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?

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?

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!

Can anyone share their experience? Very practical two questions related to an issue which exists in many PFDavg calculations. What's your approach to a safety loop that includes typical electrical final elements, e.g. contactors? Although the IEC61508 and IEC61511 standards apply to electrical devices, many such solutions widely used in industry lack certification and reliability data. And if the data is available, it's usually related to PFH and is based on B10d - not well suitable for demand mode of operation calculations. Second one: how do you confirm their systematic capability?

Dear All, Long time i don't post. I am back with my planning to verify my SIL achievement of logic solver. I am using ABB AC800M HI (SIL3 capable), and has 1oo2D architecture where both CPU & Safety Module (diverse with the CPU) is executing logic simultaneously and have cross diagnostic feature. I saw exida 8 variables of PFDavg is describing in 1oo1 architecture only, and i know that exida uses Markov Process (continuous markov) for modelling. I want to verify my SIL achievement use the same method, however i have 1oo2D architecture not 1oo1 and i need to consider the beta factor as well in my equation. Any of you have the literature to derive the PFDavg from markov process? I have discussed with AI as well and it can show me how to do from addressing the states and kormogolov differential equation, but i'm not entirely sure, i know you all may have experience regarding this matter, if you can please give me the flowchart how to do or to share some whitepaper of this matter, i may need some actual literature to back me up of my calculation later.