I recently had a discussion with a colleague who wanted to know if it was OK for a design to include a form C relay in an e‑stop circuit. You might recall that e‑stop functions are required to meet at least PLc/SIL1 requirements [1], [2]. It’s important to remember that PLc/SIL1 can be met using Category 1, 2, or 3 architectures.…
EU Machinery Directive Public Review
If you ship machinery products to the EU the Machinery Directive affects you. You have a chance to contribute to the review of this document.
Read MoreForce and injury — How hard is too hard? ISO 21260 will help
Force represents the mechanical energy that causes injury to the human body. ISO/TC 199 has been working on answering that question since 2012.
Read MoreInstructions for Use – the New ISO 20607
Instructions are one of the basic items that users expect to get when they purchase a product, and yet these important documents are often poorly written, badly translated, and incomplete. Key product features are badly described, and information on features, settings and hazards may be absent. All of this despite the fact that the minimum requirements…
Read MoreMore E‑Stop Questions
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 are three primary sources for the requirements for emergency stop devices: [1] Safety of machinery — Emergency stop — Principles for design, 3rd Edition. ISO 13850. 2015. [2] Safety of…
Read MoreCan Emergency Stop be used as an “on/off” control?
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 a recent exchange, I thought I would share the reasons for why this is such a bad idea. The short answer The short answer is an unequivocal NO. Don’t…
Read MoreIntroduction to Functional Safety Seminars
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. I am collaborating with the IEEE Product Safety Engineering Society’s Virtual Chapter to provide a series of three 35 minute seminars discussing the fundamentals of functional safety. The…
Read More1,000,000
1,000,000 views! Today marks a fantastic milestone for the Machinery Safety 101 blog – 1,000,000 views! When I started writing this blog back in October 2008, I had high hopes that a few dozens, or perhaps as many as 1 000 people would find my articles interesting enough to spend some time reading. Never in my wildest imaginings did I think…
Do-It-Yourself Safety Labels, Signs and Tags
One of the great challenges that all product designers face is the sourcing of appropriate product safety labels. There are many sources for off-the-shelf labels including some of the biggest names in marking and labelling, but until now, none have offered a way for product manufacturers to develop standards-compliant hazard warning signs and labels themselves. If…
Read MoreEmergency Stop Pull-Cords
This article was updated 2019-04-26, adding specific details related to IEC 60947 – 5‑5. 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 common emergency stop device is the pull-cord, and like the light-curtain in safeguarding…
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