Understanding EN1050

A Pilz Automation Technology product story

Edited by the Engineeringtalk editorial team Nov 24, 2003

Risk assessment is key to machinery safety, and in Europe we are encouraged to carry out risk assessments in line with the harmonised standard EN1050:1997.

Risk assessment is key to machinery safety, and in Europe we are encouraged to carry out risk assessments in line with the harmonised standard EN1050:1997 (Safety of machinery - principles for risk assessment).

As standards go, this one is less daunting than many, running to 22 pages, or just six pages if you do not count the covers, forewords, contents listing, annexes and blank pages.

Anybody who has read the standard will appreciate that it does not go into the detail of how to conduct a risk assessment; rather it presents the underlying principles and how the methods should be applied.

As such it is still an extremely important standard to follow, and it also makes it clear that it is necessary to "assess the risks during all phases of the life of the machinery".

Other useful sections include precise definitions for harm, hazardous event, safety measure and residual risk, and an explanation of how a risk assessment is made up of risk analysis and risk evaluation.

Once action has been taken to reduce the remaining risks, further iterations of the cycle of risk assessment and risk reduction must be undertaken until the residual risk is acceptably low.

EN1050 also discusses the way that risk assessment relies on judgemental decisions that are supported by qualitative methods and, as far as possible, quantitative methods.

Where data can be obtained, quantitative methods are preferred, and the standard highlights the way that quantitative methods are particularly useful if two or more alternatives strategies are being assessed.

As with so many standards, some of the most useful information is to be found in the annexes, even though they are only "informative".

Annex A of EN1050, for instance, presents a list of example hazards, hazardous situations and hazardous events.

For each item in the list there is a cross-reference to EN292 Part 1 and Part 2.

Essentially this annex provides a fairly thorough checklist, though the onus is on the risk assessor to ensure that all risks are considered, whether or not they appear on this list.

By the time the reader reaches Annex B (also "informative"), it is obvious that EN1050 is not going to provide answers to all questions about risk assessment.

Annex B briefly describes some methods for analysing hazards and estimating risk - which is probably what most readers wanted to know about in the first place.

For most of these methods the reader has to turn to books or training courses to find out how to apply the methods, though IEC standards do exist for failure mode and effects analysis (FMEA) and fault tree analysis (FTA).

Pilz comes into contact with a wide variety of companies who are building machines, using machines or modifying machines and need to conduct risk assessments.

Despite the existence of EN1050, the HSE's booklet "Five steps to risk assessment", and the vast number of books published on the subject, many people are still wary of conducting a risk assessment without guidance from an engineer experienced in assessing hazardous machinery.

While some companies prefer to send engineers to Pilz for training, others request a risk assessment to be carried out by Pilz engineers.

This may be because of a lack of in-house resources or simply that an independent risk assessment is desirable.

Moreover, if any action is subsequently required to reduce the risks, the Pilz engineers can assist the company with planning and executing the improvement programme.