Machine Safety
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Machine Safety: Functional safety and the steps to be compliant in the U.S.

Who has the steps identified for anyone considering moving their machine safety compliance to functional safety for their organization? Let’s assume for this discussion that functional safety means being compliant with EN ISO 13849-1.

April 17, 2012


Who has the steps identified for anyone considering moving their machine safety compliance to functional safety for their organization? Let’s assume for this discussion that functional safety means being compliant with EN ISO 13849-1.

To stay on target consider updates to your safety culture and your machine guarding solutions practice.In my opinion, having been exposed to various sources of training materials, the steps usually recommended for engineers designing machine control systems are generally as follows:

1.) Specify the safety functions

2.) Specify the required Performance Level(s) (PLr) (goal)

3.) Technically design the safety circuit(s) to achieve the safety function(s)

4.) Determine the specification of the Performance Level(s) & their quantitative value

5.) Verify

6.) Validate

7.) Document

There may be variations to the above and we’d certainly like to hear from you and your ideas. However, does this really answer the question?

If you’re the CEO, owner, or plant manager these steps don’t even come close. Nothing here addresses the business case, the cost benefit analysis, the existence of a possible mandate, the impact on employee injuries, or how to maintain compliance with existing machines while adopting and evolving over time to the new functional safety approach. For example, might a plant manager want his supplier of choice to provide a simple 5 X 7 card reflecting a comparison of PL to Cat certified components? This would obviously be needed in order to replace a Cat component with a PL component in an existing safety circuit. Certainly EN ISO 13849-1 takes this into consideration – doesn’t it?

Well, OK, maybe not. So, let’s look at our domestic application safety standards. Does anybody know of a domestic machine safety standard that addresses this issue? Will all suppliers (domestic and international) continue certifying safety components to Cat while adding PL? If so, maybe the 5 X 7 comparison card will not be required?

Has anybody seen a complete list of business steps for moving to and adopting functional safety for machine safety compliance? Is this an issue?

Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: Machine Safety: functional safety and the steps to be compliant in the US.

Related articles:

Updating Minds About Machine Safety

Integrated Safety Systems: Ensuring Safety and Operational Productivity, Aberdeen Group

Machine Safety – the myths of safety cultures.

Contact: www.jbtitus.com for “Solutions for Machine Safety”.



For more than 30 years, J.B. Titus has advised a wide range of clients on machine functional safety solutions, including Johnson & Johnson, Siemens, General Motors, Disney, Rockwell Automation, Bridgestone Firestone, and Samsung Heavy Industries. He holds a Bachelor of Business Administration degree from Oklahoma University in industrial management and an MBA from Case Western Reserve University in marketing and finance. He is a professional member of the American Society of Safety Engineers and is OSHA-certified in machine guarding. Titus is also TUV-certified as a Functional Safety Expert and serves on several American National Standards Institute, National Fire Protection Association, and National Electrical Manufacturers Association national safety and health standards committees. Reach him at jb(at)jbtitus.com and via www.jbtitus.com.