Machinery Safety 101

The Third Level of the Hierarchy: Information for Use

Doug Nix — Mon, 16 Jan 2012 21:06:56 +0000

I’ve written about the Hierarchy of Controls in past posts, but I’ve focused on the ‘engineering’ side of the control equation: Physical changes to machine design to eliminate hazards, and mechanical or electrical control systems that can reduce risk. The …

31-Dec-2011 — Are YOU ready?

Doug Nix — Fri, 30 Dec 2011 17:59:20 +0000

31-December-2011 marks a key milestone for machine builders marketing their products in the European Union, the EEA and many of the Candidate States. Functional Safety takes a positive step forward with the mandatory application of EN ISO 13849–1 and –2. …

Why I wear a Poppy on 11-Nov

Doug Nix — Fri, 11 Nov 2011 13:44:13 +0000

In a recent article in the Independent, Robert Fisk writes that the poppy has become nothing more than a fashion statement in the UK. Merely a way to show that you are British, or to score points with the boss, …

Inconsistencies in ISO 13849–1:2006

Doug Nix — Thu, 10 Nov 2011 13:30:02 +0000

I’ve written quite a bit recently on the topic of circuit architectures under ISO 13849–1, and one of my readers noticed an inconsistency between the text of the standard and Figure 5, the diagram that shows how the categories can …

Bye, Steve. Thanks for everything!

Doug Nix — Thu, 06 Oct 2011 14:07:20 +0000

Today marks a turning point for me. With the loss of Steve Jobs, the world is a lesser place. His brilliance, vision and charisma changed the world for the better in so many ways. As anyone who knows me well …

Standards in Music

Doug Nix — Wed, 05 Oct 2011 12:30:37 +0000

Working in a field that is standards heavy, I often get questions from clients and students about the origin of standards. Recently I heard a discussion on CBC radio talking about the origins of musical notation, and I realized that …

Interlock Architectures Pt. 6 — Comparing North American and International Systems

Doug Nix — Mon, 03 Oct 2011 12:30:09 +0000

I’ve now written six posts, including this one, on the topic of circuit architectures for the safety–related parts of control systems. In this post, we’ll compare the International and North American systems. This comparison is not intended to draw conclusions …

How Risk Assessment Fails—Again. This time at DuPont.

Doug Nix — Tue, 27 Sep 2011 14:43:12 +0000

A recent report released by the US Chemical Safety Board (CSB) looks at a series of accidents that occurred over a 33-hour period on January 22 and 23, 2010 at the DuPont Corporation’s Belle, West Virginia, chemical manufacturing plant. A number …

Interlock Architectures – Pt. 5: Category 4 — Control Reliable

Doug Nix — Mon, 26 Sep 2011 12:30:41 +0000

The most reliable of the five system architectures, Category 4 is the only architecture that uses multiple-fault tolerant techniques to help ensure that component failures do not result in an unacceptable exposure to risk. This post will delve into the …

What did TEPCO know about Fukushima before 11-Mar-11?

Doug Nix — Thu, 22 Sep 2011 14:31:05 +0000

I recently had a colleague point out an interesting paper published in the “Bulletin of the Atomic Scientists” about the level of knowledge that existed between the start of construction of the Fukushima Daiichi nuclear plant and the devastating tsunami …