Bsi bs en 13205 5 2014

The workplace performance test for samplers for the inhalable, thoracic or respirable aerosol fractions described in this document is based on a comparison of concentrations sampled from

BSI Standards Publication

Workplace exposure — Assessment of sampler performance for measurement

of airborne particle concentrations

Part 5: Aerosol sampler performance test and sampler comparison carried out at workplaces

National foreword

This British Standard is the UK implementation of EN 13205-5:2014.Together with BS EN 13205-1:2014, BS EN 13205-2:2014, PD CEN/TR13205-3, BS EN 13205-4:2014 and BS EN 13205-6:2014 it supersedes

BS EN 13205:2002 which will be withdrawn upon publication of allparts of the series

The UK participation in its preparation was entrusted to TechnicalCommittee EH/2/2, Work place atmospheres

A list of organizations represented on this committee can beobtained on request to its secretary

This publication does not purport to include all the necessaryprovisions of a contract Users are responsible for its correctapplication

© The British Standards Institution 2014 Published by BSI StandardsLimited 2014

ISBN 978 0 580 78062 2ICS 13.040.30

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 June 2014

Amendments issued since publication

NORME EUROPÉENNE

English Version

Workplace exposure - Assessment of sampler performance for

measurement of airborne particle concentrations - Part 5:

Aerosol sampler performance test and sampler comparison

carried out at workplaces

Exposition sur les lieux de travail - Évaluation des

performances des dispositifs de prélèvement pour le

mesurage des concentrations de particules en suspension

dans l'air - Partie 5: Essais de performances des

échantillonneurs d'aérosols, réalisés sur les lieux de travail

Exposition am Arbeitsplatz - Beurteilung der Leistungsfähigkeit von Sammlern für die Messung der Konzentration luftgetragener Partikel - Teil 5: An Arbeitsplätzen durchgeführte Prüfung der Leistungsfähigkeit des Aerosolsammlers und Sammlervergleich

This European Standard was approved by CEN on 7 May 2014

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, 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

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä I S C H E S K O M I T E E F Ü R N O R M U N G

Contents Page

Foreword 4

Introduction 6

1 Scope 7

2 Normative references 7

3 Terms and definitions 7

4 Symbols and abbreviations 8

4.1 Symbols 8

4.1.1 Latin 8

4.1.2 Greek 10

4.2 Enumerating subscripts 10

5 Principle 10

6 Test method 11

6.1 General 11

6.2 Performance test of personal samplers for the inhalable aerosol fraction 11

6.3 Performance test of static samplers 11

6.4 Performance test of personal samplers for the respirable or thoracic aerosol fractions 11

6.5 Experiments required for the performance test 12

6.5.1 General 12

6.5.2 Candidate sampler bias 12

6.5.3 Candidate sampler variability 12

6.5.4 Excursion from the nominal flow rate 12

6.5.5 Collected mass or internally separated mass 13

7 Calculation of sampler bias and expanded uncertainty 14

7.1 Requirements 14

7.2 Correction factor 14

7.3 Calculation of concentration ratios 14

7.4 Sources of uncertainty (of measurement) 15

7.4.1 General 15

7.4.2 Workplace (test) aerosol concentration, as determined using the validated sampler(s) 15

7.4.3 Validated sampler 16

7.4.4 Candidate sampler bias 16

7.4.5 Individual candidate sampler variability 17

7.4.6 Excursion from the nominal flow rate 17

7.4.7 Collected mass or internally separated mass 18

7.5 Combined standard uncertainty 21

7.6 Expanded uncertainty 23

8 Periodic validation 23

9 Test report 23

9.1 General 23

9.2 Testing laboratory details and sponsoring organisation 24

9.3 Description of the candidate sampler and validated sampler 24

9.4 Critical review of sampling process 24

9.5 Circumstances of field experiment 24

9.6 Details of experimental design 24

9.7 Data analysis 25

9.8 Performance 25 9.9 Summary and information for the user 25 Annex A (normative) Procedure for a workplace comparison of a candidate sampler and a

validated sampler in order to obtain a correction factor 26 Bibliography 31

at the latest by December 2014

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document together with EN 13205-1, EN 13205-2, CEN/TR 13205-3, EN 13205-4 and EN 13205-6 supersedes EN 13205:2001

EN 13205, Workplace exposure — Assessment of sampler performance for measurement of airborne particle

concentrations, consists of the following parts:

— Part 1: General requirements;

— Part 2: Laboratory performance test based on determination of sampling efficiency;

— Part 3: Analysis of sampling efficiency data [Technical Report];

— Part 4: Laboratory performance test based on comparison of concentrations;

— Part 5: Aerosol sampler performance test and sampler comparison carried out at workplaces (the present

document);

— Part 6: Transport and handling tests

Significant technical changes from the previous edition, EN 13205:2001:

— This part of EN 13205 is partly based on Annex C of the previous edition, EN 13205:2001

— The scope has been limited to aerosol samplers, and the current version of the standard is not (directly) applicable to other types of aerosol instruments

— As this is now a standard in its own right, a clause on used symbols has been added Almost all

definitions are now given either in EN 1540, Workplace exposure — Terminology or in Part 1 of this

standard

— The method of calculating the uncertainty of a sampler or a measuring procedure has been revised in order to comply with ENV 13005 The concept of “accuracy” is no longer used, instead the concept of

“expanded uncertainty” is used

— The main part of the standard states how to determine the performance of an aerosol sampler at a specific workplace This is an adaption of the laboratory method given in Part 2

— The standard gives a method on how to determine the dependence of the sampling efficiency on the collected mass or internally separated mass

The five major sources of uncertainty due to aspects of the sampling performance of an aerosol sampler (calibration of sampler test system, estimation of sampled concentration, bias relative to the sampling

convention, individual sampler variability and excursion from nominal flow rate) are described with formulae on how to incorporate these uncertainties into the expanded uncertainty of a sampler

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, 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

EN 481 defines sampling conventions for the particle size fractions to be collected from workplace atmospheres in order to assess their impact on human health Conventions are defined for the inhalable, thoracic and respirable aerosol fractions These conventions represent target specifications for aerosol samplers, giving the ideal sampling efficiency as a function of particle aerodynamic diameter

In general, the sampling efficiency of real aerosol samplers will deviate from the target specification, and the aerosol mass collected will therefore differ from that which an ideal sampler would collect In addition, the behaviour of real samplers is influenced by many factors such as external wind speed In many cases there is

an interaction between the influence factors and fraction of the airborne particle size distribution of the environment in which the sampler is used

The workplace performance test for samplers for the inhalable, thoracic or respirable aerosol fractions described in this document is based on a comparison of concentrations sampled from a specific workplace (under otherwise identical conditions) by a candidate sampler and a (previously) validated sampler Additionally, a method is described for determining a correction factor for recalculation of the concentration determined with one sampler into that of the other at specific workplaces

This method is intended for the user, rather than the manufacturer, of aerosol samplers

EN 13205 (all parts) enables manufacturers and users of aerosol samplers to adopt a consistent approach to sampler validation, and provide a framework for the assessment of sampler performance with respect to

EN 481 and EN 482

It is the responsibility of the manufacturer of aerosol samplers to inform the user of the sampler performance under the laboratory conditions1) specified in EN 13205-1 It is the responsibility of the user to ensure that the actual conditions of intended use are within what the manufacturer specifies as acceptable conditions according to the performance test

1) The inhalable convention is undefined for particle sizes in excess of 100 µm or for wind speeds greater than 4 m/s The tests required to assess performance are therefore limited to these conditions Should such large particle sizes or wind speeds actually exist at the time of sampling, it is possible that different samplers meeting this part of EN 13205 give different results

1 Scope

This European Standard specifies a method for determining the performance of an aerosol sampler under prescribed workplace conditions in order to test whether the performance of a candidate sampler fulfils the requirements of EN 13205-1

This part of EN 13205 specifies also a simple method to determine how, for a specific workplace aerosol, the concentration measured by the candidate sampler can be recalculated into that of a validated sampler

This part of EN 13205 is applicable to all samplers used for the health-related sampling of particles in workplace air Different test procedures and types of evaluation are included to enable application of this part

of EN 13205 to a wide variety of instruments

The methods specified in this part of EN 13205 are not applicable to tests where the performance of personal samplers is related to static samplers or vice versa

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

EN 1540, Workplace exposure - Terminology

EN 13205-1:2014, Workplace exposure — Assessment of sampler performance for measurement of airborne

particle concentrations — Part 1: General requirements

EN 13205-2:2014, Workplace exposure — Assessment of sampler performance for measurement of airborne

particle concentrations — Part 2: Laboratory performance test based on determination of sampling efficiency

EN 13205-4:2014, Workplace exposure — Assessment of sampler performance for measurement of airborne

particle concentrations — Part 4: Laboratory performance test based on comparison of concentrations

3 Terms and definitions

For the purpose of this document, the term and definitions given in EN 1540, EN 13205-1:2014

EN 13205-2:2014 and the following apply

NOTE With regard to EN 1540, in particular, the following terms are used in this document: total airborne particles, respirable fraction, sampling efficiency, static sampler, thoracic fraction, inhalable fraction, measuring procedure, non-random uncertainty, random uncertainty, expanded uncertainty, standard uncertainty, combined standard uncertainty, uncertainty (of measurement), coverage factor, precision and analysis

3.1

correction function

mathematical function relating aerosol concentrations measured using a candidate sampler to those measured using a validated sampler, determined by a comparison of the two samplers

4 Symbols and abbreviations

4.1 Symbols

4.1.1 Latin

partial sampling period l in run r for sampling time t, [mg/m3]

COEL appropriate occupational exposure limit value (OEL) applying to the substances

being measured, [mg/m3]

Crtl concentration for partial sampling period l in run r, for sampling time t, [mg/m3]

time t = 3 extending from partial sampling period l1 to partial sampling period l2,

[mg/m3]

c candidate sampler correction factor for bias correction, either prescribed by

sampler manufacturer or measuring procedure, or assigned the value c = 1.00, [-]

mrtl average mass collected during partial sampling period l, in run r for sampling time t

(where t = 1,2,3 represents sampling times texp, texp/3 and texp/9 respectively), [mg]

(where t = 1,2,3 represents sampling times texp, texp/3 and texp/9, respectively), [mg]

sampling time t (where t = 1,2,3 represents sampling times texp, texp/3 and texp/9, respectively), [mg]

sampling time times nominal flow rate, [mg]

maximum total airborne particle (or inhalable fraction) concentration and maximum concentration expected to be sampled by candidate sampler times intended sampling time times nominal flow rate, [mg]

NRun number of experimental runs, pairs of (average) validated sampler and candidate

sampler concentrations

NSr number of candidate samplers used in experimental run r

NSrtl number of candidate samplers used with partial period l in run r for sampling time t

NValidr number of reference samplers (validated samplers) used in experimental run r

Q0 nominal flow rate of sampler, [l/min]

Q+ higher flow rate used for the candidate sampler in the performance test for the effect of flow excursions, [l/min]

Q- lower flow rate used for the candidate sampler in the performance test for the effect of flow excursions, [l/min]

Rg geometric mean of the Rrs values, [-]

Rrs ratio of the candidate sampler individual s concentration in experimental run r to

the (average) workplace (test) aerosol concentration in experimental run r, [-]

averR r ratio of the average candidate sampler concentration to the (average) workplace

(test) aerosol concentration in experimental run r, [-]

rrtl relative concentration (ratio with respect to the time-weighted concentration

measured with candidate sampler with the shortest sampling time) for experiment

r, sampling time t and partial sampling period l, [-]

sR geometric standard deviation of the Rrs values, [-]

sampler(s) for experimental run r and candidate sampler individual s, [-]

texp experimental sampling time for tests described in 6.5.5 based on estimated

average concentration at workplace, [min]

t rtl actual time of partial sampling period l for set t in experiment r, [min]

due to the candidate sampler, [-]

due to the candidate sampler, [-]

to the sampling convention of the candidate sampler, [-]

errors) due to mass collected by the candidate sampler, [-]

excursion from nominal flow rate, [-]

(non-random errors) by the candidate sampler, [-]

(non-random errors) due to the candidate sampler, [-]

errors) due to the candidate sampler, [-]

errors) due to differences among candidate sampler individuals, [-]

errors) at the position of candidate samplers during experiments, [-]

Xrs measured candidate sampler concentration for candidate sampler individual s, for

the run (workplace (test) aerosol concentration) r, [mg/m3]

averX r average of the measured candidate sampler concentrations for the run (workplace

(test) aerosol concentration) r, [mg/m3]

Yrs workplace (test) aerosol concentration (measured with a validated sampler) for the

reference sampler individual s, for the run (workplace (test) aerosol concentration)

r, [mg/m3]

Yrs* corrected concentration measured by the candidate sampler individual s, for the

run experiment (workplace (test) aerosol concentration) r, [mg/m3 averY r average of the concentrations measured with validated samplers for the run

(workplace (test) aerosol concentration) r, [mg/m3]

YEst-Collected regression formula for the ratio rrtl as a function of mCollected =Collectedaver mrtl, [-]

y = f(x) correction function that relates the concentration measured with the candidate

sampler to those measured with the (average of) validated sampler(s), [ln(mg/m3)]

4.1.2 Greek

δPump maximum relative change in flow rate allowed by pump flow

rate stability, [-]

4.2 Enumerating subscripts

l for partial sampling periods

l1 for first partial sampling period in summation

l2 for last partial sampling period in summation

s for candidate sampler individual

t for sampling time (where t = 1,2,3 represents sampling times texp, texp/3 and texp/9

respectively)

5 Principle

The test method described in this part of EN 13205 is based on concentrations measured at a specific workplace by the candidate sampler, whether all aspirated particles are part of the sample (as for most inhalable samplers) or if a particle size-dependent penetration occurs between the inlet and the collection substrate (as for thoracic and respirable samplers)

The purpose of determining the performance of a candidate sampler at a workplace is to enable the user of the samplers to carry out measurements of dust concentration with samplers that have not been evaluated in laboratory tests according to this part of EN 13205 The validated sampler and candidate sampler shall both

be either personal or static samplers

The bias versus the sampling convention is determined by comparing the concentrations determined with the candidate sampler and a validated sampler Other sampling errors due to non-random and random sources of error are also determined, for example, individual sampler variability, excursion from nominal flow rate and experimental errors

Analysis of the field data is carried out to determine the performance of the candidate sampler The performance will be specific to the workplace activities included in the performance test and cannot be assumed to apply to different circumstances

The criteria for accepting the performance of the sampler is identical to those for a laboratory test for performance evaluation If the performance is poor, this will probably be due to either that the inherent variability at the workplace is exceedingly large, or by including too wide a range of workplace activities in the test, rather than too poor performance by the sampler In the first case the large variability can only be reduced by averaging over several sampler individuals, which can be difficult with personal samplers In the second case the performance test shall be repeated for a more narrowly-defined group of exposed persons or workplace activities, until an adequate degree of equivalence is established In some workplaces the nature or organisation of the work can make this impossible

NOTE The variability of the concentration at many workplaces can prove to be so large that it becomes impossible to determine a performance (expanded uncertainty) within the bounds specified by EN 482 To try to determine the (hopefully low) combined standard uncertainty of the sampler in the midst of an inherently large variability at the workplace can,

however, prove to be very cumbersome Such an endeavour would need an extensive experimental design in order to extract the information needed for the calculations described in this part of EN 13205

6 Test method

6.1 General

Pairs of measurements are obtained with both validated sampler individual(s) and candidate sampler individual(s) (preferably more than one individual for both the validated sampler and the candidate sampler), exposed to the same aerosol The number of pairs of measurements (experimental runs) obtained shall be as large as possible and never less than 10 The measurements shall cover the range of aerosol properties, concentrations and environmental conditions occurring at the sampling sites, and be obtained over a period of

at least five days (although a larger number of days is preferred)

Both the validated and the candidate sampler(s) shall be operated in accordance with the instructions given in the manufacturer's instruction manual for the sampler types Any deviations from these instructions shall be documented in the performance test report Only those samples obtained in accordance with documented operating procedures shall be regarded as valid and included in the data analysis

In order for the candidate sampler to be termed a validated sampler (type C) its performance shall meet the requirements of EN 13205-1:2014, 5.2 c)

6.2 Performance test of personal samplers for the inhalable aerosol fraction

For each person selected, both the validated and candidate samplers shall be worn, positioned at their normal sites of use (e.g shaller/lapel/collar bone) Both samplers shall be positioned as closely together as possible without mutual interference or deviation from their normal positions It is important to assign the validated sampler and candidate sampler randomly to the measurement positions to avoid positional bias in the results Personal samplers for the inhalable aerosol fraction can be compared using a life-size mannequin located close to a worker, but not disturbing his/her work CALTOOL is an example of such a designed mannequin2) The use of a mannequin makes it easier to perform a test based on several validated sampler individuals and candidate sampler individuals, whose concentrations may be averaged for each measured concentration

6.3 Performance test of static samplers

The inlets of the validated sampler and the candidate sampler shall be positioned as closely together as possible without mutual interference In the case of samplers with directional inlets, the position with respect to external air currents shall be the same for all samplers

Reference aerosol concentrations at the inlet of the candidate sampler can be obtained by averaging the results of several validated samplers An example of this approach is to place the candidate sampler at the centre of an equilateral triangle, and to place three validated samplers at the vertices If tests are carried out using pairs of samplers placed at various sites, then each test shall be repeated with the positions of the samplers reversed, to avoid positional bias

6.4 Performance test of personal samplers for the respirable or thoracic aerosol fractions

Candidate personal samplers for the respirable or thoracic aerosol fractions may be tested as static samplers

as the particle size distribution of these two fractions only varies very slowly with the distance from the worker

A static test has the advantage that several candidate samplers (and validated samplers) can easily be exposed to a very similar concentration A way to do this is by mounting the candidate and validated samplers

inside a vertically mounted barrel/canister that shields the candidate samplers/validated samplers from the spatially varying concentration at a workplace The entrance to the barrel/canister shall face vertically and be small enough that the concentration across the inlet would be spatially homogeneous The inlet orifices of the candidate samplers shall all be at the same height inside the barrel/canister and at the same radial distance from the axis No extra suction is required apart from that sustained from the samplers in the test For such a barrel/canister it shall be verified that the aerosol aspiration/transport losses from the outside to the inlets of the candidate and validated samplers do not reduce the size distribution of the workplace aerosol in such a way that it becomes almost completely respirable or thoracic, respectively, as this would inhibit any test of the penetration of the candidate samplers

6.5 Experiments required for the performance test

6.5.1 General

Make a critical review of the sampling process in order to determine whether any of the uncertainty sources sampler bias, candidate sampler variability, flow excursion or sampled/ internally separated mass can influence the measured concentration by the candidate sampler If the critical review shows that any of the listed sources of uncertainty to be without influence, the corresponding uncertainty components may be determined without any experiment performed

Four sets of experiments need to be carried out in order to determine the necessary error components Each experiment is based on parallel sampling and shall consist of at least five runs:

— parallel runs between the validated sampler and the candidate sampler, possibly using several sampler individuals for each sampler(see 6.5.2);

— parallel runs among at least six candidate personal sampler specimen (see 6.5.3);

— parallel runs to determine the effect on sampled mass fraction by flow rate excursions from the nominal flow rate (see 6.5.4);

— parallel runs to determine any effect of collected mass or internally separated mass (see 6.5.5)

In the first and the third experiment a validated sampler (type A) is needed (see EN 13205-1)

6.5.2 Candidate sampler bias

In the evaluation of this error component, outliers may be eliminated from the calculation, though at least 10 pairs of validated sampler concentration and candidate sampler individual shall be retained from (at least) five different experimental runs, see 7.2

Due to the wide variability between workplaces it is not possible to give a definitive statement on an outlier or the probability for inaccurate rejection The method to specify outliers has to be selected and reported by the user

6.5.3 Candidate sampler variability

This test is required neither for candidate personal samplers for the inhalable sampling convention nor for large static samplers For these samplers the corresponding uncertainty component is put equal to zero

6.5.4 Excursion from the nominal flow rate

This test is not required for candidate samplers for the inhalable fraction For samplers for the thoracic and respirable fractions, the corresponding uncertainty component is determined according to 7.4.6.2

NOTE The dependence of the aspiration efficiency of a sampler on the flow rate is usually very low in the low wind speeds characterising workplaces indoors The effect can be estimated using the theory for calm air aspiration efficiency

by Su and Vincent, see Bibliography [4] and [5]

In each run, employ one third of the candidate samplers to each of the three flow rates on which this test is based (see EN 13205-4:2014, 6.3.8) Use at least two candidate sampler individuals for each of the flow rates

6.5.5 Collected mass or internally separated mass

The two tests for collected mass and internally separated mass are similar and may be performed simultaneously, though the second test will not be applicable for samplers of the inhalable aerosol fraction Begin by determining/estimating for the workplace in the first case the maximum concentration of the sampling convention in question and in the second case the maximum total airborne particle concentration aspirated by the sampler with internal separation

NOTE This maximum concentration can be limited to twice a relevant occupational exposure limit However, the relevant occupational exposure limit for a respirable sampler, for example used for sampling quartz (crystalline silica) would be that of, for example, respirable inorganic dust not otherwise classified, rather than quartz (crystalline silica) itself

Determine the maximum collected mass, maxmCollected, by multiplying the maximum concentration with the nominal flow rate of the candidate sampler and the intended sampling time when using the candidate sampler

at the workplace Determine the maximum internally separated mass, maxmInternSep , by multiplying the difference between the maximum total airborne particle (or inhalable aerosol fraction) concentration and the maximum concentration expected to be sampled by candidate sampler, with the nominal flow rate of the candidate sampler and the intended sampling time when using the candidate sampler at the workplace, respectively

When the tests are performed the concentrations are presumably lower than the estimated maximum

concentration Calculate from the maximum collected mass an experimental sampling time, texp, based on an expected average concentration at the workplace This experimental sampling time can extend over more than one working shift The pumps used have to be selected in accordance with this test condition, or the sampling period split up into parts, with fresh pumps for each part

This experiment requires three sets of (at least two) candidate sampler individuals:

— the first set is operated throughout the experimental sampling time, texp

— the second set consists of three subsets of candidate sampler individuals Each subset is only operated

for approximately one third of the experimental sampling time, texp /3 (in order to collect approximately one third of the mass collected of the first set), and is then replaced with a fresh subset of candidate sampler individuals (i.e cleaned, and dried, sampler individuals loaded with unused collection substrates) for the next third of the experimental sampling time

— the third set consists of nine subsets of candidate sampler individuals Each subset is only operated for

approximately one ninth of the experimental sampling time, texp /9 (in order to collect approximately one ninth of the mass collected of the first set), and then replaced with a fresh subset of candidate samplers individuals (i.e cleaned, and dried, sampler individuals loaded with unused collection substrates) for the next ninth of the experimental sampling time

The calculated sampling times are only indicative When sampling occurs at the workplace it is expected that the concentration will vary considerably It is important to try to obtain similar sampled/internally separated

mass for each collection substrate in the same set per run r Therefore the actual sampling times during

sampling may be increased during times of lower aerosol concentrations and decreased during higher aerosol concentrations in order to obtain similar sampled/internally separated masses The actual experimental

The experimental sampling time shall not be allowed to become so short that analytical error can significantly influence the sampled concentrations for the third set of candidate samplers, that is those only operated for

repeated periods of texp /9

For the test on the effect of internally separated mass at least two samplers for the total airborne particle concentration shall also be employed This concentration may be estimated by the concentration of the inhalable aerosol fraction These samplers shall be replaced with fresh sampler individuals simultaneously as those of the second set of candidate samplers, that is those only operated for repeated periods of texp 3

7 Calculation of sampler bias and expanded uncertainty

7.1 Requirements

The requirements for the expanded standard uncertainty of candidate sampler tested with a type C test are given in EN 13205-1:2014, 5.2 c)

7.2 Correction factor

A correction factor, c [-], stated either in the manufacturer’s instructions for use or in the relevant measuring

procedure shall be applied to the sampled concentrations No other correction factor may be applied to the

sampled concentrations If no correction factor is stated, c, is assigned a value of 1,00 The value chosen for c

shall be clearly stated in the sampler test report

7.3 Calculation of concentration ratios

Designate the concentrations measured with the candidate sampler in experimental run r using candidate sampler individual s as Xrs Designate the concentrations measured with the validated sampler in

experimental run r using validated sampler individual s as Yrs Calculate the concentration ratio for each candidate sampler individual from Formula (1):

Rrs= Xrs

where

Rrs is the concentration ratio for candidate sampler s in run r;

Xrs is the concentration measured with candidate sampler individual s in run r;

Yr is the (average of the

NValidr ) concentration measured with the validated sampler(s) in run r;

NValidr is the number of validated samplers in run r

Exclude pairs (of averages) for which ratios Rrs > 10 or Rrs< 0.1 from further analysis, provided a) no more than one pair of results is excluded for every 10 pairs of data points; and b) there are at least 10 un-excluded

ratios for 5 different experimental runs r

Calculate the average concentration ratio for each experimental run r from Formula (2):

NSr is the number of tested candidate samplers in run r;

Rrs is the concentration ratio for candidate sampler s in run r;

averRr is the average concentration ratio for run r

7.4 Sources of uncertainty (of measurement)

7.4.1 General

The expanded uncertainty as determined in a workplace experiment can be analysed according to a modified version of EN 13205-4:2014, 8.3

The following sources of uncertainty (of measurement) shall be evaluated:

— reference concentration, as determined using the validated sampler(s) (see 7.4.2);

— reference sampler (see 7.4.3);

— candidate sampler bias (see 7.4.4);

— individual candidate sampler variability (see 7.4.5);

— excursion from the nominal flow rate (see 7.4.6); and

— collected mass or internally separated mass (see 7.4.7)

7.4.2 Workplace (test) aerosol concentration, as determined using the validated sampler(s)

Any possible inhomogeneity of the workplace (test) aerosol concentration in the test system shall be evaluated separately The calculation of the uncertainty describing the inhomogeneity depends on how it was evaluated

NOTE 1 Such methods can be found in text books on statistical methods

Calculate the standard uncertainty (of measurement) for the validated concentration weighted over all runs r

NRun is the number of experimental runs;

NValidr is the number of validated samplers used in run r;

sValidConcrs is the relative uncertainty of workplace (test) aerosol concentration at the position of the

candidate sampler(s) for experimental run r and candidate sampler individual s; and

uValidConc is the standard uncertainty (of measurement) of the validated concentration at the position of

candidate samplers during experiments

NOTE 2 If the workplace (test) aerosol concentration is averaged from

NValidr validated samplers, the random uncertainty components of the workplace (test) aerosol concentrations is reduced by a factor of

1 NValidr

7.4.3 Validated sampler

The random uncertainties due to the experiment and the measured workplace (test) aerosol concentration, as determined by the validated sampler, will incorporate the random uncertainties of the validated sampler Only the non-random uncertainty components of the validated sampler uncertainty, uValidSampl-nR, are needed This component consists of the sources termed “calibration of sampler test system”, “bias relative to the sampling convention” and “excursion from the nominal flow rate” When the performance of the validated sampler was determined, these three entities would have been determined according to EN 13205-2:2014, 8.4.2, 8.4.4 and 8.4.6, respectively

If the variation of the validated sampler individual(s) due to flow deviations are controlled in the experiment by strictly controlling/verifying its (their) flow rate(s), the non-random source of uncertainty due to flow excursion from the nominal flow rate can be disregarded for the validated sampler The remaining non-random sources

of uncertainty of the validated sampler (see EN 13205-2:2014, 8.4.2 and 8.4.6) shall be obtained from the performance test report of the validated sampler The main source of non-random uncertainty for the validated sampler would then be its bias relative to the sampling convention

NOTE If the non-random standard uncertainty of the validated sampler is dominated by the bias term, this standard uncertainty can be significantly reduced if the size distribution of the aerosol of the experiments is determined Based on knowledge of the sampled size distribution and the bias of the validated sampler (as a function of particle size distribution)

it would be possible to estimate a true concentration according to the convention, and thus this uncertainty would be significantly reduced (see CEN/TR 15547)

7.4.4 Candidate sampler bias

The bias standard uncertainty is calculated from Formula (4)

c is the correction factor;

NRun is the number of experimental runs;

NSr is the number of candidate samplers used per experiment at run r;

Rrs is the concentration ratio of the candidate sampler; and

uCandSampl-Bias is the standard uncertainty (of measurement) due to the sampler’s bias relative to the

sampling convention