SIST EN 61285:2007
(Main)Industrial-process control - Safety of analyser houses
Industrial-process control - Safety of analyser houses
This International Standard describes the physical requirements for the safe operation of the process analyser measuring system installed in an AH in order to ensure its protection against fire, explosion and health hazards. This standard extends beyond IEC 60079-16 to include houses with Zone 2 interiors and to apply to toxic hazards. (Appropriate national guidelines on toxic hazards are to be followed.) This standard does not address facilities where dust is the hazard. 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. Using n-Pentane as an example, the LEL is 1,4 % or 14 000 × 10-6. 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 × 10-6. Classification of a house interior as Zone 1 may imply that no technician can enter without protective equipment such as breathing gear. Placing an AH in a Zone 1 area would usually imply that no technician could approach the house without wearing protective equipment. Clause 7 addresses those measures for protecting personnel from materials in the atmosphere of AHs that are hazardous to health.
Prozessautomatisierung - Sicherheit von Analysengeräteräumen
Commande des processus industriels - Sécurité des bâtiments pour analyseurs
describes the physical requirements for the safe operation of the process analyser measuring system installed in an AH in order to ensure its protection against fire, explosion and health hazards. This standard extends beyond EN 60079-16 to include houses with Zone 2 interiors and to apply to toxic hazards. (Appropriate national guidelines on toxic hazards are to be followed.)
Regulacija industrijskih procesov - Varnost prostorov za analiziranje (IEC 61285:2004)
General Information
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EUROPEAN STANDARD EN 61285
NORME EUROPÉENNE
EUROPÄISCHE NORM December 2004
ICS 25.040.40; 13.110 Supersedes EN 61285:1994
English version
Industrial-process control -
Safety of analyser houses
(IEC 61285:2004)
Commande des processus industriels - Prozessautomatisierung -
Sécurité des bâtiments pour analyseurs Sicherheit von Analysengeräteräumen
(CEI 61285:2004) (IEC 61285:2004)
This European Standard was approved by CENELEC on 2004-11-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61285:2004 E---------------------- Page: 2 ----------------------
EN 61285:2004 - 2 -
Foreword
The text of document 65D/107/FDIS, future edition 2 of IEC 61285, prepared by SC 65D, Analyzing
equipment, of IEC TC 65, Industrial-process measurement and control, was submitted to the IEC-
CENELEC parallel vote and was approved by CENELEC as EN 61285 on 2004-11-01.This European Standard replaces EN 61285:1994.
This new edition includes minor updates to several sections and references.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2005-08-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-11-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61285:2004 was approved by CENELEC as a European
Standard without any modification.In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60079-10 NOTE Harmonized as EN 60079-10:2003 (not modified).IEC 61115 NOTE Harmonized as EN 61115:1993 (not modified).
__________
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- 3 - EN 61285:2004
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.Publication Year Title EN/HD Year
IEC 60079-16 1990 Electrical apparatus for explosive gas - -
atmospheres
Part 16: Artificial ventilation for the
protection of analyser(s) houses
---------------------- Page: 4 ----------------------
INTERNATIONAL IEC
STANDARD 61285
Second edition
2004-10
Industrial-process control –
Safety of analyser houses
IEC 2004 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODECommission Electrotechnique Internationale U
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 5 ----------------------
– 2 – 61285 © IEC:2004(E)
CONTENTS
FOREWORD...........................................................................................................................3
INTRODUCTION.....................................................................................................................5
1 Scope...............................................................................................................................7
2 Normative references .......................................................................................................7
3 Terms and definitions .......................................................................................................7
4 Location of AHs and connection within the process plant areas ........................................9
4.1 Response time ........................................................................................................9
4.2 Utilities....................................................................................................................9
4.3 Safety .....................................................................................................................9
4.4 Access ..................................................................................................................10
5 Design, construction and layout of AHs ..........................................................................10
5.1 General .................................................................................................................10
5.2 General requirements .............................................................................................10
5.3 Dimensions and layout ..........................................................................................11
5.4 Structural requirements .........................................................................................11
5.5 Equipment.............................................................................................................11
5.6 Labelling/instructions/documentation .....................................................................13
6 Explosion protection of AHs............................................................................................14
6.1 General .................................................................................................................14
6.2 General requirements............................................................................................14
6.3 Protection of AHs against explosion hazards by means of artificial ventilation .......14
6.4 Protection of AHs against explosion hazards by means of natural ventilation ........17
7 Measures to prevent health hazards to personnel in AHs................................................18
7.1 General .................................................................................................................18
7.2 Guidelines .............................................................................................................18
7.3 General requirements............................................................................................18
7.4 Safety measures ...................................................................................................19
7.5 External hazards ...................................................................................................20
7.6 Additional measures for abnormal working conditions............................................20
7.7 Labelling/instructions/documentation .....................................................................20
Annex A (normative) Leakage risk of modules in AHs ..........................................................22
Annex B (informative) Ventilation calculation (assumes STP conditions)..............................24
Bibliography..........................................................................................................................27
Table A.1 – Module evaluation..............................................................................................23
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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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.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
members of its technical committees and IEC National Committees for any personal injury, property damage or
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 65D: Analysing
equipment, of IEC technical committee 65: Industrial-process measurement and control.
This second edition cancels and replaces the first edition published in 1994. 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
The text of this standard is based on the following documents:
FDIS Report on voting
65D/107/FDIS 65D/110/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.---------------------- Page: 7 ----------------------
– 4 – 61285 © IEC:2004(E)
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 maintenance result date indicated on the IEC web site 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.
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61285 © IEC:2004(E) – 5 –
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.This document is designed to set forth minimum safety requirements for typical analyser
houses (AHs). It shall be superseded in all cases by national, local, or corporate
requirements, which may be more stringent.The measured output is transmitted continuously for process control, operator action or
documentation. Process analysers are used for– environmental analysis;
– personnel protection;
– equipment protection;
– quality measurement/control;
– process control (plant optimization);
– energy conservation.
In the simplest case, the analyser sensor is mounted directly in the material to be measured,
and there is no need to extract a sample. In other cases, a sample is extracted from the main
stream and transported to the analyser. The system may include many functional elements
such as– sample extraction;
– sample transport;
– sample conditioning;
– sample stream disposal and/or return to process;
– utilities and auxiliary materials supply;
– stream switching;
– automatic or manual calibration and validation system;
– signal processing;
– performance monitoring and control.
(See IEC 61115.)
Analyser elements can be arranged modularly and located separately. There are advantages
in grouping analysers and systems and further advantages in enclosing them. Advantages
include– lower cost of installation of utilities and signals;
protection of personnel and complex modules and equipment from adverse ambient
conditions;
ease of maintenance;
safety.
Analysers are constructed to various standards: some are ex-proof, some intrinsically safe,
some suitable for Zone 2 and some suitable only for a non-hazardous area. Not all analysers
are available in all variants.Process plants usually include all zones 0, 1, 2 and non-hazardous.
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– 6 – 61285 © IEC:2004(E)
The selection of the AH location, the source of ventilation air, and the classification of the
house interior and its analysers is an economic exercise.Factors include the distance from the sample point to the AH , classification of the area
around the AH, distance from the AH to the source of non-hazardous air, and the cost of
analysers of classification appropriate to the house interior.---------------------- Page: 10 ----------------------
61285 © IEC:2004(E) – 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 AH in order to ensure its protection against
fire, explosion and health hazards. This standard extends beyond IEC 60079-16 to include
houses with Zone 2 interiors and to apply to toxic hazards. (Appropriate national guidelines on
toxic hazards are to be followed.)This standard does not address facilities where dust is the hazard.
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.NOTE For most fluids, the major constraint is that the concentration of vapours, which are hazardous for
personnel, is lower than the lower explosive (flammable) limit (LEL) (see Clause 7).
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 .Classification of a house interior as Zone 1 may imply that no technician can enter without
protective equipment such as breathing gear. Placing an AH in a Zone 1 area would usually
imply that no technician could approach the house without wearing protective equipment.
Clause 7 addresses those measures for protecting personnel from materials in theatmosphere of AHs that are hazardous to health.
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.IEC 60079-16:1990, Electrical apparatus for explosive gas atmospheres – Part 16: Artificial
ventilation for the protection of analyser(s) houses3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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– 8 – 61285 © IEC:2004(E)
3.1
analyser cabinet
small housing in which analysers are installed individually or grouped together. Maintenance
is performed from outside the cabinet with the door(s) open3.2
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. The maintenance of the analysers is normally
performed in the protection of the shelter3.3
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 personnelNOTE Within the scope of this standard, the term AH is used regardless of the structure configuration as either a
room, cabinet or building and whether or not it is an integral part of, or attached to, another structure.
3.4sample conditioning room
SCR
room that is separated from the AH and has modules for sample conditioning, auxiliary
material, or sample disposal equipment.3.5
toxic material
material that is a health hazard by inhalation from the surrounding atmosphere. Atmospheric
routes such as skin absorption or ingestion are not addressed3.6
safety back-up
additional personnel, in constant contact with a person or persons in dangerous working
conditions, who could assist or get additional help3.7
external and internal hazards
distinction is made between "external" and "internal" explosion hazards. An external explosion
hazard exists when the AH is erected at a location where flammable material can be
introduced from the outside resulting in dangerous concentrations of flammable gases and
vapours inside the AH. An internal explosion hazard exists when a flammable mixture can
result from the leakage of samples or auxiliary supplies inside the AH3.8
lower explosive limit
LEL
lower flammable limit
LFL
volume ratio of the flammable gas or vapour in air below which an explosive gas atmosphere
will not be formed3.9
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
---------------------- Page: 12 ----------------------61285 © IEC:2004(E) – 9 –
3.10
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
the analysers (includes Zones 0, 1, and 2 – Division 1 and 2 are also utilized as hazardous
area definitions in many regions – refer to appropriate authorities and standards for detail
definitions)3.11
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
3.12Zone 0
area in which an explosive gas atmosphere is present continuously or for long periods
3.13Zone 1
area in which an explosive gas atmosphere is likely to occur in normal operation
3.14
Zone 2
area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it
does occur, is likely to do so only infrequently and will exist for a short period only
3.15flashpoint
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
3.16ignition temperature (T-rating)
lowest temperature of a heated surface at which, under specified conditions, the ignition of a
flammable substance in the form of a gas or vapour mixture with air will occur4 Location of AHs and connection within the process plant areas
When determining the location of the AH, the following factors should be considered.
4.1 Response timeLine 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.4.2 Utilities
Connection lengths to all utilities such as air, steam, electricity, sample return, signals, etc.
shall be estimated.4.3 Safety
4.3.1 Location
The AH should be located a safe distance from sources of toxic or flammable release, and in
a place where accumulation of these materials is not likely to occur.---------------------- Page: 13 ----------------------
– 10 – 61285 © IEC:2004(E)
4.3.2 Escape
Escape routes shall be determined and remain unobstructed and where possible be oriented
away from hazardous areas.4.3.3 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.4.3.4 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.4.4 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.
Maintenance access to process equipment such as a heat exchanger shall also beconsidered.
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.).This clause 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).
---------------------- Page: 14 ----------------------61285 © IEC:2004(E) – 11 –
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
2,5 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
Construction materials should be fire-retardant and resistant to attack from substances with
which they could come into contact.5.4.2 Walls
Local requirements such as for anti-static properties, corrosion, fire and weather resistance
shall be determined and appropriate material selected. 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. Doors shall be fitted with a "panic bar" so that
they may be opened from the inside even if locked. The doors shall contain windows with
shatter-resistant safety glass. A second door or emergency exit such as a kick-out panel,
remote from the first, should be considered, if access to the main door can be impeded either
internally or externally.NOTE Where the AH is part of a building, other safety considerations may override this.
5.4.5 WindowsUnless the AH is classified non-hazardous and is located in a non-hazardous area, any
windows should be fixed closed and vapour-tight.5.4.6 Roof
The roof shall be designed for appropriate loads (for example, snow, equipment, people, etc.)
5.5 Equipment5.5.1 Lighting
Lighting or emergency lights shall be operational at all times. Minimum light level should be
that required for maintenance work or the level specified by authorities having jurisdiction.
---------------------- Page: 15 ----------------------– 12 – 61285 © IEC:2004(E)
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. Consideration should be given to the installation of a verbal
communications link to a permanently manned location.5.5.3 Piping and valves
Under normal operation, piping, containers and apparatus in the AH shall not have any
openings that would permit hazardous material to escape into the AH. The functions and
content of piping and valves shall be clearly marked. Isolation valves shall be external to the
AH. Streams for disposal should be collected in clo...
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