{"id":3235,"date":"2023-01-04T16:22:27","date_gmt":"2023-01-04T15:22:27","guid":{"rendered":"https:\/\/www.gt-engineering.it\/normative-tecniche\/%tipologia_normativa%\/iso-14118\/"},"modified":"2025-06-08T09:49:38","modified_gmt":"2025-06-08T08:49:38","slug":"iso-14118","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/en\/technical-standards\/en-iso-standards\/iso-14118\/","title":{"rendered":"ISO 14118: Prevention of Unexpected Start Up"},"content":{"rendered":"\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9  float-right ml-6 md:ml-4 lg:ml-8 xl:ml-9 overflow-hidden shadow-content-image w-full md:w-1\/2\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Screenshot-2023-11-03-092348-150x150.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"222\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Screenshot-2023-11-03-092348-300x222.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"569\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Screenshot-2023-11-03-092348-768x569.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"759\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Screenshot-2023-11-03-092348-1024x759.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Screenshot-2023-11-03-092348.png.webp\"\r\n                                                        title=\"Screenshot 2023-11-03 092348\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p data-start=\"115\" data-end=\"239\">In general, when performing a risk assessment on machinery, <strong>a single hazard is typically associated with two distinct risks<\/strong>.<\/p>\n<p data-start=\"241\" data-end=\"446\">Let\u2019s consider an example: a robot cell. The hazard in this case is the kinetic energy of the robot arm, which can strike a person operating nearby. There are two primary risks associated with this hazard:<\/p>\n<ol data-start=\"448\" data-end=\"741\">\n<li data-start=\"448\" data-end=\"582\">\n<p data-start=\"451\" data-end=\"582\"><strong data-start=\"451\" data-end=\"582\">The risk that, upon entering the safeguarded space, the safety system designed to stop the robot fails to do so due to a fault.<\/strong><\/p>\n<\/li>\n<li data-start=\"583\" data-end=\"741\">\n<p data-start=\"586\" data-end=\"741\"><strong data-start=\"586\" data-end=\"741\">The risk that, although the robot initially stops when someone enters the area, it restarts unexpectedly because of a malfunction in the safety system.<\/strong><\/p>\n<\/li>\n<\/ol>\n<p data-start=\"743\" data-end=\"874\">The second scenario is referred to as the <strong data-start=\"785\" data-end=\"816\">risk of unexpected start-up<\/strong>, and in our opinion, it is the more dangerous of the two.<\/p>\n<p data-start=\"876\" data-end=\"985\">The standard that provides guidance on how to mitigate the risk of an unexpected start-up is <strong data-start=\"966\" data-end=\"984\">ISO 14118: 2017<\/strong>.<\/p>\n<p>&nbsp;<\/p>\n<p>Keeping a machine in a stopped condition while persons are present in danger zones is one of the most\u00a0important conditions of the safe use of machinery and hence, one of the major aims of the machine\u00a0designer and machine user.<br \/>\nIn the past, the concepts of \u201coperating machine\u201d and \u201cstopped machine\u201d were generally unambiguous; a\u00a0machine was<\/p>\n<ul>\n<li>operating when its movable elements or some of them were moving;<\/li>\n<li>stopped when its movable elements were at rest.<\/li>\n<\/ul>\n<p>Machine automation has made the relationship between \u201coperating\u201d and \u201cmoving\u201d on one hand and\u00a0\u201cstopped\u201d and \u201cat rest\u201d on the other hand, more difficult to define. Automation has also increased the<br \/>\npotential for unexpected start-up and a significant number of hazardous events have occurred where\u00a0machines, stopped for diagnostic work or corrective actions, started up unexpectedly.<\/p>\n<p>The reference Technical Standard is\u00a0<strong>ISO 14118<\/strong> &#8220;<strong>Safety of machinery \u2014 Prevention of unexpected start-up<\/strong>&#8221; latest edition in 2017; it defines the methodologies to be followed when entering, safely, a dangerous area of the machine (<strong>safeguarded zone<\/strong>).<\/p>\n<p>The general rule is <strong>Isolation and Energy Dissipation<\/strong>. In other words, before entering a dangerous area, the maintenance team should open the general electrical disconnector, open the manual pneumatic (normally 3\/2) valve required as first element is a machinery Pneumatic distribution system, switch off the hydraulic unit. If applicable, the gas train needs to be put in a zero energy state.<\/p>\n<p>In other terms, in order to prevent an unexpected start up, a <a href=\"https:\/\/www.gt-engineering.it\/en\/insights\/electrical-hazard-and-arc-flash-mitigation\/lockout-tagout-analysis\/\"><strong>zero energy<\/strong><\/a> state needs to be established.<\/p>\n<p>However, that is not always possible:<\/p>\n<blockquote><p><em><strong>[ISO 14118: 2017] 4.3 Other means to prevent unexpected (unintended) start-up<\/strong>.<\/em><br \/>\n<em>If the use of manual isolation and energy dissipation is not appropriate for frequent short interventions,\u00a0the designer shall provide, according to the risk assessment in accordance with ISO 12100, additional\u00a0automatic controlled functions (see Clause 6) to prevent unexpected start\u00adup.<\/em><\/p><\/blockquote>\n<p>Other means are therefore detailed, like the use of interlocked keys. However those are more the exception then the rule, and they need to go through a risk assessement, to deside their suitability<\/p>\n<p>One of the important aspects added in the ISO edition is the following statement:<\/p>\n<blockquote><p><em><strong>[ISO 14118: 2017] 6.3.2 Maintained stop command generated by a stop control device (level A)<\/strong><\/em><\/p>\n<p><em>The control system shall be designed so that the stop commands from the stop control device have priority over the start commands. To prevent unexpected (unintended) start-up due to unintended generation of start commands (including those generated within the control system itself), the stop manual control (or the stop control device) can be secured in the OFF\/STOP condition. Depending on the risk assessment, securing in the OFF\/STOP condition can be achieved by means of:<\/em><br \/>\n<em>\u2014 <strong>a latching-in or key-operated stop control device<\/strong> which applies a maintained stop command until the device is reset manually;<\/em><\/p>\n<p><em><strong>NOTE:<\/strong> The emergency stop function <strong>cannot be considered<\/strong> as a measure of prevention of unexpected\u00a0start\u00adup as described in ISO 12100 (see also ISO 13850:2015, 4.1.1.2).<\/em><\/p><\/blockquote>\n<p>In other words, <strong>it is not correct to use the Emergency Function<\/strong> to enter a dangerous area of the machine and <strong>perform maintenance activities.<\/strong><\/p>\n<p><strong><img decoding=\"async\" title=\"ISO 14118: Safety of machinery\" src=\"https:\/\/preview.ibb.co\/e2CKaR\/Collare_emergenza_1.jpg\" alt=\"ISO 14118: Safety of machinery\" \/><\/strong><\/p>\n<p>A good solution is the use of Interlocks or of <strong>Trapped Keys.<\/strong><\/p>\n<p><img decoding=\"async\" title=\"ISO 14118: Safety of machinery\" src=\"https:\/\/preview.ibb.co\/mqTgpm\/IMG_3316.jpg\" alt=\"ISO 14118: Safety of machinery\" \/><\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n","protected":false},"excerpt":{"rendered":"<p>Keeping a machine in a stopped condition while persons are present in danger zones is one of the most&nbsp;important conditions of the safe use of machinery and&#8230;<\/p>\n","protected":false},"author":1,"featured_media":3236,"parent":0,"menu_order":24,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[57],"class_list":["post-3235","normativa_tecnica","type-normativa_tecnica","status-publish","has-post-thumbnail","hentry","tipologia_normativa-en-iso-standards"],"acf":{"sottotitolo":"ISO 14118: Safety of machinery \u2014 Prevention of unexpected 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