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An online cure for the safety directive blues01 October 2009With the imminent arrival of new European Machinery Safety directives, machine builders and operators must not only ensure they comply with new standards, they must also prove it - a task easier said than done. Rob Sharrock describes a new, free online evaluation tool that could help companies meet their safety obligations The forthcoming standards IEC 62061 (safety of machinery - functional safety of electrical, electronic and programmable electronic control systems) and EN ISO 13849-1 (safety of machinery - safety related parts of control systems) will become mandatory at the end of 2009. Machine builders and users will need to verify and document compliance with the new directives, which are aimed at improving overall functional safety for the protection of persons and machines.
Businesses meeting the reporting and documentation requirements will enjoy a high degree of legal security and peace of mind when it comes to proving that the machines they are building or operating are safe. Ultimately, companies must be able to calculate and prove the Safety Integrity Level (SIL) or performance Level (PL) of the machine and its associated safety components, but getting to this point is likely to be very taxing for some.
When having to confront the task of proving directive compliance for machines and all the integral safety components, a number of factors will have to be considered and potentially a significant amount of data required. A number of questions will need to be assessed and answered. How reliable are the components? How can I work out the chance of failure? Is there a common cause for failure? Is there a value for failure? Can I detect subsequent failures?
In many cases, companies looking to assess a SIL or PL level could be dealing with old or legacy equipment, much of which may have been installed for a considerable period of time. Data probably won't exist in such cases to allow safety calculations to be made and this presents a big problem in verification of safety functions to meet the new standards. Indeed, it is estimated that upwards of 60% of machine component manufacturers in this area cannot deliver the essential data that will be required to support compliance with the standards. For many this may be a huge obstacle and they will be seeking ways of working around it. So, to whom should they turn?
One area worthy of consideration is that of online safety evaluation tools, which are able to assess, calculate and deliver the correct level of report documentation that will satisfy the requirements of the new machine safety directive. For example, a new safety evaluation tool from Siemens is easily accessible via the Internet and, at a time when cost considerations are paramount, is free of charge.
The principle of the tool is simple and its application straightforward. The user first specifies the desired safety function - the monitoring of a protective door, say - then examines examples of the functionality specifically or more generally. From here, the user simply enters details of the safety components that are specific to the machine in question, such as sensors, evaluation units and actuators. These components can be identified and directly selected from an existing product database (the one provided by Siemens in the case of this example), or they can be entered manually if acquired from other sources. Users of the software tool should be aware that, while it is able to accept components from other vendors, the relevant data pertaining to their suitability for the application (certification and compliance, for example) has to be obtained and input manually.
Using this information, the evaluation tool will quickly calculate the SIL or PL, and produce a report that is in line with the requirements of the new standards. The report can sit alongside the machine's documentation and used to verify that the directive has been met.
The six stages of the online evaluation tool are: definition of safety function; selection of the standard on which calculations are to be based (IEC 62061 or ISO 13489-1); description of the safety function, risk assessment and input of the required SIL or PL level sought; data entry of the selected products; delivery of the resultant SIL or PL result, and preparation of the resultant report for machine documentation.
Tools like this provide the machine builder or operator with a simple and straightforward method of generating and calculating the safety integrity of components, and assessing the overall compliance of the machine and its functions when set against the safety standards post 2009. It will save users time and help them to prove they have the appropriate safety levels, without resorting to assumptions, which could prove costly in the long run.
At a time when adherence to ever-tightening regulatory environments means everyone has to be sure that the machines they are building or operating meet current safety standards, the availability of a quick and simple method of proving compliance could be a real asset. Approaching the task of new standards adherence intelligently saves time and provides real peace of mind - something that definitely adds up.
Rob Sharrock is with Siemens Industry Automation and Drive Technologies
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