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…
Read MoreTesting Emergency Stop Systems
Updated 2020-10-31. DN I’ve had a number of questions from readers regarding testing of emergency stop systems, and particularly with the frequency of testing. I addressed the types of tests that might…
Read MoreCSA Z432 Safeguarding of Machinery – 3rd Edition
If you build machinery for the Canadian market, or if you modify equipment in Canadian workplaces, you will be familiar with CSA Z432, Safeguarding of Machinery. This standard has been…
Read MoreEmergency stop devices: the risks of installer liability
On the MachineBuilding.net blog today, Alex D’Arcy, Sales Director at Hylec-APL provides some interesting insights into the liabilities associated with the installation of emergency stop devices on machinery. Hylec-APL provides technical…
Read MoreInterlock Architectures – Pt. 5: Category 4 – Control Reliable
Ed. note: I’ve made a few updates to this article since it was first published in 2011, with the most recent on 2020-05-11. – DN – The most reliable of the five…
Read MoreInterlock Architectures – Pt. 4: Category 3 – Control Reliable

This post was updated on 2020-03-28. Category 3 system architecture is the first category that could be considered to have similarity to “Control Reliable” circuits or systems as was defined in…
Read MoreNew contact block design for Emergency Stop devices from Siemens
One issue that frequently comes up when inspecting machinery is the contact blocks used on emergency stop devices. Until now, e‑stop devices were normally fitted with the same contact blocks…
Read MoreUpdates to Popular Articles
We’ve recently updated a couple of our popular articles! Check them out! Busting Emergency Stop Myths Reader Question: Multiple E‑Stops and Resets
Reader Question: Multiple E‑Stops and Resets
I had an interesting question come in from a reader today that is relevant to many situations: “When you have multiple E‑Stop buttons I have often gotten into an argument that says…
Read MoreUnderstanding the 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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