Automation Canada Machine Safety Issue - 5

A CLOSER LOOK AT SAFETY VALVES
AND THE VALUE OF PERFORMANCE LEVEL E
BY OWEN HURST
Recently we had the chance to learn a little more about some of
Festo's output safety devices, with a focus primarily on the MS6-SV-E
Safety Valve. Insight in this was provided from several Festo product
specialists and a direct look at safety functions from Randy DeForge,
Product Manager, Festo North America.
First and foremost a safe machine should be designed in a way that
protects people and property amongst other things. Essentially the
goal is to prevent physical damage of any type. The level of protection
depends upon the level of risk. The focus on machine safety should
always consider EN ISO 13849-1.
In his recent presentation at Pack Expo Randy went into detail about

what is required to both determine the risks involved and how to ensure
that you are utilizing the required level of safety for your machine.
First is determining what measures need to be taken to reduce risk. To
determine the risk and necessary safety measures a risk evaluation is
required. Once an assessment has been performed it is necessary to
shift gears and focus on risk reduction. This could be undertaken at the
design stage but if the risk cannot be reduced within the design than
technical measures must be taken.
This is where safety functions come in to play such as safe exhausting,
safety from unexpected start-up, or safe pressurization. There are
several steps that need to be taken to determine safe functioning.

Performance level is the measure of the reliability of the safety function. These are divided through 5 levels, A-E. Level E is the highest and is
required for operations with the highest level of risk. Some engineers also like to consider the SIL (Safety Integrity Level) The higher the SIL the more
reliable the safety related system is. However, the SIL overlaps Performance Level and uses similar methodology to determine the requirement.
C A N A D I A N A U TO M AT I O N

VOLUME 2, ISSUE 6

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Automation Canada Machine Safety Issue

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