Please see test below: “Safety Interlocks [21 CFR 1020.40(c)(4)(i)]:Each door of a cabinet x-ray system shall have a minimum of two safety interlocks. One, but not both of the required interlocks shall be such that door opening results in physical disconnection of the energy supply circuit to the high-voltage generator, and such disconnection shall not be dependent upon any moving part other than the door. [Note: Safety interlock is defined in 21 CFR 1020.40(b)(11).]
The primary door interlock should be of conventional design. The second door interlock must physically disconnect the energy supply circuit to the high voltage generator. Physical disconnection means opening the energy supply circuit by removing a piece of the circuit. This is usually accomplished with a ‘knife-edge and finger stock’ or ‘plug and socket’ type connection. It is good practice to assure the primary interlock will remove power from the energy supply circuit before the physical disconnection occurs. Relays, micro switches, and ‘safety switches’ all contain moving parts and, therefore, cannot be used to satisfy the requirement that the physical disconnect interlock is "not dependent on any moving part other than the door."” Compliance Guide for Cabinet X-Ray Systems https://www.fda.gov/MedicalDevices/ucm094358.htm Mark From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Tuesday, February 5, 2019 12:31 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] A question about FDA language and interlocking devices That seems to make more sense. I don’t know anything about X-ray requirements but the FDA requirements laser interlocks are not specific, only referring to “interlocks”. -Dave From: MIKE SHERMAN [mailto:msherma...@comcast.net] Sent: Tuesday, February 05, 2019 12:27 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] A question about FDA language and interlocking devices Doug -- "knife-edge and finger stock" sounds more like the gasketing around the door to keep the radiation inside. I think you'll find similar gasketing on doors to EMC chambers. I've not heard of this term applied to interlock switches. Mike Sherman Graco Inc. On February 5, 2019 at 10:35 AM Doug Nix <d...@ieee.org<mailto:d...@ieee.org>> wrote: Colleagues, I had a question come my way yesterday that I need a little help with. Here’s the question: I have a customer that produces X-ray equipment. The FDA requires that the door that gives access to the X-ray source must have an interlock with a ‘knife-edge and finger stock’ type connection. Also the FDA mentions that interlocks should be of conventional design. What is understood by “conventional design”? My reading on this requirement is that any conventional electromechanical interlocking device like this: [Image result for keyed interlock switch images] will meet the basic requirements as described by the FDA as “knife-edge and fingerstock” connection, but I am concerned that this may not be at all what is meant. As always, any guidance you can offer will be welcomed and appreciated! Best, 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. 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