All valid points; however, I was taking my information from the established ISO/IEC standards for machinery, with which I am familiar. I do recall another standrd some years ago, mentioning contact surface area when I was looking into finger crush as well as sharp edges. And the original question was solely about speed, so that's how I responded.
All the best, ~ Doug Douglas E Powell Laporte, Colorado, USA [email protected] LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/> (UTC-06:00, US-MDT) On Mon, Jan 29, 2024 at 4:41 PM Richard Nute <[email protected]> wrote: > > > 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 <[email protected]> > *Sent:* Monday, January 22, 2024 11:16 AM > *To:* [email protected] > *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 > > [email protected] > > +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 > [email protected] > All emc-pstc postings are archived and searchable on the web at: > https://www.mail-archive.com/[email protected]/ > > Website: https://ewh.ieee.org/soc/pses/ > Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to > unsubscribe) <https://ewh.ieee.org/soc/pses/list.html> > List rules: https://ewh.ieee.org/soc/pses/listrules.html > > For help, send mail to the list administrators: > Mike Sherman at: [email protected] > Rick Linford at: [email protected] > > For policy questions, send mail to: > Jim Bacher at: [email protected] > ------------------------------ > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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