Machinery Safety 101
20 April, 2019

Can Emergency Stop be used as an “on/off” control?

by Doug Nix
in Complementary Protective Measures, Control Functions, Emergency Stop, Functional Safety /
4 Comments
Emergency Stop Button
This entry is part 16 of 16 in the series Emer­gency Stop

Every couple of months I get an email ask­ing me if there is any reas­on why e‑stop func­tions can­’t be used as the primary power con­trol (on/off but­ton) for machinery. Following… 

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4 April, 2019

Introduction to Functional Safety Seminars

by Doug Nix
in Complementary Protective Measures, Control Functions, Emergency Stop, Events, Free Talks, Functional Safety, Guards and Guarding, Interlocks, Interlocks, ISO 13849, Seminars, Standards, Training
Man training a group of people, pointing to Functional Safety topics on the whiteboard

If you are inter­ested in func­tion­al safety, and I know many read­ers are based on the stat­ist­ics I see for my oth­er func­tion­al safety-related posts, I think you will be inter­ested in this.… 

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28 August, 2018

Emergency Stop Pull-Cords

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

This art­icle was updated 2020-06-13, adding links to the Rock­well Auto­ma­tion and Schmersal pull-cord data, and on 2019-04-26, adding spe­cif­ic details related to IEC 60947 – 5‑5 [7]. When it comes to… 

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3 July, 2017

Safe Drive Control including Safe Torque Off (STO)

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, Guards and Guarding, Interlocks, Interlocks, ISO 13849, Ontario /
5 Comments
Graph illustrating STO Function
This entry is part 12 of 16 in the series Emer­gency Stop

Ed. Note: This art­icle was revised 25-Jul-17 to include inform­a­tion on safe stand­still. Safe Drive Con­trol includ­ing STO Motor drives are every­where. From DC vari­able speed drives and index­ing drives,… 

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18 June, 2017

ISO 13849 – 1 Analysis — Part 7: Safety-Related Software

by Doug Nix
in Canada, Complementary Protective Measures, Control Functions, Control Reliability, EU European Union, Functional Safety, How to, Interlocks, ISO 13849, Standards
General architecture model of software
This entry is part 7 of 9 in the series How to do a 13849 – 1 analysis

Post updated 2019-07-24. Ed. Safety-Related Soft­ware Up to this point, I have been dis­cuss­ing the basic pro­cesses used for the design of safety-related parts of con­trol sys­tems. The under­ly­ing assump­tion is… 

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16 January, 2017

ISO 13849 – 1 Analysis — Part 2: Safety Requirement Specification

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, Guards and Guarding, Hierarchy of Controls, How to, Interlocks, Interlocks, International, ISO 13849, Robotics /
4 Comments
This entry is part 2 of 9 in the series How to do a 13849 – 1 analysis

This art­icle was updated 2019-07-24. Ed. Devel­op­ing the Safety Require­ment Spe­cific­a­tion The Safety Require­ment Spe­cific­a­tion sounds pretty heavy, but actu­ally, it is just a big name for a way to organ­ize the… 

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3 January, 2017

ISO 13849 – 1 Analysis — Part 1: Start with Risk Assessment

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, Guards and Guarding, Hierarchy of Controls, How to, Interlocks, Interlocks, International, ISO 13849, Risk Assessment /
5 Comments
This entry is part 1 of 9 in the series How to do a 13849 – 1 analysis

This post was updated 2019-07-24 I often get ques­tions from cli­ents about how to get star­ted on Func­tion­al Safety using ISO 13849. This art­icle is the first in a series that will… 

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28 March, 2011

Why you should stop using the term ‘Deadman’

by Doug Nix
in Complementary Protective Measures, Control Functions, General, Robotics /
20 Comments

The Dead­man Con­trol Do you use the phrase ‘dead­man’ or ‘dead­man switch’ when talk­ing about safety-related con­trols on your machinery? I often run into this when I’m work­ing with cli­ents who… 

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28 February, 2011

Understanding the Hierarchy of Controls

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, General, Guards and Guarding, Hazardous Energy Control Procedures, Hierarchy of Controls, Interlocks, Interlocks, Lockout, Ontario, Risk Assessment, Robotics, USA /
8 Comments
The Hierarchy of Controls illustrated as an inverted triangle with each level of the hierarchy written one above the other, starting with Inherently Sfe design, then Engineering Controls, then Information for Use, then Administrative Controls and finally descending to PPE at the bottom. An arrow with the text "Effectiveness" on it runs parallel to the triangle and points downward from Inherently safe design to PPE.
This entry is part 4 of 5 in the series Hier­archy of Controls

(Eds. note: This art­icle was ori­gin­ally writ­ten in 2011 and was updated in Nov. 2018.) The “Hier­archy of Con­trols” is one approach to risk reduc­tion that has become entrenched in the… 

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27 September, 2010

Emergency Stop Categories

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Emergency Stop, EU European Union, USA /
42 Comments
Emergency Stop on machine console
This entry is part 4 of 16 in the series Emer­gency Stop

I’ve noticed a lot of people look­ing for inform­a­tion on Emer­gency Stop cat­egor­ies recently; this art­icle is aimed at those read­ers who want to under­stand this top­ic in more depth. First,… 

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