Machinery Safety 101
12 July, 2021

Understanding Safety Functions: the Safety-related stop function

by Doug Nix
in Complementary Protective Measures, Control Functions, Emergency Stop, Functional Safety, Interlocks, Interlocks, ISO 13849
A stop sign - A red octagon with a white border, and white block text reading STOP.
This entry is part of 3 in the series Under­stand­ing Safety Functions

The most used safety func­tion on machinery is the safety-related stop func­tion. The require­ments dis­cussed in this post are not gen­er­ally applic­able to pro­­cess-related stop func­tions unless the pro­cess and… 

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25 April, 2019

More E‑Stop Questions

by Doug Nix
in Canada, Control Functions, Emergency Stop, EU European Union, Standards, USA /
10 Comments
This entry is part 17 of 16 in the series Emer­gency Stop

Here are some more ques­tions I’ve been asked regard­ing emer­gency stop require­ments. These ones came to me through the IEEE PSES EMC-PSTC Product Com­pli­ance For­um mail­ing list. Primary Sources There… 

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28 August, 2018

Emergency Stop Pull-Cords

by Doug Nix
in Complementary Protective Measures, Emergency Stop /
2 Comments
This entry is part 15 of 16 in the series Emer­gency Stop

When it comes to emer­gency stop devices there is no doubt that the red mush­­room-head push but­ton is the most com­mon – they seem to be every­where. The second most… 

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10 July, 2017

Emergency Stop Failures

by Doug Nix
in Emergency Stop
This entry is part 13 of 16 in the series Emer­gency Stop

I am always look­ing for inter­est­ing examples of machinery safety prob­lems to share on MS101. Recently I was scrolling Reddit/r/OSHA and found some real-world examples of emer­gency stop fail­ures, plus one… 

20 March, 2017

ISO 13849 – 1 Analysis — Part 6: CCF — Common Cause Failures

by Doug Nix
in Canada, CE Mark, Control Functions, EU European Union, Functional Safety, Guards and Guarding, Hierarchy of Controls, Inherently Safe Design, ISO 13849
This entry is part 6 of 9 in the series How to do a 13849 – 1 analysis

Post updated 2019-07-24. Ed. What is a “Com­mon Cause Fail­ure”? There are two sim­il­ar-sound­ing terms that people often get con­fused: Com­mon Cause Fail­ure (CCF) and Com­mon Mode Fail­ure. While these… 

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