Safety Key or Escape Release?

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19 February 2014

The revised EN ISO 14119 standard explained and looks at a preventative alternative.

PreventionRather than Cure is the Key to Safety

Rob Lewis, ManagingDirector at Fortress Interlocks, explains the revised EN ISO 14119 standard andlooks at a preventative alternative.

What is anEscape Release?

EN ISO 14119 defines Escape Release as the ‘possibility torelease manually without aids the guard locking from inside the safeguardedarea to leave the area’.  Furthermore ENISO 14119 sets out the following requirements:

·       Deliberate unlocking of the guard locking frominside of the safeguarded area shall be easily possible without auxiliary meansand regardless of the operating conditions

·       The unlocking means shall be manually operatedand act directly on the principle of the locking mechanism

·       The unlocking shall generate a stop command

·       The unlocking means for the escape release shallonly be accessible from inside the safeguarded area

So in summary an Escape Release allows someone trappedinside a safeguarded area to leave the area and, in doing so, send a stop commandto the controller.

When is anEscape Release needed?

EN ISO 14119 is much less prescriptive about this, merelystating ‘Depending on the application supplementary methods of release can benecessary’.  In practice the riskassessment for the safeguarded area should consider the risk of a personbecoming trapped inside the area.  Factors to consider when making a risk assessment are:

·       Is the access full body access (i.e. can youwalk into the area or is it just a hatch)?

·       Is the safeguarded area small or large (i.e. canyou easily see if someone is in the cell)?

·       In the safeguarded area, are there blind spotswhere a person could be hidden from sight?

 

But thisdoesn’t appear to stop an accident occurring?

No it doesn’t.  AnEscape Release will allow someone trapped to get out, but the machine won’tstop until the employee is already at the door (where the escape release issited) and by that time it is highly likely an accident will occur.

Preventionis better than cure

Safety keys stop the accident occurring in the first place.Safety keys work by blocking the interlock once the door is opened.  Once all safety criteria are met the doorwill still not open until an employee removes the safety key.  In reverse, the door will not relock untilthe safety key is returned.  Thus theoperator is kept completely safe whilst the safety key is in their pocket.  Many people liken a safety key system to apadlock in a lockout procedure, and given that you can’t restart until the keyis returned, this is true.  Howeversafety keys have two major advantages over a lockout procedure.  Firstly, the safety key is always at thedoor, so you can’t forget it and be tempted just to nip inside for 1 minute……..  Secondly, unlike a lockout procedure, if youdon’t remove the safety key the door won’t open, so operators are forced tofollow the procedure.

In summary, by adopting a safety key system people enteringa dangerous area are 100% protected from an unexpected start-up, preventing anincident in the first place, whereas an Escape Release system seeks to minimisethe effect after an unexpected start-up has occurred. 

Ends

 

About

Safety Interlocking company Fortress Interlocks is a memberof the Machine Safety Alliance with Festo, Pilz Automation Technology, Troax,UK Engineering, and Werma. The Machine Safety Alliance aims to share itscollective knowledge and expertise to help machine builders and users makesense of safety and safeguard their productivity. For more information, pleasevisit the website at www.machinery-safety-alliance.co.uk or see www.fortressinterlocks.com