Bsi bs en 00379 1994 (1999)

BRITISH STANDARD

BS EN
379:1994
Implementing
Amendment No. 1 not
published separately

Specification for

Welding filters with
switchable luminous
transmittance and
welding filters with
dual luminous
transmittance

The European Standard EN 379:1994, with the incorporation of its
amendment A1:1998, has the status of a British Standard

ICS 13.340.20


BS EN 379:1994

Cooperating organizations
The European Committee for Standardization (CEN), under whose supervision
this European Standard was prepared, comprises the national standards
organizations of the following countries:

This British Standard, having

been prepared under the
direction of the Personal
Safety Equipment Standards
Policy Committee, was
published under the authority
of the Standards Board and
comes into effect on
15 May 1994
© BSI 05-1999
The following BSI references
relate to the work on this
standard:
Committee reference PSM/2
Draft for comment 90/44741 DC
ISBN 0 580 21878 3

Austria

Oesterreichisches Normungsinstitut

Belgium

Institut belge de normalisation

Denmark

Dansk Standardiseringsraad

Finland

Suomen Standardisoimisliito, r.y.

France

Association franỗaise de normalisation

Germany

Deutsches Institut für Normung e.V.

Greece

Hellenic Organization for Standardization

Iceland

Technological Institute of Iceland

Ireland

National Standards Authority of Ireland

Italy

Ente Nazionale Italiano di Unificazione

Luxembourg

Inspection du Travail et des Mines

Netherlands

Nederlands Normalisatie-instituut

Norway

Norges Standardiseringsforbund

Portugal

Instituto Portugs da Qualidade

Spain

Asociación Espola de Normalización y Certificación

Sweden

Standardiseringskommissionen i Sverige

Switzerland

Association suisse de normalisation

United Kingdom

British Standards Institution

Amendments issued since publication
Amd. No.

Date

Comments

10073

September
1998

Indicated by a sideline in the margin


BS EN 379:1994

Contents
Cooperating organizations
National foreword
Foreword
1
Scope
2
Normative references
3
Definitions
4
Requirements
5
Test methods
6

Marking
7
Information for users
Annex A (informative) Guidance on selection and use
Table 1 — General requirements
Table 2 — Classification of oculars according to the
maximum value of P1, P2 or P3
Table 3 — Switching the requirements
Table 4 — Assignment of diffusion of light class
National annex NA (informative) Committees responsible
National annex NB (informative) Cross-references

© BSI 05-1999

Page
Inside front cover
ii
2
3
3
3
3
5
6
7
8
4
4
6
6

Inside back cover
Inside back cover

i


BS EN 379:1994

National foreword
This British Standard has been prepared under the direction of the Personal
Safety Equipment Standards Policy Committee and is the English language
version of EN 379:1994 Specification for welding filters with switchable luminous
transmittance and welding filters with dual luminous transmittance, including
Amendment 1:1998, published by the European Committee for Standardization
(CEN).
EN 379 was produced as a result of international discussions in which the
United Kingdom took an active part.
There is no existing equivalent British Standard to EN 379. Attention is drawn
to BS EN 169:1992 Specification for filters for personal eye-protection equipment
used in welding and similar operations, which specifies the requirements for
these more traditional and well-established products.
A British Standard does not purport to include all the necessary provisions of a
contract. Users of British Standards are responsible for their correct application.
Compliance with a British Standard does not of itself confer immunity
from legal obligations.

Summary of pages
This document comprises a front cover, an inside front cover, pages i and ii,
the EN title page, pages 2 to 8, an inside back cover and a back cover.
This standard has been updated (see copyright date) and may have had

amendments incorporated. This will be indicated in the amendment table on
the inside front cover.
ii

© BSI 05-1999


EUROPEAN STANDARD

EN 379

NORME EUROPÉENNE

January 1994

+ A1

EUROPÄISCHE NORM

May 1998

UDC 614.893-086.52:681.7.014.3:621.791-057.21

Supersedes EN 137:1986

ICS 13.340.20

Descriptors: Safety, accident prevention, eyes, filters, welding, specifications, transmittance, dimensions, tests, marking

English version

Specification for welding filters with switchable
luminous transmittance and welding filters with dual
luminous transmittance

Spécification concernant des filtres de soudage
avec facteur de transmission dans le visible
commutable et des filtres de soudage avec
double facteur de transmission dans le visible

Anforderungen an Schweißerschutzfilter mit
umschaltbaren Lichttransmissionsgrad und
Schweißerschutzfilter mit zwei
Lichttransmissionsgraden

This European Standard was approved by CEN on 1994-01-07; amendment A1
was approved by CEN on 1998-04-26. 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,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland,
Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,

Switzerland and United Kingdom.

CEN
European Committee for Standardization
Comité Européen de Normalisation
Europäisches Komitee für Normung
Central Secretariat: rue de Stassart 36, B-1050 Brussels
© 1994 Copyright reserved to CEN members

Ref. No. EN 379:1994\A1:1998 E


EN 379:1994

Foreword

Foreword to A1:1998

This European Standard was drawn up by the
CEN/TC 85 Technical Committee, Eye protection
equipment, of which the Secretariat is held by
AFNOR.
This European Standard has been prepared under a
mandate given to CEN by the European
Communities and the European Free Trade
Association, and supports essential requirements of
EC Directive(s).
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

July 1994, and conflicting national standards shall
be withdrawn at the latest by July 1994.
In accordance with the CEN/CENELEC Internal
Regulations, the following countries are bound to
implement this European Standard: Austria,
Belgium, Denmark, Finland, France, Germany,
Greece, Iceland, Ireland, Italy, Luxembourg,
Netherlands, Norway, Portugal, Spain, Sweden,
Switzerland and United Kingdom.

This Amendment EN 379:1994/A1:1998 to
EN 379:1994 has been prepared by Technical
Committee CEN/TC 85, Eye-protective equipment,
the secretariat of which is held by AFNOR.
This Amendment to the European Standard
EN 379:1994 shall be given the status of a national
standard, either by publication of an identical text
or by endorsement, at the latest by November 1998,
and conflicting national standards shall be
withdrawn at the latest by November 1998.
This Amendment to the European Standard
EN 379:1994 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(s).
According to CEN/CENELEC Internal Regulations,
the national standards organizations of the
following countries are bound to implement this
European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France,

Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal,
Spain, Sweden, Switzerland and the United
Kingdom.

2

© BSI 05-1999


EN 379:1994

1 Scope
This standard specifies requirements for welding
filters which automatically switch their luminous
transmittance to a lower value when a welding arc
is ignited (referred to as welding filters with
switchable scale numbers). The requirements of this
standard apply if such a filter is to be used for
continuous viewing of the welding process and if it
is to be used only during the period when the arc is
being ignited.
This standard also specifies requirements for
welding filters with zones of differing luminous
transmittance (referred to as welding filters with
dual scale number).
These filters are used in welders’ eye protectors (as
specified in standards in preparation) or are fixed to
equipment.

2 Normative references
EN 165, Personal eye protection — Vocabulary.
EN 166:1995, Personal eye protection —
Fundamental specifications.
EN 167:1995, Personal eye protection — Optical test
methods.
EN 168, Personal eye protection — Non-optical
test methods.
EN 169:1992, Personal eye protection — Filters for
welding and related processes — Transmittance and
recommended applications.
EN 175, Personal eye protection — Equipment for
eye and face protection during welding and allied
processes (excluding hoods).
ISO/CIE 10526, CIE standard colorimetric
illuminants.

3 Definitions
For the purposes of this European Standard the
definitions given in EN 165 apply together with the
following.
3.1
welding filter with switchable scale number
a protective filter which automatically switches its
scale number from a lower value (light state scale
number) to a higher value (dark state scale number)
when the welding arc is ignited
3.2
welding filter with dual scale number
a protective filter with two different scale numbers

(light and dark zones) which are divided into a
maximum of three areas of the filter. The light zone
is used for brief viewing when setting the electrode
to the weld and igniting it. The dark zone is used for
viewing the welding process
© BSI 05-1999

3.3
light state scale number
the scale number corresponding to the maximum
value of luminous transmittance E1
3.4
dark state scale number
the scale number corresponding to the minimum
value of luminous transmittance Ù2
3.5
switching time
the time dependence of luminous transmittance is
described by function Ù(t)
the switching time ts is defined by the following
integral:

where:
t=0

is the time at which the arc
ignites;

t = t (Ù = 3Ù2)

is the time at which the
luminous transmittance falls
to 3 times the luminous
transmittance in the dark state

NOTE In the case of short term exposure to light, the glare is
approximately proportional to the product of the illuminance at
the eye and time. The time relationship of the darkening process
can be very different depending on the construction of the
welding filter with switchable scale number. It is therefore
appropriate to define the switching time as an integral of the
luminous transmittance over time and not merely by the initial
and final luminous transmittances.

4 Requirements
4.1 General requirements
Welding filters with switchable scale number and
welding filters with dual scale number shall comply
with the requirements given in Table 1.
4.2 Particular requirements
Where a manufacturer wishes to claim compliance
with particular requirements, these requirements
shall be as specified in clauses 7.2.2 to 7.2.7 of
EN 166:1995.
4.3 Additional requirements for welding
filters with switchable scale numbers
4.3.1 Power off
When tested in accordance with 5.1, welding filters
with switchable scale numbers shall be no more
than nine scale numbers lighter than the highest

scale number in the dark state.

3


EN 379:1994

Table 1 — General requirements
Property

General requirements for welding
filters with switchable scale number

General requirements for welding
filters with dual scale number

Spherical, astigmatic and
prismatic refractive powers

As specified in clause 7.1.2.1.2 of
EN 166:1995

As specified in clause 7.1.2.1.2
of EN 166:1995

Variations in luminous
transmittance

As specified in clause 4.3.3

As specified in clause 7.1.2.2.3
of EN 166:1995

Diffusion of light

As specified in clause 4.3.7

As specified in clause 7.1.2.3 of
EN 166:1995

Quality of material and surface

As specified in clause 7.1.3
EN 166:1995

As specified in clause 7.1.3 of
EN 166:1995

Robustness of construction

As specified in clause 7.1.4 of
EN 166:1995

As specified in clause 7.1.4 of
EN 166:1995

Stability at elevated temperature As specified in clause 7.1.5.1 of
EN 166:1995

As specified in clause 7.1.5.1 of

EN 166:1995

Resistance to ultraviolet
radiation

As specified in clause 7.1.5.2 of
EN 166:1995, but replacing
clause 7.1.5.2 b) by clause 4.3.7 of
this European standard

As specified in clause 7.1.5.2 of
EN 166:1995

Resistance to ignition

As specified in clause 7.1.8 of
EN 166:1995

As specified in clause 7.1.8 of
EN 166:1995

Table 2 — Classification of oculars according to the maximum value
of P1, P2 or P3 as specified in 4.3.3
Maximum value of P1 or P2

Luminous transmittance in dark
state

Maximum value of P3

max.

min.

Class 1

Class 2

Class 3

Class 1

Class 2

Class 3

%

%

%

%

%

%

%

%

100
17,9
0,44
0,023
0,0012

17,9
0,44
0,023
0,0012
0,000023

5
10
15
20
30

10
15
20
30
40

4.3.2 Transmittance
4.3.2.1 The requirements of clauses 4.3.2.2, 4.3.2.3
and 4.3.2.4 shall be satisfied when the
transmittances are measured as described in

clause 6 of EN 167:1995 using standard
Illuminant A.
4.3.2.2 The minimum luminous transmittance in
the light state shall be 0,16 % when measured at
both (– 5 ± 2) °C and (55 ± 2) °C.
4.3.2.3 The luminous transmittance requirements
given in Table 1 of EN 169:1992 shall apply to both
light and dark states. The measurements shall be
taken at both (– 5 ± 2) °C and (55 ± 2) °C.

15
20
30
40
60

20
20
20
20
30

20
20
20
30
40

20
20

30
40
60

4.3.2.4 The spectral transmittance in the ultraviolet
and the mean transmittance in the infra-red as
given in Table 1 of EN 169:1992 and the additional
requirements a) to d) of clause 4.1 of EN 169:1992
required for the dark state shall also apply to the
light state. The measurements shall be taken at a
temperature of (23 ± 5) °C.
4.3.3 Variations in luminous transmittance
When measured in accordance with Clause 7.2 of
EN 167:1995 at a temperature of (23 ± 5) °C the
values of P1, P2 and P3 of welding filters with
switchable scale number shall not exceed the values
in Table 2 for the assigned class. This requirement
shall apply to both light and dark states.
4.3.4 Switching times of welding filters with
switchable scale number
4.3.4.1 The switching times shall satisfy either
clause 4.3.4.2 or clause 4.3.4.3 for the darkest state.

4

© BSI 05-1999


EN 379:1994

Where the requirements of clause 4.3.4.2 are
satisfied, no further marking is required.
Where the requirements of clause 4.3.4.3 are
satisfied but the requirements of clause 4.3.4.2 are
not satisfied, the warning notice
DO NOT USE BELOW 10 °C
shall be permanently and legibly marked on the
device.
4.3.4.2 The switching time shall be measured as
described in clause 5.2 at temperatures
of (– 5 ± 2) °C and (55 ± 2) °C. The switching time
given in Table 3 shall not be exceeded at either of
these temperatures.
4.3.4.3 The switching time shall be measured as
described in clause 5.2 at temperatures
of (10 ± 2 ) °C and (55 ± 2) °C. The switching time
given in Table 3 shall not be exceeded at either of
these temperatures.
4.3.5 Manual control of dark scale number
When a manual control of the dark scale number is
provided, the means of control shall meet the
following requirements.
a) There shall be a digital indication of the scale
number for each position of the manual control.
b) The scale number in the dark state(s) shall not
deviate by more than ±1 from the set scale
number with an illuminance of (104 ± 103) lx on
the switching light source (5.2.1.1).
c) If the range of control is more than five scale
numbers, it shall be divided into two sub-ranges

with separate manual controls. Each manual
control shall control a sub-range of no more
than 5 scale numbers.
4.3.6 Dimensions
The minimum dimensions of the viewing area when
mounted in appropriate equipment shall be 90 mm
by 35 mm.
4.3.7 Diffusion of light
The diffusion of light shall be measured in
accordance with one of the reference methods
described in clause 4 of EN 167:1995.
The maximum value of the reduced luminance
factor in the light or dark state shall determine the
diffusion of light class of the welding filter as shown
in Table 4.

4.4.2 Transmittance
4.4.2.1 The requirements of clauses 4.4.2.2
and 4.4.2.3 shall be satisfied when
the transmittances are measured as described in
clause 6 of EN 167:1995 at a temperature
of (23 ± 5) °C.
4.4.2.2 The minimum luminous transmittance in
the light zone shall be 0,16 %.
4.4.2.3 The spectral transmittance in the ultraviolet
and the mean transmittance in the infra-red given
in Table 1 of EN 169:1992 and the additional
requirements a) to c) in clause 4.1 of EN 169:1992
required for the dark zone shall also apply to the
light zone.

4.4.3 Dimensions
These shall be as given in clause 7.1.1 of
EN 166:1995.
The dark zone shall be at least 25 mm vertical depth
across the horizontal length.
Any region separating the light and dark zones shall
not exceed 2 mm vertical depth across the
horizontal length. This region shall be opaque.

5 Test methods
5.1 Power off test
Measure the luminous transmittance with the
device in the dark state. Disconnect all power
supplies. Repeat the measurement of the luminous
transmittance.
5.2 Measurement of switching time
5.2.1 Test equipment
5.2.1.1 Switching light source. This consists of a
high pressure xenon lamp as a source of radiation,
producing an illuminance of (104 ± 103) lx at the test
specimen.
5.2.1.2 High speed optical shutter. A device capable
of switching on the switching light source at a speed
meeting the requirements of 5.2.2.
5.2.1.3 Measurement light source. A source of
illuminant A (see ISO/CIE 10526).

4.4 Additional requirements for welding
filters with dual scale number
4.4.1 Difference in scale number

The difference in scale number between the light
and dark zones shall be no more than five.

© BSI 05-1999

5


EN 379:1994

Table 3 — Switching time requirements
Dark shade

Light shade
1,7

2

2,5

3

4

5

6

Switching time ms

7

300

400

500

700

1 000

No requirement

No requirement

8

100

150

200

300

500

1 000

No requirement

9

40

50

70

100

200

400

700

10

20

20

30

40

70

100

300

11

6

7

10

15

30

50

100

12

2

3

4

5

10

20

40

13

0,8

1

1,5

2

4

7

10

14

0,3

0,4

0,5

0,7

1

3

5

15

0,10

0,15

0,2

0,3

0,5

1

2

16

0,04

0,05

0,07

0,1

0,2

0,4

0,7

Table 4 — Assignment of diffusion of light
class
Diffusion of light
class

1
2
3

Maximum value reduced
luminance factor
(cd/m2)/lx

1,0
2,0
3,0

5.2.1.4 Light detector and recording apparatus. A
device capable of detecting and recording the light
from the measurement light source transmitted by

the welding filter.
5.2.2 Performance of test equipment
Check that when the light beam is switched by the
high speed shutter, the rise time between 10 %
and 90 % of the light transmitted by the shutter is
no greater than 10 % of the switching time required
for the scale number difference to be measured.
See Table 3.
5.2.3 Measurement
Maintain the test specimen at the appropriate test
temperature for a minimum of 2 h before testing
and during the period of the test.
Set up the measurement light source (5.2.1.3) and
the test specimen so that the plane of the test
specimen and the light detector (5.2.1.4) are
at (90 ± 5) ° to the measurement beam.
With the switching light source on, switch the high
speed shutter to allow the light through to the test
specimen, thereby switching the test specimen to its
dark state. Record the measurement light
transmitted through the test specimen during the
switching period.

6

5.2.4 Calculation
Calculate the switching time ts from the equation
given in 3.5, with t = 0 as the time when the
illuminance at the test specimen reaches about half
the value given in 5.2.1.1.

6 Marking
This shall be as specified in clause 9 of EN 166:1995
with the following additional details.
6.1 Welding filter with switchable scale
number
The light state scale number and the dark state
scale number(s), separated by an oblique stroke,
shall be used instead of the single scale number.
Where the dark state is manually controlled, the
limits of the range of attainable scale numbers shall
be marked separated by a hyphen.
The diffusion of light class and uniformity of
luminous transmittance class shall be added,
separated by oblique strokes, to the optical class as
specified in EN 166:1995, clause 7.1.2.1.2 e.g. 1/3/2.
NOTE

Examples of marking are as follows.

a) A simple device with one light state and one
dark state: 5/11.
b) A device with one light state and manual
control of the dark state in one range: 4/9-13.
c) A device with one light state and manual
control of the dark state in two
ranges: 4/5-7/10-13.

© BSI 05-1999

EN 379:1994

If appropriate, the symbols for compliance with
particular requirements of EN 166 (see clause 4.2)
shall be given.

7 Information for users

Where appropriate, the symbols for compliance with
particular requirements of EN 166 (see 4.2) and the
warning note “Do not use below 10 °C”
(see clause 4.3.4.1) shall be added.
6.2 Welding filter with dual shade
The scale number of the light zone(s) and the scale
number of the dark zone, separated by a plus sign,
shall be used instead of the single scale number,
e.g. 6 + 10.

© BSI 05-1999

Each welding filter shall be accompanied by
instructions for use as specified in clause 10 of
EN 166:1995, together with the following additional
information:
a) information on the recognition of failure;
b) information on the intervals at which
components or the complete filter should be
changed;
c) for dual shade filters: A warning to the effect

that the welding process should only be observed
through the dark shade;
d) where the device does not meet the
performance requirements at – 5 °C
(see clause 4.3.4) a warning to the effect that it
should not be used below 10 °C.
e) any optional requirements given in EN 166
which the device satisfies (for example, protection
against high speed particles).

7


EN 379:1994

Annex A (informative)
Guidance on selection and use
Refer to Annex A of EN 169:1992.

8

© BSI 05-1999


BS EN 379:1994
National annex NA (informative)
Committees responsible
The United Kingdom participation in the preparation of this European Standard was entrusted by the
Personal Safety Equipment Standards Policy Committee (PSM/-) to Technical Committee PSM/2 upon
which the following bodies were represented:

Association for Consumer Research
British College of Optometrists
British Foundry Association
British Glass Manufacturers’ Confederation
British Non-Ferrous Metals Federation
British Plastics Federation
British Steel Corporation
City University
Department of Trade and Industry (National Physical Laboratory)
Electricity Industry in the United Kingdom
Engineering Equipment and Materials Users’ Association
Federation of Manufacturing Opticians
Flat Glass Manufacturers’ Association
Health and Safety Executive
Industrial Safety (Protective Equipment) Manufacturers’ Association
Institution of Gas Engineers
Institution of Mechanical Engineers
Institution of Occupational Safety and Health
Light Metals Founders’ Association
Manufacturing Science Finance
Ministry of Defence
National Radiological Protection Board
Safety Equipment Distributors’ Association
Steel Casting Research and Trade Association
Trades Union Congress
Zinc Alloy Die Casters’ Association

National annex NB (informative)
Cross-references
Publication referred to

Corresponding British Standard

EN 165:1986

BS 6967:1988 Glossary of terms for personal eye-protection

EN 169:1992

BS EN 169: 1992:Specification for filters for personal eye-protection equipment
used in welding and similar operations

© BSI 05-1999


BS EN
379:1994

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