Guidance on design, selection and installation of vents to safeguard the structural integrity of enclosures protected by gaseous fire-extinguishing systems (ISO/TS 21805:2018)

This document provides guidance on fulfilling the requirements contained in BS EN15004-1 and
BS 5306-4, in respect to over and under pressurisation venting - clauses 7.4.1 and 10.3.3. respectively and post
discharge extract - clauses 5.3 h) and 15.9 respectively.
It considers the design, selection and installation of vents to safeguard the structural integrity of enclosures
protected by fixed gaseous fire fighting systems and the post discharge venting provisions where used.

Anleitung für die Konstruktion, Auswahl und Installation von Entlüftungen zur Gewährleistung der strukturellen Integrität von Gehäusen, die durch ortsfeste Gaslöschanlagen geschützt sind (ISO/TS 21805:2018)

Dieses Dokument enthält Anleitungen für die Erfüllung der Anforderungen von ISO 6183:2009, 6.4.1 und 7.4.1, sowie von ISO 14520 1:2015, 5.2.1 h) und 5.3 h), in Bezug auf Über- und Unterdruckentlastungs-vorrichtung und die Nachentlüftung.
Es behandelt die Auslegung, Auswahl und Installation von Entlüftungsvorrichtungen, mit dem Ziel, die strukturelle Integrität von Räumen sicherzustellen, die durch ortsfeste Gaslöschanlagen geschützt sind, und betrachtet die Anforderungen an die Nachentlüftung, sofern verwendet.

Lignes directrices pour la conception, la sélection et l'installation d'évents pour préserver l'intégrité structurelle des enceintes protégées par des systèmes fixes de lutte contre l'incendie à gaz (ISO/TS 21805:2018)

Navodilo za projektiranje, izbiro in vgradnjo prezračevalnih naprav za zagotavljanje strukturne integritete namestitvenih prostorov, zaščitenih s sistemi za gašenje s plinom (ISO/TS 21805:2018)

Ta dokument vsebuje napotke za izpolnjevanje zahtev iz standardov BS EN15004-1 in BS 5306-4 glede prezračevanja s podtlakom in nadtlakom – točki 7.4.1 in 10.3.3. ter odzračevanja – točki 5.3 h) in 15.9.
Upošteva projektiranje, izbiro in vgradnjo prezračevalnih naprav za zagotavljanje strukturne integritete namestitvenih prostorov, zaščitenih s fiksnimi sistemi za gašenje s plinom, in določbe za naknadno odzračevanje.

General Information

Status
Published
Public Enquiry End Date
24-Oct-2018
Publication Date
14-Mar-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
04-Feb-2019
Due Date
11-Apr-2019
Completion Date
15-Mar-2019

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SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 21805:2019
01-april-2019
1DYRGLOR]DSURMHNWLUDQMHL]ELURLQYJUDGQMRSUH]UDþHYDOQLKQDSUDY]D

]DJRWDYOMDQMHVWUXNWXUQHLQWHJULWHWHQDPHVWLWYHQLKSURVWRURY]DãþLWHQLKVVLVWHPL

]DJDãHQMHVSOLQRP ,6276

Guidance on design, selection and installation of vents to safeguard the structural

integrity of enclosures protected by gaseous fire-extinguishing systems (ISO/TS
21805:2018)
Anleitung für die Konstruktion, Auswahl und Installation von Entlüftungen zur
Gewährleistung der strukturellen Integrität von Gehäusen, die durch ortsfeste
Gaslöschanlagen geschützt sind (ISO/TS 21805:2018)

Lignes directrices pour la conception, la sélection et l'installation d'évents pour préserver

l'intégrité structurelle des enceintes protégées par des systèmes fixes de lutte contre

l'incendie à gaz (ISO/TS 21805:2018)
Ta slovenski standard je istoveten z: CEN ISO/TS 21805:2019
ICS:
13.220.10 Gašenje požara Fire-fighting
91.140.30 3UH]UDþHYDOQLLQNOLPDWVNL Ventilation and air-
VLVWHPL conditioning systems
SIST-TS CEN ISO/TS 21805:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN ISO/TS 21805:2019
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SIST-TS CEN ISO/TS 21805:2019
CEN ISO/TS 21805
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
January 2019
TECHNISCHE SPEZIFIKATION
ICS 91.140.30; 13.220.10
English Version
Guidance on design, selection and installation of vents to
safeguard the structural integrity of enclosures protected
by gaseous fire-extinguishing systems (ISO/TS
21805:2018)

Lignes directrices pour la conception, la sélection et Anleitung für die Konstruktion, Auswahl und

l'installation d'évents pour préserver l'intégrité Installation von Entlüftungen zur Gewährleistung der

structurelle des enceintes protégées par des systèmes strukturellen Integrität von Gehäusen, die durch

fixes de lutte contre l'incendie à gaz (ISO/TS ortsfeste Gaslöschanlagen geschützt sind (ISO/TS

21805:2018) 21805:2018)

This Technical Specification (CEN/TS) was approved by CEN on 30 November 2018 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 21805:2019 E

worldwide for CEN national Members.
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SIST-TS CEN ISO/TS 21805:2019
CEN ISO/TS 21805:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST-TS CEN ISO/TS 21805:2019
CEN ISO/TS 21805:2019 (E)
European foreword

This document (CEN ISO/TS 21805:2019) has been prepared by Technical Committee ISO/TC 21

"Equipment for fire protection and fire fighting" in collaboration with Technical Committee CEN/TC

191 “Fixed firefighting systems” the secretariat of which is held by BSI.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this Technical Specification : Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO/TS 21805:2018 has been approved by CEN as CEN ISO/TS 21805:2019 without any

modification.
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SIST-TS CEN ISO/TS 21805:2019
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SIST-TS CEN ISO/TS 21805:2019
TECHNICAL ISO/TS
SPECIFICATION 21805
First edition
2018-12
Guidance on design, selection and
installation of vents to safeguard the
structural integrity of enclosures
protected by gaseous fire-
extinguishing systems
Lignes directrices pour la conception, la sélection et l'installation
d'évents pour préserver l'intégrité structurelle des enceintes protégées
par des systèmes fixes de lutte contre l'incendie à gaz
Reference number
ISO/TS 21805:2018(E)
ISO 2018
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SIST-TS CEN ISO/TS 21805:2019
ISO/TS 21805:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

5 Use and limitations ............................................................................................................................................................................................ 3

6 Safety ................................................................................................................................................................................................................................ 4

6.1 Structural safety ..................................................................................................................................................................................... 4

6.2 Personnel safety ..................................................................................................................................................................................... 4

7 System design — Pressure-relief venting ................................................................................................................................... 4

7.1 General ........................................................................................................................................................................................................... 4

7.2 Extinguishant characteristics ..................................................................................................................................................... 4

7.2.1 Pressure graphs ................................................................................................................................................................ 5

7.3 Enclosure characteristics ............................................................................................................................................................... 7

7.4 Pressure-relief vent paths ............................................................................................................................................................. 7

7.5 Types of pressure-relief vents ................................................................................................................................................... 7

7.5.1 General...................................................................................................................................................................................... 7

7.5.2 Gravity vents ........................................................................................................................................................................ 7

7.5.3 Counter weighted flap vent..................................................................................................................................... 8

7.5.4 Electrically operated vents ...................................................................................................................................... 8

7.5.5 Pneumatically operated vent ................................................................................................................................ 9

7.5.6 Vent accessories ............................................................................................................................................................... 9

7.6 Pressure-relief vent characteristics ...................................................................................................................................10

7.6.1 Vent efficiency .................................................................................................................................................................10

7.6.2 Minimum opening pressure ................................................................................................................................11

7.6.3 Minimum closing pressure ...................................................................................................................................11

7.6.4 Fire rating............................................................................................................................................................................11

7.7 Vent location and mounting ......................................................................................................................................................11

7.7.1 Vent location .....................................................................................................................................................................11

7.7.2 Vent mounting .................................................................................................................................................................12

7.8 Pressure-relief vent area calculations ..............................................................................................................................13

7.8.1 Use of agent-specific equations ........................................................................................................................13

7.8.2 Vent area requirement (non-liquefiable gases and CO ) ...........................................................14

7.8.3 Vent area requirements (liquefiable gases) ...........................................................................................18

7.8.4 Leakage .................................................................................................................................................................................22

7.9 Cascade venting calculations ...................................................................................................................................................23

7.9.1 Example calculation 3 ........................................................................................................................................... ....24

7.9.2 Cascade vent arrangements ................................................................................................................................25

7.9.3 Venting into adjacent enclosures ....................................................................................................................26

8 System design — Post discharge venting .................................................................................................................................28

9 Acceptance ...............................................................................................................................................................................................................28

10 Service and maintenance ..........................................................................................................................................................................28

Bibliography .............................................................................................................................................................................................................................30

© ISO 2018 – All rights reserved iii
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Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire

fighting, Subcommittee SC 8, Gaseous media and firefighting systems using gas.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved
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Introduction

The guidance presented here is based on the results of a joint research program conducted in 2006 and

2007 by several fire protection system manufacturers and interested parties. The program of work

consisted of several series of tests to evaluate the peak pressure response and pressure-relief vent

area effects for each agent addressed in this document. The key data used in the development of this

document were the values of peak enclosure pressure response (PMAX) at each value of the volume-

normalized pressure-relief vent area of the test enclosure, hereinafter referred to as the “leakage-to-

volume ratio” or LVR. Other test parameters (enclosure temperature, agent quantity, discharge time,

and humidity) were held constant or varied in a specified manner. For each test series employing a

single agent, the several pairs of LVR and resultant PMAX values were graphically analysed and a best-

fit correlation curve was determined.

The LVR vs. PMAX correlation curve for each agent or system forms the basis of the associated equations

in cases where discharge of the agent results in cooling the air temperature below its dew point. (See

Humidity effects and humidity correction factor below.) In most cases, only halocarbon agents cause

sufficient cooling to cause humidity related effects on the peak enclosure pressure. Thus, a correction

for humidity effects is included in the equations for estimating vent area and maximum pressure on the

discharge of the following agents:
— FK-5-1-12
— HFC-23
— HFC-125
— HFC-227ea

The humidity corrections used in this document are based on the results of tests conducted with HFC-

227ea at different conditions of humidity.

The resulting values for humidity correction will be assumed to be equally applicable to the agents FK-

5-1-12, HFC-125 and HFC-23 until further data or analysis indicates otherwise.

The correlations of LVR to maximum negative pressure and maximum positive pressure were based

on test work performed in a test chamber at a relative humidity (RH) of approximately 38 %. If the RH

in a protected enclosure differs from 38 % then a correction to the estimated maximum negative and

positive pressures may be required. See 7.8 and 7.9 for further information on the effect of humidity. The

temperature of the test enclosure was 21°C (nominal) for all tests that form the basis of the estimating

methods given in this document.

In conducting the research program, described above, a large number of different venting arrangements

were created in the test enclosure. The equivalent leakage area (ELA) for each test was determined by

a “door fan test” and data analysis. The average enclosure pressure in effect during the many door fan

tests varied from test to test. All values of ELA were normalized to an equivalent enclosure differential

pressure of 125 Pa. The resulting enclosure correlations of peak pressure vs. LVR, and any resulting

estimate of enclosure pressure-relief vent area, reflect a pressure-relief vent area calculated at an

effective enclosure pressure of 125 Pa for a vent with discharge coefficient of 0,61.

The effectiveness of a gaseous total flooding firefighting system depends, in part, on retention of the air-

extinguishant mixture within the protected volume for a period of time. Retention of the extinguishant-

air mixture requires that gas exchange (“leakage”) between the enclosure and the ambient environment

be restricted. In order to limit the rate of gas exchange the enclosure boundary should have a high

degree of integrity. To put it another way, the sum total of the areas of the various penetrations in an

enclosure’s bounding surfaces should be low, at least during the gas-retention period (hold time) after

the end of extinguishant discharge.

Addition of a gaseous firefighting extinguishant to an enclosure having limited pressure-relief vent area

will naturally result in a change of pressure therein. If the enclosure is sealed too tightly during the

extinguishant discharge, i.e., too little pressure-relief vent area, the pressure change could exceed the

© ISO 2018 – All rights reserved v
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structural strength of one or more of its bounding surfaces — windows, doors, walls, ceiling. Conversely,

if the enclosure has too much pressure-relief vent area then gas exchange with the ambient atmosphere

will occur rapidly, leading to short retention time of the extinguishant within the protected volume.

Thus, the use of gaseous firefighting systems should address two performance considerations:

a) Pressure management within the protected volume during the period of extinguishant

discharge, and

b) Retention of the extinguishant-air mixture within the enclosure for a specified period of time after

the completion of the discharge.

This document provides guidance for limiting pressure extremes in an enclosure during the discharge

of a clean agent fire extinguishing system. This document does not provide the information necessary to

determine all of the requirements related to the design, installation, service, maintenance, inspection,

test, and/or requalification of fire suppression systems.

Some limitations and restrictions apply to the use of the equations contained in this document. Please

refer to the text and notes that follow.

The information in this document does not supersede the manufacturer’s guidance. The information

contained in this document is presented as supplementary to the guidance provided by the respective

system manufacturers. Guidance from the system manufacturer should always be followed and used

for purposes of system design, installation, operation and maintenance.

It has been assumed in the preparation of this document that the execution of its provisions is entrusted

to people appropriately qualified and experienced in the specification, design, installation, testing,

approval, inspection, operation and maintenance of systems and equipment, for whose guidance it has

been prepared, and who can be expected to exercise a duty of care to avoid unnecessary release of

extinguishant.
vi © ISO 2018 – All rights reserved
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SIST-TS CEN ISO/TS 21805:2019
TECHNICAL SPECIFICATION ISO/TS 21805:2018(E)
Guidance on design, selection and installation of vents to
safeguard the structural integrity of enclosures protected
by gaseous fire-extinguishing systems
1 Scope

This document provides guidance on fulfilling the requirements contained in ISO 6183:2009, 6.4.1 and

7.4.1 and ISO 14520-1:2015, 5.2.1 h and 5.3 h, in respect to over and under pressurisation venting and

post discharge extract.

It considers the design, selection and installation of vents to safeguard the structural integrity of

enclosures protected by fixed gaseous extinguishing systems and the post discharge venting provisions

where used.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at https: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp

NOTE For the purposes of this document, the term “bar” signifies “gauge”, unless otherwise indicated.

Concentrations or quantities expressed in percentages (%) signify by volume, unless otherwise indicated.

3.1
back pressure
pressure downstream of a vent
3.2
fire damper
device designed to prevent the spread of fire
3.3
free pressure-relief vent area
sum of the free pressure-relief vent areas of the pressure-relief vents provided

Note 1 to entry: This is determined by the gross pressure-relief vent area x the vent efficiency.

3.4
gross pressure-relief vent area
total area of the pressure-relief vent
3.5
negative pressure

pressure in the protected room which is lower than the pressure immediately outside the enclosure

boundary
© ISO 2018 – All rights reserved 1
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3.6
peak pressure

The maximum pressure (positive and negative) generated within a an enclosure caused by the discharge

of the gaseous agent
3.7
positive pressure

pressure in the protected room which is higher than the pressure immediately outside the enclosure

boundary
3.8
enclosure strength
specified differential pressure limit for the protected enclosure
3.9
pressure-relief area
sum of the free pressure-relief vent area and the enclosure leakage area
3.10
pressure-relief vent

device that provides a flow path through an enclosure boundary to limit the pressure therein

4 Symbols and abbreviated terms
2 2

A pressure-relief vent area to limit negative pressure to a specified P , cm (in )

N N
2 2

A pressure-relief vent area to limit positive pressure to a specified P , cm (in )

P P
C agent design concentration, in percent by volume
M is the molecular weight of air = 0,029 (kg/mol)
AIR
M molecular weight of the agent, (kg/mol)
AGT
Q minimum design quantity of agent (kg)
P pressure (Pa)
P negative pressure, psf (Pa)
P positive pressure, psf (Pa)
P and P represent either
N P
— Design pressure limits for estimating A or A , or
N P
— Estimates of maximum values of P or P for given values of A or A
N P N P
R gas law constant, 8,314 (J/mol-K)
% RH relative humidity in hazard space at 21 °C (70 °F), %
s specific volume of the agent at the design temperature (m /kg)

s specific volume of the homogenous agent-air mixture (m /kg), which is the inverse of the

density
2 © ISO 2018 – All rights reserved
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t agent discharge time, s
V volume of the protected space (m )
ρ agent-air mixture density at the specified temperature and pressure (kg/m )
5 Use and limitations

This document is for the use by those competent in the design, installation, servicing and maintenance

of fixed gaseous firefighting systems. It also serves as guidance for those involved in the design,

construction and operation of buildings in which such systems are installed.

It does not replace the need for the person responsible for the design, construction and operation of the

building to fulfil their obligations in respect to providing adequate structural provisions.

There may be other trades and services involved in the complete system and the document is limited to

providing the guidance outlined in the document and does not purport to be expert in all areas.

After applying the enclosure peak pressure and pressure-relief vent area analysis of this document, the

user may conclude that an enclosure may require additional pressure-relief vent area in order to avoid

exceeding specified maximum pressure values upon discharge of a gaseous agent system. If that is the

case, it is recommended that the user advise the supplier of a supplemental venting device that such

device be specified and selected by use of this document.

The maximum pressure developed in an enclosure on discharge of a clean agent fire extinguishing

system is affected by several characteristics of the system itself and the enclosure being protected. Of

particular importance are the thermodynamic properties of the agent and the discharge characteristics

of the hardware. Each of the following sections contains correlation equations that are specific to the

agent type and manufacturer’s hardware. The equations can be used to make estimates of the following:

a) enclosure pressure-relief vent area given a specified enclosure pressure limit;

b) maximum positive or negative pressure developed in an enclosure given a stated or calculated

pressure-relief vent area.

NOTE The formulae in this document for halocarbon agents have a limited range of applicability based on the

parametric limitations of the data from which they were derived. Table 1 indicates the applicable limits of design

concentration, discharge time, and enclosure pressure response for the use of thi

...

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