Psdi

I would like to bring this subject back up, has been 4 years since there was a thread.

I read through it and the consensus was if the light curtain fails the machine is unsafe, which I do agree, but if you are using a light curtain for protection, PSDI or not that statement is true.

It was brought up that a light curtain may fail to detect a person if that is the case PSDI will not activate the machine, and due to the mandatory timeout of PSDI will shut the machine down (or apply brakes, whatever the proper interlock is.) Many applications of PSDI do require a second sensor somewhere to ensure safety.

A thought of mine is redundant light curtains.

I am not saying it is right, in many cases it is just wrong (and illegal) I would just like to bring up the conversation again.

http://www.plctalk.net/qanda/showthread.php?t=64385&highlight=PSDI

By the way this is the thread I refer to.

OSHA CFR 1910.217(h) speaks to using PSDI on mechanical power presses. It states that PSDI is prohibited on full revolution power presses, and sets the conditions under which PSDI may be used on part revolution power presses.

I've not seen anything from OSHA that prohibits PSDI on other types of machines. There's been some back and forth at my location on having a single set of light curtains used as both the protection device and the PSDI device. Some seem to think that using the light curtain as the PSDI device negates the safety function of the light curtain. I've found nothing to support this.

There's good information out there regarding PSDI and its implementation. Check out Rockford Systems, and also check with the manufacturer of your light curtains, as I know some manufacturers expressly state that their curtains are not to be used as a PSDI device.

https://www.delphisuppliers.com/vendor_documents/delphi-a/ems_reqs_for_ehsim/Archived_Documents/DA-2101_PSDI_Using_Light_Curtains_Revision_1.4_25SE06.pdf

I have been reading heavily into it, I was looking more for peoples opinions and experiences hoping to find a range of views on it, I know the method is used so I would like to hear the opinions of people with first hand knowledge of it. I understand and respect the opinion of people who say absolutely not ( like most of the posters in linked thread) but there is always two sides to every coin. Some of the comments in that post were not very helpful some of there premise's was that the PSDI would just be thrown in there with out a safety evaluation, which in that case I agree you should not do it, however if that is how you approach any project it is probably the wrong line of work.

But yeah that OSHA rule only pertains to that type of press. I have read it through and have it sitting on my desk. The ANSI standard B11.2 is supposed to have the information regarding the setup of the system, I am just trying to find out if we have it somewhere here at the plant before I go and buy it from the site.