Machine safety: Incorporating functional safety as part of your machine safety plan, Part 4

When considering “functional safety,” look at what differs compared to other safety initiatives, consider U.S. versus international standards, examine conformance responsibilities, and think about what changes are needed, if any, as a manufacturer. Part 4 of 4 looks at how manufacturers should look at their machine safety programs in light of international safety compliance requirements.


Four questions related to functional safety follow, including what changes manufacturers need to make.

1. What is so different about “functional safety”? (Part 1)

2. Are U.S. domestic standards adopting functional safety requirements from the international standards? (Part 2)

3. Do the international standards place primary conformance responsibility on manufacturers like with OSHA? (Part 3)

4. Do we have to change our machine safety program as a manufacturer in order to meet the compliance requirements? (Part 4)

Let’s take a look at these four questions addressing the fourth question in Part 4.


Definition from IEC 61508-1 - Functional safety is “part of the overall safety relating to the equipment under control and the equipment under control’s control system which depends on the correct functioning of the Electrical/Electronic/Programmable Electronic safety-related systems, other technology safety-related systems and external risk reduction facilities”.


Do we have to change our machine safety program as a manufacturer in order to meet the compliance requirements?


Note – in this discussion the term “manufacturer” is very broad and includes; end users, OEM’s, machine builders and systems integrators, for example. As such it is strongly advised that the reader understand some granularity and interpret accordingly. 


In my opinion, more than likely you will have to make some modifications to your machine safety program in order to incorporate functional safety requirements. Now, this kind of blanket statement needs some granularity for understanding and interpreting its application to your particular business. To begin with we’re talking about the current version of ISO 13849-1; 2006 Safety of Machinery – Safety-related parts of control systems. In broad scope:

·         As an OEM, machine builder or systems integrator (aka supplier) you will have to determine the performance level of a complete safety-related circuit including all components and devices and the related software. This performance level must be optimized in order to meet or exceed the performance level required for that safety function. Testing and validating will be required.

·         As an end user doing an in house machine retrofit/modification you have become a supplier doing design and build and should follow the same guidance as suggested above.

·         As an end user simply replacing a defective component or device in an existing safety-related circuit you should make every attempt to replace that component or device with another component or device with the same or greater safety rated performance. The advice is to not degrade the safety-related performance for the safety function.


There are many more details that come along functional safety and compliance to ISO 13849-1. This narrative is only intended to give you a high level opinion of what may be involved and how your safety program might see the need for modifications. Clearly there are engineering level resource requirements that you may already have access to for performing the incremental design, build, test and validating requirements.    


For the benefit of everyone I encourage you to add your comments or thoughts to this discussion by submitting your ideas, experiences, and challenges in the comments section below. I have not met anyone thus far who has all the answers!


J.B. Titus, CFSERelated articles:

Inside Machines: Does adopting ISO 13849-1:2006 change the U.S. model for compliance and enforcement?

Machine Safety: Can end user companies comply with ISO 13849-1: 2006 without design engineering resources?

Machine Safety – incorporating “Functional Safety” as part of your machine safety plan – Part 1

Machine Safety – incorporating “Functional Safety” as part of your machine safety plan – Part 2

Machine Safety – incorporating “Functional Safety” as part of your machine safety plan – Part 3


Contact: for “Solutions for Machine Safety”.

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