SIST EN 61285:2015
(Main)Industrial-process control - Safety of analyzer houses (IEC 61285:2015)
Industrial-process control - Safety of analyzer houses (IEC 61285:2015)
IEC 61285:2015 describes the physical requirements for the safe operation of the process analyser measuring system installed in an analyser house (AH) in order to ensure its protection against fire, explosion and health hazards. This standard applies for analyser houses with inner and/or external potential explosive atmospheres and it applies to hazards caused by toxic substances or asphyxiant gases. This third edition cancels and replaces the second edition published in 2004 and constitutes a technical revision. The main changes are:
- incorporation of previously issued corrigendum and
- minor updates to several sections and references.
Prozessautomatisierung - Sicherheit von Analysengeräteräumen (IEC 61285:2015)
Commande des processus industriels - Sécurité des bâtiments pour analyseurs (IEC 61285:2015)
L'IEC 61285:2015 décrit les exigences physiques requises pour un fonctionnement sûr du système de mesure constitué par l'analyseur de processus installé dans un bâtiment pour analyseur (AH) afin d'assurer la protection contre les dangers d'incendie, d'explosion et les dangers pour la santé. La présente norme s'applique aux bâtiments pour analyseurs à atmosphères intérieures et/ou extérieures potentiellement explosives et s'applique aux dangers dus aux substances toxiques ou aux gaz asphyxiants. Cette troisième édition annule et remplace la deuxième édition parue en 2004. Elle constitue une révision technique. Les principales modifications sont:
- incorporation du corrigendum paru précédemment et
- mises à jour mineures de plusieurs sections et références.
Nadzor industrijskih procesov - Varnost prostorov za analiziranje (IEC 61285:2015)
Ta mednarodni standard opisuje fizikalne zahteve za varno upravljanje sistema za analiziranje, ki je nameščen v prostoru za analiziranje (AH), da je zagotovljena zaščita pred požari, eksplozijami in nevarnostmi za zdravje. Ta standard velja za prostore za analiziranje z notranjimi in/ali zunanjimi potencialno eksplozivnimi atmosferami ter tveganja, povezana s strupenimi snovmi ali zadušljivimi plini. (Glej nacionalne smernice o toksičnih nevarnostih.)
Ta standard ne zajema objektov, pri katerih so tveganje trdne snovi (prah, prašek, vlakna). Ta standard ni namenjen obravnavi vseh vprašanj funkcionalne varnosti, povezanih s prostori za analiziranje.
Točka 4 obravnava mesto prostora za analizo in povezavo znotraj območij obdelovalnega obrata.
Točka 5 obravnava zasnovo, konstrukcijo in ureditev prostora za analizo.
Standard ne obravnava delov sistema za merilne analize, nameščenih na drugih lokacijah, kot so prostori za pripravo vzorcev (SRC) ali prostori za stikalne naprave.
Točka 6 obravnava ukrepe za zmanjšanje možnosti eksplozije v prostorih za analizo z omogočanjem vzdrževanja opreme z vklopljenim napajanjem in odprtim pokrovom.
Glavna ovira pri večini tekočin je dejstvo, da je koncentracija hlapov, ki so strupeni za osebje, nižja od spodnje meje eksplozivnosti (vnetljivosti) (LEL) (glej točko 7).
Če kot primer vzamemo n-pentan, pri katerem je spodnja meja eksplozivnosti 1,4 % ali 14.000 × 10–6, je raven, ki je takoj življenjsko nevarna ali nevarna za zdravje (kar je maksimalna raven, pri kateri lahko delavec uide v 30 min brez simptomov, ki bi ovirali pobeg, ali trajnih učinkov na zdravje) samo 0,5 % ali 5.000 × 10–6.
Točka 7 obravnava ukrepe za zaščito osebja pred materiali in atmosferami prostorov za analize, ki so nevarni za zdravje.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2015
Nadzor industrijskih procesov - Varnost prostorov za analiziranje (IEC 61285:2015)
Industrial-process control - Safety of analyzer houses (IEC 61285:2015)
Prozessautomatisierung - Sicherheit von Analysengeräteräumen (IEC 61285:2015)
Commande des processus industriels - Sécurité des bâtiments pour analyseurs (IEC
61285:2015)
Ta slovenski standard je istoveten z: EN 61285:2015
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN 61285
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2015
ICS 13.110; 25.040.40 Supersedes EN 61285:2004
English Version
Industrial-process control - Safety of analyzer houses
(IEC 61285:2015)
Commande des processus industriels - Sécurité des Prozessautomatisierung - Sicherheit von
bâtiments pour analyseurs Analysengeräteräumen
(IEC 61285:2015) (IEC 61285:2015)
This European Standard was approved by CENELEC on 2015-03-31. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61285:2015 E
Foreword
The text of document 65B/954/FDIS, future edition 3 of IEC 61285, prepared by SC 65B
"Measurement and control devices", of IEC/TC 65 "Industrial-process measurement, control and
automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
(dop) 2015-12-31
• latest date by which the document has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dow) 2018-03-31
• latest date by which the national standards conflicting with
the document have to be withdrawn
This document supersedes EN 61285:2004.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 61285:2015 was approved by CENELEC as a European
Standard without any modification.
- 3 - EN 61285:2015
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60079-0 (mod) 2011 Explosive atmospheres -- Part 0: EN 60079-0 2012
Equipment - General requirements
- - +A11 2013
IEC 60079-10-1 2008 Explosive atmospheres -- Part 10-1: EN 60079-10-1 2009
Classification of areas - Explosive gas
atmospheres
IEC 60079-20-1 2010 Explosive atmospheres - Part 20-1: EN 60079-20-1 2010
Material characteristics for gas and vapour
classification - Test methods and data
IEC 61285 ®
Edition 3.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial-process control – Safety of analyser houses
Commande des processus industriels – Sécurité des bâtiments pour analyseurs
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.110; 25.040.40 ISBN 978-2-8322-2228-7
– 2 – IEC 61285:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Location of AHs and connection within the process plant areas . 11
4.1 General . 11
4.2 Response time . 11
4.3 Utilities . 11
4.4 Safety . 11
4.4.1 Location . 11
4.4.2 Escape . 11
4.4.3 Area classification . 11
4.4.4 Peripheral hazards . 11
4.5 Access . 11
5 Design, construction and layout of AHs . 12
5.1 General . 12
5.2 General requirements . 12
5.3 Dimensions and layout . 12
5.4 Structural requirements . 12
5.4.1 Construction materials . 12
5.4.2 Walls . 13
5.4.3 Floors and foundation . 13
5.4.4 Doors . 13
5.4.5 Windows . 13
5.4.6 Roof . 13
5.5 Equipment . 13
5.5.1 Lighting . 13
5.5.2 Communications . 13
5.5.3 Piping, tubing and valves . 13
5.5.4 Utilities . 14
5.5.5 Fire extinguishers . 14
5.5.6 Ventilation . 14
5.5.7 Temperature . 15
5.6 Labelling/instructions/documentation . 15
5.6.1 Entrance . 15
5.6.2 Alarms . 15
5.6.3 Safety procedures . 15
5.6.4 Additional data. 16
6 Explosion protection of AHs . 16
6.1 General . 16
6.2 General requirements . 16
6.3 Protection of AHs against explosion hazards by means of artificial ventilation . 16
6.3.1 Classification . 16
6.3.2 Requirements for AHs where the explosion hazard originates externally . 17
IEC 61285:2015 © IEC 2015 – 3 –
6.3.3 Requirements for AHs where the explosion hazard originates from
internal gases or vapours . 17
6.3.4 Requirements for AHs where the explosion hazard originates from
internal liquids . 18
6.3.5 Requirements for AHs where the explosion hazard originates from any
combination of the above . 19
6.4 Protection of AHs against explosion hazards by means of natural ventilation . 19
6.4.1 General . 19
6.4.2 Ventilation requirements . 19
6.4.3 Heating requirements . 20
6.4.4 Gas detectors . 20
7 Measures to prevent health hazards to personnel in AHs . 20
7.1 General . 20
7.2 Guidelines . 20
7.3 General requirements . 20
7.4 Safety measures . 21
7.5 External hazards . 22
7.6 Additional measures for abnormal working conditions . 22
7.7 Labelling/instructions/documentation . 23
Annex A (normative) Leakage risk of modules in the AH . 24
A.1 General . 24
A.2 Modules with negligible leakage risk . 24
A.3 Modules with limited leakage risk . 24
A.3.1 General . 24
A.3.2 Guidance for evaluating modules . 25
Bibliography . 26
Table A.1 – Module evaluation . 25
– 4 – IEC 61285:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL-PROCESS CONTROL –
SAFETY OF ANALYSER HOUSES
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61285 has been prepared by subcommittee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
This third edition cancels and replaces the second edition published in 2004. This edition
constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
a) incorporation of previously issued corrigendum;
b) minor updates to several sections and references.
IEC 61285:2015 © IEC 2015 – 5 –
The text of this standard is based on the following documents:
FDIS RVD
65B/954/FDIS 65B/966/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61285:2015 © IEC 2015
INTRODUCTION
Process analysers measure the characteristics of a process stream continuously and
automatically. The process sample is introduced automatically and the system is designed for
unattended operation and minimal maintenance.
The placement of devices for process analysis in analyser houses is beneficial for technical
and economic reasons:
– in order to facilitate appropriate environmental conditions;
– to simplify servicing and maintenance issues;
– to enable the use of a common infrastructure (see 3.5).
This document is designed to set forth minimum safety requirements for typical analyser
houses (AHs). It is superseded in all cases by national, local, or corporate requirements, if
other or more stringent requirements will apply.
IEC 61285:2015 © IEC 2015 – 7 –
INDUSTRIAL-PROCESS CONTROL –
SAFETY OF ANALYSER HOUSES
1 Scope
This International Standard describes the physical requirements for the safe operation of the
process analyser measuring system installed in an analyser house (AH) in order to ensure its
protection against fire, explosion and health hazards. This standard applies for analyser
houses with inner and/or external potential explosive atmospheres and it applies to hazards
caused by toxic substances or asphyxiant gases. (Refer to national guidelines on toxic
hazards.)
This standard does not address facilities where solids (dust, powder, fibres) are the hazard.
This standard does not seek to address all functional safety issues related to analyser
houses.
Clause 4 addresses the location of the AH and connection within the process plant areas.
Clause 5 addresses the design, construction and layout of the AH. It does not address parts
of the analyser measuring system installed in other locations such as sample conditioning
rooms (SCR) or switchgear rooms.
Clause 6 addresses measures for reducing the danger of explosion for AHs while permitting
maintenance of equipment with the power on and the case open.
For most fluids, the major constraint is that the concentration of vapours, which are toxic for
personnel, is lower than the lower explosive (flammable) limit (LEL) (see Clause 7).
–6
Using n-Pentane as an example, the LEL is 1,4 % or 14 000 × 10 , the level immediately
dangerous to life or health (which is the maximum level from which a worker could escape
within 30 min without any escape-impairing symptoms or any irreversible health effects) is
–
only 0,5 % or 5 000 × 10 .
Clause 7 addresses those measures for protecting personnel from materials in the
atmosphere of AHs that are hazardous to health.
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.
IEC 60079-0:2011, Explosive atmospheres – Part 0: General requirements
IEC 60079-10-1:2008, Explosive atmospheres – Part 10-1: Classification of areas – Explosive
gas atmospheres
IEC 60079-20-1:2010, Explosive atmospheres – Part 20-1: Material characteristics for gas
and vapour classification – Test methods and data
– 8 – IEC 61285:2015 © IEC 2015
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
analyser cabinet
small housing in which analysers are installed individually or grouped together
Note 1 to entry: Maintenance is performed from outside the cabinet with the door(s) open.
3.2
analyser shelter
structure with one or more sides open and free from obstruction to the natural passage of air,
in which one or more analysers are installed
Note 1 to entry: The maintenance of the analysers is normally performed in the protection of the shelter.
3.3
analyser house
AH
enclosed building or part of a building containing process analysers and associated
equipment where streams for analysis are brought in and which is regularly entered by
authorized personnel
Note 1 to entry: An AH is not a permanent workplace. Within the scope of this standard, the term AH is used
regardless of the structure configuration as either a room, a walk-in cabinet, an analyser container or an analyser
building and whether or not it is an integral part of, or attached to, another structure.
3.4
sample conditioning room
SCR
room that is separated from the AH and has modules for sample conditioning, auxiliary
material, or sample disposal equipment
3.5
infrastructure
required means and supply with auxiliaries to operate an AH with all equipment therein, for
example, instrument air, nitrogen, water, power supply, incidental disposal of waste and
disposal of substances introduced to be analysed
Note 1 to entry: The infrastructure occasionally comprises the fundament of an AH, the positioning of gas bottles
and containers for gas supply and test gases. The infrastructure comprises in addition the ventilation and
climatisation of the AH and the needed alarm devices within and outside of the AH.
3.6
maintenance
servicing, inspection, repair, improvement and weakness analysis of process analyser devices
and infrastructure
3.7
toxic substances
gaseous or liquid substances that, if released in a room, will cause a health hazard by contact
with the skin or by inhalation from the surrounding atmosphere
3.8
safety back-up
additional personnel, in constant contact with a person or persons in hazardous working
condition, who could assist or call for additional help
IEC 61285:2015 © IEC 2015 – 9 –
3.9
external explosion hazard
hazard existing when the AH is erected at a location where flammable substances may
ingress from the outside resulting in dangerous concentrations of flammable gases and
vapours inside the AH
3.10
internal explosion hazard
hazard existing when a flammable mixture can result from release of samples or auxiliary
supplies inside the AH
3.11
lower explosive limit
LEL
volume ratio of the flammable gas or vapour in air below which an explosive gas atmosphere
will not be formed
3.12
explosive gas atmosphere
mixture with air, under atmospheric conditions, of a flammable material in the form of gas or
vapour in which, after ignition, combustion spreads through the unconsumed mixture
3.13
hazardous area
area in which an explosive gas atmosphere is present, or may be expected to be present, in
quantities such as to require special precautions for the construction, installation and use of
devices
3.14
non-hazardous area
area in which an explosive gas atmosphere is not expected to be present in quantities such as
to require special precautions for the construction, installation and use of the analysers
3.15
zone 0
area in which an explosive gas atmosphere is present continuously or for long periods or
frequently
[SOURCE: IEC 60079-10-1:2008, 3.6]
3.16
zone 1
area in which an explosive gas atmosphere is likely to occur in normal operation occasionally
[SOURCE: IEC 60079-10-1:2008, 3.7]
3.17
zone 2
area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it
does occur, will persist for a short period only
[SOURCE: IEC 60079-10-1:2008, 3.8]
– 10 – IEC 61285:2015 © IEC 2015
3.18
source of release
a point or location from which a gas, vapour, mist or liquid may be released into the
atmosphere so that an explosive gas atmosphere could be formed
[SOURCE: IEC 60079-10-1:2008, 3.9]
3.19
grades of release
there are three basic grades of release, as listed below in order of decreasing frequency and
likelihood of the explosive gas atmosphere being present:
a) continuous grade;
b) primary grade;
c) secondary grade.
A source of release may give rise to any one of these grades of release, or to a combination
of more than one
[SOURCE: IEC 60079-10-1:2008, 3.10]
3.20
continuous grade of release
release which is continuous or is expected to occur frequently or for long periods
[SOURCE: IEC 60079-10-1:2008, 3.11]
3.21
primary grade of release
release which can be expected to occur periodically or occasionally during normal operation
[SOURCE: IEC 60079-10-1:2008, 3.12]
3.22
secondary grade of release
release which is not expected to occur in normal operation and, if it does occur, is likely to do
so only infrequently and for short periods
[SOURCE: IEC 60079-10-1:2008, 3.13]
3.23
release rate
quantity of flammable gas, vapour or mist emitted per unit time from the source of release
[SOURCE: IEC 60079-10-1:2008, 3.14]
3.24
flashpoint
lowest liquid temperature at which, under certain standardized conditions, a liquid gives off
vapours in a quantity such as to be capable of forming an ignitable vapour/air mixture
3.25
ignition temperature
T-rating
value of ignition temperature as given in IEC 60079-20-1
IEC 61285:2015 © IEC 2015 – 11 –
3.26
equipment protection level
EPL
level of protection assigned to equipment based on its likelihood of becoming a source of
ignition and distinguishing the differences between explosive gas atmospheres, explosive dust
atmospheres, and the explosive atmospheres in mines susceptible to firedamp
[SOURCE: IEC 60079-0:2011, 3.26]
3.27
containment system
parts within the room or building containing the hazardous substance that may constitute an
internal source of release
4 Location of AHs and connection within the process plant areas
4.1 General
When determining the location of the AH, the following factors should be considered.
4.2 Response time
Line lengths from sample points to the analysers shall be estimated and the necessary flow
rates calculated to determine whether resultant dead times, sample deterioration and flow
rates are acceptable.
4.3 Utilities
Connection lengths to all utilities such as air, steam, electricity, sample return, signals, etc.
shall be estimated.
4.4 Safety
4.4.1 Location
The AH should preferably be located away from external sources of toxic or flammable
release, and in a place where accumulation of these substances is not likely to occur.
4.4.2 Escape
Escape routes shall be determined and remain unobstructed and where possible be oriented
away from hazardous areas.
4.4.3 Area classification
Area classification for the AH interior and for the ventilation air source shall be determined by
the process plant safety authority or user.
4.4.4 Peripheral hazards
Consideration shall be given to the possibility of analysers or their sample lines creating a
hazard in the AH or any adjacent room.
4.5 Access
Access is needed both for maintenance personnel and for supplies. AHs should be located at
ground level or with access to an elevator. Consideration should be given to the requirements
of heavy supplies such as gas cylinders and safe removal/installation of analysers.
– 12 – IEC 61285:2015 © IEC 2015
Maintenance access to process equipment such as a heat exchanger shall also be
considered. In addition access is needed to isolation valves for auxiliary supplies, sampling
points and sampling streams outside the AH, in order to render the AH safe as fast as
possible. Access is also needed to an external isolation switch for electrical power to shut the
entire AH down.
5 Design, construction and layout of AHs
5.1 General
Analysers and analyser sampling systems require varying degrees of protection depending on
the sample and the type of analyser, the importance of the application and the environment in
which it has to operate. Where the construction and maintenance requirements are not
suitable for the working environment, additional protection such as AHs should be provided.
This additional protection is to ensure satisfactory performance of the instrument and to
facilitate maintenance.
The selection of the housing depends on a number of factors such as
– classification of the area in which the analyser and/or sample system is to be located;
– range of ambient conditions at the site, including temperature, rain, humidity, snow, wind,
dust, sand, direct sunlight, and corrosive atmosphere;
– environment specified by the analyser vendor for reliable, accurate, and safe operation;
– protection required for equipment and personnel during maintenance;
– maintenance and accessibility requirements of the system components;
– process conditions/environment of the area in which the AH is to be located (for example,
loading, unloading or transferring of chemicals or equipment, noise, vibration, chemical
releases, etc.).
Clause 5 primarily describes AH located in hazardous (classified environments) and/or into
which flammable or toxic samples are introduced. Those AH located in an unclassified area
and into which no flammable or toxic samples, services, calibration mixtures or air from a
hazardous location are introduced need only provide the environment necessary for accurate
and reliable operation.
5.2 General requirements
This clause addresses the general requirements for safe operation of an AH regardless of
leakage or flammable material (see Clause 6) or material hazardous to health (see Clause 7).
5.3 Dimensions and layout
The size of the AH depends on the number, size and access requirements of the analysers
and auxiliary equipment. Allowance shall be made for any ventilation, drainage, spare parts
storage, electrical distribution, local recording, etc. Recommended minimum dimensions are
2,4 m length and width and 2,3 m headroom. The absolute minimum unobstructed headroom
should be 2,0 m. Spare space of 30 % is recommended to facilitate later equipment addition.
Suspended ceilings, cable trenches and other dead air spaces should be avoided.
5.4 Structural requirements
5.4.1 Construction materials
Local requirements such as for anti-static properties, corrosion, fire and weather resistance
shall be determined and appropriate material selected.
IEC 61285:2015 © IEC 2015 – 13 –
5.4.2 Walls
Where equipment is supported from the walls, appropriate reinforcement may be required.
Wall penetrations should be minimized and sealed where appropriate with materials meeting
the relevant structural and safety requirements (for example, watertight, fire-retardant, flame-
resistant, mechanical strength, etc.).
5.4.3 Floors and foundation
Floors should be non-porous, non-slip and resistant to materials likely to be spilled on them.
Requirements for floor cleaning, such as a slight slope and drain, should be considered. If a
floor drain is installed, it should be free draining to the outside of the AH, where the liquid can
be properly disposed of. Measures should be taken to prevent the entry of extraneous liquids.
Such measures can include raising the floor above the exterior grade level or providing a step
or ramp at the entrance or by appropriately sealing the house at the base.
5.4.4 Doors
Doors shall open outwards and be self-closing or controlled with an alarm device. Doors shall
be fitted with a "panic bar" so that they may be opened from the inside even if locked for use
as emergency escape. The doors shall contain windows with shatter-resistant safety glass. An
additional emergency exit, remote from the first, shall be considered depending on the floor
area of the AH, if access to the main door can be impeded either internally or externally.
Doors used to separate Ex zones are subject to specific requirements as given in
IEC 60079-10-1:2008, Clause A.2. Where the AH is part of a building, other safety
considerations may override this.
5.4.5 Windows
Windows shall be made of shatter-resistant safety glass and shall be fixed closed. Where Ex-
hazards may arise, windows shall be gas-tight. The AH shall have observation windows that
assure an unobstructed view into the room. Observation windows in the door(s) are
preferable.
5.4.6 Roof
The roof shall be designed for appropriate loads (for example, snow, wind, equipment, people,
etc.).
5.5 Equipment
5.5.1 Lighting
Lighting or emergency lights shall be operational at all times. Light level shall be that required
for all works or the level specified by authorities having jurisdiction.
5.5.2 Communications
Where safety alarm(s) from the surrounding plant cannot be detected inside the AH, they shall
be repeated inside the AH. An appropriate device for communication to a permanently
manned location shall be available.
5.5.3 Piping, tubing and valves
Containment systems inside the AH shall be designed such that no hazardous material can
escape into the AH under normal operation. The functions and content of piping, tubing and
valves shall be clearly marked. Isolation valves shall be external to the AH. Streams for
disposal shall be treated according to their hazard, for example, collected in closed systems
or transported to facilities outside the AH. Any lines capable of delivering unacceptable high
quantities of hazardous material under fault conditions into the AH shall have flow restrictors
– 14 – IEC 61285:2015 © IEC 2015
or excess flow preventers outside and before the point of entry into the AH. In addition it shall
be taken into account if the installation of automatic shut-off valves is appropriate.
5.5.4 Utilities
5.5.4.1 Hazardous quantities
The quantity of hazardous auxiliary substances should be restricted to the minimum
necessary to operate the analyser systems.
5.5.4.2 Hazard identification
Any fire, explosion or health hazard should be clearly identified.
5.5.4.3 Asphyxiants (for example nitrogen, carbon dioxide)
5.5.4.3.1 Any asphyxiant line connected into the AH shall have a flow restrictor or excess
flow preventer in the line outside the AH, to limit the flow to assist in meeting the
requirements of the ventilation system.
5.5.4.3.2 When a potential low oxygen hazard exists (for example, instrument air backed
up with nitrogen) or if significant quantities of asphyxiant substances enter the AH under
normal operation in the AH, the air inside the AH has to be monitored by low oxygen
detectors. They shall be installed with fail-safe alarms, both locally and in a remote
permanently manned location.
5.5.4.4 Storage
5.5.4.4.1 Hazardous auxiliary supplies shall be stored outside the AH if possible.
5.5.4.4.2 If the storage of auxiliary gases or calibration gases in pressurized cylinders inside
the AH is unavoidable, they shall be protected against rise in pressure when heated by fire.
This can be accomplished by storage in insulated and continuously ventilated cabinets or
through rupture disks and relief valves, which are installed at the cylinders immediately ahead
of the pressure-reducing stations. Gases escaping from the rupture discs shall be safely
carried to the outside of the AH. Exceptions to these measures may be made in agreement
with local authorities.
5.5.5 Fire extinguishers
An appropriate fire extinguisher shall be located near the door(s).
5.5.6 Ventilation
Ventilation may be installed for climate control, corrosion protection, protection from
asphyxiation, explosion protection (see Clause 6) and/or personnel safety (see Clause 7).
The ventilation air source shall be preferably in a non-hazardous area. If this is not available,
zone 2 air may be used if the equipment installed in the AH is suitable for a zone 2 or worse
location, or if the ventilation air is monitored at the intake point by means of one or more gas
detectors, which discontinue ventilation airflow when a value of 20 % or less of LEL is
exceeded. Dust filtration should be installed in the ventilation inlet.
If ventilation is applied to prevent the formation of an explosive atmosphere, a minimum of
five air changes per hour shall be provided unless a larger flow is required based on
calculations as given in IEC 60079-10-1:2008 Annex B. For flammable liquids, special
requirements apply, as given in 6.3.4.
IEC 61285:2015 © IEC 2015 – 15 –
The prevention of the formation of a toxic or asphyxiate gas atmosphere requires a risk
assessment to define the rate of ventilation and additional measures where required.
5.5.7 Temperature
For safe performance of the monitoring instruments and alarm systems, temperature shall be
kept in their recommended operating range.
5.6 Labelling/instructions/documentation
5.6.1 Entrance
An indelible marked sign indicating the type of hazard may be required according to local
regulations on the entrance to the AH stating that entering the AH is allowed only for
authorized personnel. Information such as the organization responsible for the AH can be
included on the sign (e.g. name, department, telephone number, etc.)
5.6.2 Alarms
An appropriate risk assessment shall be used to determine which of the following AH safety-
related local alarms/indicators shall be generated and visibly displayed:
a) ventilation failure;
b) shelter pressure failure;
c) flammable gas: concentration exceeds 20 % LEL;
d) toxic gas: concentration exceeds allowable levels;
e) oxygen deficiency: oxygen concentration needs to be above statutory requirements;
f) fire- or smoke-detection;
g) automatic extinguisher released;
h) gas/fire detection instrument fault.
The relative densities of the hazardous substances, size of the AH and the air flow dictate the
number and placement of flammable or toxic gas detectors. It may be necessary to detect
light gases near the roof level and heavy gases and vapours near the floor level.
Alarms shall be reported at the following locations:
1) inside the AH a common audible alarm or a highly noticeable visual light (for example,
strobe lamp);
2) at a continuously manned process location, if possible;
3) discrete alarm lamps shall be provided outside near the entrance of the AH for toxic,
asphyxiant, and LEL and should be considered for other alarms.
A positive indication of a non-hazardous condition is recommended.
5.6.3 Safety procedures
The AH safety procedures shall be documented and be kept in a readily accessible location
inside the AH. Any person working in the AH shall have adequate training for this location.
– 16 – IEC 61285:2015 © IEC 2015
5.6.4 Additional data
The following items, as appropriate, should be included in the documentation:
– design data for the ventilation system of the AH (for example, the set point for the
ventilation failure alarm);
– design data for the gas detection system (for example, measuring range, measured
component, alarm set point and corrective action);
– wiring and logic diagrams for all alarm and shut-down systems;
– design of the toxic process disposal system and information for handling contaminated
disposal streams and the exhaust air under upset conditions;
– precise written instructions in clear understandable language about procedures for the
personnel that regularly work with toxic material (for example, instructions on filling the
supply containers with auxiliary material).
6 Explosion protection of AHs
6.1 General
Clause 6 addresses requirements for AH safety by internal ventilation together with
safeguarding systems against either internal or external explosion hazards. In addition,
methods of ensuring safety with natural ventilation are also discussed. Other protective
measures for the non-hazardous operation of analytical equipment should also be observed
but they are not included in this standard.
Additional protective measures can be used at the user’s discretion.
This standard does not address hazards that originate from flammable mixtures supplied into
the AH and that may ignite inside the line or flammable mixtures discharged back into the
plant. For example, flame arresters could be installed at the sampling points whether or not
the analyser is installed in the AH.
6.2 General requirements
6.2.1 If a risk assessment does not state otherwise, all equipment installed in the AH shall
meet the classification for the interior of the AH.
6.2.2 In the event that hazardous conditions (e.g. ventilation failure or gas detection) arise,
any non-explosion-protected equipment shall be disconnected, preferably automatically or
manually by an external switch in a permanently manned location. Restarting shall not be
possible without appropriate authorization.
6.2.3 An external isolation switch s
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