The Implications of EN/ISO 14119 Safety of Machinery – Interlocking devices associated with guards

As with all new standards, there is the uncertainty of does EN/ISO 14119 affect me? When does it take effect? And do I need to do anything? I’m sure you have all read endless articles by various people highlighting minor points which can sometimes be taken out of context and can lead to potentially misinterpreting the content and may cause you to miss some of the principles that the standard is trying to bestow. No standards should ever be considered in isolation, which is why they cross-refer to other standards, to maintain as the name suggests, “a standard approach” rather than reinventing the wheel every time.

This standard highlights many new things to be considered regarding the classification of types of products and some positive reworking of the old EN1088 standard, which has been in place for many years. In my experience there are two main points regarding safety system design to be considered, which are detailed below;

1. Wiring of multiple dual channel door switches in a Category 3 wiring architecture. It has been recognised for a long time that it is possible to mask faults leading to a potential failure of the safety system under certain conditions. In your design you now have to account for this and the reduced diagnostic coverage will affect the validation of your design in ISO13849 and IEC62061. The publishing of ISO/TR24119 will offer some clarification on this, and this openly available leaked table will give you an idea of the implications. Key point to consider – are the doors opened more than once per hour?

2.Guard locking has always been a contentious area and this standard certainly clarifies all of the issues. My approach has always been ‘power to release’ for personnel protection unless the risk assessment deemed it to be unsafe as this presented addition risks, so using ‘power to lock’ was a better solution. If it was just to protect the process from uncontrolled intervention then either type could be used. There was also the unwritten law that if you were using a switch for personal protection it needed to have a holding force in excess of 1000 newton’s. This always prompted the question of how much force is 1000 newton’s when applied to the handle to open the door. The good news is, apart from the clarification of personal and process locking, this standard has a table showing all of the maximum forces that you could apply to a door. It is in Annex1, Table 1 (click here) and it is worth purchasing the standard for this information alone, as it will be a major benefit when you are completing your risk assessments and guard door design. It certainly highlights the fact that a number of safety switches on the market should only be sold for process protection, rather than personal protection as they have been in the past.

I am sure that the standard will affect you in some way and it is important to note that the full implementation date is February 2015. I would strongly suggest that you start to design your systems to comply with this standard now, as February is not far away and gives you chance to deal with the teething problems of the design changes that will no doubt ensue, before they become compulsory.

Watch a video on safety interlocking devices here or for more information on the EN/ISO 14119 click here.

Click here if you wish to purchase a Guard Locking Switch.

If you require any further information or wish to discuss your machinery safety systems with one of our specialists please contact your local Routeco branch. Alternatively email info@routeco.com or call 0370 607 1000.

Kevin Kirby – Routeco Safety Solutions Team Leader