SIST EN 61285:2007

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

• Status: Published
• Publication Date: 31-Dec-2006
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: MKP - Industrial-process measurement and control
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jan-2007
• Due Date: 01-Jan-2007
• Completion Date: 01-Jan-2007
• Ref Project: EN 61285:2004 - Industrial-process control - Safety of analyser houses

Relations

• Revised: SIST EN 61285:2015 - Industrial-process control - Safety of analyzer houses (IEC 61285:2015)
• Effective Date: 06-May-2014
• Revised: SIST EN 61285:1998 - Industrial-process control - Safety of analyzer houses
• Effective Date: 13-May-2010
• Replaced By: SIST EN 61285:2015 - Industrial-process control - Safety of analyzer houses (IEC 61285:2015)
• Effective Date: 29-Jan-2023
• Replaces: SIST EN 61285:1998 - Industrial-process control - Safety of analyzer houses
• Effective Date: 29-Jan-2023
• Replaces: SIST EN 61285:1998 - Industrial-process control - Safety of analyzer houses
• Effective Date: 07-Jun-2022

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---------------------- Page: 1 ----------------------
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).
__________
---------------------- Page: 3 ----------------------
- 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: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch

PRICE CODE
Commission 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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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

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.
---------------------- Page: 8 ----------------------
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 the
atmosphere 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) houses
3 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) 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. 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 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.

3.4
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
toxic material

material that is a health hazard by inhalation from the surrounding atmosphere. Atmospheric

routes such as skin absorption or ingestion are not addressed
3.6
safety back-up

additional personnel, in constant contact with a person or persons in dangerous working

conditions, who could assist or get additional help
3.7
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 AH
3.8
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 formed
3.9
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

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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

3.12
Zone 0

area in which an explosive gas atmosphere is present continuously or for long periods

3.13
Zone 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

3.15
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

3.16
ignition 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 occur
4 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 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.
4.2 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.
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– 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 be
considered.
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 Windows

Unless 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 Equipment
5.5.1 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
...