Essentials of Machine Safety Standards in Perspective

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.