19 Nov 2019

Evaluating risks – how it’s done!

expert doing a risk assessemnt

Many criteria must be met to market a machine in Europe. Rightly, because at the end it’s not just about efficiency, productivity and a positive ROI but also about ensuring safety. We know this isn’t always easy – with Hazard Rating Numbers we introduce a risk assessment procedure. Ever since the first machine directive was released on June 14th 1989 (almost exactly thirty years ago) much has changed. The matter of “Safety of plant and machinery” is gaining more emphasis on the market, which is generally a good change. However the main goal is far from reached. We see a long and slow process, which does however go in the right direction. For many employers this aspect is nothing new, whether they want to provide a safe machine out of conviction or because the customer’s pressure is so high that it has to be done.  All in all one has to honestly admit that the whole subject is not made easy. The machine directive may have been revised and renewed multiple times since its first release. However it does not explain in detail how meet these requirements. It simply constitutes the legal framework for the construction of a safe machine which design engineers and manufacturers can use for orientation. How to actually minimize risks is left out. For this there are standards, like EN ISO 12100:2010 Safety of machinery – General principles for design – Risk assessment and risk reduction.

The standard EN ISO 12100
The EN ISO 12100 somewhat depicts the “mother of standards” when it comes to the subjects of risk assessment and risk minimization. Many software solutions follow the content and order of this standard and successively guide the user through the risk assessment.
The following diagram shows the iterative process of risk assessment in accordance with EN ISO 12100:2010. The beginning is about the definition of limits. Point 2 highlights the identification of hazards. This are both very individual subjects in which an individual assessment of the machine or plan is required. We want to however take a closer look at the 3rd point, because after the first two steps are done, the question often arises “How do I evaluate the risk correctly?”

chart about risk assessemnt

The solution: “Hazard Rating Numbers”
Hazard Rating Numbers is an internationally approved risk assessment procedure which is widespread and offers a great help in correctly evaluating the risks of danger points. EN ISO 12100, for example, requires three criteria that have to be considered during the evaluation process:
• Risk
• Extent of damage
• Probability of occurrence
The Hazard Rating Numbers procedure furthermore determines a quantitative risk level. With its classifications it can be clearly estimated whether the risk is negligible or if the danger has to be mitigated with risk reducing measures. Our consulting office also uses this method to properly evaluate risks and to make an assessment based on the determined sum.

Four questions, one answer
But how does the Hazard Rating Numbers procedure work exactly now? Well, it’s pretty simple, all in all. You give hazard ratings to four different questions:
• Extent of the damage (S)?
• Frequency of exposure to hazard (F)?
• Number of people in danger simultaneously (N)?
• Probability that the hazard will occur (O)?
Possible answers are predefined and are assigned to a corresponding parameter.
On the basis of these decision criteria, the level of risk is quantified as follows: Risk (R) = S · F · N · O

The best possible result is 0 for a very low risk, however the range is big und goes up to a maximum value of 13500. It is needless to say that this value requires a minimization of the risk. The following show an overview of how the determined risk value is to be interpreted:
0 – 5  Negligible risk – residual risk is acceptable
6 – 50 Risk low, but exists – risk should be reduced further if possible
51 – 500 High risk – must be reduced
> 500 Unacceptable risk – must be reduced in any case

Reaching the goal with oversight
The risk assessment is completed when all danger points have reached a value between 0 and 50 – even better between 0 and 5 – so that all danger points can be classified as “adequately minimized”. This endeavor can prove itself very difficult and confusing, especially when huge “Harakiri files” are created with Word or Excel. We thereby suggest a more stringent and overseeable processing of the danger points – software-assisted in the best case.

You want to receive your own impression of the Hazard Rating Numbers procedure? Then try out the trial version of our software CE-CON Safety. The screenshot below shows you for example the risk assessment of the hazard “Crushing” at the guide rail of our demo milling machine.

CE-CON Safety Software

With CE-CON Safety you can easily and intuitively depict your machines and conduct their risk assessments. Through its modular structure and the creation of templates you will save time and can always build upon your work already done. Furthermore our cloud software supports work across locations. Just give it a try!

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