Machinery Safety 101

 This page is intended to pro­vide you with a quick and easy source for use­ful machin­ery safety related def­i­n­i­tions, col­lected from a wide vari­ety of sources. In all cases, I have cited the orig­i­nal doc­u­ment from which I drew the definition.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Access time (time for access to a dan­ger zone) — The time taken to access the haz­ardous machine parts after ini­ti­a­tion of the stop com­mand by the inter­lock­ing device, as cal­cu­lated on the basis of an approach speed the value of which may be cho­sen, for each par­tic­u­lar case, tak­ing into account the para­me­ters given in prEN 999 ‘Safety of machin­ery — The posi­tion­ing of pro­tec­tive equip­ment in respect of approach speeds of parts of the human body’.
EN 1088, §3.9

Actuator — sep­a­rate part of an inter­lock­ing device which trans­mits the state of the guard (closed or not closed) to the actu­at­ing system

NOTE 1 A guard mounted cam, a key, a shaped tongue, a reflec­tor, a mag­net, an RFID tag are exam­ples of actuators.

NOTE 2 See also Annex A to E.

NOTE 3 See exam­ples of actu­a­tors in Figure 2.
ISO 14119, §3.12

[See also Coded Actuator]

Actuating System — part of the inter­lock­ing device which trans­mits the posi­tion of the actu­a­tor and changes the state of the out­put system

NOTE 1 A roller plunger, a cam link­age sys­tem, an opti­cal, induc­tive or capac­i­tive sen­sor are exam­ples of an actu­at­ing system.

NOTE 2 See exam­ples of actu­at­ing sys­tems in Figure 2.
ISO 14119, §3.14

Adequate risk reduc­tion — the achieve­ment of a risk level unlikely to give rise to a sit­u­a­tion that could result in harm to any person.

Adjustable bar­rier guard — a fixed guard that is adjustable as a whole or that incor­po­rates adjustable parts. The adjust­ment to the guard remains fixed dur­ing oper­a­tion.CSA Z432-​​04, §3

[See Guard]

Alive — See Live

ALARP — “As Low As Reason­ably Prac­ti­ca­ble”. The ALARP Principle comes from UK OHS law:

“The main tests that are applied in reg­u­lat­ing indus­trial risks are very sim­i­lar to those we apply in day to day life. They involve determining:

1. whether a given risk is so great or the out­come so unac­cept­able that it must be refused alto­gether; or
2. whether the risk is, or has been made, so small that no fur­ther pre­cau­tion is nec­es­sary; or
3. if a risk falls between these two states, that it has been reduced to the low­est level prac­ti­ca­ble, bear­ing in mind the ben­e­fits flow­ing from its accep­tance and tak­ing into account the costs of any fur­ther reduc­tion. The injunc­tion laid down in safety law is that any risk must be reduced so far as rea­son­ably prac­ti­ca­ble, or to a level which is ‘as low as rea­son­ably prac­ti­ca­ble’ (ALARP principle).”

The Tolerability of Risk from Nuclear Power Stations, UK Health and Safety Executive, HMSO OPSI, London, 1992

At height — access posi­tions located 2.5 m above the sur­round­ing sur­face or land­ing.CSA Z432-​​04, §3

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B

Barrier (fixed dis­tance) guard — a fixed guard that does not com­pletely enclose the haz­ard but that reduces access by virtue of its phys­i­cal dimen­sions and its dis­tance from the haz­ard.CSA Z432-​​04, §3

[See Guard]

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C

Coded Actuator — actu­a­tor which is spe­cially designed (e. g. by shape) to actu­ate a cer­tain posi­tion switch

1. low level coded actu­a­tor — coded actu­a­tor for which the num­ber of code ver­sions avail­able need to be 1 to 9;
2. medium level coded actu­a­tor — coded actu­a­tor for which the num­ber of code ver­sions avail­able need to be 10 to ? 1 000;
3. high level coded actu­a­tor — coded actu­a­tor for which the num­ber of code ver­sions avail­able need to be > 1 000.

ISO 14119, §3.13

[See also Actuator]

Common cause fail­ures — fail­ures of dif­fer­ent items, result­ing from a sin­gle event, where these fail­ures are not con­se­quences of each other.
CSA Z432-​​04, §3

Common mode fail­ures — fail­ures of items char­ac­ter­ized by the same fault mode. CSA Z432-​​04, §3

Common sense — Can be expressed as a func­tion of four ele­ments:
com­mon sense = knowl­edge + expe­ri­ence + atten­tion + exposure

Where any ele­ment is miss­ing or insuf­fi­cient, there can be no com­mon sense. Wynand Serfontaine and oth­ers on the LinkedIN Safety Engineering Network

Complementary pro­tec­tive mea­sures — Protective mea­sures that are nei­ther inher­ently safe design mea­sures, nor safe­guard­ing (imple­men­ta­tion of guards and/​or pro­tec­tive devices), nor infor­ma­tion for use may have to be imple­mented as required by the intended use and the rea­son­ably fore­see­able mis­use of the machine. Such mea­sures shall include, but not be lim­ited to,

a) emer­gency stop;

b) means of res­cue of trapped per­sons; and

c) means of energy iso­la­tion and dissipation.

CSA Z432-​​04, §6.2.3.5.3

Compliance – “Compliance” is used to describe the action of doing what is required (e. g. an orga­ni­za­tion “com­plies” by mak­ing some­thing or by ful­fill­ing a reg­u­la­tory requirement).

ISO/​IEC 17000:2004, §3

Conformity – “Conformity” means ful­fill­ment of a require­ment. Specified require­ments may be stated in nor­ma­tive doc­u­ments as reg­u­la­tions, stan­dards and tech­ni­cal specifications.

ISO/​IEC 17000:2004, §3

Control Guard – See “Interlocking guard with a start func­tion”

Critical safety func­tion — a safety func­tion of a machine whose fail­ure can result in an imme­di­ate increase of risk.CSA Z432-​​04, §3

Current-​​carrying — See “Live”

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D

Danger zone — the zone around the machine (front, back, sides, top, and bot­tom) where a haz­ard is cre­ated by the motion of the machine com­po­nents.CSA Z432-​​04, §3

Deadman or Dead Man — Obsolete term used to refer to an Enabling Device. Use of the term ‘dead­man’ should be avoided.

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.
ISO 14119

defeat in a rea­son­ably fore­see­able man­ner – defeat of an inter­lock­ing device either man­u­ally or by using read­ily avail­able objects.

NOTE 1 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 Readily avail­able objects for sub­sti­tute actu­a­tion can be:

• screws, nee­dles, sheet-​​metal pieces;
• objects in daily use such as keys, coins, adhe­sive tape, string and wire;
• spare keys for the trapped-​​key inter­lock­ing devices;
• spare actu­a­tors.

ISO 14119

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E

Emergency sit­u­a­tion — an imme­di­ately haz­ardous sit­u­a­tion that needs to be ended or averted quickly in order to pre­vent injury or dam­age.CSA Z432-​​04, §3

Emergency stop —

1. A func­tion that is intended to avert harm or to reduce exist­ing haz­ards to per­sons, machin­ery, or work in progress.CSA Z432-​​04, §3.
2. The oper­a­tion of a cir­cuit that over­rides all other robot con­trols, removes drive power, causes all mov­ing parts to stop, and removes power from other haz­ardous func­tions present in the safe­guarded space but does not cause addi­tional haz­ards.ANSI RIA 15.06−99, §3.11
3. The oper­a­tion of a cir­cuit that over­rides all other robot con­trols, removes drive power, causes all mov­ing parts to stop, and removes power from other haz­ardous func­tions present in the safe­guarded space but does not cause addi­tional haz­ards.CSA Z434-​​03, §3.

Emergency stop but­ton — A red mushroom-​​headed but­ton that, when acti­vated, will imme­di­ately start the emer­gency stop sequence.CSA Z432-​​04, §3.

Emergency stop device — Manually actu­ated con­trol device used to ini­ti­ate an emer­gency stop func­tion.ISO 13850 2006, §3.2

Emergency Switching Off — An emer­gency oper­a­tion intended to switch off the sup­ply of the elec­tri­cal energy to all or part of an instal­la­tion.NFPA 79–07, §3.3.37.

Emergency switch­ing off device — Manually actu­ated con­trol device used to switch off the sup­ply of elec­tri­cal energy to all or a part of an instal­la­tion where a risk of elec­tric shock or another risk of elec­tri­cal ori­gin is involved.IEC 60204–1, 2005, §3.18

Enabling device — a device that is designed to ini­ti­ate a machine action or allow the flow of energy to a machine.CSA Z432-​​04, §3

Energy-​​isolating device —

1. a mechan­i­cal device that phys­i­cally pre­vents the trans­mis­sion or release of energy, includ­ing but not lim­ited to the fol­low­ing: a man­u­ally oper­ated elec­tri­cal cir­cuit breaker; a dis­con­nect switch; a man­u­ally oper­ated switch by which the con­duc­tors of a cir­cuit can be dis­con­nected from all ungrounded sup­ply con­duc­tors; a line valve; a block; and other devices used to block or iso­late energy (push-​​button selec­tor switches and other control-​​type devices are not energy-​​isolating devices).CSA Z460 2005
2. A mechan­i­cal device that phys­i­cally pre­vents the trans­mis­sion or release of energy, includ­ing but not lim­ited to the fol­low­ing: a man­u­ally oper­ated elec­tri­cal cir­cuit breaker, a dis­con­nect switch, a man­u­ally oper­ated switch by which the con­duc­tors of a cir­cuit can be dis­con­nected from all ungrounded sup­ply con­duc­tors and, in addi­tion, no pole can be oper­ated inde­pen­dently; a line valve; a block; and any sim­i­lar device used to block or iso­late energy.ANSI Z244.1–2003
3. A device that phys­i­cally pre­vents the trans­mis­sion or release of energy, includ­ing but not lim­ited to the fol­low­ing: A man­u­ally oper­ated elec­tri­cal cir­cuit breaker; a dis­con­nect switch; a man­u­ally oper­ated switch by which the con­duc­tors of a cir­cuit can be dis­con­nected from all ungrounded sup­ply con­duc­tors, and, in addi­tion, no pole can be oper­ated inde­pen­dently; a line valve; a block; and any sim­i­lar device used to block or iso­late energy. Push but­tons, selec­tor switches and other con­trol cir­cuit type devices are not energy iso­lat­ing devices.29 CFR 1901.147

Energy source — Any source of elec­tri­cal, mechan­i­cal, hydraulic, pneu­matic, chem­i­cal, ther­mal, or other energy.29 CFR 1910.147

See also “Hazardous Energy”

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F

FIT (unit) — Failure in Time — 1 FIT = 1 x 10^–9 failures/​h.

The FIT unit finds its ori­gin in reli­a­bil­ity engi­neer­ing for the semi­con­duc­tor indus­try. In datasheets and cer­tifi­cates for SIL rated equip­ment (mainly sen­sors, actu­a­tors and the like intended for use in the process indus­try accord­ing to IEC 61511) the unit FIT is com­monly used for pre­sent­ing fail­ure rate data (lambda values).

The FIT unit was devel­oped to ease writ­ing and read­ing the infor­ma­tion. Most instru­ments specif­i­cally designed for process indus­try SIL appli­ca­tions have fail­ure rates in the range of 1 x 10^–9/​h to 3 x 10^–6/​h. When expressed using FIT these val­ues are writ­ten as 10 to 3000 FIT.  This is eas­ier to read, and eas­ier to com­pare datasheets for instru­ments, etc.

Bert Brouwers, LinkedIn​.com, IEC 62061 and ISO 13849 machin­ery func­tional safety group, accessed 28-​​Sep-​​2011

Fixed guard — a guard kept in place (i.e., closed or attached to a fixed sur­face) either per­ma­nently (e.g., by weld­ing) or by means of fas­ten­ers (screws, nuts, etc.), mak­ing removal or open­ing impos­si­ble with­out using tools.CSA Z432-​​04, §3

See also “Guard”.

Functional Safety — Functional safety is part of the over­all safety that depends on a sys­tem or equip­ment oper­at­ing cor­rectly in response to its inputs. The term “safety-​​related” is used to describe sys­tems that are required to per­form a spe­cific func­tion or func­tions to ensure risks are kept at an accepted level. Such func­tions are, by def­i­n­i­tion, safety func­tions. Two types of require­ments are nec­es­sary to achieve func­tional safety:

• safety func­tion require­ments (what the func­tion does;) and
• safety integrity require­ments (the like­li­hood of a safety func­tion being per­formed satisfactorily).

The safety func­tion require­ments are derived from the haz­ard analy­sis and the safety integrity require­ments are derived from a risk assess­ment. The higher the level of safety integrity, the lower the like­li­hood of dan­ger­ous fail­ure.

“Functional safety of electrical/​electronic/​programmable elec­tronic safety-​​related sys­tems — Part 0: Functional safety and IEC 61508”, IEC/​TR 61508–0 Edition 1, International Electrotechnical Commission, Geneva, 2005

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G

Guard —

1. Cover or equip (a part of a machine) with a device to pro­tect the oper­a­tor.Oxford New American Dictionary
2. A part of machin­ery specif­i­cally used to pro­vide pro­tec­tion by means of a phys­i­cal bar­rier. Depending on its con­struc­tion, a guard may be called a cas­ing, screen, door, enclos­ing guard, etc.CSA Z432-​​04, §3
3. A bar­rier that pre­vents expo­sure to an iden­ti­fied haz­ard. E3.22 Sometimes referred to as a “bar­rier guard.”ANSI B11.19 2003, §3.22

[See Adjustable bar­rier guard]

[See Barrier (fixed dis­tance) guard]

[See Fixed guard]

[See Interlocked bar­rier guard]

[See Movable guard]

Guard lock­ing device

1. a device that is designed to hold the guard closed and locked until the haz­ard has ceased.
   CSA Z432-​​04, §3
2. Device intended to lock a guard in the closed posi­tion and linked to the con­trol sys­tem so that:
   • the machine can­not oper­ate trn­til the guard is closed and locked;
   • the guard remains locked until the risk has passed.

   EN 1088:1996, §3.4

3. device intended to lock a guard in the closed posi­tion and linked to the con­trol sys­tem.
   ISO 14119

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H

harm — phys­i­cal injury or dam­age to the health of peo­ple, or dam­age to prop­erty or the envi­ron­mentISO Guide 51:99

harm­ful event — occur­rence in which a haz­ardous sit­u­a­tion results in harmISO Guide 51:99

haz­ard — poten­tial source of harm

NOTE The term haz­ard can be qual­i­fied in order to define its ori­gin or the nature of the expected harm (e.g. elec­tric shock haz­ard, crush­ing haz­ard, cut­ting haz­ard, toxic haz­ard, fire haz­ard, drown­ing haz­ard).ISO Guide 51:99

Hazardous energy —

1. Any elec­tri­cal, mechan­i­cal, hydraulic, pneu­matic, chem­i­cal, nuclear, ther­mal, grav­i­ta­tional, or other energy that can harm per­son­nel.CSA Z460 2005
2. Any elec­tri­cal, mechan­i­cal, hydraulic, pneu­matic, chem­i­cal, nuclear, ther­mal, grav­ity or other energy that could cause injury to per­son­nel.ANSI Z244.1–2003, 2.10

See also “Energy Source”

haz­ardous situation

1. Circumstance in which peo­ple, prop­erty or the envi­ron­ment are exposed to one or more haz­ardsISO Guide 51:99
2. A set of cir­cum­stances that may give rise to harm to a per­son.CSA Z432-​​04, §3

hier­ar­chy of con­trols — rank­ing of mea­sures taken to pre­vent or reduce haz­ard expo­sure accord­ing to effec­tive­ness. Measures are ordered from the most effec­tive mea­sures that elim­i­nate haz­ards to the least effec­tive mea­sures that may achieve only lim­ited risk reduc­tion. Based onUniversity of Southern Queensland (USQ), Human Resources — Glossary. Accessed 24-​​Feb-​​2011

HMI — See Human-​​Machine Interface.

Hold-​​to-​​run con­trol device — a con­trol device that is designed to per­mit move­ment of machin­ery as long as the con­trol is held in a set posi­tion. Once released, this device auto­mat­i­cally returns the machine to the stop posi­tion.CSA Z432-​​04, §3

Human-​​Machine Interface — This is where peo­ple and tech­nol­ogy meet. This people/​ tech­nol­ogy inter­cept can be as sim­ple as the grip on a hand tool or as com­plex as the flight deck of a jumbo jet.ISA | Terminology, accessed 3-​​Mar-​​11.

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I

Interlocked bar­rier guard — a fixed or mov­able guard attached and inter­locked in such a man­ner that the machine tool will not cycle or will not con­tinue to cycle unless the guard itself or its hinged or mov­able sec­tion encloses the haz­ardous area.CSA Z432-​​04, §3

[See Guard]

Interlocking device (interlock)

1. Mechanical, elec­tri­cal or other type of device, the pur­pose of which is to pre­vent the oper­a­tion of machine ele­ments under spec­i­fied con­di­tions (gen­er­ally as long as a guard is not closed).EN 1088:96, §3.1
2. 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)
   ISO 12100:2010, 3.28.1

Interlocking guard

1. Guard asso­ci­ated with an inter­lock­ing device, so that:
   • the haz­ardous machine func­tions ‘cov­ered’ by the guard can­not oper­ate until the guard is closed;
   • if the guard is opened while the haz­ardous machine func­tions are oper­at­ing, a stop instruc­tion is given;
   • when the guard is closed, the haz­ardous machine func­tions ‘cov­ered’ by the guard can oper­ate, but the clo­sure of the guard does not by itself ini­ti­ate their operation.

   NOTE. In English ‘stop sig­nal’ and ‘stop com­mand’ are syn­onyms for ‘stop instruc­tion’. In German, ‘Stop-​​Signal’ and ‘Stop-​​Befehl’ are syn­onyms for ‘Halt-​​Befehl’. In French ‘ordre d’arret’ is an all-​​encompassing term.
   EN 1088:96, §3.2

2. 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.
     ISO 12100:2010, 3.27.4

[See Guard]

Interlocking guard with guard lock­ing — Guard asso­ci­ated with an inter­lock­ing device and a
guard lock­ing device so that:

• 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 of injury from the haz­ardous machine func­tions has passed;
• when the guard is closed and locked, the haz­ardous machine func­tions ‘cov­ered’ by the guard can oper­ate, but the clo­sure and lock­ing of the guard do not by them­selves ini­ti­ate their operation.

EN 1088:96, §3.3

[See Guard]

[See Guard Locking Device]

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 ISO 12100:2010, 6.3.3.2.5 gives detailed pro­vi­sions regard­ing the con­di­tion of use.
ISO 12100:2010, 3.27.6

Industrial robot — an auto­mat­i­cally con­trolled, repro­gram­ma­ble multi-​​purpose manip­u­la­tor pro­gram­ma­ble in three or more axes, which may be either fixed in place or mobile for use in indus­trial automa­tion appli­ca­tions.CSA Z434-​​03, §3

[See Robot]

Industrial robot sys­tem — equip­ment that includes the robot(s) (hard­ware and soft­ware), con­sist­ing of the manip­u­la­tor power sup­ply and con­trol sys­tem, the end-effector(s), and any other asso­ci­ated machin­ery and equip­ment within the safe­guarded space.CSA Z434-​​03, §3

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L

Live — elec­tri­cally con­nected to a source of volt­age dif­fer­ence, or elec­tri­cally charged so as to have a volt­age dif­fer­ent from that of the earth; the term may be used in place of the term “current-​​carrying”, where the intent is clear, to avoid rep­e­ti­tion of the longer term.CSA SPE-1000:99, §2

Lockout —

1. place­ment of a lock or tag on an energy-​​isolating device in accor­dance with an estab­lished pro­ce­dure, thereby indi­cat­ing that the energy-​​isolating device is not to be oper­ated until removal of the lock or tag in accor­dance with an estab­lished pro­ce­dure.CSA Z460, 2005
2. a mechan­i­cal means of lock­ing that uses an indi­vid­u­ally keyed lock to secure an energy-​​isolating device in a posi­tion that pre­vents ener­giza­tion of a machine, equip­ment, or a process.CSA Z460
3. The place­ment of a lock­out device on an energy iso­lat­ing device, in accor­dance with an estab­lished pro­ce­dure, ensur­ing that the energy iso­lat­ing device and the equip­ment being con­trolled can­not be oper­ated until the lock­out device is removed.29 CFR 1910.147

Lockout device —

1. A pos­i­tive means such as a lock that secures an energy iso­lat­ing device in a posi­tion that pre­vents the ener­giz­ing of a machine, equip­ment or process.ANSI Z244.1–2003
2. A device that uti­lizes a pos­i­tive means such as a lock, either key or com­bi­na­tion type, to hold an energy iso­lat­ing device in the safe posi­tion and pre­vent the ener­giz­ing of a machine or equip­ment. Included are blank flanges and bolted slip blinds.29 CFR 1910.147

See also “Energy Isolating Device”

See also “Tagout Device”

lockout/​tagout — The place­ment of a lock/​tag on the energy iso­lat­ing device in accor­dance with an estab­lished pro­ce­dure, indi­cat­ing that the energy iso­lat­ing device shall not be oper­ated until removal of the lock/​tag in accor­dance with an estab­lished pro­ce­dure. (The term “lockout/​tagout” allows the use of a lock­out device, a tagout device, or a com­bi­na­tion of both.)ANSI Z244.1–2003, 2.10

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M

machine or machin­ery — assem­bly, fit­ted with or intended to be fit­ted with a drive sys­tem con­sist­ing of linked parts or com­po­nents, at least one of which moves, and which are joined together for a spe­cific application.

NOTE 1: The term “machin­ery” also cov­ers an assem­bly of machines which, in order to achieve the same end, are arranged and con­trolled so that they func­tion as an inte­gral whole.

ISO 12100:2010

Movable guard — a guard gen­er­ally con­nected by mechan­i­cal means (e.g., hinges or slides) to the machine frame or an adja­cent fixed ele­ment and that can be opened with­out the use of tools. The open­ing and clos­ing of this type of guard may be pow­ered.CSA Z432-​​04, §3

[See Guard]

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P

pre­cau­tion­ary prin­ci­ple — (law & pol­icy) The pre­cau­tion­ary prin­ci­ple ensures that a sub­stance or activ­ity pos­ing a threat to the envi­ron­ment is pre­vented from adversely affect­ing the envi­ron­ment, even if there is no con­clu­sive sci­en­tific proof link­ing that par­tic­u­lar sub­stance or activ­ity to envi­ron­men­tal dam­age. The pre­cau­tion­ary prin­ci­ple is a guid­ing prin­ci­ple. Its pur­pose is to encourage-​​perhaps even oblige-​​decision mak­ers to con­sider the likely harm­ful effects of their activ­i­ties on the envi­ron­ment before they pur­sue those activ­i­ties. James Cameron and Juli Abouchar, The Precautionary Principle: A Fundamental Principle of Law and Policy for the Protection of the Global Environment, 14 B.C. Int’l & Comp. L. Rev. 1 (1991), http://​lawdig​i​tal​com​mons​.bc​.edu/​i​c​l​r​/​v​o​l​1​4​/​i​s​s​1/2. Get this paper through Google Scholar.

Alternate Definition — The pre­cau­tion­ary prin­ci­ple or pre­cau­tion­ary approach states that if an action or pol­icy has a sus­pected risk of caus­ing harm to the pub­lic or to the envi­ron­ment, in the absence of sci­en­tific con­sen­sus that the action or pol­icy is harm­ful, the bur­den of proof that it is not harm­ful falls on those tak­ing the action. Precautionary prin­ci­ple — Wikipedia

Alternate Definition — In order to pro­tect the envi­ron­ment, the pre­cau­tion­ary approach shall be widely applied by States accord­ing to their capa­bil­i­ties. Where there are threats of seri­ous or irre­versible dam­age, lack of full sci­en­tific cer­tainty shall not be used as a rea­son for post­pon­ing cost-​​effective mea­sures to pre­vent envi­ron­men­tal degra­da­tion.1992 Rio Conference. Note — This ver­sion of the prin­ci­ple is some­times referred to as the ‘weak pre­cau­tion­ary principle’.

Origin — German, 1930, Vorsorgeprinzip.

Note — The pre­cau­tion­ary prin­ci­ple is often cited in OHS work and could be para­phrased, “If a prod­uct, process or ser­vice is sus­pected of caus­ing harm to peo­ple in the work­place, in the absence of sci­en­tific con­sen­sus that the prod­uct, process or ser­vice is harm­ful, lack of full sci­en­tific cer­tainty shall not be used as a rea­son for post­pon­ing mea­sures to reduce the risk of harm to peo­ple in the work­place. Those respon­si­ble for intro­duc­ing the prod­uct, process or ser­vice into the work­place shall bear the bur­den of proof of safety relat­ing to the safety of the prod­uct, process or ser­vice.” This is a ver­sion of the ‘strong pre­cau­tion­ary prin­ci­ple. — Doug Nix

pro­tec­tive mea­sure — means used to reduce risk

NOTE Protective mea­sures include risk reduc­tion by inher­ently safe design, pro­tec­tive devices, per­sonal pro­tec­tive equip­ment, infor­ma­tion for use and instal­la­tion, and train­ing. ISO Guide 51:99

Positive mode actu­a­tion — If a mov­ing mechan­i­cal com­po­nent inevitably moves another com­po­nent along with it, either by direct con­tact or via rigid ele­ments, the sec­ond com­po­nent is said to be actu­ated in the pos­i­tive mode (or positively)by the first one.EN 1088:1996, §3.6

pos­i­tive open­ing oper­a­tion of a con­tact ele­ment — The achieve­ment of con­tact sep­a­ra­tion as the direct result of a spec­i­fied move­ment of the switch actu­a­tor through non-​​resilient mem­bers (e.g. not depen­dent upon springs). (2.2 of chap­ter 3 ‘Special require­ments for con­trol switches with pos­i­tive open­ing oper­a­tion’ of EN 60947−5−1: 1991).

NOTE: For fluid power, the equiv­a­lent con­cept may be called ‘pos­i­tive mode interruption’.

EN 1088:1996, §3.7

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R

Residual risk — risk remain­ing after pro­tec­tive mea­sures have been taken.CSA Z432-​​04, §3

Robot — Originally from the Czech, rob­ota, mean­ing drudgery.

1. A mechan­i­cal device that some­times resem­bles a human and is capa­ble of per­form­ing a vari­ety of often com­plex human tasks on com­mand or by being pro­grammed in advance.
2. A machine or device that oper­ates auto­mat­i­cally or by remote control.
3. A per­son who works mechan­i­cally with­out orig­i­nal thought, espe­cially one who responds auto­mat­i­cally to the com­mands of others.

Read more: http://​www​.answers​.com/​t​o​p​i​c​/​r​o​b​o​t​#​i​x​z​z​1​C​6​9​7​Z​eGf

See also Industrial Robot

risk —

1. com­bi­na­tion of the prob­a­bil­ity of occur­rence of harm and the sever­ity of that harmISO Guide 51:99
2. (of harm to an indi­vid­ual) a com­bi­na­tion of the prob­a­bil­ity and the degree of the pos­si­ble injury or dam­age to health in a haz­ardous sit­u­a­tion.CSA Z432-​​04, §3

Risk analy­sis — a com­bi­na­tion of the deter­mi­na­tion of the lim­its of the machine, haz­ard iden­ti­fi­ca­tion, and risk esti­ma­tion.CSA Z432-​​04, §3

Risk assess­ment — the over­all process of risk analy­sis and risk eval­u­a­tion.CSA Z432-​​04, §3

Risk esti­ma­tion — a judg­ment, on the basis of risk analy­sis, of whether ade­quate risk reduc­tion has been achieved.CSA Z432-​​04, §3

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S

safety — free­dom from unac­cept­able risk

NOTE Adapted from ISO/​IEC Guide 2:1996, def­i­n­i­tion 2.5. ISO Guide 51:99

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 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 If mon­i­tor­ing sys­tems are used for diag­nos­tics, they are also con­sid­ered as SRP/​CS.
ISO 13849–1:2006, 3.1.1

Stopping time (time for haz­ard elim­i­na­tion) — The period between the point at which the inter­lock­ing device ini­ti­ates the stop com­mand and the point at which the risk from haz­ardous machine func­tions has passed,EN 1088–1996, §3.8

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T

tagout — The place­ment of a tagout device on an energy iso­lat­ing device, in accor­dance with an estab­lished pro­ce­dure, to indi­cate that the energy iso­lat­ing device and the equip­ment being con­trolled may not be oper­ated until the tagout device is removed.29 CFR 1910.147

tagout device —

1. A promi­nent warn­ing means such as a tag and a means of attach­ment, which can be securely fas­tened to an energy iso­lat­ing device to indi­cate that the energy iso­lat­ing device and the equip­ment being con­trolled may not be oper­ated until the tagout device is removed.ANSI Z244.1–2003, 2.20.1
2. A promi­nent warn­ing device, such as a tag and a means of attach­ment, which can be securely fas­tened to an energy iso­lat­ing device in accor­dance with an estab­lished pro­ce­dure, to indi­cate that the energy iso­lat­ing device and the equip­ment being con­trolled may not be oper­ated until the tagout device is removed.29 CFR 1910.147

tol­er­a­ble risk — risk which is accepted in a given con­text based on the cur­rent val­ues of soci­etyISO Guide 51:99

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U

unex­pected start-​​up or unin­tended start-​​up — any start-​​up which, because of its unex­pected nature, gen­er­ates a risk to persons

NOTE 1: This can be caused by, for example:

• a start com­mand which is the result of a fail­ure in, or an exter­nal influ­ence on, the con­trol system;
• a start com­mand gen­er­ated by inop­por­tune action on a start con­trol or other parts of the machine such as a sen­sor or a power con­trol element;
• restora­tion of the power sup­ply after an interruption;
• external/​internal influ­ences (grav­ity, wind, self-​​ignition in inter­nal com­bus­tion engines, etc.) on parts of the machine.

NOTE 2: Machine start-​​up dur­ing nor­mal sequence of an auto­matic cycle is not unin­tended, but can be con­sid­ered as being unex­pected from the point of view of the oper­a­tor, Prevention of acci­dents in this case involves the use of safe­guard­ing mea­sures (see 6.3).

NOTE 3 Adapted from ISO 14118:2000, def­i­n­i­tion 3.2.

ISO 12100:2010

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