EN ISO 14119:2013

SLOVENSKI STANDARD
01-marec-2014
1DGRPHãþD
SIST EN 1088:2000+A2:2008
9DUQRVWVWURMHY=DSRUQHQDSUDYHSRYH]DQH]YDURYDOL1DþHOD]DQDþUWRYDQMHLQ
L]ELUR,62
Safety of machinery - Interlocking devices associated with guards - Principles for design
and selection (ISO 14119:2013)
Sicherheit von Maschinen - Verriegelungseinrichtungen in Verbindung mit trennenden
Schutzeinrichtungen - Leitsätze für Gestaltung und Auswahl (ISO 14119:2013)
Sécurité des machines - Dispositifs de verrouillage associés à des protecteurs -
Principes de conception et de choix (ISO 14119:2013)
Ta slovenski standard je istoveten z: EN ISO 14119:2013
ICS:
13.110 Varnost strojev Safety of machinery
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 14119
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2013
ICS 13.110 Supersedes EN 1088:1995+A2:2008
English Version
Safety of machinery - Interlocking devices associated with
guards - Principles for design and selection (ISO 14119:2013)
Sécurité des machines - Dispositifs de verrouillage Sicherheit von Maschinen - Verriegelungseinrichtungen in
associés à des protecteurs - Principes de conception et de Verbindung mit trennenden Schutzeinrichtungen - Leitsätze
choix (ISO 14119:2013) für Gestaltung und Auswahl (ISO 14119:2013)
This European Standard was approved by CEN on 24 August 2013.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same
status as the official versions.

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, 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: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14119:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC .4

Foreword
This document (EN ISO 14119:2013) has been prepared by Technical Committee ISO/TC 199 "Safety of
machinery" in collaboration with Technical Committee CEN/TC 114 “Safety of machinery” 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 April 2014, and conflicting national standards shall be withdrawn at the
latest by April 2015.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 1088:1995+A2:2008.
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.
For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 14119:2013 has been approved by CEN as EN ISO 14119:2013 without any modification.

Annex ZA
(informative)
Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide a means of conforming to Essential Requirements of the
New Approach Directive Machinery 2006/42/EC.
Once this standard is cited in the Official Journal of the European Union under that Directive and has been
implemented as a national standard in at least one Member State, compliance with the normative clauses of
this standard confers, within the limits of the scope of this standard, a presumption of conformity with the
relevant Essential Requirements 1.4.2.2 Interlocking movable guards of Annex I of that Directive and
associated EFTA regulations.
WARNING — Other requirements and other EU Directives may be applicable to the product(s) falling within
the scope of this standard.
INTERNATIONAL ISO
STANDARD 14119
Second edition
2013-10-01
Safety of machinery — Interlocking
devices associated with guards —
Principles for design and selection
Sécurité des machines — Dispositifs de verrouillage associés à des
protecteurs — Principes de conception et de choix
Reference number
ISO 14119:2013(E)
©
ISO 2013
ISO 14119:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 14119:2013(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Operating principles and typical forms of interlocking devices associated with guards .6
4.1 General . 6
4.2 Principles of guard interlocking without guard locking . 8
4.3 Principles of guard interlocking with guard locking . 8
5 Requirements for the design and the installation of interlocking devices with and without
guard locking .11
5.1 General .11
5.2 Arrangement and fastening of position switches .11
5.3 Arrangement and fastening of actuators .12
5.4 Actuation modes of interlocking devices .12
5.5 Interface to control systems .13
5.6 Mechanical stop .13
5.7 Additional requirements on guard locking devices .13
6 Selection of an interlocking device.18
6.1 General .18
6.2 Selection of a guard locking device .19
6.3 Environmental conditions considerations .21
7 Design to minimize defeat possibilities of interlocking devices .21
7.1 General .21
7.2 Additional measures to minimize defeat possibilities of interlocking devices .23
8 Control requirements .26
8.1 General .26
8.2 Assessment of faults .26
8.3 Prevention of common cause failures .27
8.4 Release of guard locking device .29
8.5 Fault exclusion .29
8.6 Logical series connection of interlocking devices .29
8.7 Electrical and environmental conditions .30
9 Information for use .30
9.1 General .30
9.2 Information for use given by the manufacturer of interlocking devices .30
9.3 Information for use given by the manufacturer of the machine .32
Annex A (informative) Type 1 interlocking device — Examples .33
Annex B (informative) Type 2 interlocking device — Examples .38
Annex C (informative) Type 3 interlocking device — Example.43
Annex D (informative) Type 4 interlocking devices — Examples .45
Annex E (informative) Examples of other interlocking devices .48
Annex F (informative) Example of guard locking devices .49
Annex G (informative) Application examples of interlocking devices used within a
safety function.55
Annex H (informative) Motivation to defeat interlocking device .61
ISO 14119:2013(E)
Annex I (informative) Examples for maximum static action forces .66
Bibliography .68
iv © ISO 2013 – All rights reserved

ISO 14119:2013(E)
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. 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. 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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 199, Safety of machinery.
This second edition cancels and replaces the first edition (ISO 14119:1998), which has been technically
revised. It also incorporates Amendment ISO 14119:1998/Amd 1:2007. The main changes from the
previous edition comprise
— an improved structure as a result of the differentiation and definition of four types of interlocking
devices,
— a description of their technology and their typical characteristics in annexes,
— “defeat in a reasonably foreseeable manner” defined and considered,
— the measures required to minimize defeat possibilities, and
— the consideration of new technologies and the addition of informative Annexes G, H and I.
ISO 14119:2013(E)
Introduction
The structure of safety standards in the field of machinery is as follows:
a) Type-A standards (basic safety standards) giving basic concepts, principles for design, and general
aspects that can be applied to all machinery;
b) Type-B standards (generic safety standards) dealing with one safety aspect or one type of safeguard
that can be used across a wide range of machinery:
— Type-B1 standards on particular safety aspects (e.g. safety distances, surface temperature, noise);
— Type-B2 standards on safeguards (e.g. two-hand controls, interlocking devices, pressure-
sensitive devices, guards);
c) Type-C standards (machine safety standards) dealing with detailed safety requirements for a
particular machine or group of machines.
This document is a type-B2 standard as stated in ISO 12100.
The requirements of this document can be supplemented or modified by a type-C standard.
For machines which are covered by the scope of a type-C standard and which have been designed and built
according to the requirements of that standard, the requirements of that type-C standard take precedence.
This International Standard has been prepared to give guidance to machinery designers and writers of
product safety standards on how to design and select interlocking devices associated with guards.
Relevant clauses of this International Standard, used alone or in conjunction with provisions from
other standards, may be used as a basis for verification procedures for the suitability of a device for
interlocking duties.
The informative Annexes A to F describe the technology and the typical characteristics of the defined
4 types of interlocking devices. Other solutions may be adopted, provided that they comply with the
principles of this standard. The informative Annexes G to I give information on particular aspects like
interlocking devices used within safety functions, risk assessment considering the motivation to defeat
and static action forces. ISO/TR 24119 is under preparation and will give information on the masking of
faults in series connection of interlocking devices.
vi © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 14119:2013(E)
Safety of machinery — Interlocking devices associated
with guards — Principles for design and selection
1 Scope
This International Standard specifies principles for the design and selection — independent of the
nature of the energy source — of interlocking devices associated with guards.
This International Standard covers the parts of guards which actuate interlocking devices.
NOTE ISO 14120 specifies general requirements for the design and construction of guards provided primarily
to protect persons from mechanical hazards. The processing of the signal from the interlocking device to stop and
immobilize the machine is dealt with in ISO 13849-1 or IEC 62061.
This International Standard does not necessarily provide all the specific requirements for trapped key
systems.
This International Standard provides measures to minimize defeat of interlocking devices in a reasonably
foreseeable manner.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 13849-1:2006, Safety of machinery — Safety-related parts of control systems — Part 1: General
principles for design
ISO 13849-2:2012, Safety of machinery — Safety-related parts of control systems — Part 2: Validation
IEC 60204-1:2009, Safety of machinery — Electrical equipment of machines — Part 1: General requirements
IEC 60947-5-3, Low-voltage switchgear and controlgear — Part 5-3: Control circuit devices and switching
elements — Requirements for proximity devices with defined behaviour under fault conditions (PDF)
IEC 62061:2012, Safety of machinery — Functional safety of safety-related electrical, electronic and
programmable electronic control systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100, ISO 13849-1 and the
following apply.
3.1
interlocking device
interlock
mechanical, electrical or other type of device, the purpose of which is to prevent the operation of
hazardous machine functions under specified conditions (generally as long as a guard is not closed)
Note 1 to entry: See Figure 1 and Table 1.
[SOURCE: ISO 12100:2010, 3.28.1.]
ISO 14119:2013(E)
Key
1 guard 4 position switch
2 interlocking device 5 actuating system
3 actuator 6 output system
a
Direction of opening.
Figure 1 — Example of an interlocking device
3.2
interlocking guard
guard associated with an interlocking device so that, together with the control system of the machine,
the following functions are performed:
— the hazardous machine functions “covered” by the guard cannot operate until the guard is closed;
— if the guard is opened while hazardous machine functions are operating, a stop command is given;
— when the guard is closed, the hazardous machine functions “covered” by the guard can operate (the
closure of the guard does not by itself start the hazardous machine functions)
Note 1 to entry: An interlocking guard can contain/be equipped of one or more interlocking devices. These
interlocking devices can also be of different types.
[SOURCE: ISO 12100:2010, 3.27.4.]
3.3
interlocking guard with a start function
control guard
special form of an interlocking guard which, once it has reached its closed position, gives a command to
initiate the hazardous machine function(s) without the use of a separate start control
Note 1 to entry: ISO 12100:2010, 6.3.3.2.5 gives detailed provisions regarding the condition of use.
[SOURCE: ISO 12100:2010, 3.27.6.]
3.4
guard locking device
device intended to lock a guard in the closed position and linked to the control system
2 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
3.5
interlocking guard with guard locking
guard associated with an interlocking device and a guard locking device so that, together with the
control system of the machine, the following functions are performed:
— the hazardous machine functions “covered” by the guard cannot operate until the guard is
closed and locked;
— the guard remains closed and locked until the risk due to the hazardous machine functions “covered”
by the guard has disappeared, and
— when the guard is closed and locked, the hazardous machine functions “covered” by the guard can operate
(the closure and locking of the guard do not by themselves start the hazardous machine functions)
[SOURCE: ISO 12100:2010, 3.27.5.]
3.6
safety–related part of a control system
SRP/CS
part of a control system that responds to safety-related input signals and generates safety-related
output signals
Note 1 to entry: The combined safety-related parts of a control system start at the point where the safety-related
input signals are initiated (including e.g. the actuating cam and the roller of the position switch) and end at the
output of the power control elements (including, for example, the main contacts of a contactor).
Note 2 to entry: If monitoring systems are used for diagnostics, they are also considered as SRP/CS.
[SOURCE: ISO 13849-1:2006, 3.1.1.]
3.7
defeat
action that makes interlocking devices inoperative or bypasses them with the result that a machine is
used in a manner not intended by the designer or without the necessary safety measures
3.8
defeat in a reasonably foreseeable manner
defeat of an interlocking device either manually or by using readily available objects
Note 1 to entry: This definition includes the removal of switches or actuators using tools that are needed for the
intended use of the machine or that are readily available (screw drivers, wrenches, hexagon keys, pliers).
Note 2 to entry: Readily available objects for substitute actuation include screws, needles and sheet-metal pieces,
objects in daily use such as keys, coins, adhesive tape, string and wire, spare keys for the trapped-key interlocking
devices, and spare actuators.
3.9
automatic monitoring
diagnostic function which initiates a fault reaction function if the ability of a component or an element to
perform its function is diminished, or if the process conditions are changed in such a way that hazards
are generated
3.10
direct mechanical action
positive mechanical action
movement of a mechanical component which arises inevitably from the movement of another mechanical
component either by direct contact or via rigid elements
ISO 14119:2013(E)
3.11
direct opening action
positive opening operation
achievement of contact separation as a direct result of a specified movement of the
switch actuator through non-resilient members (for example not dependent upon springs)
[SOURCE: IEC 60947-5-1:2003, K 2.2.]
3.12
actuator
separate part of an interlocking device which transmits the state of the guard (closed or not closed) to
the actuating system
EXAMPLE Guard-mounted cam, key, shaped tongue, reflector, magnet, RFID tag.
Note 1 to entry: See also Annexes A to E.
Note 2 to entry: Examples of actuators are shown in Figure 2.
3.13
coded actuator
actuator which is specially designed (e.g. by shape) to actuate a certain position switch
3.13.1
low level coded actuator
coded actuator for which 1 to 9 variations in code are available
3.13.2
medium level coded actuator
coded actuator for which 10 to 1 000 variations in code are available
3.13.3
high level coded actuator
coded actuator for which more than 1 000 variations are available
3.14
actuating system
part of the interlocking device which transmits the position of the actuator and changes the state of the
output system
EXAMPLE Roller plunger, cam mechanism, optical, inductive or capacitive sensor.
Note 1 to entry: Examples of actuating systems are shown in Figure 2.
3.15
output system
part of the interlocking device that indicates the state of the guard to the control system
EXAMPLE Contact element (electromechanical), semiconductor output, valve.
3.16
Type 1 interlocking device
interlocking device with mechanically actuated position switch with uncoded actuator
EXAMPLE Hinged interlocking devices.
Note 1 to entry: See Annex A for detailed examples.
3.17
Type 2 interlocking device
interlocking device with mechanically actuated position switch with coded actuator
EXAMPLE Tongue-actuated position switches.
4 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
Note 1 to entry: See Annex B for detailed examples.
3.18
Type 3 interlocking device
interlocking device with non-contact actuated position switch with uncoded actuator
EXAMPLE Proximity switches.
Note 1 to entry: See Annex C for a detailed example.
3.19
Type 4 interlocking device
interlocking device with non-contact actuated position switch with coded actuator
EXAMPLE RFID tag actuated position switches.
Note 1 to entry: See Annex D for detailed examples.
3.20
stop command
signal generated by the interlocking device that causes the hazardous machine function to disappear
3.21
overall system stopping performance
time interval between the stop command given by opening the guard and the termination of the
hazardous machine function
[SOURCE: ISO 13855:2010, 3.1.2, modified.]
3.22
access time
time taken by a person to reach the hazard zone after initiation of the stop command by the interlocking
device, as calculated on the basis of an approach speed of the body or part of the body
Note 1 to entry: For the selection of the approach speed and the calculation, see ISO 13855.
3.23
holding force
force that a guard locking device can withstand without being damaged so that its further use will not
be impaired and the guard will not leave the closed position
3.24
prevention of inadvertent locking position
feature of a guard locking device which ensures that the locking means (e.g. a locking bolt) cannot take
the locking position when the guard is not closed
3.25
emergency release of guard locking
possibility to release manually without aids the guard locking from outside the safeguarded area in case
of an emergency
Note 1 to entry: The guard locking with emergency release can be necessary for releasing trapped persons or
fire-fighting, for example.
3.26
auxiliary release of guard locking
possibility to release manually by means of a tool or a key the guard locking from outside the safeguarded
area in case of its failure
Note 1 to entry: The guard locking with auxiliary release is not suitable for emergency or escape release of
guard locking.
ISO 14119:2013(E)
3.27
escape release of guard locking
possibility to release manually without aids the guard locking from inside the safeguarded area to
leave the area
3.28
guard locking for protection of a person
application of a guard locking device to protect a person against a hazard
3.29
guard locking for protection of the process
application of a guard locking device to protect the working process from being interrupted
3.30
tool
implement such as a key or wrench designed to operate a fastener
Note 1 to entry: An improvised implement such as a coin or a nail file cannot be considered as a tool.
[SOURCE: ISO 14120:2002, 3.9.]
3.31
power interlocking
interlocking which directly interrupts the energy supply to the machine actuators or disconnects
moving parts from the machine actuators
Note 1 to entry: Resumption of the energy supply is only possible with the guard in the closed and locked position.
“Directly” means that, unlike control interlocking, the control system does not play any intermediate role in the
interlocking function.
3.32
safety function
function of a machine whose failure can result in an immediate increase of the risk(s)
[SOURCE: ISO 12100:2010, 3.30.]
4 Operating principles and typical forms of interlocking devices associated with
guards
4.1 General
Interlocking techniques involve a broad spectrum of technological aspects. Interlocking devices can be
classified using a great variety of criteria, e.g. the nature of the link between guard and output system,
or the technological type (electromechanical, pneumatic, electronic, etc.) of the output system.
Interlocking devices have a guard position monitoring function that senses whether the guard is closed
or not and produce a stop command when the guard is not in the closed position. An interlocking device
can also be used in the control of other functions e.g. application of a brake to stop hazardous machine
functions before access is possible. Some interlocking devices also have a guard locking function to keep
the guard locked while hazardous machine function is present. A guard locking device status monitoring
function monitors whether the guard locking device is engaged or released and produces an appropriate
output signal (see 4.3.1 a) and b)).
NOTE 1 The guard locking device (see 3.4) can be an integral part of an interlocking device, or a separate unit.
NOTE 2 See also ISO 12100:2010, 6.3.3.1 for additional information on guards.
Table 1 shows the actuation principles and actuators for the defined interlocking device types.
NOTE 3 The four types of interlocking device are not presented in a hierarchical order. The correct application of
each type of interlocking device will be dependent on the risk assessment that should be made for the specific machine.
6 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
Table 1 — Overview of interlocking devices
Actuation principle examples Examples: see
Actuator examples Type
a
Annex
Rotary cam A.1
Uncoded Linear cam Type 1 A.2, A.4
Physical con-
Mechanical Hinge A.3
tact/ force
Tongue (-shaped actuator) B.1
Coded Type 2
Trapped-key B.2
Inductive Suitable ferric metal
Magnetic Magnet, solenoid
Capacitive Uncoded Any suitable object Type 3 C
Ultrasonic Any suitable object
Non- contact
Optic Any suitable object
Magnetic Coded magnet D.1
RFID Coded Coded RFID tag Type 4 D.2
Optic Optically coded tag —
a
Examples of other interlocking devices are given in Annex E.

a) Type 1 interlocking device b) Type 2 interlocking device c) Type 3 or 4 interlocking
(uncoded cam-operated, guard (coded tongue-operated, guard device (uncoded or coded
closed) not closed) non-contact actuated, guard
closed)
ISO 14119:2013(E)
Key
1 movable guard 4 position switch
2 interlocking device 5 actuating system
3 actuator: 6 output system
a c
Cam. E.g. RFID, reflector, suitable surface.
b d
Tongue. Movement direction.
NOTE In some exceptional cases, the position switch can be installed on the movable guard and the actuator on
the stationary part of the machine. In these cases “1” is the stationary part of the machine.
Figure 2 — Principle of Types 1, 2, 3 and 4 interlocking devices
4.2 Principles of guard interlocking without guard locking
When guard interlocking function without guard locking is used, the guard can be opened at any time
regardless of the function of the machine.
If the guard is not closed, the interlocking device shall generate a stop command.
The access time shall be longer than the overall system stopping performance.
NOTE 1 For interlocking with the machine control system see Clause 8.
NOTE 2 Examples of interlocking devices without guard locking are shown in Annexes A, B, C and D.
NOTE 3 A functional diagram of interlocking devices without guard locking is shown in Figure 3.
Figure 3 — Functional diagram of interlocking devices without guard locking
4.3 Principles of guard interlocking with guard locking
4.3.1 General
When interlocking with guard locking is applied, opening of the guard shall be prevented by a guard
locking device (see 3.4) unless all hazardous machine functions covered by this guard have disappeared.
There are two alternatives for the design of the guard locking function (see Figure 4).
a) Unlocking of the guard can be initiated at any time by the operator. When unlocking is started, the
guard locking device generates a stop command. This is called unconditional unlocking. The time
necessary for the guard to be unlocked shall be greater than the time necessary for the hazardous
machine function to disappear.
b) Unlocking of the guard is possible only when the hazardous machine functions have disappeared.
This is called conditional unlocking.
8 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
Unconditional unlocking              Conditional unlocking
NOTE In conditional locking, the change from state 2 to state 3 or from state 3 to state 2 can happen
without time delay.
Figure 4 — Functional diagrams of interlocking devices with guard locking
Examples of guard locking devices are given in Annex F.
4.3.2 Interlocking device with mechanically operated guard locking
The mechanical part (e.g. bolt) which locks the interlocking guard can be
— manually applied and manually released (see Figure F.5);
— spring (or similar) applied and power-ON released [see a) in Figure 5];
— power-ON applied and spring (or similar) released [see b) in Figure 5];
— power-ON applied and power-ON released [see c) in Figure 5].
Mechanically operated guard locking shall use the principle of direct mechanical blocking due to form.
Friction and force alone shall not be relied upon.
ISO 14119:2013(E)
4.3.3 Interlocking device with electromagnetically operated guard locking
The guard is kept closed (locked) without any mechanical locking means by an electromagnetic force
(see F.4). The electromagnetic guard locking operates on the principle of power-ON applied and power-
OFF released [see d) in Figure 5].
Spring applied Engaged
a)
Power-ON
Released
released
Power-ON
Engaged
applied
b)
Spring released Released
Power-ON
Engaged
applied
c)
Power-ON
Released
released
10 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
Power-ON
Engaged
applied
d)
Power-OFF
Released
released
Figure 5 — Operating modes of guard locking device in power-actuated guard locking devices
5 Requirements for the design and the installation of interlocking devices with
and without guard locking
5.1 General
Interlocking devices shall be installed in a suitable robust manner and in accordance with any
instructions provided by the manufacturer (see Clause 9).
5.2 Arrangement and fastening of position switches
Position switches shall be arranged so that they are sufficiently protected against a change of their
position. In order to achieve this, the following requirements shall be met:
a) fasteners of the position switches shall be reliable and loosening them shall require a tool;
b) Type 1 position switches shall have provisions for permanently fixing the location after adjustment
(e.g. by means of pins or dowels);
c) necessary means of access to position switches for maintenance and checking for correct operation
shall be ensured. Prevention of defeat in a reasonably foreseeable manner shall also be considered
when designing the access means;
d) self-loosening shall be prevented;
e) defeat of the position switch in a reasonably foreseeable manner shall be prevented (see Clause 7);
ISO 14119:2013(E)
f) the position switch shall be located and, if necessary, protected so that damage from foreseeable
external causes is avoided;
g) the movement produced by mechanical actuation or the gap of the proximity device actuating
system shall remain within the specified operating range of the position switch or actuating system
specified by the switch manufacturer to ensure correct operation and/or prevent overtravel;
h) a position switch shall not be used as a mechanical stop, unless this is the intended use of the position
switch as declared by the manufacturer;
i) misalignment of the guard that creates a gap before the position switch changes its state shall not be
sufficient as to impair the protective effect of the guard (for access to hazard zones, see ISO 13855
and ISO 13857);
j) the support and fastening for the position switches shall be sufficiently rigid to maintain correct
operation of the position switch.
5.3 Arrangement and fastening of actuators
5.3.1 General
Actuators (see Figure 2) shall be so fastened to minimize the possibility that they come loose or change
their intended position relative to the actuation system during the intended lifetime.
NOTE A regular check can be necessary (see 9.3.2).
The following requirements shall be met:
a) fasteners of the actuators shall be reliable and loosening them shall require a tool;
b) self-loosening shall be prevented;
c) the actuator shall be located and, if necessary, protected so that damage from foreseeable external
causes is avoided;
d) an actuator shall not be used as a mechanical stop, unless this is the intended use of the actuator as
declared by the manufacturer;
e) the support and fastening for the actuators shall be sufficiently rigid to maintain correct operation
of the actuator.
5.3.2 Cams
Rotary and linear cams for Type 1 interlocking devices shall meet the following requirements:
a) they are fixed by fasteners requiring a tool for loosening them;
b) final fixing is achieved by form (e.g. spline or pin) or other methods that provide equivalent
integrity of fixing;
c) they do not damage the position switch or impair its durability.
5.4 Actuation modes of interlocking devices
When a single Type 1 or Type 2 interlocking device is used to generate a stop command, it shall be
actuated by direct mechanical action between guard, actuator and actuating system and the contact
element shall have direct opening action (see 3.10, 3.11 and Table 2).
Non-direct mechanical action for a Type 1 interlocking device shall be used only in conjunction with a
Type 1 or Type 2 interlocking device with direct mechanical action between guard, actuator and output
12 © ISO 2013 – All rights reserved

ISO 14119:2013(E)
system. Combining one interlocking device with direct mechanical action with a second interlocking
device with non-direct mechanical action avoids common cause failures (see 8.3).
Table 2 — Direct and non-direct mechanical action of Type 1 interlocking devices
Example of behav-
Mechanical
Guard closed Guard not closed Working mode iour in case of
action
failure (see 8.3.2)
Plunger held Output system
depressed by cam as remains in safe state
long as guard is not when guard is not
closed closed even if spring
breaks
Direct
When guard closed,
output system
changes its stat
...