Hi Doug and Brian:
I thought I would offer my (radical) point of view on the issue of “speed of moving parts.” Consider moving aluminum foil and moving aluminum block, both at the same speed. The aluminum foil has very little mass, while the aluminum block has relatively high mass. The foil is not likely to cause injury, while the block may cause injury. Consider an aluminum needle and an aluminum block, both having the same speed and mass. The needle is likely to cause injury, while the block is not likely to cause injury. Consider the time of contact with a moving part. If the time is long, then injury is not likely. If the time is short, then injury is likely. So, in addition to speed, we must consider mass of the block, contact area, and duration of the contact in predicting injury. In other words, energy per area (mv2 per area in this case) whether mechanical, thermal, radiant, chemical, or electrical, transferred to a body part for a (usually short) period of time, causes injury. The same energy magnitude transferred over a long period of time is not likely to cause injury. An injury occurs only when energy per contact area of sufficient magnitude and duration is imparted to a body part. Both the safety science article and the IRSST paper discuss energy of moving parts and area, but do not address the other parameters. Both introduce (to me) the concept of “force” on various body parts. I’m not sure of how this fits into this safety discussion. Consideration of speed alone is over-simplification. Best regards, Rich From: Doug Nix <d...@ieee.org> Sent: Monday, January 22, 2024 11:16 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Reduce Speed of Moving Part to Reduce Risk Hi Brian, In the machinery sector, 250 mm/s has long been used as the threshold for avoidability. This figure comes from the robot standards and has been used for about 30 years. Studies done at the Polytechnique de Montréal [1] and IRSST [2] have shown that a speed closer to 140 mm/s is more universally avoidable by people working in various environments, but the long use of 250 mm/s has entrenched that higher speed. Related to that is the IRSST’s Repoer R-956. I’ve attached copies of these documents for you. You can find the 250 mm/s number quoted in most machinery safety standards where reduced speed is considered for risk reduction. The origin is in ANSI/RIA R15.06 1992, which made its way into CSA Z434 and then eventually to ISO 10218. [1] Y. Chinniah, B. Aucourt, and R. Bourbonnière, “Study of Machine Safety for Reduced-Speed or Reduced-Force Work R-956,” IRRST - Institut de recherche Robert-Sauvé en santé et en sécurité du travail, Montreal, 2017. [2] Y. Chinniah, B. Aucourt, and R. Bourbonnière, “Safety of industrial machinery in reduced risk conditions,” Safety Science, vol. 93, pp. 152–161, Mar. 2017, doi: 10.1016/j.ssci.2016.12.002. Best regards, Doug Nix d...@ieee.org <mailto:d...@ieee.org> +1 (519) 729-5704 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to EMC-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
