guard Archives | Machinery Safety 101

29 May, 2015

Presence Sensing Devices – Reaching over sensing fields

in Canada, Guards and Guarding, Hierarchy of Controls, Ontario, Robotics /

This entry is part 2 of 7 in the series Guards and Guarding

I recently heard about an application question related to a light curtain where a small gap existed at the top of the sensing field, between the last beam in the field and the surrounding structure of the machine. There was some concern raised about the gap, and whether or not additional guarding might be needed to close the gap.…

1 June, 2012

Interlocking Devices: The Good, The Bad and the Ugly

by Doug Nix

in Canada, CE Mark, Components, Control Functions, Control Reliability, EU European Union, EU Robotics, Guards and Guarding, Hierarchy of Controls, Interlocks, Interlocks, International, International Robotics, ISO 13849, North American Robotics, Ontario, Robotics, USA /

7 Comments

This entry is part 1 of 7 in the series Guards and Guarding

Note: A shorter version of this article was published in the May-2012 edition of Manufacturing Automation Magazine. When designing safeguarding systems for machines, one of the basic building blocks is the movable guard. Movable guards can be doors, panels, gates or other physical barriers that can be opened without using tools. Every one of these guards…

21 June, 2011

Hockey Teams and Risk Reduction or What Makes Roberto Luongo = PPE

by Doug Nix

in Canada, Control Functions, EU European Union, General, Guards and Guarding, Hazards, Hierarchy of Controls, International, Risk Assessment /

5 Comments

This entry is part 2 of 5 in the series Hierarchy of Controls

Special Co-Author, Tom Doyle Last week we saw the Boston Bruins earn the Stanley Cup. I was rooting for the green, blue and white, and the ruin of my voice on Thursday was ample evidence that no amount of cheering helped. While I was watching the game with friends and colleagues, I realized that Roberto Luongo and Tim…

2 March, 2011

Retained fastenings for fixed guards

by Doug Nix

in CE Mark, EU European Union, Guards and Guarding /

No Comments

If you are building machinery that will be CE marked or is subject to the EU Machinery Directive, you need to read this article at MachineBuilding.net This article reviews some of the retained fastenings that are available for use on fixed machine guards, as required by the new Machinery Directive 2006/42/EC and the guarding standard…

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 Occupational Health and Safety (OHS) sector. There are other approaches to risk reduction which are equally effective but are less rigidly structured. If you…

3 September, 2010

Guarding Emergency Stop Devices

by Doug Nix

in Control Functions, Emergency Stop /

8 Comments

This entry is part 3 of 16 in the series Emergency Stop

Can emergency stop devices that a prone to unintended operation be guarded? Find out!

17 July, 2010

Interlocked gate testing

by Doug Nix

in Asides, Guards and Guarding, Interlocks /

5 Comments

Did you know that interlocked gates require stopping performance testing?

Machinery needs to be able to stop in the time it takes a person to open the guard and reach the hazard. If the distance from the guard opening to the hazard is short enough that a person can reach the danger point before the hazard can be controlled, the guard is useless. The resulting situation may be worse