At the time of writing (9 October 2007) the BSI website states that BS EN 1050:1997 'Safety of machinery. Principles for risk assessment' is withdrawn and superseded by BS EN ISO 14121-1:2007 'Safety of machinery. Risk assessment. Principles'. Although EN ISO 14121-1 has not been published in the Official Journal of the European Union yet, it will be very soon - at which point it will be harmonised to the Machinery Directive. This means that people currently working with BS EN 1050 should consider buying a copy of the new standard and conforming with its requirements.
Fortunately the changes are generally only small, but the main point to note is that BS EN 1050 Annex B, 'Methods for analysing hazards and estimating risk', does not exist in BS EN ISO 14121-1. This is because ISO 14121 is in two parts, with Part 1 covering 'Principles', and Part 2 covering 'Practical guidance and examples of methods'. When Part 2 is published it will therefore contain considerably more material than Annex B of EN 1050 contains, which is likely to be a great help when actually performing risk assessments.
Throughout BS EN ISO 14121-1 there are numerous textual changes, but the following is a summary of the main differences from BS EN 1050.
As is common with the more modern standards, the 'Terms and definitions' in BS EN ISO 14121-1 are more extensive (17 items) than the 'Definitions' in EN 1050 (four items).
'Determination of limits of machinery' has been expanded into five sub-clauses: General; Use limits; Space limits; Time limits; Other limits. However, everything in the sub-clauses appears to be reasonable. Note that sub-clause 5.1 refers to sub-clauses '5.2 to 5.6', yet there is no sub-clause 5.6 in the published standard.
'Hazard identification' has been expanded. In addition, the clause refers to 'all phases of the machine life cycle' and identifies them as follows: transport, assembly and installation; commissioning; use; decommissioning, dismantling and disposal. In contrast, BS EN 1050 was less specific, just referring the reader to EN 292-1 for life phases.
Another new feature of Clause 6 is a statement of what could be included in task identification, with a useful checklist.
Unlike the corresponding Clause in BS EN 1050, Clause 7.2.2, 'Severity of harm', does not say that severity can be estimated by taking into account 'persons; property; environment'. The reason for this can be found in the Scope (Clause 1), which states that the standard is not applicable to risks posed to domestic animals, property or the environment.
This Clause is now titled 'Suitability of protective measures', whereas the corresponding Clause was 'Reliability of safety functions' in BS EN 1050. Nevertheless, the content is essentially the same.
'Achievement of adequate risk reduction' (corresponding to 'Achievement of risk reduction objectives' in BS EN 1050) is now split into 8.2.1 ('Three-step method') and 8.2.2 ('Presumptions of adequate risk reduction'). While the three-step method was not referred to by that name in BS EN 1050, the new Clause 8.2 really just clarifies what was contained in Clause 8.2 of BS EN 1050.
Annex A (informative)
The Annex retains the same title, 'Examples of hazards, hazardous situations and hazardous events', but has undergone major changes. Table A.1 has been revised so that for each type of hazard (eg mechanical, electrical, thermal) the examples are now split into 'origin' (eg approach of a moving element to a fixed part) and 'potential consequences' (eg crushing).
Table A.2 gives some pictorially illustrated examples of the hazards from Table A.1 (eg crushing, impact and shearing due to moving elements). The idea is to use the 'origins' or 'potential consequences' from Table A.1, depending on which is most useful when choosing appropriate protective measures. But clearly there is scope to consider various combinations for each type of hazard.
Table A.3, 'Examples of hazardous situations', is to be used as well as Tables A.1 and A.2 for situations where a person is exposed to at least one hazard. For each phase of the machine life cycle Table A.3 lists examples of tasks.
Table A.4, 'Examples of hazardous events', is to be used as well as Tables A.1, A.2 and A.3. Table A.4 lists hazardous events (eg contact with moving parts) that could be associated with various origins (eg moving parts of the machine).
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