Essentials of Machine Safety Standards in Perspective

Why Safety?

Legal Framework

AS 4360 Risk Management A Type AS 4024 Safety of Machinery AS Functional Safety EN954-1EN418EN294 IEC B Type AS60621 Safety of Machiner y AS61511 Process Safety AS61513 Oil & Gas AS1755 Conveyor s AS1219 Power Presses AS2939 Robot Cells C Type Australian Standards

Occupation Safety and Health Act supported by The General Duties Resolution of Issues Safety and Health Representatives Safety and Health Committees Enforcement of Act and Regulations Occupation Safety and Health Regulations and 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 Guidance Material Codes of Practice Advisory Standards National Codes of Practice and National Standards developed by the NOHSC Australian Standards developed by Standards Australia Legal Framework

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.

“It is the control of the design and design- associated 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 Safe Design

Hierarchy of Control Making it safe

Basic concepts According to the requirements of standard EN/ISO , the machine designer’s job is to reduce all risks to a value lower than the acceptable risk It gives guidelines for the selection and installation of devices which can be used to protect persons and identifies those measures that are implemented by the machine designer and those dependent on its user ●This standard recognises two sources of hazardous phenomena: ●moving parts of machines ●moving tools and/or workpieces

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)Likelihood b)Degree of Harm c)What the person knows about the risk and ways of eliminating that risk d)Availability and suitability of ways to eliminate or reduce the risk e)Cost of eliminating or reducing the risk

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

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 => Performance Level (PL) EN/IEC => Safety Integrity Level (SIL) –Risk reduction Risk Assessment Principles

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 , 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: - (1) For designated architectures only d

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.system [1]probability Probability is the likelihood or chance that something is the case or will happen.Probability

Change of Standards The qualitative approach of the EN 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 will totally replace the EN 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 and EN/ISO are valid For complex machines using programmable systems for safety-related control, the sector specific standard EN/IEC has to be considered –EN/IEC based on EN/IEC 61508

Standard EN/IEC 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 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, DC avg, MTTF d 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.