IEC 61285:2004
(Main)Industrial-process control - Safety of analyser houses
Industrial-process control - Safety of analyser houses
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.)
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INTERNATIONAL IEC
STANDARD 61285
Second edition
2004-10
Industrial-process control –
Safety of analyser houses
Reference number
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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
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Commission Electrotechnique Internationale U
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
– 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
61285 © IEC:2004(E) – 3 –
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
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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
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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.
– 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.
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.
– 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.
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
...
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