SIST-TS CEN/TS 15730:2008
(Main)Earth-moving machinery - Guidelines for assessment of exposure to whole-body vibration of ride-on machines - Use of harmonized data measured by international institutes, organizations and manufacturers (ISO/TR 25398:2006)
Earth-moving machinery - Guidelines for assessment of exposure to whole-body vibration of ride-on machines - Use of harmonized data measured by international institutes, organizations and manufacturers (ISO/TR 25398:2006)
This Technical Report provides guidelines for those such as employers, national authorities and manufacturers of earth-moving machinery who are required to determine, assess and document the daily whole-body vibration exposure for ride-on machines as defined in ISO 6165. It also provides guidelines for reducing vibration levels on machines and for determining the vibration reduction from machine improvements to reduce vibration levels. It is intended to assist in establishing documentation for specific earth-moving
machinery under typical operating conditions. It gives guidance on determining the daily vibration exposure A(8), in accordance with ISO 2631 and EN 14253, offering a simple method for determining the daily vibration exposure by means of a table which indicates the daily exposure as a function of the equivalent vibration total value and the associated exposure duration. Both methods can be used even in cases of multiple exposures on the same day. Methods are provided for calculating exposure using reported emission values, valid for machines equipped with a seat in accordance to ISO 7096.
Mechanische Schwingungen - Anleitung zur Beurteilung der Belastung durch Ganzkörpervibrationen auf Erdbaumaschinen mit aufsitzendem Maschinenführer - Unter der Verwendung hamonisierter Daten gemessen von internationalen Instituten und Herstellern (ISO/TR 25398:2006)
Dieser Fachbericht enthält Anleitungen für diejenigen (z. B. Arbeitgeber, nationale Behörden, Hersteller von Erdbaumaschinen), die die tägliche Ganzkörper-Schwingungsbelastung auf Erdbaumaschinen nach ISO 6165 mit aufsitzendem Maschinenführer zu ermitteln, beurteilen und dokumentieren haben. Er enthält auch Anleitungen zur Minderung der Schwingungen auf Erdbaumaschinen sowie zur Ermittlung der Schwingungs¬reduzierung durch eine Maßnahme zur Schwingungsminderung an der Maschine. Dieser Fachbericht hilft, die Dokumentation für eine bestimmte Erdbaumaschine bei typischen Betriebsbedingungen zu erstellen.
Er enthält Anleitungen, wie die Tages-Schwingungsbelastung A(8) nach ISO 2631 und EN 14253 ermittelt wird, indem auch ein einfaches Verfahren genannt wird, nach dem die Tages-Schwingungsbelastung mit Hilfe einer Tabelle ermittelt wird, die die Tagesbelastung als Funktion des äquivalenten Schwingungsgesamtwerts und der zugehörige Einwirkungsdauer angibt. Die Verfahren können auch im Falle mehrerer Belastungen am selben Tag angewandt werden.
Es werden Verfahren zur Berechnung der Belastung angegeben, bei denen die angegebenen Schwingungs¬emissionswerte verwendet werden, die für Maschinen mit einem Sitz nach ISO 7096 gelten.
ANMERKUNG Zusätzliche Informationen sind in den Normen der Reihen EN 474 und EN 500 enthalten.
Arbeitsplatzmessungen sind erforderlich, wenn keine geeigneten Daten verfügbar sind, die die Schwingungen unter den speziellen Arbeitsbedingungen charakterisieren, oder wenn die Berechnungsergebnisse keine Entscheidung ermöglichen, ob der Grenzwert oder der Auslösewert für die Schwingungsbelastung überschritten wird.
Es ist wichtig, dass die Schwingungswerte, die bei der Beurteilung der Belastung verwendet werden, für den spezifischen Gebrauch der Maschine repräsentativ sind.
Dieser Fachbericht behandelt nicht die Beurteilung von Belastungen durch Stöße.
Engins de terrassement - Lignes directrices pour l'évaluation de l'exposition des vibrations à l'ensemble du corps sur les machines à conducteur porté - Utilisation des données harmonisées mesurées par des instituts internationaux, des organisations et des fabricants (ISO/TR 25398:2006)
L'ISO/TR 25398:2006 fournit des lignes directrices destinées aux utilisateurs, tels qu'employeurs, autorités nationales et fabricants, chargés de déterminer, d'évaluer et d'établir une fiche sur l'exposition quotidienne aux vibrations transmises à l'ensemble du corps pour les engins de terrassement à conducteur porté, tel que défini dans l'ISO 6165. Il fournit également des lignes directrices pour réduire les niveaux de vibrations des engins ainsi que pour déterminer la réduction de vibrations résultant d'améliorations apportées aux engins dans ce but. De plus, il aide à établir une documentation pour un engin spécifique dans des conditions de fonctionnement habituelles.
Stroji za zemeljska dela - Smernice za ocenjevanje izpostavljenosti (celotnega) telesa vibracijam - Uporaba harmoniziranih podatkov, ki so jih izmerili mednarodni inštituti, organizacije in proizvajalci (ISO/TR 25398:2006)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 15730:2008
01-november-2008
Stroji za zemeljska dela - Smernice za ocenjevanje izpostavljenosti (celotnega)
telesa vibracijam - Uporaba harmoniziranih podatkov, ki so jih izmerili mednarodni
inštituti, organizacije in proizvajalci (ISO/TR 25398:2006)
Earth-moving machinery - Guidelines for assessment of exposure to whole-body
vibration of ride-on machines - Use of harmonized data measured by international
institutes, organizations and manufacturers (ISO/TR 25398:2006)
Mechanische Schwingungen - Anleitung zur Beurteilung der Belastung durch
Ganzkörpervibrationen auf Erdbaumaschinen mit aufsitzendem Maschinenführer - Unter
der Verwendung hamonisierter Daten gemessen von internationalen Instituten und
Herstellern (ISO/TR 25398:2006)
Engins de terrassement - Lignes directrices pour l'évaluation de l'exposition des
vibrations à l'ensemble du corps sur les machines à conducteur porté - Utilisation des
données harmonisées mesurées par des instituts internationaux, des organisations et
des fabricants (ISO/TR 25398:2006)
Ta slovenski standard je istoveten z: CEN/TS 15730:2008
ICS:
13.160 Vpliv vibracij in udarcev na Vibration and shock with
ljudi respect to human beings
53.100 Stroji za zemeljska dela Earth-moving machinery
SIST-TS CEN/TS 15730:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN/TS 15730:2008
TECHNICAL SPECIFICATION
CEN/TS 15730
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
August 2008
ICS 13.160; 53.100
English Version
Earth-moving machinery - Guidelines for assessment of
exposure to whole-body vibration of ride-on machines - Use of
harmonized data measured by international institutes,
organizations and manufacturers (ISO/TR 25398:2006)
Engins de terrassement - Lignes directrices pour Mechanische Schwingungen - Anleitung zur Beurteilung der
l'évaluation de l'exposition des vibrations à l'ensemble du Belastung durch Ganzkörpervibrationen auf
corps sur les machines à conducteur porté - Utilisation des Erdbaumaschinen mit aufsitzendem Maschinenführer -
données harmonisées mesurées par des instituts Unter der Verwendung hamonisierter Daten gemessen von
internationaux, des organisations et des fabricants (ISO/TR internationalen Instituten und Herstellern (ISO/TR
25398:2006) 25398:2006)
This Technical Specification (CEN/TS) was approved by CEN on 18 April 2008 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, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15730:2008: E
worldwide for CEN national Members.
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CEN/TS 15730:2008 (E)
Contents Page
Foreword.3
2
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CEN/TS 15730:2008 (E)
Foreword
The text of ISO/TR 25398:2006 has been prepared by Technical Committee ISO/TC 127 “Earth-moving
machinery” of the International Organization for Standardization (ISO) and has been taken over as CEN/TS
15730:2008 by Technical Committee CEN/TC 151 “Construction equipment and building material machines -
Safety” 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 [and/or CENELEC] 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 announce this Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO/TR 25398:2006 has been approved by CEN as a CEN/TS 15730:2008 without any
modification.
3
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SIST-TS CEN/TS 15730:2008
TECHNICAL ISO/TR
REPORT 25398
First edition
2006-10-01
Earth-moving machinery — Guidelines
for assessment of exposure to
whole-body vibration of ride-on
machines — Use of harmonized data
measured by international institutes,
organizations and manufacturers
Engins de terrassement — Lignes directrices pour l'évaluation de
l'exposition des vibrations à l'ensemble du corps sur les machines à
conducteur porté — Utilisation des données harmonisées mesurées par
des instituts internationaux, des organisations et des fabricants
Reference number
ISO/TR 25398:2006(E)
©
ISO 2006
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ISO/TR 25398:2006(E)
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Published in Switzerland
ii © ISO 2006 – All rights reserved
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ISO/TR 25398:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Estimation of vibration magnitude. 5
5 Estimation of daily exposure duration . 5
6 Consideration of uncertainties. 6
7 Determination and assessment of vibration exposure. 7
8 Documentation. 16
Annex A (informative) Machine types and their typical operating conditions. 17
Annex B (informative) Equivalent vibration values of whole-body vibration emission of
earth-moving machinery . 21
Annex C (informative) Calculation form for total vibration exposure points . 23
Annex D (informative) Example documentation form for whole-body vibration exposure. 24
Annex E (informative) Guidelines for use and working conditions of earth-moving machinery to
reduce vibration levels. 25
Annex F (informative) Guidelines for establishing and reporting vibration reduction of earth-
moving machinery . 27
Bibliography . 28
© ISO 2006 – All rights reserved iii
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ISO/TR 25398:2006(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.
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.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
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/TR 25398 was prepared by Technical Committee ISO/TC 127, Earth-moving machinery, Subcommittee
SC 2, Safety requirements and human factors.
iv © ISO 2006 – All rights reserved
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ISO/TR 25398:2006(E)
Introduction
This Technical Report provides information on how to assess the whole-body vibration exposure of operators
of earth-moving machines. The method is based on measured vibration emission under real working
conditions. It needs to be noted that vibration emissions are influenced by many different parameters,
originating from
⎯ operator (e.g. training, behaviour, mode, stress),
⎯ jobsite (e.g. organization, preparation, environment, weather, material), and
⎯ machine (e.g. type, quality of seat and suspension system, attachment, equipment, condition).
It is therefore not possible to obtain precise exposure figures. The values given in this Technical Report need
to be used with great care since they were measured for a limited number of operators, defined work
situations, and machine types.
On the one hand, the actual work situation for a specific machine operator can be very different, thus creating
different vibration. On the other hand, values from real work that can be found in the literature are only correct
for the specific work situation and time when they were measured. The user of this Technical Report needs to
be aware that the exposure to vibration depends not only on the machine used but also to a large extent on
the operator, jobsite and machine, and other factors. All these factors need to be taken into account in order to
make a practical assessment of vibration magnitude.
There are typical operating conditions for machine types in accordance to ISO 6165 identified and listed in
Annex A. This list may not be complete, but it represents most of the real working conditions.
Properly adjusting and maintaining machines, operating machines smoothly, and maintaining the terrain
conditions can reduce whole-body vibrations. The guidelines given in Annex E can help users of earth-moving
machines reduce the whole-body vibration levels.
The daily vibration exposure to be assessed depends on both the magnitude of vibration at the surface in
contact with the whole body and the total daily duration for which an employee is in contact with that vibration.
The vibration levels for the same type of machine are assumed to be the same. If a vibration-reduction feature
is added to the machine, then a lower vibration level can be used. In order to determine the reduction in
vibration levels for a machine vibration-reduction feature, the appropriate vibration measurements must be
made. Annex F provides guidelines for vibration measurements.
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SIST-TS CEN/TS 15730:2008
TECHNICAL REPORT ISO/TR 25398:2006(E)
Earth-moving machinery — Guidelines for assessment of
exposure to whole-body vibration of ride-on machines — Use
of harmonized data measured by international institutes,
organizations and manufacturers
1 Scope
This Technical Report provides guidelines for those such as employers, national authorities and
manufacturers of earth-moving machinery who are required to determine, assess and document the daily
whole-body vibration exposure for ride-on machines as defined in ISO 6165. It also provides guidelines for
reducing vibration levels on machines and for determining the vibration reduction from machine improvements
to reduce vibration levels. It is intended to assist in establishing documentation for specific earth-moving
machinery under typical operating conditions.
It gives guidance on determining the daily vibration exposure A(8), in accordance with ISO 2631 and
EN 14253, offering a simple method for determining the daily vibration exposure by means of a table which
indicates the daily exposure as a function of the equivalent vibration total value and the associated exposure
duration. Both methods can be used even in cases of multiple exposures on the same day.
Methods are provided for calculating exposure using reported emission values, valid for machines equipped
with a seat in accordance to ISO 7096.
NOTE Additional information is given in the EN 474 and EN 500 series of standards.
Workplace measurements are required where suitable data are unavailable to represent the vibration under
the specific working conditions, or if the calculation results are not useful for determining whether or not the
vibration exposure limit value or exposure action value is likely to be exceeded.
It is important that the vibration values used in the exposure assessment are representative of those in the
specific use of the machines.
This Technical Report does not deal with assessments of exposure to shock.
NOTE The guidelines for determining, assessing and documenting the daily vibration exposure from use of ride-on
operated earth-moving machinery also cover the requirements of the European Physical Agents Directive (Vibration)
2002/44/EC.
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 2631-1:1997, Mechanical vibration and shock — Evaluation of human exposure to whole-body
vibration — Part 1: General requirements
ISO 6165: 2001, Earth-moving machinery — Basic types — Vocabulary
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ISO/TR 25398:2006(E)
ISO 7096:2000, Earth-moving machinery —- Laboratory evaluation of operator seat vibration
EN 14253:2003, Mechanical vibration — Measurement and calculation of occupational exposure to
whole-body vibration with reference to health — Practical guidance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2631 and ISO 6165 and the
following apply.
3.1
operating time
ride-on time
daily duration of the operating time on the earth-moving machinery
NOTE It includes the interruptions required by the operating conditions and the break periods directly related to use.
3.2
exposure duration
T
total duration during which the whole body is in direct contact with the vibrating surface (seat) and exposed to
relevant vibration
NOTE It is often confused with the operating time when determining the daily exposure duration, T. For example, the
operating time on a wheel loader in a quarry is estimated by the operator at 7,5 h per day. However, the exposure duration
is 5 h loading dumper (e.g. waiting for dumpers) and 1 h mining application (e.g. waiting for detonation), which yields
T = 6,0 h.
3.3
equivalent vibration value
a
w,eq
maximum of the time-averaged totals of the vibration values of the various machines and their typical
operating conditions, a , during their associated exposure durations, T
wi,x,y,z i
NOTE 1 It is the maximum of a , a or a , calculated using Equation (1):
w,eqx w,eqy w,eqz
n
1
2
aa=⋅()T
w,eqx ∑ wxii
T
i=1
n
1
2
aa=⋅()T (1)
w,eqy ∑ wyii
T
i=1
n
1
2
aa=⋅()T
w,eqz ∑ wzii
T
i=1
where n is the number of partial equivalent vibration values considered.
NOTE 2 Vibration values for the x and y directions are multiplied by a factor of 1,4, and this is included in the data in
Annex B. If data are used from another source, care needs to be taken to ensure that the factor is included there also.
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3.4
daily vibration exposure
A(8)
value on which assessment of the level of exposure to vibration is based, expressed as the equivalent
continuous acceleration over an 8 h period and calculated as the highest (rms) value of the
frequency-weighted accelerations determined on the three orthogonal axes (1,4a , 1,4a and a for a
wx wy wz
seated operator)
NOTE 1 For the determination of A(8), see Clauses 5, 6 and 7, Annex A and Annex B, and ISO 2631-1.
NOTE 2 It is the maximum of the A(8) values, calculated using Equation (2):
x,y,z
n
1
2
A(8)=⋅()aT
xw∑xii
8h
i=1
n
1 2
A(8)=⋅aT (2)
()
∑
ywyii
8h
i=1
n
1
2
A(8)=⋅()aT
zw∑zii
8h
i=1
where n is the number of partial equivalent vibration values considered, a is the equivalent vibration value and T is
w,x,y,z,i i
the associated exposure duration.
NOTE 3 Vibration values for the x and y directions are multiplied by a factor of 1,4, and this is included in the data in
Annex B. If data are used from another source, care needs to be taken to ensure that the factor is included there also.
3.5
partial vibration exposure points
P
Eix,y,z
index describing the vibration exposure from a single machine and operating condition during the associated
exposure duration in the x,y and z directions
NOTE 1 It is calculated for the corresponding direction using Equation (3):
2
⎛⎞
aT
wxii
P=⋅⋅ 100
⎜⎟
Exi
⎜⎟2
8h
0,5m /s
⎝⎠
2
⎛⎞a
T
wyi
i
P=⋅⋅ 100 (3)
⎜⎟
Eyi
⎜⎟2
8h
0,5m/s
⎝⎠
2
⎛⎞
aT
wzii
P=⋅⋅ 100
⎜⎟
Ezi
⎜⎟2
8h
0,5 m/s
⎝⎠
where a is the equivalent vibration value and T is the associated exposure duration.
w,x,y,z,i i
2
NOTE 2 Equation (3) sets a value of 100 points for a vibration exposure of 0,5 m/s A(8). Another vibration exposure
2
value A(8) can be set to 100 points by substituting it for 0,5m/s in the equation.
NOTE 3 Vibration values for the x and y directions are multiplied by a factor of 1,4, and this is included in the data in
Annex B. If data are used from another source, care needs to be taken to ensure that the factor is included there also.
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3.6
total vibration exposure points
P
Etot
maximum of the totals of the partial vibration exposure points P within one day
Eix,y,z
NOTE 1 It is the maximum of P , P or P , calculated using Equation (4):
E,totx E,toty E,totz
n
PP=
Etotx ∑ E ix
i=1
n
PP= (4)
Etoty ∑ E iy
i=1
n
PP=
Etotz ∑ Eiz
i=1
where n is the number of partial equivalent vibration values considered.
NOTE 2 Vibration exposure points are a simple alternative to determining the A(8) value of an operator’s total daily or
partial vibration exposure. An example of the relationship is given by Equation (5), in accordance with the European
Physical Agents Directive (vibration) 2002/44/EC:
2
A(8)= 0,5m/s P 100 (5)
Etot
2
A score of 100 points for the total vibration exposure in a day is equal to the exposure action value of A(8) = 0,5 m/s and
2
a score of 529 points is equal to the exposure limit value of A(8) = 1,15 m/s . The example is plotted in Figure 1.
Key
X total vibration exposure points, P
Etot
2
Y daily vibration exposure A(8), m/s
Figure 1 — Example of relationship between vibration exposure points and daily vibration exposure
for whole-body vibration
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4 Estimation of vibration magnitude
4.1 General
Data for estimating vibration levels are provided in Annex B. The vibration magnitude is expressed as a
2
frequency-weighted root-mean-square acceleration value in metres per second squared (m/s ), in accordance
with ISO 2631.
The vibration magnitude for a machine can be highly variable. For example, an operator and his driving style
(e.g. aggressive, smooth), different operating conditions, ground conditions, machine speeds or different
materials all influence the actual magnitude. The magnitude also often varies over time. It is usually difficult or
even impossible to obtain a precise value or narrow value range. The average value and a description of its
uncertainty is the best reflection of the real, typical operating conditions. When estimating exposure, account
should be taken of the fact that values are obtained within a range of uncertainty (see Clause 6).
4.2 Additional sources of information
Vibration magnitudes may be measured at the operator’s position by the employer, or on his behalf. However,
this can be difficult, non-reproducible and uneconomical, and is not always necessary.
Other sources of vibration data include specialist vibration consultants, employers’ organisations (trade
associations) and government bodies. Data can also be found in various technical or scientific publications
and on the Internet. If an employer uses data from one of these sources, the quality and accuracy of the data
should be checked. Comparing data from two or more sources is thus recommended. Employers should try to
find a value (or range of values), which represents the likely vibration magnitude for the particular machine
and operating conditions.
5 Estimation of daily exposure duration
The employer should determine the daily exposure duration for each operator and the relevant machines and
operating conditions.
This may be based on
a) measurement of the actual exposure durations of a small number of operations or work cycles and
calculating the average, and
b) information on the number of operations or work cycles per working day.
The first of these will be a measurement to determine how long an operator is exposed to vibration, and from
what source, during a specified period. Various techniques may be used, for example:
⎯ use of a stopwatch;
⎯ analysis of video recordings;
⎯ activity sampling.
A source of information may be work records, e.g. the number of lorries loaded and unloaded by fork-lift trucks.
However, it is important to ensure that the information is compatible with the information required for an
evaluation of daily vibration exposure. For example, work records might give very accurate information on the
number of completed work items at the end of each day, but where there is more than one operator, or
unfinished work items at the end of a shift, this information might not be directly applicable to a vibration
exposure evaluation.
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NOTE Operators asked for information on their typical daily vibration exposure duration will normally give an estimate
which includes periods of time when there is no vibration (e.g. idling, lifting for a fork-lift truck). Therefore, such an
approach often results in an overestimation of the exposure duration.
It should be recognised that for most machines the vibration exposure duration is shorter than the operating time.
6 Consideration of uncertainties
The accuracy of the overall assessment of the exposure depends on the accuracy of the established vibration
value and its ability to represent the actual vibration value. It also depends on the accuracy of the exposure
duration as estimated. The datasets given in Annex B are based on from at least five and to more than
100 measurements under typical operating conditions. The standard deviation gives information about the
distribution of the measured values.
The uncertainty in the estimation of exposure duration is affected by the uncertainty of
⎯ measurements of the duration of operations or work cycles,
⎯ estimates of the number of operations or work cycles per day,
⎯ exposure time estimates supplied by the operators (see Note to Clause 5), and
⎯ variability of the working task from one day to another.
The uncertainty in the evaluation of daily vibration exposure is affected by the uncertainty of
⎯ evaluation of vibration magnitude, and
⎯ evaluation of exposure duration.
NOTE Additional information about uncertainties of the measured vibration emission value is given in EN 14253.
The accuracy of the vibration value has more influence on the accuracy of the daily vibration exposure than
that of the exposure duration because the vibration exposure is proportional to the vibration value and to the
square root of the exposure duration.
The average values given in Annex B are likely to be exceeded in about half of all conditions. When making
an initial estimate of exposure or where it is suspected that the conditions for a machine operation are
particularly severe, it is recommended that the values used be the mean plus one standard deviation. There
will be cases when even the value of the mean plus one standard deviation is exceeded. This is likely to occur
in the 17 % most severe cases, i.e. the value (mean plus one standard deviation) will cover 83 % of all
conditions. Machine vibration values will be less than the average values given in Annex B in about half of all
conditions.
Conditions likely to lead to variability in levels of whole-body vibration include roughness or smoothness of
terrain, driving speeds (adequate or inadequate), and adequate or inadequate operator skill and training.
Vibration levels can be reduced by following the guidelines given in Annex E.
6 © ISO 2006 – All rights reserved
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SIST-TS CEN/TS 15730:2008
ISO/TR 25398:2006(E)
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