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Eradicated

Integration of safety circuits...

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I was wondering recently how far can you go when it comes to integration of safety circuitry. Here's an example: I've got a small production line composed of 4 independent machines (system of conveyors, one check-weigher and two processing machines). Now, three of those were provided by an external company, these are stock models incorporating basic safety circuits (mainly E-Stop and several guard doors). Now, imagine I want to have a complete, integrated safety circuit so in case of emergency one does not have to wonder which e-stop button to press and that all the machines will stop immediately. Can I mingle with the safety circuits and develop a single-centralized circuit (obviously under assumption that the person responsible knows what he's doing in accordance with the standards). Or maybe one should avoid at all cost such integration and stick to stopping individual machines with individual e-stop buttons, where the remaining machines will be stopped with standard, non-safety information. I believe there is no single, universal answer to this question, but I would like to ask other experienced people what's their opinion on this subject. I would be grateful for any suggestions as this is not the first time when I'm wondering how far you can, and how far you must go when integrating safety circuitry.

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I'll have a go at answering this and maybe this will start a debate... Emergency stops. Under what circumstances would you expect the emergency stop to be used? Assuming the emergency stop is local. For the emergency stop to be actuated the operator must be exposed to a hazard. If the operator is exposed to a hazard then this must have been accounted for in the risk assessment. You are almost certainly expecting the operator to be able to operate the emergency stop when encountering the hazard. Is this a reasonable request? Remote emergency stops. Again, under what circumstances would you expect a remote e-stop to be used to protect someone on another machine? Here you are hoping someone at a remote point will recognize another operator is in danger from a remote hazard and react accordingly. Is this reasonable? Guard doors. What is the function of guard doors? To protect the operator from whatever is beyond those doors. What would be the benefit of making a hazard safe that was not behind the door in question? If you agree with and follow the logic above you would come to the conclusion that: 1. there is no need to integrate the emergency stops are you cannot justify their use in any hazardous situation. 2. there is no need to integrate safety guards and doors as they only protect against hazards which are behind those guards. Now I'm going to disagree with my own logic.... The Machinery Directive offers the following assistance: “In the case of machinery or parts of machinery designed to work together, the machinery must be designed and constructed in such a way that the stop controls, including the emergency stop devices, can stop not only the machinery itself but also all related equipment, if its continued operation may be dangerous.” (EHSR’s 1.2.4.4. - Assembly of machinery) General rule: I would integrate emergency stops for a line or group of machines working in concert. Safety guards - a machine stop should be sufficient unless the operator will use them as an emergency stop. This then leaves the practical problem of how to implement this as this has problems of it's own. Edited by Veganic

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really good , i like your suggestion , I will defiantly try it.. but persons like to add guards...then what are solutions .. actually having some old setup and not able to replace guards...

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