ISO 29042-4:2009

INTERNATIONAL ISO
STANDARD 29042-4
First edition
2009-02-15
Safety of machinery — Evaluation of the
emission of airborne hazardous
substances —
Part 4:
Tracer method for the measurement of
the capture efficiency of an exhaust
system
Sécurité des machines — Évaluation de l'émission de substances
dangereuses véhiculées par l'air —
Partie 4: Méthode par traceur pour le mesurage de l'efficacité de
captage d'un système d'échappement

Reference number
©
ISO 2009
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©  ISO 2009
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ii © ISO 2009 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 Principle.2
5 Simplified expression of the capture efficiency.2
6 Test method .3
6.1 General procedure.3
6.2 Measurement of concentration, C .5
6.3 Application to a specific group of machines.6
7 Control parameters and influencing factors.6
7.1 General .6
7.2 Control parameters .6
7.3 Influencing factors on capture efficiency .8
8 Test report.8
Annex A (informative) Simplified calculation of random component of uncertainty on C (95 %) .9
Bibliography.10

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 29042-4 was prepared by Technical Committee ISO/TC 199, Safety of machinery.
ISO 29042 consists of the following parts, under the general title Safety of machinery — Evaluation of the
emission of airborne hazardous substances:
⎯ Part 1: Selection of test methods
⎯ Part 2: Tracer gas method for the measurement of the emission rate of a given pollutant
⎯ Part 3: Test bench method for the measurement of the emission rate of a given pollutant
⎯ Part 4: Tracer method for the measurement of the capture efficiency of an exhaust system
The following parts are under preparation:
⎯ Part 5: Test bench method for the measurement of the separation efficiency by mass of air cleaning
systems with unducted outlet
⎯ Part 6: Test bench method for the measurement of the separation efficiency by mass of air cleaning
systems with ducted outlet
⎯ Part 7: Test bench method for the measurement of the pollutant concentration parameter
A room method for the measurement of the pollutant concentration parameter and a decontamination index
are to form the subjects of future parts 8 and 9.
iv © ISO 2009 – All rights reserved

Introduction
The structure of safety standards in the field of machinery is as follows:
a) type-A standards (basic safety standards) giving basic concepts, principles for design, and general
aspects that can be applied to all machinery;
b) type-B standards (generic safety standards) dealing with one safety aspect or one type of safeguard that
can be used across a wide range of machinery:
⎯ type-B1 standards on particular safety aspects (e.g. safety distances, surface temperature, noise);
⎯ type-B2 standards on safeguards (e.g. two-hand controls, interlocking devices, pressure-sensitive
devices, guards);
c) type-C standards (machine safety standards) dealing with detailed safety requirements for a particular
machine or group of machines.
This part of ISO 29042 is a type-B standard as stated in ISO 12100-1.
The requirements of this document can be supplemented or modified by a type-C standard.
For machines which are covered by the scope of a type-C standard and which have been designed and built
according to the requirements of that standard, the requirements of that type-C standard take precedence.
ISO/TC 199 has a mandate in this area to produce type-A and type-B standards, which will allow verification of
conformity with the essential safety requirements.
ISO 29042-4 is based on EN 1093-4:1996, amended by Amendment 1:2008, published by the European
Committee for Standardization (CEN).
INTERNATIONAL STANDARD ISO 29042-4:2009(E)

Safety of machinery — Evaluation of the emission of airborne
hazardous substances —
Part 4:
Tracer method for the measurement of the capture efficiency of
an exhaust system
1 Scope
This part of ISO 29042 specifies a method based on a tracer technique for measuring the capture efficiency of
an exhaust system installed on a machine. It is applicable to all types of test environment — test bench, room
or field (see ISO 29042-1) — but is only applicable if the tracer shows aerodynamic behaviour comparable to
that of the real pollutant.
The measurement of the capture efficiency of an exhaust system can serve for
a) evaluation of the performance of a machine's exhaust system,
b) evaluation of the improvement of an exhaust system,
c) comparison of exhaust systems for machines of similar design,
d) ranking of exhaust systems according to their capture efficiency,
e) determination of the air flow rate of an exhaust system to achieve a given level of capture efficiency, and
f) determination of the state-of-the-art of machine exhaust systems with respect to capture efficiency.
2 Normative references
The following referenced documents are indispensable for the application 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 12100-1:2003, Safety of machinery — Basic concepts, general principles for design — Part 1: Basic
terminology, methodology
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100-1 and the following apply.
3.1
capture efficiency
η
c
ratio of the mass flow rate of a given pollutant directly collected by an exhaust system to the uncontrolled
mass flow rate of this pollutant emitted from the machine
3.2
tracer technique
use of gaseous substances with an aerodynamic behaviour comparable with the hazardous substance under
consideration and for which concentrations can be reliably measured
4 Principle
The principle of the measurement method consists of:
a) emitting a tracer simulating the aerodynamic behaviour of the real pollutant, with the tracer flow rate, q ;
E
b) measuring the flow rate, q , of the tracer collected by the exhaust system.
C
5 Simplified expression of the capture efficiency
The capture efficiency, η , expressed as a percentage, is given by Equation (1):
c
q
C
η=×100 (1)
c
q
E
The tracer flow rate, q , is determined by emitting the tracer at constant flow rate directly into the exhaust duct
E
and by measuring the average tracer concentration in a cross-section of the duct, then using Equation (2):
qQ=−()C C (2)
E2 1
where
Q is the average air flow rate in the duct during the measurement period of q ;
E
C is the average ambient concentration of the tracer before the measurements (background level);
C is the average concentration of the tracer in the duct (emission of tracer in the duct).
The tracer flow rate, q , is determined by emitting the tracer at a constant flow rate, q , at a characteristic
C E
point or zone of the emission of the real pollutant (e.g. at the locations in the emission zone furthest from the
exhaust system) and by measuring the average concentration of tracer in the same points of the duct, then
using Equation (3):
′′
qQ=−()C C (3)
C3 1
where
Q′ is the average air flow rate in the duct during the measurement period of q ;
C
C′ is the average ambient concentration of the tracer after the background level is stabilized;
C is the average concentration of the tracer in the duct (emission at a selected location).
The capture efficiency is expressed as a percentage using Equation (4):
′′
qQ()C −C
C31
η=× 100= ×100 (4)
c
qQ()C −C
E21
2 © ISO 2009 – All rights reserved

If the exhaust flow rate can be considered as being constant, then Q = Q′, and the expression can be
simplified a
...