Health and safety in welding and allied processes - Requirements, testing and marking of equipment for air filtration - Part 3: Determination of the capture efficiency of on-torch welding fume extraction devices (ISO 21904-3:2018)

ISO 21904-3:2018 defines a laboratory method for measuring the welding fume capture efficiency of on-torch extraction systems. The procedure only prescribes a methodology, leaving selection of the test parameters to the user, so that the effect of different variables can be evaluated.
ISO 21904-3:2018 is applicable to integrated on-torch systems and to systems where a discrete extraction system is attached to the welding torch close to the arc area. The methodology is suitable for use with all continuous wire welding processes, all material types and all welding parameters.
The method can be used to evaluate the effects of variables such as extraction flow rate, extract nozzle position, shielding gas flow rate, welding geometry, welding torch angle, fume emission rate, etc., on capture efficiency.

Arbeits- und Gesundheitsschutz beim Schweißen und bei verwandten Verfahren - Anforderungen, Prüfung und Kennzeichnung von Luftreinigungssystemen - Teil 3: Bestimmung des Erfassungsgrades von brennerintegrierten Absaugeinrichtungen für Schweißrauch (ISO 21904-3:2018)

Dieses Dokument legt ein Laborverfahren zur Bestimmung des Erfassungsgrades von brennerinte¬grierten Absaugeinrichtungen für Schweißrauch fest. Das Verfahren schreibt ausschließlich eine Methodik vor und überlässt die Auswahl der Prüfparameter dem Anwender, sodass die Auswirkungen der verschiedenen Variablen evaluiert werden können.
Es ist anwendbar auf brennerintegrierte Systeme und Systeme, bei denen eine eigenständige Absauganlage am Schweißbrenner nahe des Lichtbogen Bereiches angebracht ist. Das Verfahren eignet sich für den Einsatz bei allen kontinuierlichen Drahtschweißverfahren, allen Materialtypen und allen Schweißparametern.
Das Verfahren kann angewendet werden, um die Auswirkungen von Variablen wie Absaugdurchflussrate, Position der Absaugdüse, Schutzgasdurchfluss, Schweißgeometrie, Schweißbrennerwinkel, Rauchemissions¬rate usw. auf den Erfassungsgrad zu bestimmen.

Hygiène et sécurité en soudage et techniques connexes - Exigences, essais et marquage des équipements de filtration d'air - Partie 3: Détermination de l'efficacité de captage des torches aspirantes (ISO 21904-3:2018)

ISO 21904-3:2018 définit une méthode de mesure en laboratoire de l'efficacité de captage des fumées de soudage des torches aspirantes. Le mode opératoire spécifie seulement une méthodologie, en laissant à l'utilisateur le choix des paramètres d'essai, afin de pouvoir évaluer l'effet de différentes variables.
ISO 21904-3:2018 est applicable aux systèmes à torche intégrée et aux systèmes dans lesquels un système d'extraction distinct est attaché à la torche de soudage à proximité de la zone d'arc. La méthodologie convient pour une utilisation avec tous les procédés de soudage à dévidement de fil continu, pour tous les types de matériaux et tous les paramètres de soudage.
La méthode peut servir à évaluer les effets sur l'efficacité de captage de variables, telles que le débit d'extraction, la position de la buse d'extraction, le débit du gaz de protection, la géométrie de soudage, l'angle de la torche de soudage, le taux d'émission de fumées, etc.

Zdravje in varnost pri varjenju in sorodnih tehnikah - Zahteve, preskušanje in označevanje opreme za filtriranje zraka - 3. del: Ugotavljanje učinkovitosti vgrajenih naprav na gorilniku za odsesavanje plinov pri varjenju (ISO 21904-3:2018)

Ta standard opredeljuje laboratorijsko metodo za merjenje učinkovitosti zajema varilnega dima vgrajenih sistemov na gorilniku za odsesavanje plinov pri varjenju. Uporablja se za vgrajene sisteme na gorilniku in sisteme, pri katerih je ločen sistem za odsesavanje pritrjen na gorilnik za varjenje poleg obloka. Metodologija je primerna za uporabo z vsemi neprekinjenimi postopki varjenja z žico, vsemi vrstami materialov in vsemi parametri varjenja.
Metodo je mogoče uporabljati za ocenjevanje učinkov spremenljivk, kot so hitrost pretoka odsesavanja, položaj šobe za odsesavanje, hitrost pretoka zaščitnega plina, geometrija zvarov, kot gorilnika za varjenje in stopnja emisij dima, na učinkovitost zajema.

General Information

Status
Published
Publication Date
20-Mar-2018
Technical Committee
Drafting Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
21-Mar-2018
Completion Date
21-Mar-2018

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SLOVENSKI STANDARD
SIST EN ISO 21904-3:2018
01-oktober-2018
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R]QDþHYDQMHRSUHPH]DILOWULUDQMH]UDNDGHO8JRWDYOMDQMHXþLQNRYLWRVWL
YJUDMHQLKQDSUDYQDJRULOQLNX]DRGVHVDYDQMHSOLQRYSULYDUMHQMX ,62


Health and safety in welding and allied processes - Requirements, testing and marking of

equipment for air filtration - Part 3: Determination of the capture efficiency of on-torch

welding fume extraction devices (ISO 21904-3:2018)
Arbeits- und Gesundheitsschutz beim Schweißen und bei verwandten Verfahren -
Anforderungen, Prüfung und Kennzeichnung von Luftreinigungssystemen - Teil 3:
Bestimmung des Erfassungsgrades von brennerintegrierten Absaugeinrichtungen für
Schweißrauch (ISO 21904-3:2018)
Hygiène et sécurité en soudage et techniques connexes - Exigences, essais et

marquage des équipements de filtration d'air - Partie 3: Détermination de l'efficacité de

captage des torches aspirantes (ISO 21904-3:2018)
Ta slovenski standard je istoveten z: EN ISO 21904-3:2018
ICS:
13.100 Varnost pri delu. Industrijska Occupational safety.
higiena Industrial hygiene
25.160.01 Varjenje, trdo in mehko Welding, brazing and
spajkanje na splošno soldering in general
SIST EN ISO 21904-3:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21904-3:2018
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SIST EN ISO 21904-3:2018
EN ISO 21904-3
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2018
EUROPÄISCHE NORM
ICS 13.100; 25.160.01
English Version
Health and safety in welding and allied processes -
Requirements, testing and marking of equipment for air
filtration - Part 3: Determination of the capture efficiency
of on-torch welding fume extraction devices (ISO 21904-
3:2018)

Hygiène et sécurité en soudage et techniques connexes Arbeits- und Gesundheitsschutz beim Schweißen und

- Exigences, essais et marquage des équipements de bei verwandten Verfahren - Anforderungen, Prüfung

filtration d'air - Partie 3: Détermination de l'efficacité und Kennzeichnung von Luftreinigungssystemen - Teil

de captage des torches aspirantes (ISO 21904-3:2018) 3: Bestimmung des Erfassungsgrades von

brennerintegrierten Absaugeinrichtungen für
Schweißrauch (ISO 21904-3:2018)
This European Standard was approved by CEN on 1 March 2018.

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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21904-3:2018 E

worldwide for CEN national Members.
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SIST EN ISO 21904-3:2018
EN ISO 21904-3:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 21904-3:2018
EN ISO 21904-3:2018 (E)
European foreword

This document (EN ISO 21904-3:2018) has been prepared by Technical Committee ISO/TC 44 "Welding

and allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding and allied

processes”, the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by September 2018, and conflicting national standards

shall be withdrawn at the latest by September 2018.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 21904-3:2018 has been approved by CEN as EN ISO 21904-3:2018 without any

modification.
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SIST EN ISO 21904-3:2018
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SIST EN ISO 21904-3:2018
INTERNATIONAL ISO
STANDARD 21904-3
First edition
2018-02
Health and safety in welding and
allied processes — Requirements,
testing and marking of equipment for
air filtration —
Part 3:
Determination of the capture
efficiency of on-torch welding fume
extraction devices
Hygiène et sécurité en soudage et techniques connexes — Exigences,
essais et marquage des équipements de filtration d'air —
Partie 3: Détermination de l'efficacité de captage des torches
aspirantes
Reference number
ISO 21904-3:2018(E)
ISO 2018
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Test equipment and materials ............................................................................................................................................................... 2

5.1 General requirement .......................................................................................................................................................................... 2

5.2 Test equipment ....................................................................................................................................................................................... 2

6 Test procedure ........................................................................................................................................................................................................ 4

6.1 Preliminary tests ................................................................................................................................................................................... 4

6.1.1 Setting the shielding gas flow rate .................................................................................................................... 4

6.1.2 Measuring the flow rates and determination of leakage ............................................................... 4

6.1.3 Establishing the arcing time for total fume emission rate test ................................................ 5

6.1.4 Setting up the test equipment .............................................................................................................................. 5

6.2 Capture efficiency tests .................................................................................................................................................................... 6

6.2.1 General...................................................................................................................................................................................... 6

6.2.2 Test procedure ................................................................................................................................................................... 6

6.2.3 Calculation of the results .......................................................................................................................................... 7

7 Test parameters for generating capture efficiency data ............................................................................................. 8

8 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Equipment notes .......................................................................................................................................................10

Annex B (normative) Trial tests .............................................................................................................................................................................12

Annex C (informative) Examples of test chambers .............................................................................................................................14

Annex D (normative) Test procedures.............................................................................................................................................................16

Annex E (informative) Data processing for test method 3 ..........................................................................................................17

Annex F (normative) Test parameters form to be filled ................................................................................................................19

Annex G (informative) Information about the necessity to measure leakage ........................................................20

Bibliography .............................................................................................................................................................................................................................21

© ISO 2018 – All rights reserved iii
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 44, Welding and allied processes,

Subcommittee SC 9, Health and safety.
A list of all parts in the ISO 21904 series can be found on the ISO website.

Requests for official interpretations of any aspect of this document should be directed to the Secretariat

of ISO/TC 44/SC 9 via your national standards body. A complete listing of these bodies can be found at

www .iso .org.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Introduction

Welding generates fumes and gases which, if inhaled, can be harmful to human health. Therefore,

control of the fume and gases needs to be exercised to minimize worker exposure.

The most effective method of welding fume control is local exhaust ventilation (LEV) which captures

the fumes at source before they enter the general environment and the breathing zone of workers.

One form of LEV used in welding is on-torch extraction in which the extraction system is either an

integral part of the welding torch or is attached to it close to the arc area. Anecdotal evidence within the

fabrication industry suggested that it is impossible to capture fume efficiently while maintaining weld

metal integrity but research (see Bibliography entry [6]) has shown this not to be the case, certainly as

far as weld metal porosity is concerned.

It has been presumed in the drafting of this document that appropriately qualified and experienced

people would execute its provisions and interpret the results obtained.
© ISO 2018 – All rights reserved v
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SIST EN ISO 21904-3:2018
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SIST EN ISO 21904-3:2018
INTERNATIONAL STANDARD ISO 21904-3:2018(E)
Health and safety in welding and allied processes —
Requirements, testing and marking of equipment for air
filtration —
Part 3:
Determination of the capture efficiency of on-torch
welding fume extraction devices
1 Scope

This document defines a laboratory method for measuring the welding fume capture efficiency of on-

torch extraction systems. The procedure only prescribes a methodology, leaving selection of the test

parameters to the user, so that the effect of different variables can be evaluated.

It is applicable to integrated on-torch systems and to systems where a discrete extraction system

is attached to the welding torch close to the arc area. The methodology is suitable for use with all

continuous wire welding processes, all material types and all welding parameters.

The method can be used to evaluate the effects of variables such as extraction flow rate, extract nozzle

position, shielding gas flow rate, welding geometry, welding torch angle, fume emission rate, etc., on

capture efficiency.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 15767, Workplace atmospheres — Controlling and characterizing uncertainty in weighing collected

aerosols
ISO/IEC Guide 98 (all parts), Uncertainty of measurement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
test chamber

semi-enclosed extracted chamber in which welding fume capture efficiency testing is performed

3.2
isokinetic sampler

device for collecting aerosol samples at the same velocity as the air being sampled

© ISO 2018 – All rights reserved 1
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
3.3
test chamber sampling duct

duct between the test chamber and an extraction fan in which all the fume generated can be collected

or sampled isokinetically
3.4
emission rate
mass of the particles emitted by the welding fume source per unit time
Note 1 to entry: The emission rate is expressed in mg/s.
4 Principle

Automatic welding is performed using the on-torch extraction torch under test, on a test piece, inside

a continuously extracted test chamber. Testing is carried out using identical welding parameters with

and without the on-torch extraction activated. The ratio of measurements in the test chamber sampling

duct is used to calculate the capture efficiency of the on-torch extraction torch.

Three methods of measuring the fume can be used. Two methods employ gravimetric measurement.

The first method measures the total fume generated while second method employs isokinetic sampling

in the test chamber sampling duct. The third method employs a direct reading measuring technique in

the test chamber sampling duct.
5 Test equipment and materials
5.1 General requirement

The test setup shall enable containment of the fume generated in the arc area within the test chamber

while ensuring the air velocity in the welding area below the torch does not exceed 0,2 m/s without

welding and with the on-torch extraction off. See also B.1.

NOTE It is possible that not all of the fume generated by spatter production be contained within the test

chamber.
5.2 Test equipment

5.2.1 Test chamber, constructed of materials that withstand close proximity to the heat and spatter

generated by the welding or designed so that the materials used are sufficiently distant from the arc to

avoid problems arising from heat and spatter generation. See Figures C.1 and C.2.

Compliance with the requirements of 5.1 shall be verified.
5.2.2 Isokinetic samplers.

The sample flow rate shall be such that the velocity through the sample inlet is the same as the

surrounding air velocity.
This ensures that:
— the particle size distribution is not affected by the sampling process; and

— the sample represents the particles present in the sampling duct. See also B.2 and B.3.

5.2.3 Total fume and isokinetic filters, manufactured from glass or quartz fibre, with particle

retention properties down to approximately 1 µm to 2 µm.

The filters shall not tear or perforate during testing (see A.2) and shall not be so friable that fibres can

be lost from the filters during handling.
2 © ISO 2018 – All rights reserved
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Filters shall be treated according to the procedures defined in ISO 15767.

5.2.4 Extraction fan, capable of maintaining a constant flow rate (±2 %) in the test chamber sampling

duct during testing when using during testing with isokinetic sampling or direct reading equipment.

The air flow generated by the fan shall be capable of retaining the entire fume generated within the test

chamber (see A.3).

5.2.5 On-torch extraction unit, capable of maintaining a constant flow rate (±2 %) in the on-torch

extraction line during testing.

5.2.6 Equipment for measuring welding current, welding voltage, wire feed speed and arcing

time, capable of measuring the current, voltage, wire feed speed and arcing time within ±1 %.

Electronic integrating equipment with frequent sampling intervals and a logging capability is

recommended.

In the absence of such equipment, current may be measured using a shunt or a Hall effect probe

connected to a moving coil meter. Voltage may be measured using a moving coil meter. Wire feed speed

may be determined by measuring the length of wire exiting the welding torch in a measured time.

5.2.7 Equipment for direct-reading of fume concentration, with a reading that is directly

proportional to the fume concentration with a maximum linearity error of 5 % over the expected

concentration range.

NOTE Equipment suitable for direct-reading of fume concentration is described for example in

CEN/TR 16013.
5.2.8 Equipment for measuring the mass of fume collected.

— Balance capable of measuring the mass of isokinetic sample filters and isokinetic sample filters

plus fume with an accuracy of ±0,01 mg or better.

— Balance capable of measuring the mass of total fume collection filters and total fume collection

filters plus fume with an accuracy of ±1 mg or better.

5.2.9 Equipment for measuring shielding gas volume flow rate, calibrated for the shielding gas in

use, capable of measuring the volume flow rate to within ±5 % or better. See A.4.

5.2.10 Device for automatic welding, permitting the capture efficiency test to be performed under

automated conditions, capable of advancing the test piece under a stationary welding torch at an

appropriate rate (welding speed).

It shall be possible to secure the test piece to the device, such that it cannot bow during welding.

5.2.11 Device for measuring contact tip to workpiece distance (CTWD).

— Gauge, made by machining a metal block to a thickness equivalent to the required CTWD to within

±5 % or better; or
— Metal wedge with distance markings at appropriate points.

5.2.12 Device for measuring static pressure, capable of measuring static air pressure in the on-torch

extraction line with an uncertainty of measurement not exceeding ±1 % of the reading. See A.6.

5.2.13 Device for measuring the mass flow rate to an accuracy of ±5 % or better (e.g. according to

ISO 5167). See A.7.
© ISO 2018 – All rights reserved 3
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)

5.2.14 Test pieces, of a material and dimensions that are suitable for the capture efficiency test to be

carried out, that allow a weld of sufficient length to be continuously deposited. See A.5.

The same batch of filler wire and test pieces shall be used for each test series.

6 Test procedure
6.1 Preliminary tests
6.1.1 Setting the shielding gas flow rate
Set the shielding gas flow rate using the equipment described in 5.2.9.
6.1.2 Measuring the flow rates and determination of leakage

Measure the mass flow rate at two points shown in Figure 1, without welding, by using appropriate

devices and calculate the air volume flow rate. See also A.7 and Annex G.
Key

1 device to permit mass flow rate measurement at extraction inlet on the connector of the torch

2 measurement point of the mass flow rate at the connector Q
m,c
3 connection between the torch and the extraction system
4 on-torch extraction torch

5 device to permit mass flow rate measurement at extraction inlet on the torch (see A.7)

6 measurement point of the mass flow rate at the nozzle Q
m,n
7 sealing
Airflow.
Figure 1 — Points for measuring the flow rate
QQ−
m,cm,n
The leakage ratio is
m,c
where
Q is the mass flow rate in the nozzle;
m,n
Q is the mass flow rate in the connector.
m,c
4 © ISO 2018 – All rights reserved
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)

From Q and Q , the volume flow rates (Q and Q ) are calculated with the theoretical conditions

m,n m,c v,n v,c
of temperature and pressure of 20 °C and 101 325 Pa (1 013,25 hPa):
Q =
where ρ is the air density at 20 °C = 1,204 kg/m .
6.1.3 Establishing the arcing time for total fume emission rate test
Follow the procedure stated in B.4.
6.1.4 Setting up the test equipment

Set up the test equipment as shown in Figure 2, in an interference-free environment (see A.8).

© ISO 2018 – All rights reserved 5
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Key
1 method 1 (total mass measurement), according to Table 1
2 method 2 (isokinetic sampling with a weighed filter), according to Table 1

3 method 3 (direct reading in the duct or after isokinetic sampling), according to Table 1

4 flowrate measurement at connector of the torch
5 static pressure measurement
6 total fume filter
7 welding unit
8 sample filter
9 direct reading instrument
10 flowrate measurement in sampling duct
11 extraction fan
12 on-torch extraction unit fan
Figure 2 — Setup for the different measurement methods
6.2 Capture efficiency tests
6.2.1 General

Before starting the capture efficiency test, make sure that all welding conditions and flow rates are set

to the desired values by performing trial tests. Guidance on performing trial tests is given in Annex B.

6.2.2 Test procedure

The steps for carrying out the three different test methods are given in Table 1. For the setup for the

different measurement methods, see Figure 2.
6 © ISO 2018 – All rights reserved
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Table 1 — Test procedure
Step
Method 1 Method 2 Method 3
number
1 Switch on the on-torch extraction unit.

Measure and record the static pressure at the entry to the extraction system on the welding

torch. See A.6.

Measure and record the air flow rate at the entry to the extraction system on the welding torch.

See A.7.
Position the probe in the
Install a pre-weighed filter in the appropriate position, see
4 appropriate position, see
Figure 2.
Figure 2.

Renew or reposition the test piece so that the next weld will be on unused material.

Check that the CTWD is correct, see Annex D.

Position the test piece under the torch, ready to commence welding, at least 25 mm from any

edge. Switch on the extraction fan to the test chamber (5.2.1). Check the flow rate and, if neces-

sary, adjust to the value established according to B.2.
Switch on the pump for the
Start to record the
6 isokinetic sampler. Check and
concentration signal.
adjust the flow rate, if necessary.

Start the device for automatic welding. Wait for the initial pulse of shielding gas to disappear and

a stable shielding gas flow rate is obtained.
Commence welding and begin timing.

Stop welding after the required arcing time and record the time. For determining the required

arcing time see B.4.

Leave the extraction fan on until the fume generated has been cleared from the test chamber (at

least 60 s).
Switch off the pump to the Stop recording the
isokinetic sampler. concentration signal.
9 Switch off the on-torch extraction unit and the extraction fan.
10 Remove the filter and reweigh it after appropriate conditioning.
11 Repeat steps 4 to 10, i.e. with the on-torch extraction off.

Repeat steps 1 to 11 four times, i.e. five tests with the on-torch extraction on and five tests with

the on-torch extraction off.
6.2.3 Calculation of the results

The steps for carrying out the calculations for the three different test methods are given in Table 2.

© ISO 2018 – All rights reserved 7
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SIST EN ISO 21904-3:2018
ISO 21904-3:2018(E)
Table 2 — Calculation of test results
Step
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