number concentration in ambient air in a range up to about 107 cm–3 for averaging times equal to or larger than 1 min. The standard method is based on a Condensation Particle Counter (CPC) operated in the counting mode and an appropriate dilution system for concentrations exceeding the counting mode range. It also defines the performance characteristics and the minimum requirements of the instruments to be used. The lower and upper sizes considered within this document are 7 nm and a few micrometres, respectively. This document describes sampling, operation, data processing and QA/QC procedures including calibration parameters.
CEN/TS 16976:2016 is classified under the following ICS (International Classification for Standards) categories: 13.040.20 - Ambient atmospheres. The ICS classification helps identify the subject area and facilitates finding related standards.
CEN/TS 16976:2016 has the following relationships with other standards: It is inter standard links to EN 16976:2024. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
You can purchase CEN/TS 16976:2016 directly from iTeh Standards. The document is available in PDF format and is delivered instantly after payment. Add the standard to your cart and complete the secure checkout process. iTeh Standards is an authorized distributor of CEN standards.
Die CEN/TS 16976:2016 bietet eine umfassende technische Spezifikation zur Bestimmung der Partikelzahlkonzentration von atmosphärischem Aerosol in der Umgebungsluft. Der Geltungsbereich dieser Norm ist klar definiert und ermöglicht eine präzise Analyse von Partikelkonzentrationen im Bereich von bis zu etwa 10^7 cm^–3, was für eine Vielzahl von Anwendungen in der Umweltüberwachung und -forschung von Bedeutung ist. Ein wesentlicher Stärke dieser Norm liegt in ihrer methodischen Grundlage, die auf einem Kondensationspartikelzähler (CPC) basiert, der im Zählmodus betrieben wird. Dieses Gerät ermöglicht eine akkurate und reproduzierbare Messung der Partikelzahlkonzentration. Des Weiteren umfasst die Norm auch ein geeignetes Verdünnungssystem für Konzentrationen, die den Zählmodusbereich überschreiten, wodurch die Flexibilität und Anwendbarkeit unter unterschiedlichen Bedingungen erhöht wird. Die Norm legt auch die Leistungsmerkmale und die Mindestanforderungen an die zu verwendenden Instrumente fest, was zu einer einheitlichen Qualität der Messungen führt. Die Dokumentation betrifft sowohl die Größenbereiche von 7 nm bis zu einigen Mikrometern, was eine breit gefächerte Analyse von Aerosolpartikeln ermöglicht. Zudem werden Verfahren für die Probenahme, den Betrieb, die Datenverarbeitung sowie die Qualitätskontrolle (QA/QC) und Kalibrierungsparameter detailliert beschrieben, was die Zuverlässigkeit der Ergebnisse weiter erhöht. Die Relevanz der CEN/TS 16976:2016 ergibt sich aus der zunehmenden Bedeutung von Luftqualitätsmessungen im Kontext von Gesundheit und Umwelt. Durch die standardisierte Vorgehensweise wird sichergestellt, dass die gewonnenen Daten konsistent und vergleichbar sind, was für politische Entscheidungen und öffentliche Gesundheit von entscheidender Bedeutung ist. Daher ist diese Norm nicht nur für Fachleute im Bereich der Atmosphärenwissenschaften von Bedeutung, sondern auch für Behörden, die Verantwortung für die Luftqualität übernehmen.
CEN/TS 16976:2016 presents a comprehensive framework for the determination of particle number concentration in ambient air, meticulously detailing the standard method applicable for concentrations up to approximately 10^7 cm–3. The strength of this Technical Specification lies in its robust methodology which utilizes a Condensation Particle Counter (CPC) operated in counting mode, complemented by a suitable dilution system to address concentrations that exceed the operational range of the CPC. One of the notable aspects of this standard is its clear definition of performance characteristics and minimum instrument specifications, ensuring that users can achieve consistent and reliable results. The specification includes detailed sections on sampling techniques, operation protocols, data processing, and stringent quality assurance/quality control (QA/QC) procedures. These elements are crucial for maintaining the integrity of results in atmospheric aerosol studies. Additionally, the standard defines a size range for particle measurement, specifically from 7 nm to a few micrometers, which is crucial for researchers and regulators aiming to understand and manage air quality and its associated health impacts. The inclusion of guidelines for calibration parameters further strengthens the standard, providing users with a pathway to maintain the accuracy and reliability of their measurements. In terms of relevance, CEN/TS 16976:2016 addresses a critical need within environmental monitoring by providing a standardized approach to quantifying atmospheric aerosols. This focus is increasingly important as global attention on air quality and the implications of particulate matter on public health continues to grow. Overall, the standard serves as an essential tool for environmental scientists and policymakers alike, facilitating reliable monitoring and evaluation of ambient air quality.
La norme CEN/TS 16976:2016 traite de la détermination de la concentration en nombre de particules des aérosols atmosphériques dans l'air ambiant. Son champ d'application est clair et précis, englobant une plage allant jusqu'à environ 10^7 cm–3 pour des temps de moyenne égaux ou supérieurs à 1 minute. Cette spécification technique est essentielle pour les mesures environnementales, car elle fournit un cadre pour la quantification des particules présentes dans l'air, ce qui est crucial non seulement pour la recherche scientifique, mais aussi pour la surveillance de la qualité de l'air. Les points forts de la norme incluent sa méthodologie rigoureuse qui repose sur l'utilisation d'un Compte des Particules par Condensation (CPC) fonctionnant en mode de comptage, ainsi qu'un système de dilution approprié pour gérer les concentrations dépassant la plage de comptage. Ces caractéristiques assurent une mesure précise et fiable de la concentration des particules, élément fondamental pour les études d'impact sur la santé et l'environnement. De plus, la norme définit clairement les caractéristiques de performance et les exigences minimales des instruments à utiliser, ce qui permet d'uniformiser les pratiques de mesure au sein de la communauté scientifique et environnementale. Les détails relatifs à l'échantillonnage, à l'opération, au traitement des données et aux procédures d'assurance qualité/contrôle qualité (AQ/CQ), y compris les paramètres de calibration, renforcent encore la pertinence de la norme dans le domaine de la recherche sur la qualité de l'air. Ainsi, le document constitue une référence incontournable pour les professionnels souhaitant garantir l'exactitude et la crédibilité de leurs mesures de la concentration en nombre de particules des aérosols atmosphériques.
CEN/TS 16976:2016 표준은 대기 중 에어로졸의 입자 수 농도를 측정하기 위한 표준 방법을 제시합니다. 이 표준은 1분 이상의 평균 시간에 대해 최대 약 10^7 cm–3 범위 내에서의 입자 수 농도를 획득할 수 있도록 설계되었습니다. 또한, 이 문서에서는 카운팅 모드에서 작동하는 응축 입자 카운터(CPC)와 농도가 카운팅 모드 범위를 초과할 경우 필요한 적절한 희석 시스템을 기반으로 하고 있습니다. 이 표준의 강점은 입자 수 농도 측정을 위한 명확한 지침을 제공하는 것에 있으며, 이는 대기 질 모니터링 및 연구에 있어 매우 중요한 역할을 합니다. 표준에서는 사용해야 할 기기의 성능 특성 및 최소 요구 사항을 명확히 정의하고 있어, 정확하고 신뢰할 수 있는 결과를 얻을 수 있습니다. 또한, 7 nm에서 몇 마이크로미터까지의 입자 크기를 고려함으로써, 대기 중 다양한 크기의 입자를 분석할 수 있는 유용성을 제공합니다. SIST-TS CEN/TS 16976:2017 문서는 샘플링 절차, 운영 과정, 데이터 처리 및 품질 보증/품질 관리(QA/QC) 절차를 포함하여 측정의 신뢰성을 높이는 다양한 방법론을 포함하고 있습니다. 이러한 점에서 CEN/TS 16976:2016 표준은 대기 질 관리를 위한 매우 실질적이고 중요한 기준을 제공하며, 관련 분야의 전문가와 연구자들에게 유용한 지침서 역할을 합니다.
CEN/TS 16976:2016は、周囲の空気中の大気エアロゾルの粒子数濃度を測定するための標準的な方法を定義しています。この技術仕様は、1分以上の平均時間において、約107 cm–3までの範囲での粒子数濃度を測定するための規定を含んでいます。標準的な手法は、カウントモードで操作される凝縮粒子カウンター（CPC）に基づいており、カウントモードの範囲を超える濃度に対しては適切な希釈システムが必要です。 この標準の強みは、その性能特性や使用する機器の最小要件を明確に定義している点です。これにより、異なる測定環境での一貫性が保証され、信頼性の高い結果を提供します。また、文書には、サンプリング方法、操作手順、データ処理、品質保証および品質管理手順、さらにキャリブレーションパラメータも詳細に記載されています。このような包括的なガイドラインは、計測技術を一貫して適用するための重要な要素です。 CEN/TS 16976:2016は、低サイズ（7 nm）から数マイクロメートルの粒子に焦点を当てており、これにより幅広いエアロゾルの研究や環境モニタリングにおいて、そのリレバンスが明確になります。この標準は、環境科学者や公衆衛生専門家にとって、周囲の空気質を理解し、管理するための重要なツールとなるでしょう。
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