I would like to present a very common analytical scenario for discussion. It's related to a hazardous scenario which requires us to cut off the flow of the process medium to a some part of the installation. This is achieved by shutting down the pump. However, the system comprises two pumps (A and B) where one is in operation and the other in a standby mode. When verifying SIL, should we assume a single SIF with a 2oo2 configuration for the pump shutdown, or should we analyze two separate functions, each responsible for shutting down an individual pump?

I’ve always been interested in the management side of functional safety rather than the calculations. If you’re currently managing functional safety on a project, what is the one thing that causes you the most frustration? Don’t give me the textbook answer — tell me what actually annoys you. What do you find yourself repeatedly chasing, checking, updating or worrying about? I’m looking at ways we could make the management of functional safety significantly easier, so I’d really value some real-world examples from the group. Even if it seems like a small problem, put it below. 👇

I'll hold my hands up: I've been quiet in here for longer than I would have liked. Project work took over, and the community hasn't had the attention it deserves. That's changing from this week. Here's what's coming: - Decision Review Live is back — Friday 17th July, 6pm. Bring a real grey-area decision from a live project and we'll work through it together. - A new cohort of the nuclear programme opens in September — more on that shortly. - Q&A is coming back, running bi-weekly. - New SILVerify features are in development and will be live soon. - More case studies and guides on the way. Got a question sitting in your drafts? Post it, and let the community do its thing.

Good morning Everyone, For valve SIL calculations, do we need to include the failure rates of all valve components, such as the solenoid, actuator, and valve body? Should the actuator and valve body also be included?

Good day everyone, I have few questions on SIL Calculation. I have a PILZ controller in SIF and try to make some calculation by hand. Controller has DI and DO with CPU. 1. If I would like to calculate PFDavg for Controller then I should combine DI, DO and CPU PFD avarage, correct? (No redundancy at DIs and DOs) For ex, PFD input, single + PFD output, single+ PFD CPU = 2,20 x 10^-4 + 1,30 x 10^-5 + 6,20 x 10^-5 (See please certificate) 2. As you see the certificate shows only PFD but not λ DU. Can I calculate my λDU from PFD as referencing the formula below? PFDavg = (λDU * T)/2 . Actually, the certificate does not say what T has been taken into account on PFD calculation as well, but I am going to take it as 1 year. 3. CPU Part: 773103 ( PNOZ m1p ETH) ; Certificate Link: https://www.pilz.com/download/open/PNOZmulti_TUEV-Sued_BM_M6A-020132-0284-R01_R4_4_valid_2030-Jun-24_1002803-BM-34.pdf Thank you!