BRITISH STANDARD

Non-electrical
equipment for use in
potentially explosive
atmospheres —
Part 2: Protection by flow restricting
enclosure ‘fr’

The European Standard EN 13463-2:2004 has the status of a
British Standard

ICS 13.230

12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:

BS EN
13463-2:2004


BS EN 13463-2:2004

National foreword
This British Standard is the official English language version of
EN 13463-2:2004.
The UK participation in its preparation was entrusted to Technical Committee
FSH/23, Fire precautions in industrial and chemical plant, which has the
responsibility to:
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aid enquirers to understand the text;

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A list of organizations represented on this committee can be obtained on
request to its secretary.
Cross-references
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Summary of pages
This document comprises a front cover, an inside front cover, the EN title page,
pages 2 to 13 and a back cover.
The BSI copyright notice displayed in this document indicates when the
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This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 22 July 2005

© BSI 22 July 2005

ISBN 0 580 46126 2

Amendments issued since publication
Amd. No.

Date

Comments


EUROPEAN STANDARD

EN 13463-2

NORME EUROPÉENNE
EUROPÄISCHE NORM

November 2004

ICS 13.230


English version

Non-electrical equipment for use in potentially explosive
atmospheres - Part 2: Protection by flow restricting enclosure 'fr'
Appareils non électriques destinés à être utilisés en
atmosphères explosibles - Partie 2: Protection par
enveloppe à circulation limitée 'fr'

Nicht-elektrische Geräte für den Einsatz in
explosionsgefährdeten Bereichen - Teil 2: Schutz durch
schwadenhemmende Kapselung 'fr'

This European Standard was approved by CEN on 14 October 2004.
CEN 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 CEN 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 CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies 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.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36

© 2004 CEN


All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

B-1050 Brussels

Ref. No. EN 13463-2:2004: E


EN 13463-2:2004 (E)

Contents
page
Foreword......................................................................................................................................................................3
Introduction .................................................................................................................................................................4
1

Scope ..............................................................................................................................................................5

2

Normative references ....................................................................................................................................5

3

Terms and definitions ...................................................................................................................................5

4
4.1
4.2


General............................................................................................................................................................5
General requirements....................................................................................................................................5
Determination of suitability ..........................................................................................................................5

5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8

Specific requirements and limitations.........................................................................................................6
Nature of ignition source ..............................................................................................................................6
Test requirements..........................................................................................................................................6
Enclosures without the provision for carrying out checks after installation ..........................................6
Enclosures with provisions for carrying out checks after installation ....................................................6
Resilient gaskets............................................................................................................................................7
Poured seals and encapsulating compounds ............................................................................................7
Internal fans or similar devices ....................................................................................................................7
Limits of operation.........................................................................................................................................7

6
6.1
6.2
6.2.1
6.2.2

6.2.3
6.2.4

Verifications and tests ..................................................................................................................................7
Preconditioning for seals and gaskets used to maintain the flow restricting effect..............................7
Tests................................................................................................................................................................7
Equipment with provisions for checking of flow restricting properties ..................................................7
Equipment without provisions for checking of flow restricting properties.............................................7
Equipment where the nominal volume of the enclosure changes due to pressure ...............................8
Routine production test ................................................................................................................................8

7

Instructions for use .......................................................................................................................................8

8

Marking ...........................................................................................................................................................8

Annex ZA (informative) Clauses of this European Standard addressing essential requirements or
other provisions of EU Directives ................................................................................................................9
Bibliography ..............................................................................................................................................................13

2


EN 13463-2:2004 (E)

Foreword
This document (EN 13463-2:2004) has been prepared by Technical Committee CEN/TC 305 “Potentially explosive

atmospheres - Explosion prevention and protection”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by May 2005, and conflicting national standards shall be withdrawn at the latest by
May 2005.
This document has been prepared under a mandate given to CEN by the European Commission and the European
Free Trade Association, and supports essential requirements of EU Directive 94/9/EC of 23 March 1994.
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.
This European Standard consists of the following parts:
EN 13463-1, Non-electrical equipment for potentially explosive atmospheres - Part 1: Basic method and
requirements.
EN 13463-2, Non-electrical equipment for use in potentially explosive atmospheres - Part 2: Protection by flow
restricting enclosure "fr".
prEN 13463-3, Non-electrical equipment for potentially explosive atmospheres - Part 3: Protection by flameproof
enclosure 'd'.
EN 13463-5, Non-electrical equipment intended for use in potentially explosive atmospheres - Part 5: Protection by
constructional safety "c".
prEN 13463-6, Non-electrical equipment for potentially explosive atmospheres - Part 6: Protection by control of
ignition source 'b'.
EN 13463-8, Non-electrical equipment for potentially explosive atmospheres - Part 8: Protection by liquid
immersion 'k'.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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.

3


EN 13463-2:2004 (E)


Introduction
An explosive atmosphere surrounding an enclosure can penetrate it mainly due to the influence of three
mechanisms:
⎯

ventilation;

⎯

equalisation of pressure differences between the inside and outside (breathing);

⎯

diffusion.

If such an enclosure is effectively sealed, but not necessarily gas-tight, it can be assumed that ventilation and
diffusion will not cause a significant short-time exchange of atmosphere. Under these conditions, an exchange of
the external and internal atmospheres through the seals will only take place if there is a pressure difference across
them. Such pressure differences may be caused by changes in temperature and will result in the enclosure
"breathing" but will not cause a significant flow of explosive atmosphere into or through the enclosure.
Experience has shown that even simple enclosures can prevent a surrounding explosive atmosphere from
reaching ignition sources inside them. Flow restricting enclosures are such simple enclosures, which will prevent,
with adequate probability, the atmosphere inside the enclosures becoming explosive if the atmosphere outside the
enclosure becomes explosive rarely and for short durations only. For this reason their use is restricted to the
fulfilment of category 3 requirements.
This document is a type B standard as described in EN 1070.

4



EN 13463-2:2004 (E)

1

Scope

This document specifies the requirements for the construction and testing of flow restricting enclosures for nonelectrical equipment intended for use in potentially explosive atmospheres if the atmosphere outside the enclosure
becomes explosive rarely and for short durations only.
This document supplements the requirements in EN 13463-1 the contents of which apply in full to equipment
constructed in accordance with this document.
Equipment complying with this standard meets the requirements of Group II – Category 3 equipment. The type of
ignition protection described in this standard is unsuitable for use in combination with another type of protection to
produce equipment of any other category than category 3.

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.
EN 13463-1:2001, Non-electrical equipment for potentially explosive atmospheres — Part 1: Basic method and
requirements.

3

Terms and definitions

For the purposes of this document, the terms and definitions given in EN 13463-1:2001 and the following apply.
protection by flow restricting enclosure

type of ignition protection which, by means of an enclosure, reduces the probability of ingress of a surrounding
explosive atmosphere into the enclosure to an acceptably low level so that the concentration inside the enclosure is
below the lower explosive limit

4
4.1

General
General requirements

The requirements of this document apply in addition to the requirements of EN 13463-1.
Flow restricting enclosures used to protect Group II Category 3 equipment may contain ignition sources which
occur during normal operation provided the enclosure itself is not an ignition source.
The type of protection shall not be used if the ignition source is an open flame.

4.2

Determination of suitability

The equipment manufacturers ignition hazard assessment required by EN 13463-1 shall have determined that
protection by flow restricting enclosure is appropriate to achieve the level of protection required by Group II
Category 3 equipment.
NOTE
Equipment manufacturer means the manufacturer who applies flow restricting enclosures to protect the equipment
that may contain ignitions sources under normal operation. It is not the manufacturer of the empty enclosure.

5


EN 13463-2:2004 (E)


5
5.1

Specific requirements and limitations
Nature of ignition source

Protection by flow restricting enclosures may be applied in the following circumstance:
a) Enclosures containing mechanical sparks, and other ignition sources in normal operation but with a limitation in
dissipated power such that the averaged air temperature within the enclosure does not exceed the external
ambient temperature by more than 10 K. However the internal air temperature may exceed the external
ambient temperature by up to 20 K if the rate of temperature decay, when the apparatus is de-energized, is
limited to not more than 10 K/h;
The effects of changes in weather conditions e.g. the sun’s direct heating on the exterior of the enclosure or
rapid cooling by rain showers shall be taken into account. These can cause a larger temperature change than
the 10 K allowed.
b) Where an enclosure is provided with "anti-frost" or "anti-condensation" heating, the 10 K and 20 K temperature
rise in a) may apply above the internal non-operating temperature with the heating in operation, provided that
the source of energy for the heating is independent of the main source of power for the enclosure. It is
essential that simultaneous loss of heating and removal of functional power is unlikely. If the "anti-frost" or
"anti-condensation" heating raises the internal temperature more than 10 K (or 20 K with not more than 10 K/h
decay) above the external ambient, the instructions supplied with the equipment shall require that the operator
of the equipment is satisfied that the equipment is free of hazardous atmosphere before the heating is
reapplied following a shut-down.
NOTE
The use of flow restricting enclosure to protect against ignition from sparks and other permanent ignition sources is
not allowed where, because of high internal temperatures, there is an increased risk of drawing the hazardous atmosphere into
the enclosure when the apparatus is de-energised.

Protection by flow restricting enclosure shall not be used in conjunction with any other type of ignition protection

listed in EN 13463-1.
Flow restricting enclosures are not suitable for equipment operated on a short time duty cycle because of the
increased probability that the equipment might be de-energised when a flammable gas or vapour surrounds the
enclosure.

5.2

Test requirements

Flow restricting enclosures shall comply with Clause 6. Any gasket or special part necessary to comply with the
criteria shall be supplied with the enclosure and shall be subjected to the pre-conditioning described in 6.1 before
subjected to the test specified in 6.2.

5.3

Enclosures without the provision for carrying out checks after installation

Flow restricting enclosures without the provision for carrying out checks after installation or maintenance shall be
type tested including the entries for pipes, shafts etc. These enclosures shall meet the requirements of 6.2.2.
The installation instruction provided with the enclosure shall contain information on proper sealing of the entries.

5.4

Enclosures with provisions for carrying out checks after installation

Provisions shall be made for carrying out checks to ensure that the requirements for flow restricting enclosures are
complied with after installation or after maintenance. The enclosures shall meet the requirements of 6.2.1.
The installation instruction provided with the enclosure shall contain information on proper checking of the
enclosure after installation and maintenance.


6


EN 13463-2:2004 (E)

5.5

Resilient gaskets

Resilient gasket seals shall be positioned so that they are not subject to mechanical and/or chemical damage
under normal operating conditions and they shall retain their sealing properties over the expected life of the
equipment.
Alternatively the manufacturer shall recommend a nominated replacement frequency.
Environmental conditions shall be taken into account.

5.6

Poured seals and encapsulating compounds

Poured seals and encapsulating compounds shall have a continuous operating temperature at least 10 K higher
that occurring when operating in the most onerous rated service conditions.

5.7

Internal fans or similar devices

If internal fans or similar devices are fitted, their operation shall not cause such pressure differences inside the
enclosure that the degree of sealing of the enclosure to the environment is decreased.
NOTE
If an internal device causes an increased pressure difference between inside and outside of the equipment at a

potential source of leakage, an increased flow into the enclosure would result.

5.8

Limits of operation

The manufacturer's instructions shall state that his type of protection shall not be used in situations where there are
static pressure differences over the enclosure walls that could cause a constant flow through the enclosure.

6

Verifications and tests

6.1

Preconditioning for seals and gaskets used to maintain the flow restricting effect

If the equipment contains a gasket or seal of thermoplastic or elastomeric material, the gasket or seal shall be
conditioned in an air oven for 7 days at a temperature at least 10 K higher than the temperature of the gasket or
seal in the most onerous rated service conditions or (80 ± 2) °C whichever is greater.
Seals and gaskets having the proven property to meet at least the requirements given above need not to be
subjected to the preconditioning.

6.2
6.2.1

Tests
Equipment with provisions for checking of flow restricting properties

Under constant temperature conditions, the time interval required for an internal pressure of 300 Pa (3 mbar) below

atmospheric pressure to change to 150 Pa (1,5 mbar) below atmospheric pressure shall be not less than 80 s.
6.2.2

Equipment without provisions for checking of flow restricting properties

Under constant temperature conditions the time interval required for an internal pressure of 3 kPa (30 mbar) below
atmospheric pressure to change to 1,5 kPa (15 mbar) below atmospheric pressure shall be not less than 180 s.
NOTE
For the tests of 6.2.1 and 6.2.2, if the design of the enclosure is such that the rate of breathing is independent of the
direction of the pressure the test may alternatively be performed with a positive pressure within the enclosure.

7


EN 13463-2:2004 (E)

6.2.3

Equipment where the nominal volume of the enclosure changes due to pressure

The enclosure shall be pressurized with air maintained at an overpressure of 400 Pa (4 mbar). The rate of supply
of air in litres per hour (l/h) required to maintain this overpressure shall be measured. This value divided by the net
-1
enclosure volume in litres (l) shall not exceed 0,125 h .
6.2.4

Routine production test

For flow restricting enclosures without a means of checking flow restricting properties after installation, the test of
6.2.2 shall be performed as a routine production test. This test may be shortened by checking that the time taken

for the pressure change of 3 kPa (30 mbar) to 2,7 kPa (27 mbar) is greater than 27 s.

7

Instructions for use

Every enclosure conforming with the requirements of this document shall be accompanied by the instructions and
particulars required by EN 13463-1.
These instructions shall include:
⎯

information advising the user to install it in such a way as to ensure that there is no static pressure difference
over the enclosure walls that could cause flow through the enclosure;

⎯

warning about the effects of the sun’s direct heating on the exterior of the enclosure or by rapid cooling due to
rain showers, water sprays etc.;

⎯

information on proper checking of the enclosure after installation and maintenance according to 5.4;

⎯

information on proper sealing of the entries according to 5.3.

8

Marking


In addition to the marking requirements of EN 13463-1, the specific marking for the complete equipment necessary
for compliance with this document shall include:
⎯

the symbol 'fr' (designating the type of explosion protection);

⎯

a warning label advising the user to install it in such a way as to ensure that there is no static pressure
difference over the enclosure walls that could cause flow through the enclosure.

Example of the marking in relation to the explosion protection:

II 3G fr T6

NOTE
For completeness a temperature class of T6, which will have been determined according to EN 13463-1, has been
used in this example.

8


EN 13463-2:2004 (E)

Annex ZA
(informative)
Clauses of this European Standard addressing essential requirements or
other provisions of EU Directives


This European Standard has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association and supports essential requirements of EU Directive 94/9/EC of 23 March 1994
concerning equipment and protective systems intended for use in potentially explosive atmospheres.
WARNING : Other requirements and other EU Directives may be applicable to the product(s) falling within the
scope of this standard.
The clauses of this standard are likely to support requirements of Directive: 94/9/EC.
Compliance with the clauses of this standard provides one means of conforming with the specific essential
requirements of the Directive concerned and associated EFTA regulations.
The following check list gives the correspondence between the ESR and the relevant clauses of this standard.

9


EN 13463-2:2004 (E)

Table ZA.1 — Essential safety requirements
Essential Safety Requirement

Reference
in this standard

Reference
in other standards

1

Common Requirements

1.0.1


Principles of integrated explosion safety

1.0.2

Design considerations, take account of
faults/misuse

1.0.3

Special checking and maintenance conditions

1.0.4

Foreseeable area conditions

1.0.5

Marking

Clause 8 in combination
with EN 13463-1

1.0.6

Manufacturer’s instructions

Clause 7

1.1


Selection of materials

1.1.1

Must not trigger an explosion

Clause 4 in combination
with in EN 13463-1

1.1.2

Limits of operation

Scope and 5.1 and 5.8

1.1.3

Effects on predictable changes in materials
characteristics

1.2

Design and construction

1.2.1

State of the art design of explosion protection

1.2.2


Safe functioning of replacement components

not applicable

1.2.3

Enclosed structures and prevention of leaks

not applicable

1.2.4

Safety with dust deposits

Dealt with in
EN 13463-1

1.2.5

Additional means of protection for external
stresses

Dealt with in
EN 13463-1 by virtue of
impact and drop tests,
pressure tests, etc.

1.2.6

Safe opening


Dealt with in
EN 13463-1

10

Dealt with in
EN 13463-1

Clauses 5 and 6

Dealt with in
EN 13463-1

Dealt with in
EN 13463-1


EN 13463-2:2004 (E)

Table ZA.1 (continued)
Essential Safety Requirement

Reference
in this standard

Reference
in other standards

1.2.7


Other hazards

a)

Electrical dangers

b)

Surface temperatures

c)

Non-electrical dangers

1.2.8

Overloading of equipment, control devices, power
limitation.

Not applicable to the
type of protection
covered by this
standard

1.2.9

Flameproof enclosure systems

Not applicable to the

type of protection
covered by this
standard

1.3

Prevention of potential ignition sources

Clauses 5 and 6

1.3.1

Hazards arising from hot surfaces and
mechanical sparks.

5.1 and…

1.3.2

Hazards arising from static electricity

1.3.3

Hazards arising from stray electric and leakage
currents

Not applicable to the
type of protection
covered by this
standard


1.3.4

Hazards arising from overheating

5.1 and…

1.3.5

Hazards arising from pressure compensation
operations or shock waves.

Not applicable to the
type of protection
covered by this
standard

1.4

Hazards rising from external effects

1.4.1

Safe functioning

Other external effects
are the subject of
agreement between the
manufacturer and user.


Dealt with in
EN 13463-1

1.4.2

Mechanical and thermal stresses and
withstanding attack by existing or on foreseeable
aggressive substances

Resistance to chemical
attack is subject to
agreement between the
manufacturer and user.

Dealt with in
EN 13463-1

Not applicable in nonelectrical explosion
protection standards.
Dealt with in
EN 13463-1

…dealt with in
EN 13463-1
Dealt with in
EN 13463-1

…dealt with in
EN 13463-1


11


EN 13463-2:2004 (E)

Table ZA.1 (continued)
Essential Safety Requirement

Reference
in this standard

1.5

Requirements in respect of safety-related
devices

Safety Related Devices
are not intended to be
within the scope of this
standard

1.6

Integration of safety requirements relating to
the system

Integrated systems are
not intended to be
within the scope of this
standard.


2

Supplementary requirements in respect of
equipment

2.3

"Group II Category 3"

–

2.3.1

Explosive atmospheres caused by gases,
vapours or mists

–

2.3.1.1

Design and construction of equipment to prevent
foreseeable ignition of gas or mist during normal
operation

2.3.1.2

Surface temperatures not to exceed stated
figures


2.3.1.3

Explosive atmospheres caused by air/dust
mixtures
Design and construction of equipment to prevent
ignition of air/dust mixtures during normal
operation

Equipment constructed
in accordance with this
standard will prevent
ignition by virtue of the
fact that an explosive
atmosphere of gas or
mist will not occur
inside the enclosure
during normal working.
Dealt with in
EN 13463-1
temperature limitation
clauses
Equipment constructed
in accordance with this
standard will prevent
ignition by virtue of the
fact that an explosive
atmosphere of dust will
not occur inside the
enclosure during
normal working.


2.3.2.3

Prevention of dust particles mixing with air in
equipment to cause ignition inside the equipment.

Clause 5 - the
equipment is required
to be effectively sealed.

3

Requirements for 'Protective Systems'

Protective systems are
not intended to be
within the scope of this
standard.

12

Reference
in other standards


EN 13463-2:2004 (E)

Bibliography

[1]


EN 1070, Safety of machinery — Terminology.

13


BS EN
13463-2:2004

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