Essentials of Machine Safety Standards in Perspective Why Safety? Legal Framework Australian Standards A Type EN954-1 EN418 EN294 AS 4360 Risk Management AS 4024 Safety of Machinery B Type IEC 61508 AS 61508 Functional Safety AS1755 AS1219 AS2939 AS60621 AS61511 AS61513 Conveyor s Power Presses Robot Cells Safety of Machiner y Process Safety Oil & Gas C Type Legal Framework Occupation Safety and Health Act  The General Duties  Resolution of Issues  Safety and Health Representatives  Safety and Health Committees  Enforcement of Act and Regulations supported by Occupation Safety and Health Regulations  Set minimum requirements for specific hazards and work practices  Reference to National Standards developed by NOSH  Australian Standards developed by Standards Australia  National Standard of Plant and Guidance Material  Codes of Practice  Advisory Standards  National Codes of Practice and National Standards developed by the NOHSC  Australian Standards developed by Standards Australia Safety - Acceptable Risk Level • Risk 0 does not exist but it must be reduced up to an acceptable level • Safety is the absence of risks which could cause injury or damage the health of persons. • It’s one of the machine designer job to reduce all risks to a value lower than the acceptable risk. Safe Design “It is the control of the design and designassociated activity that leads to a responsibility as an obligation bearer, not their classification as a manufacturer, supplier, etc.” National Occupational Health and Safety Commision Safe Design Project Report 2000 Making it safe Hierarchy of Control Basic concepts • According to the requirements of standard EN/ISO 12100-1, the machine can be used to protect persons and identifies those measures that are designer’s job implemented by the machine designer and those dependent on its useris to reduce all risks ● This standard recognises two sources of hazardous phenomena: to a value lower ● moving parts of machines ● moving tools and/or workpieces than the acceptable risk Reasonably Practicable How WorkSafe applies the law in relation to Reasonably Practicable WORKSAFE POSITION A GUIDELINE MADE UNDER SECTION 12 OF THE OCCUPATIONAL HEALTH AND SAFETY ACT 2004 (November 2007) In applying the concept of reasonably practicable, careful consideration must be given to each of the matters set out in section 20(2) of the Act. No one matter determines ‘what is (or was at a particular time) reasonably practicable in relation to ensuring health and safety’. The test involves a careful weighing up of each of the matters in the context of the circumstances and facts of the particular case with a clear presumption in favour of safety. Weighing up each of the matters in section 20(2) should be done in light of the following: a) b) c) d) e) Likelihood Degree of Harm What the person knows about the risk and ways of eliminating that risk Availability and suitability of ways to eliminate or reduce the risk Cost of eliminating or reducing the risk Risk Assessment • NOTE: A risk assessment must never been a bill of materials or allow the controls selection to be driven by what the vendor has to offer. Risk Assessment Principles • Machines are sources of potential risk and the Machinery Directive requires a risk assessment to ensure that any potential risk is reduced to less than the acceptable risk • Risk assessment consists of a series of logic steps which make it possible to systematically analyse and evaluate machinery-related risks • Risk assessment steps: – Identification of the potential hazard – Risk estimation – Risk evaluation • EN/ISO 13849-1 => Performance Level (PL) • EN/IEC 62061 => Safety Integrity Level (SIL) – Risk reduction Risk Evaluation • On the basis of the risk assessment, the designer has to define the safety related control system. To achieve that, the designer will chose one of the two standards appropriate to the application: – either standard EN/ISO 13849-1, which defines performance levels (PL) – or standard EN/IEC 62061, which defines safety integrity levels (SIL) • The table below gives relations between these two definitions • To select the applicable standard, a common table in both standards gives indications: d (1) For designated • Reliability - the ability of a system or component to perform its required functions under stated conditions for a specified period of time.[1] It is often reported as a probability. • Probability is the likelihood or chance that something is the case or will happen. Change of Standards • The qualitative approach of the EN 954-1 is no longer sufficient for modern controls based on new technologies (Electronic and Programmable Electronic systems): – insufficient requirements for programmable products, – The reliability of the components is not taken into account, – too deterministic orientation (designated architectures). • Standard EN ISO 13849-1 will totally replace the EN 954-1 in November 2009, and will upgrade the qualitative approach by the new quantitative (probabilistic) approach and is consistent with safety standards in general. – At the moment both standards EN 954-1 and EN/ISO 13849-1 are valid • For complex machines using programmable systems for safety-related control, the sector specific standard EN/IEC 62061 has to be considered – EN/IEC 62061 based on EN/IEC 61508 Standard EN/IEC 62061 • Specific to the machine sector within the framework of EN/IEC 61508: – gives rules for the integration of safety-related electrical, electronic and electronic programmable control systems (SRECS) – does not specify the operating requirements of non-electrical control components in machine (ex.: hydraulic, pneumatic) • The probability of failure associated to the required SIL (Safety Integrity Level) depends on the frequency of usage of the safety function to be performed Safety of Machinery application EN/IEC 62061 Standard EN/ISO 13849-1 • The Standard gives safety requirements for the design and integration of safety-related parts of control systems, including software design. • The Risk Graph helps to determine the required PL (Performance Level) of each safety function – S - Severity of injury > S1 Slight injury > S2 Serious or permanent injury or death – F - Frequency and / or exposure to a hazard > F1 Seldom to less often and / or short time > F2 Frequent to continuous and / or long time – P - Possibility of avoiding the hazard or limiting the harm > P1 Possible under specific conditions > P2 Scarcely possible Relationship Between Different Criteria • Relationship between Categories, DCavg, MTTFd and PL *In several application the realisation of performance level c by category 1 may not be sufficient. In this case a higher category e.g. 2 or 3 should be chosen.