Safety categories

Rson

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Join Date
Jun 2017
Location
Michigan
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Years ago I attended a great presentation from Banner concerning safety categories, etc for machine control.

I thought I had kept all of the literature, but I can't seem to find any of it. My current position doesn't deal with safety that often, but I'm trying to do some research for a project about the different categories and how to maintain the rating.

Does anyone have any good slideshows, PDFs, videos, books, etc that go into decent detail about Category B, 1, 2, 3, 4 and the differences/etc?

Thanks in advance!
 
The region specific standards, certainly. If you don't have access to those then here are some good resources:


Allen Bradley Safe Book 5:
https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/safebk-rm002_-en-p.pdf


Pilz Safety Compendium:
https://www.pilz.com/download/open/TechBo_Pilz_safety_compendium_1004669-EN-01.pdf


Omron Application Examples:
http://www.omron.com.au/service_support/technical_guide/safety_component/safety_circuit_example.asp


Some of the references to "Category" will be dated, as we now use the Performance Level system, and Categories are more an architecture meeting that requirement. I would also use a number of references, as well as the standards, because over the years I have some across some slightly varying definitions of the categories.
 
A couple of years ago I attended a Siemens Machine Safety class/certification. We were led to believe categories are on the way out, being replaced by SiL levels. Not sure if that ever happened or not. Many safety components now come with Sil ratings.
 
A couple of years ago I attended a Siemens Machine Safety class/certification. We were led to believe categories are on the way out, being replaced by SiL levels. Not sure if that ever happened or not. Many safety components now come with Sil ratings.

Lately all the safety requirements I get for proposals and inquiries have all been to SIL levels.

The customers are getting more familiar with SIL, and the supplier personnel also.

I was talking to a salesperson at a trade show about 5 years ago about if their items were SIL rated. I had to explain what SIL was, referencing its relevance to nuclear plants, and all he could ask was how many nuclear plants I had built. He had no concept of safety in controls for anything else. (BTW - none of his products were SIL rated and I don't think they are still in business)
 
In Australia my observation more often than not has been that machine safety uses Performance Level and process safety uses SIL. Categories still very much exist, but refer to the system architecture rather than the level itself (Like they once did). Being an OEM machine builder, I will generally deal with Performance Level, Design Category and Stop Category.
 
The thing you must be aware of is how devices are "SIL" rated. The machine industry uses one standard, and the process industry another. For the process guys, SIL is probability of failure on demand. For machine guys the system is always in demand and the rating is based upon mean time between failures.

So when you are specing out a system, you need verify which standard the devices meet.
 

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