Siemens S7-414F

[seanatkinson]

Hello all,
For a safety critical application (SIL 2, possibly SIL3) Siemens have suggested S7-414F. Is there some experience in the group in using this PLC

 

[Mike6158]

Just curious- what are you working with that requires SIL2 or SIL3? I have just ordered the add-on packages for Step 7 Professional that are required to work with the 414-FH. The 414-FH is NOT a friendly package to use.

 

[seanatkinson]

Process safety interlocks, e.g. No addition to batch reactors unless agitiation is adequate, Safety interlocks on headers to incinerator, machine safety related to crushers, bag loaders, tippers etc. These are mainly SIL1 with some SIL 2. SIL 3 is not part of the current situation but I would like to be prepared for it if it arises in the near future.

 

[Mike6158]

Thanks for the response. I work in the gas processing / pipeline industry and other than the occasional boiler or fired heater we rarely see the need for using a PLC or other electronic device for our SIS applications. Ie we typically do it all with hardwired safety relays. Your situation is obviously different and I am not trying to suggest that you do the same. My question was based purely on personal interest in other industries and how they "do things".

One of the problems that we have (as I see it anyway) is that our company has not taken the time to define the criteria for SIL1 or SIL2. For that matter there are not many of us that even understand what an SIS or SIL level is (to clarify something- Our parent owns a high percentage of the nuclear power plants in this country. I feel quite sure that they completely understand the terms and properly implement their SIS designs. Unfortunately (or possible fortunately) we do not get the benefit of trickle down engineering. Based on a risk ranking example (qualitative) that is given in the book Safety Shutdown Systems: Design, Analysis, and Justification we would not require greater than SIL2 and even that would be rare. 99% of the time the risk ranking qualitative example would yield an answer of "no SIS required". However, unless we define our own criteria I don't see how, even though we sometimes do, we can ever correctly make the determination that one of our process's is SILX.

Sorry for cluttering your post with my corporate dirty laundry and thanks again for responding.

 

[seanatkinson]

Mike, It's always interesting to see how others solve very similar problems in novel ways. For some extra guidance about mixing SILs into the petroleum industry there are 2 excellent documents from the Norwegian Oil Industry, (in english). I dont recall the web links for download but if you reply offline to sean.atkinson@roche.com I can send the PDFs to you.